weird stutter/boost loss at WOT

[calreef18]

Hey everyone, after I recently changed some spark plugs my car has been having a weird stutter/cut of boost, normally it rests at about 19psi at WOT but now it bounces from 15-19psi and I hear the exhaust sputter like it feels rich, although it can't be because I didn't change the tune and I swapped back my old plugs already. Any suggestions? I've boost leak checked, would an intermittent exhaust leak change things? Thanks in advance.

 

[TwoLiterLaser]

Did you get rough with your plug wires while you were changing the plugs? Heck, did you change to wires too or just the plugs? If a cylinder is not firing, then that could be causing your loss of boost and the stutter. I would chase after plug wires before anyhting else.

 

[calreef18]

Just plugs, wires seem fine they were changed not too long ago. It might actually be my boost controller, I unhooked it and ran it and no problems.

 

[TwoLiterLaser]

So what boost are you at without the boost controller?

 

[calreef18]

10psi, spikes up to 12 but settles immediately. It is really weird though because on the freeway I can sometimes get it to hold around 16 or 17 without the controller depending on how I manipulate the throttle. Maybe its the actuator?

 

[calreef18]

Boost definitely creeps up from 10psi to 17psi when WOT, and only starts to creep in the upper rpm's, say 5k up. It then stutters around 17psi. Any thoughts?

 

[No Mo STi]

I had an issue with the car studdering when I got in to the high RPM range. Check all your boots and make sure there isn't a tear in one of them. I tore a boot on my coil-on and I had the #1 cylinder arcing. Hope this helps

 

[99turbogst]

Check that you have the correct gap on your plugs (.028-.032) and I would replace your wires with a set of known working ones to rule that out.

 

[TwoLiterLaser]

Check that you have the correct gap on your plugs (.028-.032) and I would replace your wires with a set of known working ones to rule that out.

Bingo on this. Do you have a log you could email of this happening?

 

[calreef18]

Bought a new set of wires that are coming tomorrow, rechecked gap on plugs and they are fine. Also am getting a new boost controller today just in case. Otherwise we'll see if it had to do with the turbo when I swap to a 16g this weekend.

 

[calreef18]

So what its not so far:
plug gaps
mbc
turbo (swapped to my 16g and same problem)
boost leaks (I fixed a couple though)

Hopefully its the wires, I'm still waiting for them to get in since UPS dropped the ball and didn't deliver them on friday like they were supposed to. I also ran a log and it was a bit rich, I leaned it out and have a good log other than experiencing the intermittent boost loss. Around 15psi it stutters 13-15-13-15 etc. As a side note, at 15psi I'm flowing about as much if not more than my 14b at 18psi. I can't wait to crank up the boost after fixing this and putting in the evo pump I have

 

[calreef18]

And the culprit was... plug wires. Whew, I was afraid it was going to be something much worse. Now time to lean out and turn up the boost.

 

[boostin20lbs]

I am having a similar problem...the car ran great 2 days ago after I did a TB/water pump change, the next day I swapped out the side tranny mount and now my car runs fine under minimal boost 10psi, but when I go WOT to 19psi the car sputters bad...I ck'd all the connections that were in that area, changed plugs, ck'd my spark plug wires, reloaded my tune(link), boost leak ck'd and still have the problem, I have not logged yet with the problem yet

 

[da_golden1]

have you adjusted you tps or might need a new one.

TPS Adjustment