Stuttering after warmed up and driving

[Turbo6BK]

New to the GN world. 87 GN
3 inch down pipe, 60 lb injectors, TT chip, LT1 with MAF translator, front mount RJC intercooler, Alky kit, 3 inch full exhaust, 5831 precision turbo, power plate, scan master

I took my GN out today for a spin and it ran fine for about 5 miles and all of a sudden it started acting as if it didn’t want to accelerate. It was stuttering and running real sluggish. I made it to my destination and let it cool down for about a hour and the same thing happened. Within the first mile I got into it and got it up to 21lbs boost and heard a pop. Checked all of the connections to the front mount and turbo and it was all intact. Here are the numbers from the scan master after letting it run for 5 minutes.

02 - 480-496
AF- 6
LB-34
Bat- 14.3
Int- 128
BL- 130
CLE- 148
ATS- 48-51
TPS-46
IAC-0
CC- numbers bouncing from 30-220

Any help would be appreciated.

 

[TexasT]

when you apply the throttle and the TPS goes up, how does that af move? could be a maf on its way out. how does that o2 move with that same experiment?
could also be a coil or coil module. what are your ohms across each of the coil posts? cold and warmed up.

when you touch the vacuum lines does it leave black on your hands? when were these vac lines last replaced?

 

[mblum]

In addition to what TexasT mentioned to check, are you monitoring fuel pressure? Are you getting the correct 1:1 pressure increase with each PSI of boost? What fuel pump? How old is the pump? Fuel filter fresh?

 

[MikeS]

Fuel pump hotwired? Check condition of plugs and resistance in plug wires. Consider adding extra grounds, your original wiring is now 36yrs old. Walmart sells lengths of 4 ga wire with ring terminals for about $5 each.

 

[Turbo6BK]

when you apply the throttle and the TPS goes up, how does that af move? could be a maf on its way out. how does that o2 move with that same experiment?
could also be a coil or coil module. what are your ohms across each of the coil posts? cold and warmed up.

when you touch the vacuum lines does it leave black on your hands? when were these vac lines last replaced?

When I drive it the AF goes up. I just put a brand new MAF on it from TT. The o2 went down to .070 then went up to 698 fluctuating. I’m going to check the ohms tomorrow on the coil posts. The vacuum lines hasn’t been replaced yet and I don’t see anything on my fingers. I did a smoke test and I only seen some smoke coming from near the tps but couldn’t find the source.

 

[Turbo6BK]

In addition to what TexasT mentioned to check, are you monitoring fuel pressure? Are you getting the correct 1:1 pressure increase with each PSI of boost? What fuel pump? How old is the pump? Fuel filter fresh?

The fuel pump is about a year old and it’s hot wired. I’m running the Walbro 255. The fuel pressure is set to 46 with the vacuum line off. I’m not sure about how to make sure that I’m getting the correct pressure increase

 

[mblum]

A gauge is needed to monitor fuel pressure, or a pressure transducer in conjunction with powerlogger. If your not getting a 1:1 pressure increase with each PSI of boost you could run very lean. You don't want to be lean under boost.

I had a bad coil pack on my 86 and it would start to break up around 12psi. The coil ohm'd bad and once replaced the issue was fixed.

 

[Turbo6BK]

A gauge is needed to monitor fuel pressure, or a pressure transducer in conjunction with powerlogger. If your not getting a 1:1 pressure increase with each PSI of boost you could run very lean. You don't want to be lean under boost.

I had a bad coil pack on my 86 and it would start to break up around 12psi. The coil ohm'd bad and once replaced the issue was fixed

I’m going to replace mine as well as the o2 sensor to see if it fixes the issue. Thanks