Question about 1991 Chevrolet C1500
I have a 91 chevy C1500 4.3L V6. I started having issues with it bucking every now and then about a month ago. It eventually got worse and then died on me. After that I could start it but it wouldn't idle and would start bucking and cut off. I rebuilt the throttle body thinking maybe it had to do with that but that didn't help so I sent it to a mechanic. They replaced the distributor (crack in it) and put in a new computer but it still did not fix the problem and sent it back to me. I noticed the timing chain was in bad shape so I replaced that, fuel pump, fuel filter, gear set, coil and plugs and wires but still nothing. I took the vacuum hose off the map sensor and plugged it with my finger. The idling got a little better and the engine light started flashing so I replaced the map sensor. It was a little better but it STILL will not idle and keeps cutting off if not kept reved up. I really don't know what else to check or replace. Do you have to program the computer? If so, how do I do that. Any suggestions or input would be helpful. Thanks
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Posted on Jan 02, 2017
do you get check engine codes?..have you done a leak down test and compression test to determine mechanical engine health?
Posted on Oct 07, 2008
My problem was solved when I repaired my 4 wd activation dash switch. The switch was contacting on 2WD & 4HI at the same time. The front differential activation is vacuum activated possibly creating a tug of war that didn't actually engage it but drained off vacuum from the engine? A theory at best but stumbbled across it because I knew the switch wasn't working properly I repaired it and low and behold rough idle disappeared and all is good for 3 weeks running.
Posted on Dec 10, 2008
Please go to the crossfire injection forum to get some straight answers to the 82 corvette CFI system and how to troubleshoot it properly. There's a lot of misinformation given here, so much so, I don't know where to begin.
One thing is, the 82 corvette CFI does NOT have a MassAir Flow sensor system, it uses MAP and O2 mostly. The CTS sends a signal to the ECM telling it what the temp of the motor is and in turn the ECM controls the amount of fuel being dumped. On the older (orignal) CTS sensors, they have one wire and takes its ground from the threads. If any coorosion takes place, usually the CTS will report a cold engine and request lots of fuel.
To repair this issue, install one of the newer style CTS sensors that have two wires, one for signal and the other is ground.
Fuel pressure and vacuum leaks on any CFI motor play key roles. Set the FP to 14-15psi measured inbetween the TBs. The regulator is located on the rear TB and must be slightly moded to make it adjustable and can be done in a few minutes.
Posted on Mar 07, 2009
Spray the intake with carb cleaner to find the vacuum leak. Check where the EGR mounts and the throttle body gasket sense you had both off.
Posted on May 10, 2009
my 89 corvette is hard to start when it is cold, and runs very rough for about a minute. replaced the IAC and Maf sensors had the throttle body cleaned, now it idles very high and emits the same problems. i also had the injectors cleaned.
Posted on Sep 19, 2009
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