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I was thrilled when I found this forum a few months ago. I have owned a Turbo Coupe since 1996, and had to figure out many problems by myself. I have three of these cars now - two 88's and one 87 parts car. I think I have experienced every problem these cars can develop, but this one has me stumped.
Ever since I bought my White 88 (see signature) it has had an idling problem. The idle was erratic at times when the car was at operating temperature (idle always increasing), but never idled up above 1200 RPMs. Then at about 180,000 it blew a head gasket (the rear oil passage began to leak), so I changed the head gasket and installed a re-manufactured head (the old one cracked). Ever since I replaced the head the idle problem has gotten worse. Here are the things I have done:
Replaced the VAM with an aftermarket one from Advance in 2000- since then computer will occasionally throw a 42 code (thanks to this site I now know it is not due to the O2 sensor!)
Replaced the TFI and PIP, distributor looked good with no play in shaft
Replaced IAC and TPS and adjusted it per instructions from this site
Replaced ECU with a known good one
Checked for vacuum leaks (replaced overboost sensor, cruse control module and all vacuum lines), now no leaks when tested at the vacuum port coming off the intake.
Checked and cleaned all engine compartment grounds and the ground at the computer
Doing all these things helped the car idle correctly about 70% of the time when at operating temperature. When the car is cold or barely warm it will idle correctly. If you are cruising on the interstate and exit it will idle correctly. It mainly acts up when doing around town driving. In stop and go traffic if you take off and have to stop again in a short distance the idle will begin to increase. With each stop and go it will usually increase a bit more, but never going above 1700RPM. If you turn the car off and immediately restart it the idle will be correct. When it is acting up I have gotten out and disconnected the IAC and it has dropped down to 700-800 RPM like it should. Nothing is sticking in the throttle body either. I also disconnected the vacuum line to the EGR valve and it still acted up. I really am at a loss now as to what the problem is. Sometimes the car will run correctly all day long, even in stop and go traffic. It seems to just depend on its mood! It is not outside temperature related either. It will act up at random on warm or cold days.
Sorry about the long post, but this problem is really getting to me and I wanted to give you all the whole story. Hopefully I have not forgotten any of the details. I have been searching these forums for months but still have not found the solution to my idle problem. After 15 years of fighting this I really want to get it solved!
Ever since I bought my White 88 (see signature) it has had an idling problem. The idle was erratic at times when the car was at operating temperature (idle always increasing), but never idled up above 1200 RPMs. Then at about 180,000 it blew a head gasket (the rear oil passage began to leak), so I changed the head gasket and installed a re-manufactured head (the old one cracked). Ever since I replaced the head the idle problem has gotten worse. Here are the things I have done:
Replaced the VAM with an aftermarket one from Advance in 2000- since then computer will occasionally throw a 42 code (thanks to this site I now know it is not due to the O2 sensor!)
Replaced the TFI and PIP, distributor looked good with no play in shaft
Replaced IAC and TPS and adjusted it per instructions from this site
Replaced ECU with a known good one
Checked for vacuum leaks (replaced overboost sensor, cruse control module and all vacuum lines), now no leaks when tested at the vacuum port coming off the intake.
Checked and cleaned all engine compartment grounds and the ground at the computer
Doing all these things helped the car idle correctly about 70% of the time when at operating temperature. When the car is cold or barely warm it will idle correctly. If you are cruising on the interstate and exit it will idle correctly. It mainly acts up when doing around town driving. In stop and go traffic if you take off and have to stop again in a short distance the idle will begin to increase. With each stop and go it will usually increase a bit more, but never going above 1700RPM. If you turn the car off and immediately restart it the idle will be correct. When it is acting up I have gotten out and disconnected the IAC and it has dropped down to 700-800 RPM like it should. Nothing is sticking in the throttle body either. I also disconnected the vacuum line to the EGR valve and it still acted up. I really am at a loss now as to what the problem is. Sometimes the car will run correctly all day long, even in stop and go traffic. It seems to just depend on its mood! It is not outside temperature related either. It will act up at random on warm or cold days.
Sorry about the long post, but this problem is really getting to me and I wanted to give you all the whole story. Hopefully I have not forgotten any of the details. I have been searching these forums for months but still have not found the solution to my idle problem. After 15 years of fighting this I really want to get it solved!
1988 White Turbo Coupe, 5-Speed 227,XXX miles, no mods.
1988 Black Turbo Coupe, 5-Speed (was Auto), 129,xxx miles, no mods.
1987 Black Turbo Coupe, 5-speed parts car (too far gone to restore)
1988 Black Turbo Coupe, 5-Speed (was Auto), 129,xxx miles, no mods.
1987 Black Turbo Coupe, 5-speed parts car (too far gone to restore)