Stumble and stall at idle!!!!!FUCK???

[Mkid]

After some hard launches on new motor last weekend my truck sounds like ass and wants to die at idle! $$$hit no codes!

It starts up at 1500 rpms then in like ten seconds it boucnes up and down between 500 and 800 before it slowly dies. fuuuuuuck i wish i could afford a $can tool, what kind should i get anyway and how much??

Seriuosly this sucks, my new motor was sooo much fun now i can't even drive the bitch.

New motor,ATR cam,conrad cap&rotor,walbro fuel pump,kenne bell red hot wires,CR42TS plugs,stock turbo and exhaust,new vacuum lines and check valves.1000 miles an all!

It's not just the idle, even if i keep it at 1000 rpms it still has this "stumble". I did the bicycle tire vacuum test and there was a serious leak at the throtle body plate cuz THERE WAS NO Gasket there!!

I fixed that with a new gasket and then the egr was leaking LIKE a BITCH where the rod is,So i put on a egr block off plate and pluged the line:same idle but starts up a lot easier. Then it still wouldn't hold much presure at all. I am doing this test correctly????

Do i need to disconect the PCV valve to throtle body hose and plug it at the throtle body or disconnect the brake booster hose to do this test correctly???

Cuz i don't hear any leaking but it still won't hold any presure.

also when i disconnected the IAC the idle was steady at 1900 to 2100 rpms,

In the manual it states like 200 things that could cause it to "stumble" and slowly die!!

this sucks,
malik

 

[Tooky]

There is pretty much only one or two scan tools out there, and nowadays most people are going with just one, that's DataMaster from TTS Power Systems (www.ttspowersystems.com). It costs about $90 for the software and a little less than that for the cable if I remember right. Laptop should be at least a Pentium 133, Pentium 200 or better preferable. You can get these type of laptops quite cheap nowadays. In fact most large companies with these will simply throw them out so if you have any friends who work in the right places you might score.

 

[Mkid]

Thanks dude,

malik

 

[V6 Kompressor]

Yep, without a scantool, your pretty much sol, but it sounds like you now have a vacuum leak in the intake system somewhere causing the engine to go lean...quite possible due to the engine being new and sometimes the intake bolts have to be tightened up again, usually after a week of break in on a new engine...hose clamps on the new hoses also... Check the o2 readings as well as the idle air control, BLM (Block learn)ect....Also, is there any black smoke coming from the exhaust?

 

[Mkid]

Thanks man,

No black smoke just crappy idle, but i think i've tracked down the leak. When i wiggle the throtle body where the cables connect i can hear the air comming out? Mabey there's a seal or something in there?

I'm taking my throtle body off today and gonna replace all the gasket's!


Thanks again,

malik

 

[GM TURBO]

If you can wiggle it - it prolly just needs to be tightened.

 

[smeagol]

Could be a million things...

How do you mean wiggle the cables?

I'd say to track down all the vacuum lines & check valves, make sure none of them are leaking... make sure you have a good solid vacuum line to the MAP sensor & FPR, NO check valve inline to either at all.

 

[kwick6]

You could be out of range for IAC correction.

Need to hook up scantool and adjust the IAC count, or pull the IAC off and clean it if its not working well.

Check for vacuum leaks as well, that will throw everything off.

Scott

 

[Wes]

Do you have an air foil on the throttle body?

 

[93 Black/Blk TY]

1. One easy way to find vacuum leak(s) cheap, is a can of carb cleaner. Your post states you had some gaskets missing that you have now installed. A can of carb cleaner can help locate intake leakes at idle.
Because the engine is Turbo charged you my have blown out some other inlet gaskets.
Take a can of carb cleaner and with the engine idling, spray at all gasket areas and see if the engine speeds up or slows down. Any change means a leak. Spray around the intake manifold and see if you have a leak(s) which means the intake has blowen a gasket. It does not take long to find a intake leak useing this method.
2. Check your fuel filter (even if new) and make sure you are getting fuel. If so, check the fuel pressure at the test port on the rail that the injectors their fuel. You need 45psi. Did you rebuild your injectors?
3. You can isolate one cyclinder by grounding the spark plug wire on each cyclinder or pulling the wire from the distributor cap, one at a time. If one does not make a change in RPM, that is the bad area and helps get you going in the right direction.
These are some simple, fast, and cheap methods to diagnosis without a scan tool.
Good Luck,
Garry

 

[V6 Kompressor]

Excellent troubleshooting tips, but be careful with the carb cleaner if it says "Extremely Flamable" on the label, If the fumes ignite from a spark, it looks just like a barbeque grill going with excess lighter fluid!!! Use the plastic tube to direct the spray, and keep it out of the distributor cap.