Multiple Problems?

[cantrun10s]

I really hope somebody has heard of something like this before, or can at least point me in the right direction.

1990 GSX with Walboro pump, 550's, Manuall boost controller set at 16, APEXi SAFC (currently everything is set to 0, if it wont run right normally I'm afraid to tune it), Crushed stock BOV, Stock internals.

I have about a 45 mile commute to work each day, so I'm trying to explain this based in terms of distance from my house.

I start it up in the morning, runs great. Hit's full boost at 3,500 rpm, pulls HARD, everything normall. Highest the EGT will get is about 800.

Ten miles in it starts. Will not hit full boost untill 5 to 6k rpm. From idle to 3,500 it's horrible. The motor stutters, shakes, will not run, it's bad. Not just a little stutter either. It's almost like two of the cylinders just go dead. Above 3,500 boost comes up to about 6 psi and it's bearable, but not pulling hard. Hit's 5k and takes of like it normally should at 3,500. But by then I'm worried about my EGT getting reallllllll close to the 1100 zone, and am trying not to run the car. If I pull over and idle at this point, my EGT levels off at about 850 idling. When I take off, the EGT climbs up to 11, I upshift two gears to let it do the horrible stutter, and it drops off to about 600. Downshift to a normal gear, and the EGT will climb from 6 to 11 before I can even concider another shift.

After about 10 miles of this, it stops. Full boost again at 3,500, but my EGT stays high. Real High. 900 at idle, but has never gone over 1100.

Now personally, 1100 was about 200 degrees higher than I ever wanted this car to go. I have tried running it rich, Same results.

Never once has the MIL come on, No fuel cut ever, no boost leaks, brand new NGK BPR4ES plugs

Please Help. This thing is about to get scrapped and I really like this car =(

[edit; even after it returns to the normall full boost at 3,500, it stutters horribly below 3,500, and doesn't pull as hard as it should above. New coil pack didn't help.]

 

[kenamond]

I'm a 2g guy, so take this with a grain of salt.

I thought BPR6ES were the suggested plugs on both 1g and 2g motors (gapped to 0.028"). Folks usually go to BPR7ES if they're boosting more than around 18psi.

Also, if you're running 550s without any SAFC adjustment, you should be running really rich. Have you pulled the plugs? What do they look like?

The weird problem after 10 minutes may be related to warmup, but I don't know if the ECU uses warmup maps until the coolant temps are at ~195ºF or if there's some other signal it keys off of.

Also, I thought 1100ºF EGTs weren't high (I'm thinking 1300º is okay). DOUBLE CHECK THIS. But that's my recollection. If you're running rich, that might have something to do with cooler EGTs and backfires.

If you have a logger, posting a log for a 3rd gear pull would tell a lot.

That's all I can think of.

EDIT: And you have a Walbro 255 without AFPR. You may be overrunning the stock FPR.

 

[romeen]

The plugs that you are using are a very hot plug that is not intended for high speed operation. Switch to the 6's like Mack suggested. No guarantees of course that this will fix it but it is easy and cheap to switch the plugs so it is a good place to start. Even if that doesn't take care of the problem those are still the plugs that you should be running. Try it and let us know if anything changes.

Boost leak tests are always a good idea as well.

 

[cantrun10s]

Changed the plugs to BPR7ES like Kenamond suggested. It definatly improved (TY TY TY TY)

but .... It was still stuttering bad. Changing the plugs made it pull much harder under full boost, but I'm was still getting an intermittent condition where the thing just wouldn't hit over 5psi untill I hit at least 5k on the tach.

So I did another leak test. Or started to anyway. My impeller is jacked. Compressor side. Bad. Missing fins, chunks of shavings everywhere, and the housing is pitted from whatever got in there smashing around. I never heard anything that would have caused this. Pulled the intercooler and found a chunk of a bushing (that did not come from my car, anywhere).

The odd thing is there is NO shaft play, and I can still hit full boost on a third gear pull. Regardless it's parked. Luckily nothing went past the intercooler so there wont be chunks of head missing when I rebuild it. So now I get to decide weither I want to go full bore and get the 20g, or another Big 16......... Gotta love Turbo's. I'll post some pics of the damage if anybody is interested.

 

[turbosax2]

That sucks what happens. I would like to see pics though if you get a chance.

 

[kenamond]

Ouch! Could you tell if the compressor fin pieces in the IC had been there a while? I imagine the balance of the compressor wheel is off unless by some miracle just enough broke off in the right places to keep it balanced. But if it is still balanced or not bad enough, it may have been broken for a while. Dunno.

 

[cantrun10s]

Definatly been there awhile. Last time I cleaned the IC was at about 70k miles. Currently at about 120k. The little chunklets were coated with roughly the same amount of oil as the interior of the intercooler. Funny thing was it actually wasn't that much oil, and the car didn't smoke. I'm actually lucky I have to pull my intake side to get my compressor side off, or I never would have looked at the compressor. Funny with that much crap run thru the turbo it didn't blow massive amounts of oil through it. Even stranger that if I was willing to risk it, I could still drive it and as long as I stay above 3,500, I'd probably not notice untill the whole impeller grenaded and jacked the motor.