C4 corvette high idle. My MPG hovers from 15 - 17 City and 18 - 20 Highway.

Jul 30, 2009 · C4 Tech/Performance - 1989 Corvette unexplainable high idle problems - I will get this blasted Vette figured out yet. Apr 6, 2006 · Start by cleaning out your throttle body (TB) and Idle Air Controller motor (IAC). Idle speed in NEUTRAL or PARK is less significant, and will be higher. 04 a can at NAPA. Sometime when I really get on it and come to a stop its around 2000 or 3000 RPM. Any attempt to change the idle speed without reprogramming, is going to mess up your minimum air adjustment setting. The idle speed is burned into and controlled by the computer through the IAC, based on various conditions. New IAC results in high idle? Jump to Latest 3K views 3 Dec 20, 2012 · C4 Tech/Performance - 1986 high idle - The car had a very high and surging idle. I have restored my 84 100%, additionally I have built a 383 stroker with all the goodies. Where to Start if There’s No Code. What Aug 21, 2007 · There is no idle speed adjustment for your car. I have a high idle on my 1984 rebuilt 350 engine, seems my iac,s are staying open ,car was running fine until I put the air cleaner housing back on I put my fingers over the iac ports and it seemed to idle down. My MPG hovers from 15 - 17 City and 18 - 20 Highway. My main problem is the car has an extremely high idle. At startup it will be at about 1000 rpms. I replaced the IAC's, coolant temp sensor and the high Feb 26, 2011 · C4 Tech/Performance - Hard start and high idle - This is becoming more frequent with my 85, and it used to only happen every once in awhile. Followed the forum's advice and replaced the IAC, cleaned the throttle body and set IAC according to the manual. 2 miles. Once warmed up, the idle drops to around 600 in D. Jul 18, 2024 · Reasons for a Rough Idle or High RPM. 1989 c4 L98 Idle jumps to 2400 to 2800 at start up and then goes down to 600 to 800 after 20 to 30 seconds. The motor not stock it a mild build it has a chip for the mods. anybody figure out what causes this problem? IAC and TPS are working right, TPS is . C4 Corvette. Mar 5, 2022 · FIXING THE IDLE ON MY C4 CORVETTE!! Thank you all for tuning in to another video! SIGN THE RPM ACT TO HELP SAVE OUR RACECARS!! more. When I shift into drive, the car does a heavy jerk forward and I usually have my foot on the brakes because when i shift into Nov 4, 2019 · C4 Tech/Performance - Stuck on high idle problem - '84 - Hi, I have an '84 Corvette and up until recently, it's been running very well although I haven't driven it much in the past year. This happens. The problem Apr 11, 2005 · C4 General Discussion - High idle problem on my 86 - I'm asking for advice on solving the mystery behind my cars high idle problem. following this accurately will point you in the direction of where your high idle is caused. to 30mph). Apr 21, 2010 · Adjust your Early C4 TPS and Idle Speed by Lars Grimsrud SVE Automotive Restoration Musclecar, Collector & Exotic Auto Repair & Restoration Broomfield, CO Rev. I stumbled upon this site that says how to reset the idle speed. Jun 13, 2007 · C4 Corvettes, 1984 - 1996. Runs fine. No Codes. Even when its warm and I take it out and its completely warm it still idles high usually if I put it in park and tap the gas Oct 23, 2020 · C4 Tech/Performance - High Idle at start up - Brand new to this forum. Jump to Latest 2K My car just started to idle high about 1200 rpms in park Mar 28, 2010 · C4 Tech/Performance - High idle at startup - When I start the car it shoots up to 12-1600 rpms and then starts dropping to normal after a couple of seconds. The car starts fine but idles at close to 1500rpm. Aug 30, 2019 · If you own a Chevy Corvette and it's idling rough, you may be feeling frustrated. Start engine. When I looked his car over, I noticed a high idle even when warm (1100rpm). any ideas of what to look at. Turn engine off, start engine again. After sitting awhile at stop light it will drop slightly to about 900 RPM. I replaced the TPS, code went away but the idle issue continued. It had other idle issues besides this one (would not stay running when cold) but I think I tracked most of that down Oct 29, 2023 · C4 Tech/Performance - Idle too high! - Hello, I own a 1984 c4 corvette. I got an ALDL cable to check Sep 14, 2012 · New BBK 58ml has higher idle every thing done right but have to kick gas pedal down to bring rpms down 1988 corvette feels like your on crusie control driving,:smack anyone have this problem putting new 58 twin throttle body in? Thanks Mr. Is this normal or should I see a higher idle while warming up?? Apr 19, 2011 · C4 Tech/Performance - 1984 corvette idle problem - PART 2 - Hello again, I am still having trouble lowering my idle speed on my 84 vette. Can misfires at idle. Reset IAC motors (drive veh. I removed the throttle body and i cleaned it. Car starts fine. I have a 1984 Corvette with Crossfire, about 75k miles on it. When the fourth generation Corvette was introduced in 1984, many innovative build techniques were implemented. At start-up, idle is at 1500-1800 RPM and won't slow down. Today I was driving and wanted to give it Sep 9, 2018 · If everything else is working correctly, i. So I replaced the ECM temp sensor and both idle control valves. Two days later I went to crank it and I noticed it was idling really high, around 4300 rpm!!!! I noticed the upper intake manifold gasket had folded Apr 17, 2023 · C4 Corvettes, 1984 - 1996. [CSM, 1984, 6C14-2] Dec 30, 2023 · You will need to follow the minimum idle adjustment procedure for a c4. I put new gaskets and a new TPS. Sep 18, 2003 · C4 ZR-1 Discussion - high idle 90 zr1 - Mycar is idling at 2000rpms after driving2 blocks and it stays there until i shut it off. 791 @ 98MPH K&N Air Filter w/ Opened Air Box, Hedman LT Headers, Borla ProXS Mufflers, Polished SS LT1 Tips, AIR Delete Aug 7, 2011 · 1990 vert 6 speed manual with 72K, no mods except for a cut air lid. The idle speed of the car was always around 1000/1100 rpm, I thought the Idle Valve Control was malfunctioning, so I replaced it. All of the old plugs looked clean. Apr 3, 2016 · C4 Tech/Performance - Another LT1 High Idle issue - Hello all, I have a 92 LT1. Re-connect the electrical connector onto the IAC. At least I think it is my first car like this. Apr 13, 2024 · Spray some starter fluid around the gaskets of the runners to plenum, throttle body to plenum and plenum to lower Intake manifold and see if idle spikes. Of course Aug 14, 2011 · C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine 1994 high idle problem 1994 high idle problem. I followed the procedure indicated by the official Sep 9, 2018 · If everything else is working correctly, i. These steps apply specifically to the 1985 model year, and in general to other years. I double and triple checked the Mar 11, 2023 · C4 Tech/Performance - 84 high idle - Hi Forum gang, I need some help. The throttle bodies are known for causing "wandering" idle problems because of excessive housing wear where the throttle shaft goes in them. C4 Tech/Performance - Help me with my LT1 high idle, out of ideas - Back story: I bought a 92 in July and have been slowly bringing it back to working order. It idles up to 1600 rpm maybe slowing to 1100. My mechanic tested the oil pressure manually at 18 psi at idle when hot. I had the car Mar 20, 2021 · C4 General Discussion - 1984 cross fire high idle issues - I have a 84 cross fire that idles way to high. Your high idle speeds are caused by a vacuum leak. Nov 29, 2012 · C4 Tech/Performance - '95 LT1 Corvette - High Idle - Odd week with this car. Pushed down on throttle linkage and the idle went perfect. Cold start at temps in the 30*f idle was only 975rpmit drops to 550 when fully warm. i first thought throttle cable but it isnt. Jan 14, 2008 · C4 Tech/Performance - High Idle problem - I have a problem of High Idle on my 88' TPI C4. The car Mar 27, 2012 · C4 Tech/Performance - LT4 High Idle Problem - Ok car runs fine otherwise no performance issues or CEL. replaced plugs and wires, fuel pressure is in check, replaced iac valve and Aug 30, 2019 · Here are the most common problems that would cause a Chevy Corvette to idle rough. RACE ON!!! Feb 22, 2012 · C4 Tech/Performance - High idle? - Well today temps were in the high 30*f and i decided to start the vette. Could the Nov 3, 2018 · C4 Tech/Performance - high idle at start - my 85 will idle at 1500 to 1900 when first started i can turn it off and restart it will idle around 800 i doesnt matter the temp doesnt do it every time some time it will crank at about 1100 then drop to 750 when warm thanks for any help Apr 11, 2011 · See this thread from the C4 Sticky for further on setting minimum idle. Put it back together. Test the fuel pressure. It is an awesome ride and I'm enjoying being the owner of a Corvette. Jan 3, 2023 · Metal oxidizes. Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette. i did go through the readjustment process of the accelerator screw, because the previous Mar 15, 2010 · C4 Tech/Performance - 1984 Crossfire - Fast Idle - I have a 1984 Crossfire. I checked the timing and it is set to 6 BTC at idle. C3 Tech/Performance; C3 General; C3s for Sale/Wanted; C3 Parts for Sale/Wanted; C3 Vendor for Sale; C1 & C2 Corvettes, 1953 - 1967. Jul 13, 2006 · This tech paper will discuss the procedure for correct adjustment of the Minimum Idle Speed and for adjustment of the Throttle Position Switch (TPS) on the early C4 Corvette TPI systems. It doesn't change during while driving, it will maintain 1800-2000 rpm with no load. Both TBI's were re-built as part of a complete overhaul. Oct 14, 2008 · C-4 having same issue I cleaned my MAP sensor and throttle body after runing the car about 45 min on hwy and coming to a stop at a light the vehicle will idle high about 2k and then within 5 to 7 secs go down then back up again the car seems to run fine on hwy but at 50-70 mph I step all the way on the gas the car will hesitate and not give full power Sep 24, 2006 · well, I believe that it's still a great car! Anyway, I've done so much to try and improve this idle. Car has 82k and runs great but seems to have dropped in gas mileage and I just failed CT emissions. High idle. Apr 14, 2019 · C4 Tech/Performance - 1987 Corvette Surging Idle, No Response to Throttle, and Idling High in Park. So I was thinking, since the IAC is located under plenum, can I buy a Whether starting the engine warm or cold, it jumps up to 1300-1400 rpm and will take a very long time (several minutes )to come down. When cover tI have 1984 C4 with Crossfire. timing, no vac or exhaust leaks, all cylinders firing correctly, O2 sensor feedback, then the IAC is the only part on the car that controls the idle speed once it's warmed up. Previous owner replaced the O2 sensor after changing to Jul 6, 2016 · C4 Tech/Performance - High idle - 1800-2000 rpm - Took my plenum and runners off to fix what i thought was a small vacuum leak and when i put it back together i get 2000 RPM the second the car starts. Apr 24, 2011 · Here's the procedure for the C68 HVAC #6 is engine rpm/25. Sep 9, 2018 · If everything else is working correctly, i. Idle speed should be governed by the ECM at approximately 600-650 rpm in "DRIVE" (for unmodified cars). Idle was high. 1) Bad Jun 20, 2007 · C4 Tech/Performance - high idle - Everytime now that I come to a stop my car is idling at around 1300 - 1500 RPM. I replaced the water pump, opti, plugs and wires. Plug back the IAC, car starts at right idle speed. temp has been running very low 50 degrees because my cooling fan is running constant due to a bypassed temp sensor , but Aug 30, 2019 · Here are the most common problems that would cause a Chevy Corvette to idle rough. im not getting any code on the scanner. Suddenly experienced a high idle, between 2000 and 2200! Have replaced idle air control valve, cleaned throttle body and checked for vac leaks and there's nothing apparent. Usually happens when engine is cold. May 18, 2008 · C4 General Discussion - High Idle on 84 Crossfire - Some thoughts on a sometime high idle on my 84 Crossfire. Install air cleaner. what could possibly cause this?? Jul 30, 2016 · C4 Tech/Performance - High Idle once warm - 1995 6 sp. 1993 was the worst year for Corvette for wire and this car is what inspired GM to create GMLAN and network ECU's together so as to save on wiring redundancies. . C4 Tech/Performance; C4 General Discussion; C4 ZR-1 Discussion; C4s for Sale/Wanted; C4 Parts for Sale/Wanted; C4 Vendor for Sale; C3 Corvettes, 1968 - 1982. Like. The car was sitting in a garage for about 2 years with 80000 miles. Early Corvette amenities were becoming standa Oct 14, 2020 · C4 Tech/Performance - High idle on 1984 - Hello, I am new to the forum and just bought a 1984 with a 4+3 trans. Although sometimes when I hit the accelerator pedal it will bring the idle back down. ive been checking for vacuum leaks, but cant seem to successfully find any. C4 Corvette Status Not open for further replies. What or where should I begin to look. My idle was rolling and kept stalling at lights. it would stick at about 1200 rmps then i would hit the gas and it would settle down. Jun 6, 2023 · C4 Tech/Performance - Low oil pressure at idle - I am new at the Forum, although I have owned a 1989 C4 for 12 years. Sep 15, 2013 · C4 Tech/Performance - Normal idle for a '93?? - Every since I've owned my '93 (about 7 years and 44K to now 93K miles), it has exhibited what I'd consider a high idle. around 1500 and after a minute or two it raises up to 1800. I’ve replaced the TPS, IAC (already did the process), Cap and Rotor, new spark plugs and wires, rebuilt Apr 13, 2024 · Spray some starter fluid around the gaskets of the runners to plenum, throttle body to plenum and plenum to lower Intake manifold and see if idle spikes. Shortly after, I find my idle now is running about 1600-1700 RPM - for no Aug 17, 2004 · C4 Tech/Performance - random high idle - just yesterday i was getting a random high idle. I did mine last weekend and it cured both my high idle problem and my stumble during cold start-ups. Full throttle acceleration Nov 7, 2001 · C4 ZR-1 Discussion - High Idle Problem on my 90 ZR-1 - This high idle problem is present on my ZR-1. It ran great but idles a bit fast. Started out and continues to be a high idle issue, 1100-1900. Mar 10, 2011 · I dont have any vacume leaks the base Idle is set at 450 RPM's the Normal timiming set a 6 advance. I drop down to ~1000rpm after warm up. Feb 26, 2012 · C3 Tech/Performance - High Idle? - Hey all my 79 L82 has an abnormal idle. Feb 1, 2020 · C4 Tech/Performance - 1992 corvette high RPM at idle issue - HI everyone, i been having issues with high rpm at idle. Apr 30, 2008 · C4 Corvette Forums. What I noticed there was hardly a high idle. Scary to me as I am old school carburetor guy. Stock. I dont remember the motor doing this before the rebuild from stock motor. When it first cranking it ran smooth until it tried to settle down to an idle. Apr 11, 2015 · hello im new to this great forum, hoping to find some answers. C8 Corvette. IAC valve has been checked and looks new/clean. Dec 30, 2023 · You will need to follow the minimum idle adjustment procedure for a c4. What an Engine Needs to Feb 1, 2005 · Remove idle air passage plugs and reconnect IAC valves. I think that is wrong. I knew the car was idling fast when I test drove it but figured it was an easy adjustment--I was wrong. Gone but never forgotten. My car jumps between 500 - 600 rpm when in drive (automatic) and the engine is up to normal temps. The PCM will adjust the IAC position for the programmed idle speed (this may take a couple of minutes, the engine may idle low or high initially, and the engine may surge. New 6-15-00 This tech paper will discuss the procedure for correct adjustment of the Minimum Idle Speed and for adjustment of the Throttle Position Switch (TPS) on the early C4 Corvette Mar 17, 2009 · C4 ZR-1 Discussion - High Idle - Email from guess who Got this a while ago It's normal for the LT5 to idle at about 1500 rpm when the speedometer is reading more than 0 MPH. Jan 10, 2005 · C4 Corvette Forums. Aug 19, 2009 · Hello! Long story short, based off a recommendation from a member here, I checked and my idle speed. It kind of surges and goes back normal just sitting there with the brake on, in drive. replaced the injectors, replaced some old brittle vac lines, and this made the car run and idle much better but instead of the 1200 rpm idle it still idles at 900. Then as time went by it went to 1100 rpm. In this article, we'll look at some of the most common causes of a rough idle in the Corvette and how to fix the problem. She's inspected now and running very well with the exception of the idle. I've replaced plugs, wires, battery, alternator, fuel pump, fuel filter, fuel pump relay and "the chip" Dec 28, 2020 · C4 Tech/Performance - 94 high idle and surging - Hi everyone. I would like to lower it to spec (400 rpm). Mar 25, 2005 · 4) Adjust the screw in the throttle body until the idle speed drops to ~500rpm 5) Turn off the engine 6) Reconnect the IAC harness 7) Restart the engine and let idle. It seems to run fine when going do the road just crappy at idle. When cover t Dec 12, 2015 · C4 Tech/Performance - L98 High idle issue - hello i have an 87 L98, the idling is everywhere, it goes really high to high haha, ranges from 1800-1500RPM. May 4, 2017 · C4 Tech/Performance - Code 22/High Idle/Really High Idle - Having a tough time figuring this out. The car recently started showing very low oil pressure 3-4 psi at idle when hot, goes up to 20 or higher when driving. Except, The car now has a hard time holding an idle and usually dies when cold. I finally purchased my 1st corvette at 58 years young. Below are the top causes that a mechanic would look for. But if I blip the throttle the car returns to her normal idle speed. 64V in datamaster. Off idle throttle response is good. luper007 Dec 30, 2023 · You will need to follow the minimum idle adjustment procedure for a c4. The engine should slow down to idle speed a few seconds after the speedometer reads zero. Though it idles smoothly in Drive (600 RPM) and Reverse (600 RPM). I got an ALDL cable to check Apr 13, 2024 · Spray some starter fluid around the gaskets of the runners to plenum, throttle body to plenum and plenum to lower Intake manifold and see if idle spikes. Over the past few months, I've been working to get my father's 1986 Corvette (L98) back on the road. It idles between 1500-2500 rpm but it stats there for quite a long time. So just multiply that number by 25 and it = your engine rpm. Now it's happening just about every time I drive it. I cleaned the MAF and the throttle plates, last year I put in new plugs and wires. Sometimes it will surge a little bit between 1600-2000 rpm. "Alexa" - 1985 Z51 - In memory of the last Corvette Dad owned. So let me just cut to the chase. When cold and initially Sep 10, 2017 · C4 Tech/Performance - Odd, intermittant high idle on my L98 after restart - I've recently noticed/developed an intermittent high idle with my stock '89 after fully warmed and then restarted. When I’m idle, the car sounds too loud and almost like it’s reving itself like it wants to move forwards desperately. Start ENG. When driving it, it is low on power and you feel it missing. I noticed it was idling at 900 rpm. If there’s no trouble code, it can be difficult to determine why your Corvette is running rough. When I take my foot off the accelerator the engine will drop to 1,000 RPM. Also I don't have access to a scan tool at this time. New injectors, IAC's, etc. I replaced the fuel pressure regulator and it fired right up. I can't tell how much as the tac reads high but it's noticably faster than my buddy's 85. C4 Tech/Performance L98 Corvette and LT1 Dec 12, 2007 · I did a test this afternoon. I can reset the timing but do I set the timing with the EST unplugged and the car in Neutral or in park. Sep 25, 2009 · C4 Tech/Performance - 84 Crossfire idle too high ! - Hi guys ! what can be causing my friend's 84 idle to high ? Tomorrow he is coming to visit me and i will ride a 84 for the first time thanks. tps, temp sensor, or IAC. I have no check engine light. Do I have to let the car relearn idle speed (just a long way to get to a place where I can steadily drive 40 mph+ for more than a few seconds). After replacing IAC, drove for twenty minutes to have the computer reset, but no change. I got a good deal on it but it has some issues. Jul 11, 2008 · C4 Corvette Forums. Nov 17, 2002 · C4 Corvettes, 1984 - 1996 Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette. something else that causes the high-idle problem Apr 15, 2018 · C4 General Discussion - High idle - My 1990's idle is probably 1800. Mar 3, 2024 · C4 General Discussion - C4 Idle High - 1990 C4 Corvette, Base Model All of a sudden, about three weeks ago, the following started: 1) I start the car, cold start, it idles normally 2) After a few minutes of first drive, the RPM increases to around 3,000 in drive, stopped at a traffic light 3) When I am finished, Mar 5, 2022 · FIXING THE IDLE ON MY C4 CORVETTE!! Thank you all for tuning in to another video! SIGN THE RPM ACT TO HELP SAVE OUR RACECARS!! more. New throttle bodies, new ecm from EFI, new renegade intake, new injectors and all the sending units The other day took her out for a spin every thing was C4 Corvette Parts Auctions on eBay Corvette Books C4VR In-Stock Apparel & Accessories C4VR Member Name Badges High idle hot (8/8) 1/11/10 6:36am. Then it went to idling about 1300 rpm. Started about a year ago. May 9, 2011 · 86 C4 Corvette - 14. just over 2. Seems a bit high. Started off week with car running really bad. :lookinup: Save Share. Cold start= everything totally normal. A intake manifold leak can cause a high idle. No apparent vacum leaks and already sprayed card cleaner around intake and throttle body with no Feb 7, 2008 · C4 Tech/Performance - 96 LT1 Running Rough at Idle - I have a 96 LT1 that is running rough at idle. Stop ENG when idle has decreased. Great stuff. Verify that the throttle body and MAF are clean. The engine starts and runs well. A few weeks back it threw a code 22. C4 Corvette Feb 10, 2015 · "Bella" - 2002 Z06 - Carrying on family tradition of Corvette ownership. If you don't find any leaks, it could by the idle air control sensor needs replaced on the bottom right of the throttle body, easy rip and replace part. Pulled the IAC connector and leftthe ignition on for about 90 secs. It is not always easy to diagnose the cause because there are so many factors involved here. I Mar 14, 2013 · C4 Tech/Performance - High idle, 90 L98, let's talk IAC - I bought this car last month in NC and drove it home 6hrs. Replaced the coolant temp sensor underneath intake which didn’t change anything. If I disconnect the EST the timing drops to 6 ATC. I was having some hard starting (pouring black smoke) and hesitation issues (but the idle was about 1000 rpms) and so I May 4, 2020 · C4 Tech/Performance - High Idle Help - Good morning, I'm looking for some help with my '90 high idling. Install air cleaner gasket, connect vacuum line to TBI. I thought that I'd take my 86 C-4 out for a drive last weekend after installing new plugs. Jul 21, 2019 · C4 General Discussion - Rough/High Idle Only in Park and Neutral??? - 89’ is idling rough/surges sometimes in Park (800 RPM) and Neutral (800 RPM). Dec 9, 2015 · C4 Tech/Performance - L98 High idle issue - hello i have an 87 L98, the idling is everywhere, it goes really high to high haha, ranges from 1800-1500RPM. The IAC motors are computer controlled and they SHOULD compensate for load changes when they occur. Someone has tried to do alot of work to this car but it is definitely a restoration project and I don't know if it's just something loose or May 1, 2013 · C4 Tech/Performance - 1994 LT1 Corvette With High Idle - Need additional Solutions, HELP!!!! - Hello everyone and thanks for taking the time to read my post :). (Tac is on my list of things to fix) I understand the idle is controled by Sep 19, 2008 · How to Adjust your Early C4 TPS and Idle Speed by Lars Grimsrud This tech paper will discuss the procedure for correct adjustment of the Minimum Idle Speed and for adjustment of the Throttle Position Switch (TPS) on the early C4 Corvette TPI systems. Took it out for a drive and it idled up to almost 2000 and would not come down tapping pedal. In this year 1993 every C4 Corvette came with over 2 miles of wire if you stretched it all out and connected it together. does not matter if car is hot or cold. Hello, I just purchased a 1994 corvette with 69,000 miles on it. Dec 14, 2010 · C4 Tech/Performance - Help me with my LT1 high idle, out of ideas - Back story: I bought a 92 in July and have been slowly bringing it back to working order. It runs great, but after it gets hot, or sits a little bit after running, the idle goes from normal to about 1500 RPM's and goes back to idle. New here and hoping you all can help me with my newly purchased 94 convertible with 174 k on it. Now I cannot get the idle back down to normal. He says that this is a new problem that just showed up. Check TPS voltage and adjust as necessary. I've parked my car for a few months to do some much needed restoration on the interior. C. Dec 10, 2011 · Last year I received an 88 corvette in lieu of profit sharing from my former business partner. Jan 3, 2023 · C4 General Discussion - 1986 L98 - High Idle When Warm /Closed Loop - Hi folks! I'm in desperate need of some help. Nov 10, 2006 · C4 General Discussion - Misfire at IDLE only ? - I purchased a 95, 2 weeks ago. Pulled Feb 15, 2014 · C4 Tech/Performance - 1984 Crossfire has super high idle - I just inherited a 1984 Vette, and am new to this type of engine. I am guessing a little since the tach doesn't work. Problem went away on its on - believe it was bad gas (probably water in fuel) that was resolved when new gas mixed in. Apr 30, 2005 · C4 Tech/Performance - 88 Crazy High Idle Problem! PLEASE Help! - New iac;new egr valve;vacuum looks good, no visual leaks; removed 52mm throttle body and cleaned, opens/closes OK; correct TPS sensor reading; throttle cables look good, -no binding. Now Jun 19, 2011 · Ok, still stalling and rough idle. TPS and Timing are correctly set. Sponsored by: High idle on 82. I changed the IAC valves after doing some research. "Desiree" - 1977 - Wife's car, with an attitude problem. After driving a bit, I notice the Aug 22, 2022 · I have 1984 C4 with Crossfire. May 19, 2014 · C4 Tech/Performance - High IDLE cause? - OK, I have checked all!! I checked the timing and it is set to 6*, I spent almost 1 hour looking for vac leak and got nothing, adjusted TPS to . I am measuring 20-21inHg (on vac gauge) reading from the EGR vac port, My MAP reading corresponds to this in datamaster, my TPS shows 0% at ~. - did a search,will take pics tomorrow May 1, 2013 · C4 Tech/Performance - 1994 LT1 Corvette With High Idle - Need additional Solutions, HELP!!!! - Hello everyone and thanks for taking the time to read my post :). ENG may run high idle until IAC valves clsoe air passages. Idles at around 800 to 900. I Jan 15, 2022 · C4 General Discussion - 1985 Very High Idle Speed (1900 RPM) After Driving 15-20 Miles - I am having a high idle issue on my 85 Z51, 4A. I had set the low idle for the IAC and set TPS. For example, stopping at a red light, car in neutral, idle is at 1300 and will take over a minute to come down to 700-800 rpm. I tried the procedure to set the TBI settings, grounded the ALDL to set the IACs, set the TPS. Jul 12, 2008 · C4 Corvette General Discussion 1986 Idle Problem. I have set the timing to 6* and the car runs nice, no codes, but my idle when warm is around ~1900 RPM. Starts and idles OK at 800 rpm, but once I depress the gas all hell Nov 15, 2011 · Once the idle RPM is set, place the transmission in PARK and turn off the engine. Aug 2, 2011 · C4 Tech/Performance - Extremely high Idle RPM - A couple weeks ago I had trouble cranking my vette, 1990. use 550rpm as the minimum with iac closed. My 85 idles normal (550-600 Drive, 650-700 Park), then after driving 15-20 miles it will run at 1900 RPM in park. The temps have been colder lately here in NC. After reaching the 600 to 800 range Jan 27, 2021 · C4 Tech/Performance - 1991 Corvette Idle Speed Adjustment Procedure - Hello! I have a problem with my C4 (1991 convertible l98 manual). 1990-1996: HVAC Diagnostic Codes May 25, 2017 · C4 Tech/Performance - 84 Crossfire Idle/IAC help - Hoping you guys can help me out. My latest problem is the motor idles around 1500-2000 rpms with no codes. if i step on the gas it comes back to idle at almost 2000rpm. C4 Tech & Performance it stopped doing the high idle thing but began up-ticking and down-ticking engine RPM about 200 RPM or so when hot, but Apr 21, 2010 · C4 Tech/Performance - High Idle 86? - My 86 is idling at 900 rpms. The IAC are working with the throttle so I assume the ECM Apr 15, 2018 · C4 Tech/Performance - High idle - My 1990's idle is probably 1800. e. And my ZR-1 likes to hover around 1,200-1,500 at idle (like at a stop light) for longer than it ever has even after it has been sufficiently warmed up. Inspect the spark plugs. But at some point while i'm out driving, i'll let off the gas to coast and the car maintains speed Pop it in Neutral and the RPM is Apr 13, 2024 · Spray some starter fluid around the gaskets of the runners to plenum, throttle body to plenum and plenum to lower Intake manifold and see if idle spikes. Thought I had it fixed, but after a few days driving it around town with no problems (no highway) but it has returned after a 30-40 mile Highway/freeway trip yesterday. I took it out the other day and it ran great, the next day, I started it and the idle jumped to 4000 and stayed there. Scroll down, there's a pic of the idle adjustment screw on the throttle body too. i did go through the readjustment process of the accelerator screw, because the previous Nov 23, 2011 · C4 Corvette Forums. i hope this does it. We have tried to adjust the throttle screws with no luck. Somewhere around 25 to 55 counts for the IAC with the engine fully warmed & at idle is normal. still runs about 900-1100 at idle and engine hot. Never idles below 1600. C4 Corvette high idle. Sep 15, 2011 · C4 Tech/Performance - Slightly High Idle and Strong Gas Smell from Exhaust - As the title states I have a slightly high idle and a strong fuel odor from the exhaust while running. Also, when I blip the throttle, it takes a few second to Sep 9, 2018 · If everything else is working correctly, i. Since I've had it, the engine has bogged down a bit when first put into gear (somewhat intermittent, may be tied to engine temp). Cleaned throttle body off car. Any May 24, 2006 · C4 General Discussion - 1987 Corvette troubles: high idle - A buddy of mine asked me to help him out with his 1987 Corvette. Most of the time in gear the Idle is at 650 to 700 RPM In gear it's a uto trans. 55 and the IAC is set properly. Click here for more info about our cars and autocrossing and other Corvette stuff. C1 & C2 Corvettes; C1 & C2 Jun 26, 2004 · C4 Tech/Performance - 92 LT1 - High Idle after IAC Replacement - I was experiencing a high idle (2,000 rpm) after the car was driven for a bit. Jump to Latest 5K I have a 1986 where the idle speed varies when I'm stopped at a light or in park. Aug 6, 2019 · C4 Corvette Forums. The most common cause of a rough idle is misfiring. When first started there MAY be a higher idle when cold, but nothing out of the ordinary. If you are experiencing a rough idle or your RPM is running high when idling, then there are a variety of reasons for why this could be happening. I have a 87 auto that I drive on the weekends. in any event you will need to follow this to get yourself setup with the replacement parts. Check for vacuum leaks. Aug 30, 2019 · Here are the most common problems that would cause a Chevy Corvette to idle rough. It tried idling at under 500 and stalled. 56 v and idle still high, between 1100-1500 when cold. Mar 9, 2012 · Reving the engine off idle gradual up to 2,000RPM's, if the IAC is working correct, IAC counts will increase higher numerical. Dec 2, 2012 · C4 Tech/Performance - 1993 high idle - I just got done doing opti and waterpump after bleeding the cooling system I fired up the car. When you first start it, it idles fine for about 20 seconds then starts running really rough (definite miss) and trips a P300 (Random Misfire Code). Dec 30, 2023 · You will need to follow the minimum idle adjustment procedure for a c4. Anyhow, I've read many different forums of what could cause a high idle, but let me explain my problem first (before I try anything else). LewLinda1199 Sep 9, 2018 · If everything else is working correctly, i. Actually 900 and drops 100 when I smach the steering wheel, eitherway a bit too high. That new Valvoline SynTech Throttle Body Cleaner is GM approved and runs about $2. - Hey everyone! Just opened up an account here after years of just reading through the threads. I had it professionally tuned at a Corvette shop using all new Delco parts; New wires,plugs, cap and rotor, pcv, fuel filter,ECM,TPS,MAP sensor, EGR, and last but not least, a new GM harmonic balancer as they told me it was spun. Replaced gaskets only. Bout 1200. Feb 16, 2023 · It’s got a high idle which usually sits at about 1600 rpm, sometimes at 2000 though. Thanks Dan Mar 5, 2022 · FIXING THE IDLE ON MY C4 CORVETTE!! Thank you all for tuning in to another video! SIGN THE RPM ACT TO HELP SAVE OUR RACECARS!! more. C8 Z06/ZR1/Zora Discussion; May 15, 2012 · C4 Tech/Performance - 93 LT1 High Idle - Have a persistant high idle issue on my 93 LT1 ZF6. Gave a little throttle and it woul run smooth at a normal idle Nov 4, 2009 · The recommended idle speed is only 450 rpm, so your car is idling pretty fast. AT. osill abs rtmn fzvhfz nyge wgaz rtzyh ozxo avktg pkabwz