Big Problems with my 5.0 .. .. ..

NEED HELP!!
I have a 92 GT, with a heads, cam, intake & a Hellion kit with a 62-1 turbo, 9 lb spring.



Here's my problem:

When I try to accelerate, either rolling into it, or just standing on her ( w.o.t. ) ; just when it's about to make decent boost ( 80% or more throttle )( and always above 3500 rpm's. around 4-4500 I think )

The car will suddenly fall on it's face! It's like it just goes dead, for just a split second ( as if you shut the car off ) then roars back to life with more power than I've felt her have before.

At first, it would only do it once in a while, now I can't even get full throttle, cause the second it gets up there and starts to make boost in the upper rpm's, she just bucks real bad!!

It will cut out as if I shut down the car completely, and if I keep into it, the car will roar back, but fall flat again instantly, over and over. It doesn't clear up anymore. ( I'm afraid I will break something very soon ).

When the car bucks, so to speak, the wideband is showing that car is running fat ( 10.2 / 10.8 / 11.2 numbers like this @ w.o.t. ). The boost gauge shows it hitting full boost, then nothing, then back to full boost.


I have checked the following:

- pulled the plugs. good coloring. Checked the gap: .32 thou
- checked the plug wires: All good. Had an extra set, so I threw them on anyway.
- checked the Digital 6, seems to be fine.
- pulled the MAF and cleaned it, seems good
- checked the timimg, seems fine
- I have never heard detonation from my car ever, so ruled out timing

The car has a tune, witch is just set up for more safety reasons than performance right now. ( till the tunes finished at least ) just keeping it fat and safe for now, till the bugs are worked out )

I did strap the car down, and untuned, completely stock untouched bottom end, she put down 500 rwhp & 540 torque.

And it never hic upped, or fell on her face, this just started about 2 weeks ago. Right from nothing it seems

So. I am at a big loss here. Has anyone had this problem before? Any ideas?

PLEASE HELP!!!


I hope I posted in the right section, if not please let me know.

Thanx

86bluecobra said:

BTW very nice looking engine bay. I wish I had a turbo on my 351w.

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Thanks.

I'll check the sensor. I've been getting allot of recommendations to change the gap in my plugs to .25 - .28. Another thing I have rule out.

I checked the sensor, everything seems to be good.

Someone suggested the Digital 6, the power and ground. I have heard many stories of MSD boxes causing headaches. So I have to rule it out.

The other biggest suggestion I got was to change the gap in my plugs,
from .32 to .25-.28.
I will try that after checking the MSD.

As for my tune, I'm kinda in the middle of it. I had AFI in Edmonton set it up so it's safe to drive ( and stand on her too ). So there is a custom tuned chip in the car, but it's more set for safety ( a/f of 10.2/9.8/11.2 under w.o.t. )

Untuned she put down 500rwhp/560tq at the wheels @ 7psi.

So this is what I have t work with.

I'll be testing out the new plug gap at the track tonight. We have the

Friday Nite Street Legals tonite!!

2002BLGT said:

so was the problem right after the chip , or was the car running fine after the chip and then started messing up out of now where ? might want to pull the chip and just make sure its making a good connection with the J3 port in the ECM , tape in it with some package tape , check the ground on the ECM as well while you are right there at it .......check all your wires going to your MAF to make sure none are skinned up and grounding out as well

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the problem started after the chip was in.

I'm still thinking it might be the tune.

2002BLGT said:

how were you adjusting timing before the chip and how did you adjust the fuel before as well ? what was the air/fuel before .....?

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Before the chip, I would pull the timing tab thingy, and adjust with a decent quality timing light I had. I don't think I messed with anything else timing wise, besides upgrading to an MSD dist., Digital 6, and Blaster coil.

Now that I think about it, that coil is probably 3 years old, at least. I would have bought it right after getting the car. That was almost 4 years ago.
Could that be giving grief? Is there a way to check them, even though it only does it at high rpm's?

As for the fuel, I installed an adjustable fuel pressure reg. It was at 42 or 44 psi ( not sure ) then we turned it down to 38. Then I tried to turn it down again while troubleshooting this issue. But there's no more adjustment to turn the pressure down. I turned the allen key adjustment and it went down a 1 or 2 psi, and then the allen key was loose. No more adjustment. Is this right?

Anyway, after I put the heads, cam, intake on, it was tuned shortly after.

It had a stumbling problem once before, and I thought I had it. I had the MSD in the cockpit of the car, and I don't think it was wired very well. I moved it to the engine compartment, and I thought it was fixed. But now I wonder?

We put the timing back to 10 degree's, I believe, ( I didn't physically change it ), when the turbo went in. I will double check that.

With the chip in right now, i think all the timing is controlled by the tune. Not sure.