95 GSX Running poorly above 3k rpm. Boost

[GSX95AWD]

Hey Guys, Great forum here.!
I've recently purchased a 95 Gsx for 800, What a steal right ? Well the car has some problems that i've tried diagnoising on my own, but still can't get it to run right! It will idle fine and drive fine till you WOT or go above 3k rpm when the turbo starts to kick in. It will start sputtering and backfiring bad under boost. I've done a BLT and found a few leaks and fixed them. This did not help. I've purchased new BPR6ES plugs, gapped to 0.028 and this helped slightly but not enough. There is no cel on either. The only 2 problems i see are, 1 - there is a stud missing from the exhaust header where it bolts to the head. And 2 - behind the cat where the flange bolts up is a big gash in the pipe right before the post cat o2 sensor. Would that affect this ? Only mods the car has is a megan racing bolt on axle back pipe. As far as everything else, its stock. 213k miles on it. Any suggestions? Thanks!

 

[Kng Nothg]

How long has the car been sitting? might be rust in the fuel tank. had the same problem on my 98 gst.

 

[GSX95AWD]

How long has the car been sitting? might be rust in the fuel tank. had the same problem on my 98 gst.

I would say it's been sitting for around 5 months. The gas gauge nor the oil pressure gauge works so i just put 20$ of premium gas in it when i first bought it and it just runs like complete crap. If you sit still and idle, and rev up, it'll go to 7k rpm no problem, but in gear it will go to 3k and from there up it'll hesitate really bad and spit.

 

[c2ypt1c]

I've purchased new BPR6ES plugs, gapped to 0.028 and this helped slightly but not enough.

My guess would be the spark plug wires.

1 - there is a stud missing from the exhaust header where it bolts to the head.

This shouldn't be a problem.

And 2 - behind the cat where the flange bolts up is a big gash in the pipe right before the post cat o2 sensor. Would that affect this ?

No. The rear o2 is used only for smog test purposes.

Like I said, try new plug wires. NGK all the way:
STM: NGK PREMIUM WIRE SET | 90-99 DSM

 

[GSX95AWD]

My guess would be the spark plug wires.



This shouldn't be a problem.



No. The rear o2 is used only for smog test purposes.

Like I said, try new plug wires. NGK all the way:
STM: NGK PREMIUM WIRE SET | 90-99 DSM

It has Bosch Premium wires that look recently added to the car.

 

[c2ypt1c]

It has Bosch Premium wires that look recently added to the car.

That could very well be the problem. Many people consider Bosch wires to be junk...NGK are tried and true, DSM'ers swear by them.

 

[Firegst]

Same thing happened to me when I bought my car. Install new plugs and wires check coil pack OHM'S and do a boost leak test. Chances are you needed the plugs and wires anyways and you'll find a boost leak causing the car to fall on its face! When there is a boost leak the MAS reads incoming air brought in via the turbo and compensates for it with fuel, if you have a leak as soon as the car builds boost or you hear the turbo it will fall on its face. The EcU is being told to add fuel for more air but the air is never reaching the combustion camber causing it to foul out the plugs until less air and fuel are present. A basic tune up and a BLT and you should be on your way! Do the test set plugs at 0.30 and let's us know! Goodluck.

 

[GSX95AWD]

I'm gonna go out and gap the plugs to .030 and then do another BLT while im at it. The last BLT held up to around 8psi of boost before any leaks were heard. Also does anyone know where i can find a cat back exhaust pipe only? i already have the axle back exhaust, but my current pipe going to it has a crack in as shown in the picture in post #1. Thanks

 

[Firegst]

I'm gonna go out and gap the plugs to .030 and then do another BLT while im at it. The last BLT held up to around 8psi of boost before any leaks were heard. Also does anyone know where i can find a cat back exhaust pipe only? i already have the axle back exhaust, but my current pipe going to it has a crack in as shown in the picture in post #1. Thanks

^Thats a little bigger than a CRACK! . But the exhaust shouldn't be effecting your BLT, unless you hear your air from the BLT coming from the exhaust continue with the BLT. Also try more like 15 Psi constant during your leak test with lots of soapy water.Do the test from the turbo intlet check everything, then move to the intercooler charge pipe connect everything and then move to the TB and check everything. Soapy water is a life saver. I had a leaking coupler, BISS screw and BOV flange...My car wouldn't make it passed 3500k

 

[jared98gst]

Coil or plugs same thing happened to me, gst would go to red line with what was basically spark blow out

 

[GSX95AWD]

The biss screw is stuck into the TB housing. The actual screw head broke off and wont come out, but it's not leaking from the screw. Theres a leak sound coming from behind the TB housing.

 

[GSX95AWD]

The boost will hold steady till 12 psi, where the BOV leaks, and there is a leak coming from the TB where the accelerator is hooked up to. I'm guessing the seals are bad ?

 

[GSX95AWD]

Well as of today, i go to start the car, And it'll idle rough for a few mins then it'll settle down around 700 rpms. But the second i put my foot on the gas WOT it'll sputter and stall out. If i put my foot on the gas very slowly it'll rev up fine but the second i mash the gas it spits and cuts off. I've done 3 BLT and the only small leak is the BOV, (stock) and the TB shaft seals at 12psi. Everything else seems perfect. im clueless.

 

[c2ypt1c]

Everything else seems perfect. im clueless.

Did you try swapping the wires with NGKs? My money's on that...$10 via paypal, do I have any takers?

 

[slow4g6392tsi]

Fuel filter?

 

[rEclipserGST]

I think I read that you found the boost leaks.... but you haven't fixed them yet? That is probably your problem. Upgrade to a 1g bov. The stock 2g plastic one is garbage.

Order shaft seals for your throttlebody, or buy one that is good. These leaks don't fix themselves. A lot of people seem to think that about cars in general

 

[GSX95AWD]

I have not switched the wires yet, I have replaced the plugs with bpr6es and it did help the problem a little bit. Fuel filter, i'll have to check that right now, And i wouldnt think the tb shaft seals would leak enough to cause the car to stall out like it is. It's a fuel/ ignition problem from what i can tell. i have 165-172 psi across all 4 cylinders. No oil leaks etc.. If i put the car in reverse, clutch in, turn the car off and on and give it hell it'll boost all the way up and fly back fast, but thats only if i start the car and in gear really quick.

 

[PrimerPLus]

I had a boost leak at the Throttle body shaft seals and as soon as I got into boost it felt like I had smashed into a wall. Replaced the shaft seals and no more walls
Also check your fuel filter and the plug wires as others have suggested.

 

[GSX95AWD]

Turns out my car was low on gas
Put a gallon premium in er and she fired right up like new. When the turbo kicked in i was sliding all over the gravel road. Success! My Fuel Sender gauge does not work so i have to guess when im getting low on gas. Any ideas what it might be? The actual gauge on the cluster? or the unit ?

 

[Aphix]

I didnt go through the entire thread, but the leak coming from behind the TB is likely your TB shaft seals. They are a very common leak in our cars due to their age and definitely worth your time to replace.