CAN'T FIGURE THIS OUT!!!! (I've searched)

[1997_GST]

Okay so here's my story... I had a 97 gst and It got wrecked so I bought a 96 shell and switched the ecu wiring harness that goes out through the firewall... I swappe the motor and everything.. I went to start it and with the maf sensor unplugged, it idles but really bad... And when I plug the maf up it just dies... Or it will start up the immedately dies.. I can't figure out why.. Maybe I have something hooked up wrong?? I don't know!!! Any help would be GREATLY appreciated!!!!



I have tried searching buy couldn't find anything that helped.

 

[Rob10_99]

Sounds like a vacuum leak.

 

[liquidz28]

Sounds like a vacuum leak.

+1 if you have an electronic boost gauge check to see what your vac is at idle. at 1k rpm you should be from 18 to 20 inHG...thats a good place to start. or a vaccume gauge would help too ;p..

also is your maf all in 1 piece? IE has it been hacked/modded at all?

 

[Demon33]

Okay so here's my story... I had a 97 gst and It got wrecked so I bought a 96 shell and switched the ecu wiring harness that goes out through the firewall... I swappe the motor and everything.. I went to start it and with the maf sensor unplugged, it idles but really bad... And when I plug the maf up it just dies... Or it will start up the immedately dies.. I can't figure out why.. Maybe I have something hooked up wrong?? I don't know!!! Any help would be GREATLY appreciated!!!!



I have tried searching buy couldn't find anything that helped.

I had a similar issue when I forgot to screw in my PCV valve after removing the valve cover. The car actually idled better, albeit roughly, with the MAS disconnected due to the vacuum leak. Check to make sure you don't have a vacuum leak caused by a missing hose such as the PCV valve, brake booster and vent hose at the passenger side of the valve cover. Also, make certain your valve cover bolts are evenly torqued so as not to create a leak at the valve cover gasket. Another place to check is the intake path AFTER the MAS such as the blowoff valve, recirculation hose, intercooler connections and piping, throttle body gaskets, etc. Any unmetered air entering the engine will cause a lean mixture and a rough idle. For the engine to die as a result of a lean mixture, I suspect the leak has to be pretty substantial. Good luck.

 

[1997_GST]

Okayy I'll check in the morning... Thanks for the replies.. I'll post updates!! Thanks again!!

 

[1997_GST]

Haha yea I had a nasty vacuum leak through my intake manifold gasket... Come to find out autozone gave me one from a first gen... But now it purrs smoothly!!! thanks for the help guys!!