No boost below 5k rpm

[krazy skwerel]

I have had my CA for a long time now, but it just devolped a problem where it stumbles below 4k rpm and will not make boost until 5k+ rpm. When it does finally get to the 8 psi it holds steady and doesn't drop. I have tigtened all of my intercooler couplers, checked my exhaust manifold bolts, the turbo nuts are still secured with the plates, and I changed my fuel filter and ran seafoam through the gas.

If I held the car close to redline for about 15-30 seconds while driving the lower rpm stumble would go away, but I still had little to no boost unless above 5k rpm.

The car wouldn't idle either, but I fixed a massive exhaust leak between my turbo elbow/DP and it idles now. The idle isn't awesome fluctuates between 600-1100 rpm constantly, but it doesnt try and die now. I have been searching for about 2 weeks and havent found anyone with this exact problem or if I found a similar one they never said what they did to resolve it. Please any help would be appreciated.

Mods:

Walbro 255
Megan FPR
Front mount
HKS SSQV
Isis T25/28 replacement turbo set to 8 psi

[sjbsuperman1425]

Is the HKS SSQV vented to atmosphere or recirculated?

I'd start by pulling the spark plugs and seeing what they look like. I'm assuming you have no codes on the ECU correct?

[krazy skwerel]

I haven't had time to check honestly. I'll try and take a look tonight after work. As far as the ssqv it's vented atmosperic but it has been that way for almost seven years. So I am pretty sure it isn't that.

Also I'll note that it just doesnt like to get to 3500 rpm but once there it revs just fine through the rest of the band.

[sjbsuperman1425]

maybe check your timing as well. I had some strange idle issues and what not last year and it had to do with timing and ignition.

[boost_boy]

Check the turbo and it's wastegate. The wastegate flapper-door is probably not fully seated or the wastegate's actuator is bad. Or the turbo's blades could be dragging as well. Still should check for codes on the ecu, too.

[krazy skwerel]

yeah I thought it might be the waste gate actuator. If it's the turbo well I am screwed for a while until i can get money and time to replace the turbo again. I'll try and check the blades and actuator tonight.

[float_6969]

Sounds like a bad wastegate actuator to me.

[krazy skwerel]

ok so i am dumb. I fixed the stuttering problem. My wastegate actuator arm was adjusted out too long. I shortened it and the stumble is gone. The adverse effect of this is now I'm boosting higher. So I am gonna try and tweak it a bit this weekend if it isnt aweful cold. it seems to be hitting full boost around 4.5k rpm which is way too high for the little turbo but it is at least boosting in all gears again. Once it isn't aweful cold out I will try and get it back to 100% but for now it runs decent. Thanks guys for all of your input.

[float_6969]

Slow spool time is probably caused by the arm still being too long, a hole in the diaphragm inside the wastegate actuator, or an exhaust leak, pre-turbo. If shortening the arm helped the situation, shorter still will help more. This may cause more boost as well though. IIRC the actuators that come with the ISIS turbo's are designed for 1 bar (14.7psi) so if you're not running that much boost, you probably still have the arm too long.

[krazy skwerel]

If its set for 1 bar then I guess i will have to watch my throttle. I'll try adjusting it more and see if it spools better. I contated enjuku and they said a new actuator was 20 bucks so thats not bad if that does end up being the issue.

[krazy skwerel]

Well I finally got time to find the problem. My compression on the #3 cylinder is at 60psi. Jumps to 180 when i pour oil in the cylinder. I am basically screwed though as I have nowhere to rebuild the engine. Now I am gonna have to tow the damn thing all the way back from cheyenne to Nashville. So many things have gone wrong with this car since i got back to the states.

[float_6969]

That sucks. I'm sorry to hear that. I do hope that you stick with it and get the engine rebuilt!

[krazy skwerel]

Even if I decide to go another route with the S13 the CA will go to the S12 I gave my wife. I love the little engine and always have. Plus it outlasted most of the SR cars my friends have had over the years