Mechanics

IDLE SURGE

1993 Plymouth Colt

Engine Performance problem
1993 Plymouth Colt 4 cyl Front Wheel Drive Manual 70,000 miles

idle surges after warm up. Has repaired computer, new ISC, temp sensor, 02, fuel pressure regulator, all sensors test with in spec. Timing is good. New plugs, cap & rotor, fuel filter all vacuum hoses replaced. Starts fine, when it reaches operating temp starts to surge, between 1100 rpm & 1900 rpm. If the ISC motor is disconnected it will continue to surge. NO CODES! HELP!
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Chesterbird
December 26, 2009.




Hi chesterbird, Welcome to 2carpros and TY for the donation and selecting us as your auto repair site Feel free to ask questions at anytime and Merry Christmas and a Happy New Year 2010

Check the fuel pressure if its within specs if okay-check and test the throttle position sensor, Manifold absolute pressure sensor, airflow sensor and the PCV and EGR valves

Rasmataz
Dec 26, 2009.
Thank you, all that you recommended has been done. My first thought was EGR or a vacuum leak, car dose not have EGR or MAP sensor. Do you have any other ideas?

Tiny
Chesterbird
Dec 27, 2009.
What engine liter do you have is it a 1.5L or 1.8L

Check again on the TPS and idle air control motor to include vacuum leaks

Rasmataz
Dec 27, 2009.
1.8L tps is at spec. There are no vacuum leaks, and the ISC MOTOR is working, it is new
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Tiny
Chesterbird
Dec 27, 2009.
Check the fuel pressure if its within specs and comeback with the readings

Rasmataz
Dec 27, 2009.
OK, I'll be going through it all again, and will get back to you in a couple of days.

Tiny
Chesterbird
Dec 28, 2009.
Hi, the fuel pressure is 47.5psi w/ vacuum hose off and 38psi w/ hose on still trying to find a vacuum leak. If the fuel pump was going out, would fuel pressure be ok if you had more than half tank of fuel and not ok with less than half tank? Thanks bill

Tiny
Chesterbird
Jan 3, 2010.
The fuel pressure is within specs with and w/o vacuum.

Try running an injector cleaner thru the system and also check the coil resistances primary/secondary.

Rasmataz
Jan 3, 2010.
Today I tried to adjust basic idle seed, and could not get any response form idle speed screw. I followed the factory procedure. Book said to replace throttle body, if you can't adjust. Coils are in spec. I've been through everything at lease twice. Today vacuum was 18 and steady. Serge only starts when engine reaches operating temp. I never believed ghost until now. Thanks, Bill

Tiny
Chesterbird
Jan 3, 2010.

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