surging idle on cold starts...please help
11-19-06, 03:18 PM
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surging idle on cold starts...please help
Please help....I just got a 1990 gtu n/a with some custom headers, exhaust and intake. When the car is first started the idle surges between 1200 and 2000. I can hold the engine at 2000 with the pedal and it does not surge above that. When the car warms up it sometimes settles down to 750/800 and other times settles at like 1100.
Can anyone help?
Can anyone help?
02-21-07, 04:22 PM
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I'm having the same problem, though I have taken carb cleaner and pretty well coated the engine compartment without hearing the engine rev. I also get an error code 12 (TPS issue) when the car is warm and I'm idling, but as soon as i apply a little throttle, the light turns off. Could my tps being incorrectly set cause the surging idle when the engine is cold?
02-21-07, 09:25 PM
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Yea i think tps, vaccum lines, and maybe even grounding issues would be your obvious culprits but whoknows maybe your lucky and got something obscure and hard to figure out lol.
02-21-07, 10:22 PM
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I don't think the surging is normal. I know that idle is supposed to be 3000 for about 20 seconds, then i heard it's "supposed" do drop to 1500 and then slowly drop to 750 as it warms up. For me it shoots to 4000 when started for 20 seconds, then drops to 2000 for about a minute, then drops to 1500, then back to 2000 (it does this repeatedly for like 5 minutes) and then it will lower to 1500 fluctuating to 1000 and back, then it finally slows down to 750 and is stable. after it's warm it idles smooth, no smoke, no stutters or hesitation.
02-21-07, 10:51 PM
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if you dont like your idle like that, adjust it. mine surges from 3k to 2k back to 3k for 5-10 minutes in the morning and it doesn't bother me. you should probably check your TPS while you're at it.
this should've been covered.
this should've been covered.
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02-22-07, 12:51 AM
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Originally Posted by RX7Georgia from rx7world.com
(once the car is warmed up of course)
First, check your TPS (Throttle Position Sensor) to make sure it's adjusted properly.
Second check your Timing.
Third make sure your idle is set right.
If none of the above cures your idle, the problem lies elsewhere. Check to make sure the vacuum hose on the valve for your choke on the Throttle body is intact. Check for any other vacuum hoses missing.
If your problem is still not cured...SOME have found that if their cats were clogged pretty good and the exhaust was no longer "free-flowing" OEM exhaust setup should be replaced then and the problem was solved by getting rid of the 2-pre converter 1-main converter setup and going with one high flow cat and a decent catback exhaust system. Not sure how valid these claims are...
In my opinion, I'd check to make sure just about everything is operational within specs. Check for correct resistance on electrical parts (i.e. Air Flow Meter, TPS, etc.) and also make sure your valves (i.e. Air Control Valve, 5th and 6th ports, Bypass Air Control Valve, etc.) are all functioning and opening and closing. Most common I've seen the BACV not doing anything because it's faulty and usually the 5th/6th ports are stuck open or closed due to lack of use (these only kick in at 3850 rpms though). If you find some of these parts were indeed not working, they may not cure the surging idle (good luck though) you should at least see a slight increase in gas mileage (especially if your 5th/6th ports were stuck OPEN).
The first three points are the most common...again good luck!
First, check your TPS (Throttle Position Sensor) to make sure it's adjusted properly.
Second check your Timing.
Third make sure your idle is set right.
If none of the above cures your idle, the problem lies elsewhere. Check to make sure the vacuum hose on the valve for your choke on the Throttle body is intact. Check for any other vacuum hoses missing.
If your problem is still not cured...SOME have found that if their cats were clogged pretty good and the exhaust was no longer "free-flowing" OEM exhaust setup should be replaced then and the problem was solved by getting rid of the 2-pre converter 1-main converter setup and going with one high flow cat and a decent catback exhaust system. Not sure how valid these claims are...
In my opinion, I'd check to make sure just about everything is operational within specs. Check for correct resistance on electrical parts (i.e. Air Flow Meter, TPS, etc.) and also make sure your valves (i.e. Air Control Valve, 5th and 6th ports, Bypass Air Control Valve, etc.) are all functioning and opening and closing. Most common I've seen the BACV not doing anything because it's faulty and usually the 5th/6th ports are stuck open or closed due to lack of use (these only kick in at 3850 rpms though). If you find some of these parts were indeed not working, they may not cure the surging idle (good luck though) you should at least see a slight increase in gas mileage (especially if your 5th/6th ports were stuck OPEN).
The first three points are the most common...again good luck!
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