Car will not idle...

[SynHaven]

Ok i have a 95 gst with a brand new 6 bolt swap with a 7 bolt head. now when i go to start the car it turns over stumbles and dies. it also sounds like its missing too. Here's the kicker, when i unplug the MAS, it idles perfect! it idles a little high (1200 rpm) but it doesn't miss and it will run indefinitely. i already swapped in a known working MAS and it did the same thing.... someone please help me...

 

[jpmxrider489]

Is your mas plug bad? Did you test it? Just a thuaght, you can go to gm maf or sd.

 

[spoolinspyder98]

if it was a bad plug doesnt the car need the MAF plugged in y when he unglugs it it runs fine?

 

[rlacasse1]

Have you checked for any massive boost leaks?

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[SynHaven]

i swapped in a known working MAS, and same thing.... and everything is secure so no i dont have any massive leaks.... i sprayed down the intact track with carb cleaner to see f the idle changed, nd nothing...

 

[stuckwithgsx]

Strange. This may be a pretty far fetched but i'm thinking possible. Your BISS screw? Or even the screw that adjusts the throttle plate? (forgot the correct terms there)

Try bringing your idle up with those, and make sure you do it the proper way for the BISS. Then plug in the maf again, and continue adjusting.

Did you have your TPS off at any time during the build? It may be off quite a bit.

Check the torque on the intake manifold as well. Better yet did you do a full boost leak test? I would do this first.

 

[LandoAWD]

Spelling, Eric...

Without a proper BLT, you're still just guessing. I know you don't have a compressor, but SOMEONE has to around your way.


Follow the fast idle checklist as well.

Try bringing your idle up with those, and make sure you do it the proper way for the BISS. Then plug in the maf again, and continue adjusting.

I gave him the VFAQ link to ground the timing connector as this was a thought as well. (on FB)

 

[92AWDHX40]

Read the post so much information there, on idle could be boost leak start somewhere. Sprayed but did you do a boost leak, could be ecu, fuel pump, a number of things to help pick one, then go on to the other so we can help.

 

[stuckwithgsx]

I personally don't think a BLT will really tell him anything. This is pre-turbo problem, it idles fine with no maf pluggen in. That tells me that it will idle fine with the maf plugged in somehow. Unless there's a part of the i/c piping completely missing, then that could be a problem

How do you know that both maf's are good? There's a very very slight possibility that they're both bad, but that's 99% of the time not the case.

Do you still have emissions? Egr? IAC? If you're missing your IAC valve then that would cause a cold engine to do this. Unplugging the maf makes it run more rich, correct?

 

[SynHaven]

i do need to do a boost leak test but i cant at the moment... but my this is wouldnt it have to be a pretty big leak for the car to stumble nd die like that? and my tps was off during the build, but that doesnt have anthing to do with the car running with the mas unplugged....

EGR blocked off and checked like 50 times, and how do i check the IAC???

 

[snowborder714]

The 2g TPS has the idle switch built in, so with the ECU not getting that signal, it could cause a really "off" idle. Reinstall it and see how it idles.

Hopefully you mean you bypassed the FIAV and didn't completely block it off. If you completely blocked it off, you won't have an ISC to test. If you still have the ISC, you'll need a multimeter. Follow the instructions on this site to figure out what pins on the ISC to probe and what the expected results should be.
http://web.archive.org/web/20100815101158/http://dmtalon.v8eaters.com/ISC.html

 

[SynHaven]

would a video off how it behaves help u guys?

i tested the isc this morn with a multimeter... checked out fine.

 

[stuckwithgsx]

A video wouldn't hurt

If your tps was off and egr blocked then i'm guessing it's somewhere in that area. Double check all vacuum lines in that area. Do you still have a charcoal canister? Have you gotten it started and kept it running long enough to get to operating temp?

 

[kenuwine4g63]

To be honest, Check your firing order. When i rebuilt my first motor it would crank and everything but i could not drive it, it would rev to like 5k but stumble hard as hell to get there. Come to find out my firing order was off, car was running on 2 cylinders. I did everthing you did, maft test, blt, plugs, plug wires, coil, power transitor everything...Check that simple problem first. 4123
4321
thats the firing order, the top numbers are from the coil and the bottom numbers are the pistons number order, match the numbers with the spark plug wires. Hope this helps

 

[JuGs]

Im having the same ecaxt issue. any update on what it was?



edit

i think the only differance i have is i can still rev the piss out of it while its unpluged. it has a slight sputter but ztill revs unplug to what i have my launch limit set to

 

[JuGs]

No one? if it helps on cold srarts it doesnt matter if maf is plugged in or not. when cold it wont idle eiher way.

 

[snowborder714]

Did you swap your spark plug wires?
swapplugwires [ECMTuning - wiki]

And do you have "Use non-95/96 CAS" checked in link?

 

[JuGs]

Yeah plug wirs were swaped and i checked invert cas in link. 2 days ago i had it idleing when it was at temp with the maf unplugged. now that its cold it wont idle at all plugged in or not. this is the motor from my 91 and i nevef had this issue. its something to do with the 95 has to be a sensor. when i bought the 95 it didnt idle at all either so im back to where it was when i bought it. im having a electrical nightmare with this car