Topic: LGT studdering on acceleration? (Read 852 times)

mikesiena268 · « **on:** November 30, 2011, 04:53:50 PM »

alright so when i push the clutch in in my car i can rev it up and when it hits around 4k rpms it studders like ba ba ba ba till it hits arounnd 5k rpms. or when im drving and i get affter it, it studders and jerks around then a second or 2 later it will start pulling, do you have any idea? say i get on it it like delays for a second then it kinda drops back and starts pulling..... i just put injector cleaner and dry gas in it to see if it was that but does anyone have any clue on it?

Kavik · « **Reply #1 on:** November 30, 2011, 05:23:00 PM »

So, just in general, why are you reving up to 5k with the clutch in, and how often to you drop it into gear at that point?
My money's on.....slipping clutch?

RedRoof2 · « **Reply #2 on:** November 30, 2011, 05:49:05 PM »

If he's free-revving with the clutch in, no it's not a slipping clutch.

It's some sort of misfire. Sounds like the ignition's breaking up. My bet would be on several things, but I'd start by scanning the computer for any diagnostic codes present or pending. Could be an item like a dying coil pack, could be several other things.

Kavik · « **Reply #3 on:** November 30, 2011, 06:24:44 PM »

you're right....I was thinking about the act of over revving (for........fun?), and the stuttering in gear, not about the stuttering with the clutch depressed

mikesiena268 · « **Reply #4 on:** November 30, 2011, 06:29:26 PM »

i wasnt over reving, the car has been having the studdering problem so i step on the clutch and rev it up to see if it was doing it only in gear or if its in general an firing problem, cant be clutch slip its brand new clutch and the car hasnt thrown any codes ill check it out more tommarow when i drive it, its been doing it, but doesnt do it everytime your get after it, somtimes it has smooth pulls where it wont studder or somtimes its all studdery and jerks at first.

Kavik · « **Reply #5 on:** November 30, 2011, 07:07:37 PM »

sorry man, it's just with the order you wrote it out in, it sounded like while 'free revving' was when you first ran into the problem

anyway, scanning for codes wouldn't hurt.....but am I remembering right that you got this car already with a tune on it? So no idea what codes may have been suppressed in the tune? (sorry if I'm thinking of the wrong car, but more info might end up being helpful)

hydrochloric · « **Reply #6 on:** November 30, 2011, 07:22:24 PM »

In my experience, Subaru knock sensors require a seriously bad misfire to actually trigger a code. When my plug wires went, last winter or before, the car was so bad I had to floor the throttle and dump the clutch just to do a hill start, or risk stalling... But the misfire codes never came up. I experimented with it, and it required such a severe misfire to trigger the code, you wouldn't be able to drive the car (think bucking bronco-style jerking).

So I would say either plugs or wires (or both). I didn't believe it at the time, but it was so obviously the issue after I changed the wires... When was the last time you did those things?

mikesiena268 · « **Reply #7 on:** November 30, 2011, 07:27:58 PM »

i havnt since i got the car, i got a tune on the car by john v so im currently gave him some data logs, but im thinking its the spark plugs at least, mabey the wires and alttle more to do witht he ignition thats the only thing that i could see being wrong with it,

hydrochloric · « **Reply #8 on:** November 30, 2011, 07:33:44 PM »

It definitely sounds like ignition, but if you've never done plugs/wires, do them now, before winter gets worse, because the problem will get worse as winter goes on. If you want to try to save aggravation, try just the plug wires for now, that might be it. You should still do the plugs soon, though.

deadlydave · « **Reply #9 on:** December 01, 2011, 09:59:51 AM »

Quote from: hydrochloric on November 30, 2011, 07:33:44 PM

It definitely sounds like ignition, but if you've never done plugs/wires, do them now, before winter gets worse, because the problem will get worse as winter goes on. If you want to try to save aggravation, try just the plug wires for now, that might be it. You should still do the plugs soon, though.

Don't forget us turbo folks use coil-on-plug, not traditional wires setup.

RedRoof2 · « **Reply #10 on:** December 01, 2011, 10:00:45 AM »

I'd do both plugs and wires as preventive maintenance. Then if it still does it, wait till it trips a check engine code and see what cylinder's nailing you.

hydrochloric · « **Reply #11 on:** December 02, 2011, 12:30:43 AM »

Quote from: deadlydave on December 01, 2011, 09:59:51 AM

Don't forget us turbo folks use coil-on-plug, not traditional wires setup.

D'oh! See, this is why I need a turbo swap!

RedRoof2 · « **Reply #12 on:** December 03, 2011, 11:36:51 AM »

Here I am, still stuck in the world of distributor-powered turbo cars and iron blocks. If you've got no pending or present codes for a misfire, then this will get dicey. Until you have something that gives you an idea of where the misfire's located (If any cylinders in particular are responsible), it'll be hard to figure this one out. Replace plugs as a precaution and for a fresh baseline. May want to take a look at your MAF as well and see if someone has a spare you can swap to test things out. That's where I'd start.

FastfreddyRs · « **Reply #13 on:** December 03, 2011, 01:00:39 PM »

you could be ober boosting and hitting boost cut, do you know what boost level this is happening at? do you know what boost you should be running at? if your car was tuned in the summer and know we are getting that colder air it is common to over boost. Depending on the car your car will cut fuel or ignition to control the over boost.

RedRoof2 · « **Reply #14 on:** December 03, 2011, 02:35:52 PM »

He's free-revving the car under no load. I don't think he can generate enough load to hit boost cut with the clutch in. Could be wrong though.

hydrochloric · « **Reply #15 on:** December 03, 2011, 03:08:48 PM »

Hmm. I would have been prepared to bet (exceedingly small amounts of) money that it was plugs, but when my car was doing that, it was wires, not plugs, and that's not applicable here. I suppose plugs could still cause the issue, especially if one were mis-gapped, but even when mine were changed, they had 1/4" gouges in the emitter, and they still worked (mostly) fine.

I don't really know if it's a good idea, but I remember the only way I could get my car to throw a misfire code when the wires went bad was to go WOT at low RPM and very low speed, in 5th gear (really high load on the engine). You could try that, I guess, to see if you could get it to kick and toss a code.

Jg195951 · « **Reply #16 on:** December 03, 2011, 07:28:08 PM »

I'm interested to see what the problem is. My old wrx had this exact same problem sometimes during acceleration (although i never tried to make it do it with the clutch in like you did). my car had this happen so bad that it actually stalled once on central. had to have the car towed, (unfortunately to pep boys) where they couldn't figure it out. ended up starting fine after about 15 min of waiting. Just out of curiosity does it do it at certain times? mine seemed to only have the problem around corners…or at least thats the only time it happened in the short time i owned the car.

hydrochloric · « **Reply #17 on:** December 03, 2011, 09:18:37 PM »

Quote from: Jg195951 on December 03, 2011, 07:28:08 PM

I'm interested to see what the problem is. My old wrx had this exact same problem sometimes during acceleration (although i never tried to make it do it with the clutch in like you did). my car had this happen so bad that it actually stalled once on central. had to have the car towed, (unfortunately to pep boys) where they couldn't figure it out. ended up starting fine after about 15 min of waiting. Just out of curiosity does it do it at certain times? mine seemed to only have the problem around corners…or at least thats the only time it happened in the short time i owned the car.

If it wouldn't start back up after dying until it had cooled some, I would bet you had a cracked coil pack.

kaisertech · « **Reply #18 on:** December 04, 2011, 10:31:49 AM »

My wrx does this too, and I've heard of other people with the same issue. My car being solid mounted makes it exaggerated a bit. Im curious to know what it is keep us posted.

mikesiena268 · « **Reply #19 on:** December 14, 2011, 08:06:51 PM »

could it possibly be the timing belts and other belts just skipping a beat at first? and no it will randomly do it weather im driving or just free reving, it does it at about 4k rpms i can be driving and just get after it at around 3k rpms and it will hobble and jump and shit, im only boosting at that point around 4psi then it hobbles and jumps up a few rpms and it hits around 10-12psi, i am only running about 16psi of boost, i can hit 18psi when im in 4th or 5th gear higher speeds with the car at full boost but at that it wont doo it..... im really wondering,,,,, i have to get them plugs changesd..... just havnt had the time to yet :/

KA_Killuh · « **Reply #20 on:** December 14, 2011, 08:13:31 PM »

If your timing belt skipped, you would have some pretty serious engine problems, so I would says its unlikely at this point.

RedRoof2 · « **Reply #21 on:** December 14, 2011, 09:12:32 PM »

If the timing belt ever jumps, you will immediately stop the engine and have the car flatbedded to a shop to get it fixed. Then you'll go to church every weekend and give thanks, if your engine is NOT destroyed as a result.

The thing's misfired since November 30th. Get a solid diagnosis on it, at least. If you keep romping on it every day to see if it still acts broken, guess what, it won't heal itself. You're going to break something if you continue this way and it's going to be expensive.

hydrochloric · « **Reply #22 on:** December 15, 2011, 11:15:27 AM »

Quote from: RedRoof2 on December 14, 2011, 09:12:32 PM

If the timing belt ever jumps, you will immediately stop the engine and have the car flatbedded to a shop to get it fixed. Then you'll go to church every weekend and give thanks, if your engine is NOT destroyed as a result.

When I changed my timing belt, I noticed the belt guide wasn't on the car. Turns out, my timing belt had jumped, about 3 teeth. I'd been driving it like that... probably since I owned the car (It never felt different until I changed the belt). It still runs fine. I MIGHT have tweaked a valve, because one cylinder doesn't like low-RPM high load (it afterfires alot). But still, not bad enough to cause any significant issues.

KA_Killuh · « **Reply #23 on:** December 15, 2011, 11:31:56 AM »

Your single cam engine is a non-interference motor. If the belt breaks or you install it wrong, it just doesn't run or runs like crap.

That 2.5 DOHC turbo engine is a different animal. Being just one tooth off can be enough in some cases to bend valves.

hydrochloric · « **Reply #24 on:** December 15, 2011, 11:58:07 AM »

I'm pretty sure all Subaru engines are interference, regardless of the cams...

Author Topic: LGT studdering on acceleration? (Read 852 times)