just for your information
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Joined: Oct 2001
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From: loxahatchee fla
just for your information
my neighbors 1986 corvette started to slowly develope a a problem in that it would not idle unless the throttle was blipped constantly untill the engine temp reached 187-190f degrees. now the engine showed NO CODES, and ran fairly well once it reached those temps but even then the throttle responce was less than ideal.
I checked all the sensors and pulled codes and checked voltages and ohms readings
/values, everthing checked out just fine!, yet still the problem persisted and no codes dropped , I checked for loose ground wires, nothing?
carefull testing with a digital meter and timing light and fuel pressure gauge, revealed the logical conclusion that since the spark remained strong, the fuel pressure steady at 42lbs and that all the injectors tested clean flowing, the TPS was set at .545 volts, the IAC , O2 sensors,ects,eots,opss,MAF, all tested good it was a real head scratcher, no vacume leaks, no smoke , no oil use above normal!
well further testing found all the problems were caused by a MAF that had a (OPEN CIRCUIT)only at times and that tended to only show up under the vibration of the engine running, I swapped each component out for the same sensors from my 1985 corvette one at a time, if I found no improvement his parts were reinstalled and the next sensor checked by swapping it with a known good sensor! when the MAF was swapped the trouble swapped cars even though the digital meter showed the same ohms readings and voltage reading on both MAFs ( just thought you guys might like to know that even us older experianced guys need to result to testing sometimes . hes installed a new MAF and has no further problems!
heres the info you need to check things
http://www.c4vettes.com/l98.htm http://www.c4vettes.com/ecm.htm</A> <A HREF="http://www.c4vettes.com/sensorinformation.htm" TARGET="_blank">http://www.c4vettes.com/sensorinformation.htm
[Modified by grumpyvette, 5:47 PM 6/2/2003]
I checked all the sensors and pulled codes and checked voltages and ohms readings
/values, everthing checked out just fine!, yet still the problem persisted and no codes dropped , I checked for loose ground wires, nothing?
carefull testing with a digital meter and timing light and fuel pressure gauge, revealed the logical conclusion that since the spark remained strong, the fuel pressure steady at 42lbs and that all the injectors tested clean flowing, the TPS was set at .545 volts, the IAC , O2 sensors,ects,eots,opss,MAF, all tested good it was a real head scratcher, no vacume leaks, no smoke , no oil use above normal!
well further testing found all the problems were caused by a MAF that had a (OPEN CIRCUIT)only at times and that tended to only show up under the vibration of the engine running, I swapped each component out for the same sensors from my 1985 corvette one at a time, if I found no improvement his parts were reinstalled and the next sensor checked by swapping it with a known good sensor! when the MAF was swapped the trouble swapped cars even though the digital meter showed the same ohms readings and voltage reading on both MAFs ( just thought you guys might like to know that even us older experianced guys need to result to testing sometimes . hes installed a new MAF and has no further problems!
heres the info you need to check things
http://www.c4vettes.com/l98.htm http://www.c4vettes.com/ecm.htm</A> <A HREF="http://www.c4vettes.com/sensorinformation.htm" TARGET="_blank">http://www.c4vettes.com/sensorinformation.htm
[Modified by grumpyvette, 5:47 PM 6/2/2003]
