Hesitating when spooling

[dmgsx]

Ok, first of all, I'm sorry if my english isn't that great, but please bear with me. So, my 98 GSX is hesitating when it's spoolin, when it done spooling it runns fine. It's just that second when its spooling up, it feels like the power comes in stages to begin with.
I don't know if its related, but the car also acts weird when I'm cruising for a longer period of time or when it has been idling for awhile. it's like it builds boost, but there is no power at all. Then again, when i drive it hard (never below 3000rpm) it's superb, gotta love the mountain-roads in Norway! I tried turning up the boost to pressure to 13 psi but then it whasn't coopertive at all, just bucking and al sort of things. So now it stands on minimum. Ive got no CEL!

Things i've done to (try) fixing it:
Changed MAS
Changed and regapped plugs, NGK's at 0.027"
Boostleak tested (found huge boost leak)
Changed fuel filter
Checked CPU for caps
Changed front o2 sensor
Cleaned EGR-valve

New coilpack fuelpump got shipped from the states yesterday.

Any suggestions on what to try next? Cause I really dont have any.
And because the 4G63 isn't that known over here, the comunity at DSMtuners seems to be my best hope!

 

[And_44]

Did you fix the boost leak you found? If you did that's one less problem. When you read boost there is no power is what I understand from your post. Phantom knock or knock. When that happens your ECU is retarding your timing. Or maybe a exhaust leak.

 

[ArmyGSX]

I have the same issues with mine that I have been chasing for the past 2 1/2 months. I have done all that you have, and still the same issue. My next step is to change my TPS. If that dosent fix it I will be really stumped!

 

[highlandgst]

had the same issue .. cleaned my throttle body , changed tps ,spark plugs and it ran liek a champ again

 

[Blackjet18t]

I ran into the same problem. What I did was removed the throttle body, cleaned it, replaced the gaskets and put some silicone on there for added insurance. Fixed it perfect!

 

[pj91gsx]

low grade or old gasoline or boost leaks, you didnt detect with soapy water.

 

[onelowgst98]

my car is also doing the same thing i gotta try cleaning the throttle body

 

[dmgsx]

Thanks! Yes, I fixed the boostleak. Found out the car has been running rich because of that and fouled my o2 sensor. Thats also fixed. But still didn't fix the problem.
I'm going to look up all the suggestions, so just keem them comming!

I'm going to remove the thottle body asap. I will post a reply about the result!

 

[noavgjoe]

Im having a similar issue. I'm going to start with a blt and then move toward changing the plugs to the recommended NGK bpr6es w/correct gap and changing the fuel filter.

 

[Dert]

try gaping plugs to .028, also did you only change plugs or wires also? Try swapping in a fresh set of wires with a fresh set of plugs gapped at .028

 

[Ineedboostman]

Did you check the shaft play on your t25? I was having the same problem but not all time it it felt like the turbo was hanging from rubbing the housing. Swapped in a 16g and no more problem.

 

[ArmyGSX]

Not tryin to hijack the thread but...

I fully rebuilt my TB and still did not fix the studdering issue. I check the turbo every time I do a BLT and, tbh its a very solid little turbo! I have been thinking it was/is the TPS for a while. Like it has a "dead" spot on the sensor. My only question is could the crank position sensor cause this issue? I know it can cause missfires and thats what it feels like...

Please Keep us posted to what fixes the problem for you.

 

[dmgsx]

Please do the same you as well.
Well. Cleaning the throttle body, didn't change anything. Starting to think it's my TPS to. Tried turning on it yesterday to see if anything would change. But everything was exactly the same. Anybody know how to troubleshoot the TPS? Could a vacuumleak cause theese symtoms?

 

[dmgsx]

Just an update.
My T25 has no shaft play. Borrowed some other plugwires, didn't change anything.

Bought an OBD-tool, found out i had an P1500 - Alternator FR Terminal circuit.
The alternator was changed the month before i got it, so the the alternator has no FR terminal. Could this be causing the problem? it seems so unlikely to me.
I also checked the ignition timing while driving.
Idling = 5 - 8 deg.
steady speed, 2000rpm = 29 - 32 deg.
WOT = 0 - 6 deg.
Is this normal??