Shutting down problem

lost2a6

Member
Joined
Nov 5, 2002
I'm working on a friends 86 GN. Problem is when I go WOT with it and it hits second, the car acts like you just shut the key off and then back on. It does this several times and if you stay in it, the power is not much more than an idle. It doesn't bust up or backfire, sort of reminds you of hitting the speed limiter in a late model vehicle. At first it only did this above 15 lbs of boost. I thought of valve springs as it has no codes and fp looks good. The springs was a little weak when I tested them so I replaced with a heaver spring. However I'm still having the same results. I have swapped coil pack/module with a known good working one. I swapped ECM with a good known working one. I unplugged the cam sensor while it was running and still the same thing. I removed the waste gate rod to where it only had about 3-5 psi of boost and when it hit the upper RPM's, it acted up. I've replaced the plugs and gapped them at .032. I've checked fuel pressure and I'm getting 1 psi to 1 psi of boost. The only thing that I have to data log with is a old school OTC 4000 which has a very slow update rate however I've logged several runs and nothing looks out of the ordinary. MAF is staying maxed out at 255 until it pretty much just shuts down. It does have a aftermarket LS 85mm MAF sensor and translator. Someone has cut the factory fuseable links and spliced in new wires with fuses so I think this is going to be something to look at. I'm also wondering if the crank sensor could be loosing it's signal but you would think that you would see the RPM go squirrely when I data log. I've looked at battery voltage while data logging and didn't see any huge fluctuations. Normal driving seems to be ok however at light throttle, it does seem to have a slight miss. Also the car seems to idle ruff.
 
Check your fuseable links down at the starter . They run right by your hot ass headers and break down over time . I have seen muiltable issues with the fuseable links grounding out and causing all sorts of issues . Double check your grounds aswell
 
When my car did that the downpipe was touching the battery cable. But only when I punched it. During normal driving it was fine. Something to check maybe
 
It could be drowning in fuel, if the MAF is hitting 255 too early, or the car is not making as much power as the chip was programmed for (if it has an aftermarket chip).
 
How long has it been acting like this, meaning did your friend purchase the car and knew that there were some bugs to be worked out or did it start acting like this all of a sudden. Are you sure that it is the motor and not the trans? Does it pull like a freight train in first gear?
 
I had that issue and it was the alternator charge wire heading to the battery that was dead shorting against the DS header.
 
Sorry for the late response, we had a small hurricane come through. Eric, it has your TT chip for 60lbs injectors but no power logger or even scanmaster. I cut the FP from 43 psi to around 40psi and it made absolutely no difference. As I'm typing this, I just remembered that your chips are tunable by some sort of sequence with the A/C and gas pedal. I had forgot because I have had the powerlogger in my car for years. It could be flooding it out with fuel. The narrow band O2 values are a little on the rich side but it's not terrible. I also know that the narrow band is very inaccurate when it's out of it's range. Someone has cut the original fuseable link wires and spliced in some BS with fuses, so this is a potential problem. These spliced wires are against the block and the trans lines. The trans lines are also against the crossover pipe, which all needs to be addressed. The car didn't have this problem when I started fooling with it, but it was also a dog. As I got it running better, these problems surfaced. Another problem that I see is it still has the stock down pipe along with the stock exhaust pipes. That would be ok for a stock car but this one has a TE 60 turbo, 60 lbs injectors, unknown roller cam, front mount intercooler, 85mm MAF meter, and aftermarket air intake. I can see the exhaust choking it down and not making full power potential, however it shouldn't be doing this.
 
I just wanted to bring this back up. I stopped working on it for a bit and just started back. I'm thinking a bad ground somewhere. Observing the MPH on the scanner, I can drive around 25 MPH and the computer jumps up to 60, the converter locks in. It will go back down to around 30 of course the converter will unlock. The MPH that the computer sees is very erratic. Also when I turn on the head lights, the high beam light will slightly glow which indicates a bad ground. But what is weird, the engine grounds attach to a different location than the body grounds. I believe that this car has had wiring issues for a long time due to seeing where others have butchered up the wiring harness. I'm almost at the point of trying to find a virgin engine side harness due to all of the hacking that has been done on this one. I believe that this car might have been involved in a flood due to surface rust that I found under the dash, however the car does have T tops so that rust could have came from the tops leaking.:banghead:
 
The surface rust is just from 30 years of bare metal being in a humid environment most likely. Good idea on the harness if it's hacked.
 
Sorry for the late response, we had a small hurricane come through. Eric, it has your TT chip for 60lbs injectors but no power logger or even scanmaster. I cut the FP from 43 psi to around 40psi and it made absolutely no difference. As I'm typing this, I just remembered that your chips are tunable by some sort of sequence with the A/C and gas pedal. I had forgot because I have had the powerlogger in my car for years. It could be flooding it out with fuel. The narrow band O2 values are a little on the rich side but it's not terrible. I also know that the narrow band is very inaccurate when it's out of it's range. Someone has cut the original fuseable link wires and spliced in some BS with fuses, so this is a potential problem. These spliced wires are against the block and the trans lines. The trans lines are also against the crossover pipe, which all needs to be addressed. The car didn't have this problem when I started fooling with it, but it was also a dog. As I got it running better, these problems surfaced. Another problem that I see is it still has the stock down pipe along with the stock exhaust pipes. That would be ok for a stock car but this one has a TE 60 turbo, 60 lbs injectors, unknown roller cam, front mount intercooler, 85mm MAF meter, and aftermarket air intake. I can see the exhaust choking it down and not making full power potential, however it shouldn't be doing this.
You are correct about the gas pedal but idk what you are talking about with the AC . I believe is 3 wot of the pedal and hold it n the 3rd on then it will cycle through settings on your scanmaster
 
SM to LV8. Gas pedal...press...press...hold. It'll cycle through 4 parameters. Let go of the pedal when you get to the one you want...and then make your adjustment. Key off to lock it in.
 
IT'S FIXED!!!:D I only worked on it here and there as timed allowed. It turned out that someone had ran a hose that was really soft from the turbo to the MAF sensor. As it turns out, when I stuck it in the corner, it apparently was sucking flat. You could see on the inside, close to the turbo, where it had been touching top and bottom. This had just about made me pull my hair out and hopefully if someone else has this same problem they will read this thread. (y)
 
Thanks for letting us know what finally resolved your problem. Too many times you see an issue with our cars but never know what or if it was ever fixed.
 
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