New engine starts then dies

[markrussell0927]

Just got my engine put back together. Stock 109 block and heads. Valve job new rotating assembly and valve train. Car starts then dies immediately. If I unplug the MAF the car idles rough but will stay running. Got another maf from the forum and it does the exact same thing. Fuel pressure doesn't fall off when the car dies. Set at 43psi vacuum line off. When the Maf is unplugged you can stab the throttle and the engine will rev but will not hold throttle. Casper cam cap, new TT chip, and new 340lph pump. Looked through all threads I can find and I'm stumped.

 

[mtocrs1]

There is another thread in the engine tech section that is similar. His problem ended up being his turbo tweak chip.
That seems very unlikely.
I would check for vacuum leaks. Check and make sure all vacuum lines are connected properly. Intercooler hoses on correctly, upper plenum gasket ok and tightened down. Etc etc.
I had this same problem after a fresh engine. It went away by itself. I think it was lifters not pumping up at first......


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[EVIL]

listen the screws a bit on the Caspers cap.

Mine did that a few years ago. It was the cap.

Or try the factory cap.

Maf translator and lt1 or ls1 maf. works wonders

Just an option.

D

 

[markrussell0927]

Lifters are pumping up because with the Maf unplugged car has all the response in the world. Revs nice and crisp no valve train chatter at all. Car has 75psi at cold idle with an Earl Brown front cover. It's something stupid I've just exhausted all my own thoughts on what it could be. I'm gonna try and go over all my grounds and everything again but I've been thru every wire in this harness (was a mess before I got the car) unfortunately it's one of those stupid electronic gremlins that we all hate chasing.

 

[markrussell0927]

I had the cap loose today thinking that was it and I could literally turn the cap and it made no difference. I will try and just loosen it up a bit. I'm gonna try and snag a buddies chip and maf just to make sure. The maf translator was next on my list lol just wasn't wanting to do it right away. Doing the fab work myself on my pipes etc so waiting for some other stuff

 

[TurboDave]

You'd be better off looking for a large vacuum leak. Check ALL air handling hose clamps, and especially check the vacuum block on top of the throttle body. If it didn't get properly tightened it will do exactly what yours is doing.

 

[MDavis]

Does the chip have a security feature?
I had a similar prob last week it was my fuel pump. But I did double check my security feature. Myake sure Electrical connections are fully engaged.

 

[markrussell0927]

It's a TT chip so I do not believe it has a security feature. Definitely not to my knowledge.

A large vacuum leak would make it run with the Maf unplugged but not when it's plugged in?? Interesting. every gasket on this engine is new and installed properly except for the vacuum block on the upper plenum I didn't change or mess with that. I will triple check all of those today and report back

Thanks!

 

[markrussell0927]

Found my problem. Big vacuum leak at the vacuum block, go figure the one thing I didn't touch had the problem. Running like glass now thanks everybody for help

 

[EVIL]

Awesome. There’s nothing better than an easy way out.

D

 

[TurboDave]

Found my problem. Big vacuum leak at the vacuum block, go figure the one thing I didn't touch had the problem. Running like glass now thanks everybody for help

Your welcome