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View Full Version : Surging/lagging in 2.0 w/manual trans


redbat
05-23-2015, 05:13 PM
Hey all, long-time lurker, first-time poster. I need a little help.

I've been pounding my head against the wall with a particular issue for a while now, and I haven't been able to fix it yet, or find another post that definitively seems to identify the problem I'm having.

Basically, the car is down on power, and it feels for all the world like turbo lag is occurring when I mash the gas. I can hear the turbo spooling, but it takes a few beats and then sort of surges, but not as much as it's supposed to. And the turbo only seems to kick in at higher RPMs, whereas before it was pretty much instantaneous. There's also some shuddering happening, but only in 2nd gear, and only while going uphill. [confused]

Here's what I've done so far:

1) New DV (piston-style) a few years ago
2) current rev stock PCV (I had a BSH in there but the dealer took it out and it's been fine since)
3) HPFP, cam follower, valve cover gasket & camshaft replaced by dealer under warranty 2 days ago (no change in problem)
4) current rev vacuum pump (was leaking oil)
5) current rev coil packs
6) new copper plugs, properly gapped

I'm pretty sure the shaking is coming from shot upper control arm bushings and/or shot engine mounts (both of 'em), but the lag/surge thing is stumping me. Could I be looking at a vac leak or stuck n75? Maybe a bad or dirty MAF...?

Dealer said the clutch was worn as well, but I don't think that would cause this problem...
keithandstef
05-23-2015, 05:41 PM
It could be a carbon clogged valve situation. I spent about $800 to have a valve replaced (mine threw a code on piston three) and a ton of black carbon (literally caked on) cleaned off my other three valves. Car had a lot of the same symptoms as yours and after the surgery, it has run like new. Just an idea.
Biged243
05-23-2015, 05:48 PM
It could also be the cat clogging up. Any codes?
redbat
05-23-2015, 06:03 PM
No codes at all, which is frustrating. The last code I got was a few years ago for a misfire in cylinder 4 (new coilpack and plugs made no difference) so I ignored it and it went away.

I remember being worried about carbon buildup at that time...
keithandstef
05-23-2015, 06:34 PM
No codes at all, which is frustrating. The last code I got was a few years ago for a misfire in cylinder 4 (new coilpack and plugs made no difference) so I ignored it and it went away.

I remember being worried about carbon buildup at that time...

I went through the coil pack exercise hoping it would fix the issue, but it did not. I was lucky I guess in the sense that mine threw a code on #3 and then we swapped the coil pack and plug for that piston and it threw a code three weeks later on the same piston. So that ruled out the pack and plug. I also had the DV and HPFP replaced a year or so ago. I can't recall what the issues were as much at that time. Similar though. Sputtery and laggy. I don't recall feeling like the car was running really well until the carbon cleaning. The DV and HPFP didn't really transform her. I have almost 90k miles on mine and the performance went downhill gradually over the last 20k miles. The carbon cleaning and new valve made a huge improvement. No telling of course if that's your car's issue. Good luck with it.
keithandstef
05-23-2015, 06:57 PM
Mine is also a manual transmission FYI.
redbat
05-23-2015, 09:33 PM
Thanks, keithandstef. Looks like I'll get a chance to use my new borescope to check out the situation down there. Hoping this is a job that can be done over the long weekend.
redbat
05-23-2015, 09:36 PM
It could also be the cat clogging up. Any codes?

Thanks, Biged. Would there be a code if the cat was clogged? Any way to check for that if there's no code?
Aim high
05-23-2015, 11:06 PM
Po440 I think. It'll read as catalyst efficiency below threshold bank 1. Ask me how I know