Warm-up Problem

Jeff7477 · 10-05-2001, 01:35 PM

I have a '90 GT, and when I start it in the morning, it will idle fine for a few seconds then try to stall, then regain its idle. It does this over and over until its warmed up. I know that they have open loop and closed loop, and I think it is something with that. Can anyone give me some more info or help?

88PONY · 10-05-2001, 02:13 PM

Your coolant temp sensor could be bad. The one that tells the computer to go richen or lean the A/F ratio.

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88 Notch Natually aspirated 750 carb Edelbrock Victor Jr. Intake and heads 306/ATI C-4 4500 stall 4:10's 26x10.5 M/T MAC longtubes/prochamber Dynomax Race magnumss dumped, Caged and ready to go!!! 11.8@115

And remember friends don't let friend drive MOPARS!!!

95mustanggt · 10-05-2001, 02:14 PM

Jeff, you have to throw out a little more information.

Could be several things. What have you done to your car? How does the car run when it's warm?

The first place to start is getting the codes in the EEC (if any)?

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1995 Mustang GT

[This message has been edited by 95mustanggt (edited 10-05-2001).]

Jeff7477 · 10-06-2001, 12:57 AM

All I have done is Shortie headers, off-road h-pipe and flowmaster cat-back. It runs perfect when warm, and there are no codes

95mustanggt · 10-07-2001, 12:00 AM

No codes...and you did the KOEO and the KOER tests?

My car was doing something similar and I tested the resistance on the coolant sensor and it was out of spec. Changed it and then changed the MAF the car runs fine now. I also had problems when the car was warm though.

No sure what to recommend, check your sensors resistances and voltages and see what you come up with.

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1995 Mustang GT

PKRWUD · 10-07-2001, 04:40 AM

Sounds like the EGR valve may be giving you some trouble. Try disconnecting the vac. to it (and plug the vac line) before you start it and see if it makes a difference. Also, as mentioned above, a KOER test is important.

Take care
~Chris

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Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

10-05-2001, 01:35 PM	#1
Jeff7477 Registered Member Join Date: Jun 2001 Location: Lincoln, Nebraska USA Posts: 67	Warm-up Problem I have a '90 GT, and when I start it in the morning, it will idle fine for a few seconds then try to stall, then regain its idle. It does this over and over until its warmed up. I know that they have open loop and closed loop, and I think it is something with that. Can anyone give me some more info or help?

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10-05-2001, 02:13 PM	#2
88PONY Registered Member Join Date: Nov 2000 Location: INDIO CA USA Posts: 141	Your coolant temp sensor could be bad. The one that tells the computer to go richen or lean the A/F ratio. ------------------ 88 Notch Natually aspirated 750 carb Edelbrock Victor Jr. Intake and heads 306/ATI C-4 4500 stall 4:10's 26x10.5 M/T MAC longtubes/prochamber Dynomax Race magnumss dumped, Caged and ready to go!!! 11.8@115 And remember friends don't let friend drive MOPARS!!!

10-05-2001, 02:14 PM	#3
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Jeff, you have to throw out a little more information. Could be several things. What have you done to your car? How does the car run when it's warm? The first place to start is getting the codes in the EEC (if any)? ------------------ 1995 Mustang GT [This message has been edited by 95mustanggt (edited 10-05-2001).]

10-06-2001, 12:57 AM	#4
Jeff7477 Registered Member Join Date: Jun 2001 Location: Lincoln, Nebraska USA Posts: 67	All I have done is Shortie headers, off-road h-pipe and flowmaster cat-back. It runs perfect when warm, and there are no codes

10-07-2001, 12:00 AM	#5
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	No codes...and you did the KOEO and the KOER tests? My car was doing something similar and I tested the resistance on the coolant sensor and it was out of spec. Changed it and then changed the MAF the car runs fine now. I also had problems when the car was warm though. No sure what to recommend, check your sensors resistances and voltages and see what you come up with. ------------------ 1995 Mustang GT

10-07-2001, 04:40 AM	#6
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Sounds like the EGR valve may be giving you some trouble. Try disconnecting the vac. to it (and plug the vac line) before you start it and see if it makes a difference. Also, as mentioned above, a KOER test is important. Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!