*ISSUE* Everytime car is at idle and im about to accel. the motor backfires from intake manifold sounds like the car wants to stall out but doesnt, it also does this when i am cruising at idle and the rpm falls below 2K but 2k and after the car is a beast...*
ok here we go again im surprised i havent gaven up on this thing... but heres what iv replaced so far... IAC, TPS set at .67, ICM, COIL, AIT, PVC Valve, MAP, KNOCK so i scanned my car for codes and recieved map sensor voltage too high... 2nd is the PCV valve hose supposed to lead right back into the intake manifold? now i know probably everyones tired of hearing my problem but i have nowhere else to turn too thanks

 

Last motor I had do that had an intake vacuum leak.

 

hmmm i swear i looked everywhere for a vacuum leak

 

I get the same code because of my cam. Only pops up at idle but doesnt stay long. Data log it and let injuneer diagnose ya.

 

yea same here at idle light comes on but then its all good while driving

 

Did you just recently install this motor? If you did and all those components were working before why start throwing money at your car. You will most likely find it to be something you crossed/installed wrong..
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Cody

 

its just the oddest thing for it to be doing that it cant be the opti could it before then it would act up throughout the whole rpm range right?

 

Yes, the PCV is supposed to turn right back into the intake manifold.

 

oh ok thanks for the input, yea because i bought like a 4 inch hose and connected it to the pcv valve then there is another port right below the brake booster and i installed in there

 

oh yea i forgot to mention at idle when i apply the brake i really got to step on it to stop

 

What year is it? IS the Timing chain on correct? Is the Opti on correct?

 

That says vacuum leak to me.

Bret

 

its a 94 Z, ok now the car is really actin up so im not driving it anymore until problem is solved, on my way home from work in the car the car was runnin as if it was flooded with fuel no acceleration what so ever throughout the rpm range and car was backfiring at the same time(sounded like boat), the car didnt die out on my but seems like it was trying to stay on so about a half a mile check engine light comes so i guess the computer switched to default mode and i was able to make it home it was the weirest thing ever

 

You are getting the MAP voltage high because your vacuum is low - either because your engine is trying to die out frequently or from the big cam. Still, you need to be sure there are no vacuum leaks and the intake manifold is properly sealed.

 

I think I'd pull the intake manifold and reinstall at this point. Let it sit for 24 hours after installing it to let the RTV cure and see where it goes from there. It's just gonna cost ya a set of gaskets and a tube of RTV and about 2 hours time.