car pukes and dies quarter throttle

[tyson]

I have an 87 gn. 55k miles on motor. 6031 turbo(new) 80lbs injectors and TT chip(new) for e 85. 62MM TB and plenum. 204/214 cam(new)
3" THDP(I think) front mount off a powerstroke. G bodyparts crossover pipe, poston Pass. header(stock drivers). adjustable fuel reg. 340 walbro hot wired. I'm trying to get the car to run descent. It was running ok up until about 14-15 lbs of boost, then it would die. I got 8.5mm msd wires, new ac delco plugs(one step colder than stock) gapped to .030. It wasn't running any better, the car actually started running rougher, about 1/4 throttle to 1/2 throttle it would just die. Found the rubber fitting from the vacuum line to map sensor was cracked. I replaced it, still the same. I can have the car in park, slowly rev it up to about 1/4 throttle or so and it will just die. sometimes it will just die then backfire afterwards. I noticed now that my iac count is 140 and I can't get it to change, the sensor isn't that old but I am going to go get a new one anyway. I've gotten a very slight knock reading but very low( when I was actually getting it to build boost).My scanmaster reads 02 is around 398 at idle. around 715-720 or so normal driving, blm is 128. I can't get any reading under boost really now, it dies pretty much as soon as I can hear the turbo starting to spool. I'm starting to wonder if it is an ignition module?? coil pack?? esc module or another vacuum leak(I'm still searching for leaks)???

 

[tyson]

I have a (used)later model 3" maf with a translator also.

 

[No disintegrations]

does it pop through the intake or out the tailpipe?
popping through the intake is classic lean condition.

 

[tyson]

It was more of the tail pipe. I think I got it fixed. It's raining so I can't take it for spin right now. I did find another small vacuum leak but I think the big problem was me over looking what should have been obvious. The car has been an on again off again project for about 4 years now. I'm finally close to having on the road. I've alway kept my k & n filter clean but with the car sitting so much I guess I didn't even think that was the issue as I know it has pretty much no miles since I've cleaned it. I took a look at it a little while Ago and it was filthy. I cleaned it put it back on and so far it seems to be running fine. I'll know for sure when it's dry out.

 

[Chuck Leeper]

I've alway kept my k & n filter clean but with the car sitting so much I guess I didn't even think that was the issue as I know it has pretty much no miles since I've cleaned it. I took a look at it a little while Ago and it was filthy. I cleaned it put it back on and so far it seems to be running fine.

I doubt that the dirt on the filter was/is the issue...
It may be that the last cleaning applied a coating of oil to the MAF.. That'll do it... every time.

 

[Mr URL]

The Translator chips have a valet mode if you do (and have an anti-theft chip) the anti-theft sequence with a xxx amount of pumps more that will kill off the engine past 1/4 throttle.

Glad you found the problem. Just FYI if anybody else sees that with a translator chip/translator setup.

 

[jbeier]

Totally sound like a MAF issue. Either the MAF got oil on it from the K&N filter, or you may even have a boost leak somewhere that's making the MAF read more air than what is actually being put into the engine.

 

[michael evans]

I had a new GM NOS coil pack and a new module on the engine and it was bad. Found it on the dyno. Brian Lorenz swapped it to one he had at his shop and the pop went away.

Put a timing light on it and see if it loses fire.