Turbo stutter during spoolup?

[Siberian]

Stock 2G turbo, no mods whatsoever. Never had any turbo problems in 75,000 miles.

But now, during any spoolup, the power stutters or shudders until full boost is reached, when it smooths out just fine. It's a very fast shudder, as if it's cutting out like 10 times per second. Kinda feels like the shudder ABS does - it's that fast.

It's not the usual BSC cutout feeling: that always feel like the boost/advance is just cut completely for a few seconds, then comes back on. This is different - I've never felt it before. I'm assuming the BCS would take care of it if it was bad fuel (knock).

Part-throttle is really bad, as it takes longer to reach full-boost, and it stutters the whole time up.

It's bad enough that my wife riding as passenger feels it.

Oddly, it doesn't seem to take any/much longer to reach full-boost - it's just a miserable experience getting there.

Any ideas where to start looking?

How long does a stock turbo normally last anyway? What are the symptoms of a dying turbo?

Or is it more likely a leak somewhere, such as the stock BOV?

 

[greeneclipse]

how are your plugs and wires???

 

[Siberian]

Originally posted by greeneclipse
how are your plugs and wires???

Hmmm, that's an interesting thought: plugs (NGK) prob only have 8,000 miles on 'em, but the wires are original (75,000 miles, 6 years old).

Fouling occured to me, it's just that it seems fine for that split second before the turbo starts to spool, then stutters all the way to max boost, when it suddenly goes smooth again. Doesn't seem to be RPM-related - it stutters at low and high RPM as long as the turbo is spooling up. Likewise, it's fine when at full-boost at low or high RPMs.

It's during spool-up time... low or high rpm... that it feels awful. Literally almost feels like ABS in the gas pedal.

I'm curious what happens when a turbo starts to die. Would play in the shaft feel like that? I'm wondering if the thing is basically wobbling while it spins up.

 

[greeneclipse]

have you physically checked for shaft play???

if there is no play...i would just try new wires and check for boost leaks.

i had somewhat of a similiar prblem. my car would stutter/misfire at full boost, and i found a couple holes in the wire boots.

once i replaced them...problem solved.

and get rid of that 2g bov and get a 1g one.

 

[Speed112]

I am having the same problem as you...Originally diagnosed it as fuel cut(I am lightly modded) but am now leaning toward a dying turbo. my 1g bov also makes a weird sound...instead of blowing off in one burst it breaks up into several small dumps. my car is also getting up there in mileage...I changed all plugs/ wires, cleaned my fuel filter, checked for shaft play(none)Problem still persists. I have a turbo to upgrade with and will be bolting it on tommorrow....Ill let you know if it fixes the problem

ps. Still change all your wires and plugs and maybe try unhooking and blowing out your fuel filter. these things will definatly cause our problems!

 

[Siberian]

Originally posted by Speed112
Still change all your wires and plugs and maybe try unhooking and blowing out your fuel filter. these things will definatly cause our problems!

Yuppers, thanks, got some new NGK plugs and wires on the way. I'll check the turbo, hose clamps, and filter as soon as the outside temps are fit for organic life again

After doing some more searching on more forums, plugs & wires seems to be a very common cause of these symptoms. I hope that's all it is.

The weird thing though is how it's fine at WOT and full boost. You'd think that'd be where it'd fail the most if the wires were arcing.

Then again, it'd make sense if the plugs were fouling at low revs... and blowing clean at high revs/boost. But I ain't no gearhead, just guessing here.

Wouldn't you know it: my extended warrantee just expired a few weeks ago, so you just KNOW it's gonna be a failed turbo

 

[Siberian]

Arg, OK, new NGK wires and plugs, and the dang thing still stumbles BAD during spoolup. WOT full-boost is fine, it's just getting there that's the problem.

It's like, give it half-throttle, and you hear it start to spool, stumble, stumble, stumble, then it "catches" and spools to full boost.

I checked and tightened every intake hose clamp.

Have yet to check the turbo and fuel filter.

Any other places to look?

Would a dying turbo (stock T-25) feel like that? I mean, it *feels* as if it doesn't want to spin up, like it's "stuck," then breaks free after a few seconds. I know that's not literally true, but that's the feeling.

The clue is why would it be WORSE when under less of a load? I'd think that knock from bad fuel (etc.) would be more of a problem at full-boost, not during spoolup.. am I wrong?

 

[Newlogics]

Normally, a dying turbo will be accompanied by slow spool-up and possibly a black smoke trail out of your tailpipe.

I doubt that turbo is the culprit in your situation, but still check for shaft-play to rule that out. Sometimes, when oil seal is gone on turbo, it will spray so much oil into the intake, that you'll have hard time sparking under boost.


Make sure plugs are gapped to .28 (or .028) forgot which one.
Dying coils could be a possible reason.

Which wire are you using?

Krage/Pep-boys/Autozone wires will often arc since new. (I've been through that)

Get OEM or Magnecores.

It looks to be fuel/ignition related problem, rather then something mechanical as turbo.

 

[Siberian]

Originally posted by Newlogics
Normally, a dying turbo will be accompanied by slow spool-up and possibly a black smoke trail out of your tailpipe.

Make sure plugs are gapped to .28 (or .028) forgot which one.
Dying coils could be a possible reason.

Which wire are you using?

It looks to be fuel/ignition related problem, rather then something mechanical as turbo.

New NGK wires and plugs, gapped to .028.

T-25 not belching smoke. Yea, I know, DARN

I agree with ya. Next step is to get fuel somewhere different. If that fails, have Mitsu replace the fuel filter (I hear it's not a fun DIY project).

I'm also getting suspicious of the O2 sensor... a pocketlogger would tell me, yes?

 

[Zenja]

I read that someone had this problem and fixed it by fixing his boost/vacuum leaks.

Half the problems that people get seemed to be caused by leaks, .

 

[IMMORTALSPYDER]

Any check engine lights? My wife's ranger did a similar thing when her MAF sensor went up.

 

[tlnpwr]

mine is having a similar problem. i was thinking about checking the turbo for any play. what's the best way to check for any vacuum leaks?

 

[midnght]

Originally posted by tlnpwr
mine is having a similar problem. i was thinking about checking the turbo for any play. what's the best way to check for any vacuum leaks?

http://www.vfaq.com/mods/ICtester.html

 

[tlnpwr]

thanks for that link

 

[tlnpwr]

speed112, let us know if ur turbo upgrade fixes the problem

 

[Siberian]

Originally posted by Newlogics
Dying coils could be a possible reason.

Bingo! You get a gold star

Yep, according to Mitsu, my stumbling problem at low revs and part-throttle was dying coils.

 

[tlnpwr]

dying coils, huh? u mean a coilpack?

 

[boostnbuds]

yea man...he means coilpack...

 

[tlnpwr]

thanks

 

[Newlogics]

Originally posted by Siberian
Bingo! You get a gold star

Yep, according to Mitsu, my stumbling problem at low revs and part-throttle was dying coils.

Don't get ahead of yourself here. Mitsu likes to blame many things on those coilpacks, but I've seen relatively few truly fail.

I do sugest replacing those just to eliminate that possibility, since they're too easy to replace.

 

[Siberian]

Originally posted by Newlogics
Don't get ahead of yourself here. Mitsu likes to blame many things on those coilpacks, but I've seen relatively few truly fail.

Tech's report on bill:

O2 SENSOR INDICATING RICH EXHAUST CONDITION. IGNITION SYSTEM TEST FOUND SECONDARY IGNITION SIDE OF COIL INTERMITTENTLY SHORTING TO GROUND. REPLACED FAULTY COIL.

Just picked it up. It's PURRfect again. Yay!

 

[Newlogics]

Originally posted by Siberian
Tech's report on bill:

O2 SENSOR INDICATING RICH EXHAUST CONDITION. IGNITION SYSTEM TEST FOUND SECONDARY IGNITION SIDE OF COIL INTERMITTENTLY SHORTING TO GROUND. REPLACED FAULTY COIL.

Just picked it up. It's PURRfect again. Yay!

Congrats! I think I might replace my coils too, just to take that variable out of the equation.

 

[AwdMikey]

My car is having similar problems. How can i test the coils?

 

[KLikLo]

I am having the same problem! How can i test it?

 

[UrMyStlkAl]

me 2222222222222222222, maybe that will fix them? how much did that cost?