Car is falling on its face at 4k

[1fstSS]

i adjusted the timing to roughly 7 degrees, i followed the vfaq also. after i put it there i took it for a test run, seems to run fine untill 4 grand, this was my issue before but i figured it was timing, so i adjusted it and screwed it all up then re did it the rightway and it was back to where it was. on my logger at idle it reads 7-11 degrees, when you rev it up it jumps to 25 degrees. thoughts?

 

[weith1111]

Set your base timing to 5* BTDC.

Post a log 3k to redline, WOT.

 

[AL92]

If ignition is good,wires,plugs,coils and power transitor and fuel is good ,fuel filter ,injectors,pump then would suspect boost leak.
I just got my 91 fwd turbo running yesterday ,bought it not running with a fried computer.
I put in new plus,wires ,power transistor and the guy put in a new fuel pump.I will change fuel filter shortly.
The car won't rev right wot..I am almost 100% sure its boost leak.I have boost/vac gauge coming in the mail but would bet money on it.
You have to check everywhere..turbo outlet hose to intercooler,intercooler itself for especiall pinholes on innlet or outlet parts,upper hose for rips,tears,the tb for gaskets ,the one by elbow and one behind tb and the throttle seal o ring things.Then intake manifold gasket and injector seals.
Betting somewhere in there is my leak and yours too.Boost tester is your friend!!
I will be checking mine shortly.Had same problem on my old 92. I found lots of leaks,throttle seals,intercooler..oh yeah blow off gasket or blow off sometimes too.

 

[blackrosenova40]

I have the exact same problem with my 90 Gsx, it falls on its face at 4000, but I pull 20 inches of vaccum at idle when warm.

 

[AL92]

You can pull vacuum and still have bad boost leaks..two different things!

 

[swarm]

I had a very similar issue for a very long time. Take a few minutes and pull your valve cover and take a look around inside... i had a rocker arm that had come off... car fell on it's fact after 4k.. didn't feel like fuel cut.. just felt nonturbo after 4k....

 

[blackrosenova40]

Mine dont feel like (non-turbo) , it gets whiney, kinda sound sounds like a snomobile.

Would a bad ignition turn spark plugs pure white?

When I had a bad turbo in my car (no boost) it would fall on its face between 3600-4000 and now that im boosting it still does the same exact thing.

Sound like ignition to me, cant keep up after 3600-4000

I just dont know how to test the coil packs or the transistor.

 

[RotaryRyan]

Also double check and make sure your TPS is plugged in/plugged is all the way.