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350 5.7 TPI runs great...idles rough...plz help

10-12-2005, 03:25 PM
I am new to AF so i hope you guys can help me My mother has a 91 Z28, it has a 350 5.7 TPI in it and it runs verrry good but when you stop at a stop sign it idles really rough. she has took it to a local mechanic like 3 times and it is still doing the same thing. Is it something with the injectors???? plz let me know your thoughts as to what might be wrong

10-13-2005, 08:55 AM
i have a 1997 Z28 with the LT1 and i was having the same problem as car would idle rough and it would cut off sometimes when put in gear. i got to looking under the hood and noticed a vacuum line off of the intake that was busted..i replaced that and now it runs fine. this could be the cause of your problem.

10-13-2005, 05:53 PM
alright....i'll check that out.....thanx man

10-15-2005, 02:08 AM
Definitely sounds like a vacuum leak. It could also be a dirty injector, but a good mechanic would have cleaned those with the pressurized can first. Then again, a good mechanic would have found a vacuum leak too. Sometimes an engine with low compression in one or more cylinders can do this too - run a compression check. Could be a blown or leaky head gasket, or a burned valve if there's a problem with low compression and the car does not smoke. While being far from precise, you can see if an engine has low compression in a cylinder by disabling the distributor (pull the pink or pink/white wire off of the coil) and cranking the engine. It should produce a uniform RPM throughout 2 revs of the crank. If there's a point where the starter speeds up momentarily and back down again, that's a good indication of a low-compression cylinder. You will still need a gauge to determine which cylinder is low.

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