Starting and idling problems on '94 GT

jruppert · 09-22-2002, 11:43 PM

I have a '94 GT and around 3 years ago I had an E-303 cam and GT-40 P heads on my car. I also had a custom chip to help it idle because it had such a hard time without it. Anyway, I blew up the engine and so I stuck a stock 5.0 in it and was gonna sell. I never sold the car and this past week I went to put the heads and cam back in. For whatever reason I cant get the darn thing to idle decent and this is with my custom chip. If I start the car up cold it idles fine. If I drive it and it warms up then shut it off, it wont start without me pressing the gas down all the way. After it starts, it wont idle on its own. It wants to stall and a stoplight, etc. If I drive the car a few blocks then its fine. I did a fuel pressure test and I get 35 psi under idle with vacuum line hooked to regulator. If I unhook the vacuum line it rises to 40. When I am driving the car when its warm and it wants to stall, usually if I press the clutch in, the tach falls like a rock and it stalls. I dont know if its a TPS or what. I do get a check engine light. I run codes but I dont get anything except a 511. I was told that the 511 is caused from the chip I have plugged in. Kinda odd... The car was running fine when I had the stock heads and cam in it. Also, I noticed today that the fan isnt turning itself on. If the car idles for a long enough time, the temp peaks out and fan doesnt run. However, if I run the A/C the fan turns on and when I run for codes on self-test the fan kicks on. Is there a relay that runs this?? Anyone have any thoughts or suggestions??? Thanks

girlhound · 09-30-2002, 06:55 AM

I just recently put a p1 sc supercharger on my car and it does the same thing...Idles fine when its cold..as soon as it heats up...forget it......let off the gas and the tach drops like a rock....Anybody got suggestions?

jruppert · 09-30-2002, 05:13 PM

It seems to be running a lot better now. I unhooked the bettery, took the IAB off and cleaned it. Then put it back on with it unplugged and hooked the batter back up. Then started the car for 2 minutes and adjusted my idle to 900 rpms (because of my cam). Then shut it off and plugged the IAB back in. Started it back up without accessories running for 2 minutes. Then shut it off for 2 minutes, then started it back up for 2 minutes with accessories running. I went and drove the car and it made a world of a difference. I still had some trouble as far as the idle. I would come to a light and press the clutch in and the idle would float around 1200-1800 rpms. Then I went and backed off the set screw that is located above the IAB on the throttle body. I turned it counter clockwise quite a bit. Now my car runs fine. Maybe you should try resetting the IAB also. Good luck!

09-22-2002, 11:43 PM	#1
jruppert Registered Member Join Date: Jul 2001 Location: Reed City Mi Posts: 106	Starting and idling problems on '94 GT I have a '94 GT and around 3 years ago I had an E-303 cam and GT-40 P heads on my car. I also had a custom chip to help it idle because it had such a hard time without it. Anyway, I blew up the engine and so I stuck a stock 5.0 in it and was gonna sell. I never sold the car and this past week I went to put the heads and cam back in. For whatever reason I cant get the darn thing to idle decent and this is with my custom chip. If I start the car up cold it idles fine. If I drive it and it warms up then shut it off, it wont start without me pressing the gas down all the way. After it starts, it wont idle on its own. It wants to stall and a stoplight, etc. If I drive the car a few blocks then its fine. I did a fuel pressure test and I get 35 psi under idle with vacuum line hooked to regulator. If I unhook the vacuum line it rises to 40. When I am driving the car when its warm and it wants to stall, usually if I press the clutch in, the tach falls like a rock and it stalls. I dont know if its a TPS or what. I do get a check engine light. I run codes but I dont get anything except a 511. I was told that the 511 is caused from the chip I have plugged in. Kinda odd... The car was running fine when I had the stock heads and cam in it. Also, I noticed today that the fan isnt turning itself on. If the car idles for a long enough time, the temp peaks out and fan doesnt run. However, if I run the A/C the fan turns on and when I run for codes on self-test the fan kicks on. Is there a relay that runs this?? Anyone have any thoughts or suggestions??? Thanks

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09-30-2002, 06:55 AM	#2
girlhound Registered Member Join Date: Jul 2002 Location: Jacksonville, FL Posts: 22	I just recently put a p1 sc supercharger on my car and it does the same thing...Idles fine when its cold..as soon as it heats up...forget it......let off the gas and the tach drops like a rock....Anybody got suggestions?

09-30-2002, 05:13 PM	#3
jruppert Registered Member Join Date: Jul 2001 Location: Reed City Mi Posts: 106	It seems to be running a lot better now. I unhooked the bettery, took the IAB off and cleaned it. Then put it back on with it unplugged and hooked the batter back up. Then started the car for 2 minutes and adjusted my idle to 900 rpms (because of my cam). Then shut it off and plugged the IAB back in. Started it back up without accessories running for 2 minutes. Then shut it off for 2 minutes, then started it back up for 2 minutes with accessories running. I went and drove the car and it made a world of a difference. I still had some trouble as far as the idle. I would come to a light and press the clutch in and the idle would float around 1200-1800 rpms. Then I went and backed off the set screw that is located above the IAB on the throttle body. I turned it counter clockwise quite a bit. Now my car runs fine. Maybe you should try resetting the IAB also. Good luck!