erratic idle, dies after mods

[Mustang_Mike]

Hi Guys, a little help? I have a 95 GT vert- Just got her back on the road after putting on the following: cold air intake, (stock mas) BBK 70 MM TB, Trick Flow street intake (70 MM opening) manifold, 1.7 cobra rockers, BBK shortie equal length headers, stock cats, Borla cat back exhaust, 3 dgress advanced timing... (Gears are coming!)

After about 3-4 minutes of driving, the check engine light comes on... my shop guy checked it and said it isn't throwing any codes. I drove it about 200 miles on the highyway this weekend and she runs great there, but in traffic it idles at 800 rpm, but sometimes bounces up, and then down, then dies. Lastly, upon lifting to shift, she actually revs up about 200 rpm, or the rpm "hesitates" for a second before falling off.

OK, it's drivable, but anybody have any clues to help me get these issues sorted? I understand (now) that a 70 MM TB may be too big for my mods, how much is it hurting? Will I see a significant improvement with a 65MM TB?? Would a larger MAS make a big difference or help my situation?

Thanks much,

Mike

 

[S/CBlack95GT]

Very first thing you need to do is: Check to make sure there is not a vacuum leak. Make sure all the fittings are tight and no lines are broken or disconnected. After that have your shop guy check the codes again. If the light is on there should be a code in there.

If you find nothing with those two things then install your stock TB again and see if that fixes the problem. The BBK may have the throttle plate messed up like some have before. Also make sure the TPS voltage is not crazy high or low. It should be around .800-.998

The last thing is to check your rocker preload. Make sure you did not put more than one full round on the rocker bolts before the torque wrench clicked off at 18ft-lbs. You will have an erratic idle if you just tossed the rockers on there and then cranked the bolts down a couple rounds.

Lastly, what do you mean by three degrees advanced timing? Did you bump the timing from 10 to 13? The timing should be somewhere from 8-14 degrees BTDC.

 

[Mustang_Mike]

Thanks Shaun, I will check with him and let you know. Your help is greatly appreciated. I've also read (someplace else) that drilling a small hole in the TB plate (??? part that opens and closes) can cure an idle problem. This sounds rash... and permanent if it doesn't work... I will have him do what you said first.

Thanks again,

(Sorry for my limited knowledge- I'm learning!)

Mike

 

[wytstang]

Check your mas air also check your o2 sensors maybe there bad . Welcome to the boards. good luck

 

[blackEagle]

If the cold air kit has a bend in front of the mass air, this could be causing the problem. Also check the connecor to the IAT. Sometimes they can pull out slightly when the engine torques over on accleration(sp) causing the check engine(this one happend to me).

 

[Mustang_Mike]

Thanks everyone, appreciate the help. Mike

 

[HazMat404]

hmmm...what part of orland do you live in? im off tomorrow and have nothing going. i know its supposed to rain but ive got a 75mm maf we can swap in offa mine just for fun (as long as it goes back in by the time i leave ). wouldnt mind helpin ya out. we can test just about all the little things and if your CE light is going on, there is a code being thrown. i think its something with the tb screw cause my dad's friend messed with mine one day instead of the idle screw to up my idle and threw off a decently running car. still tryint to get it in its rightful place but its a lil off