Sudden power loss/misfire

[Gus]

My '92 Turbo (sedan, ATM, 162k) just started acting up on the way to work this morning and I'm looking for direction here...

It suddenly started cutting out under acceleration and seems to be only under load. For instance at around 35mph, if I try to accelerate to quickly get it up to 45mph, it will accelerate normally, then miss for a second, then accelerate again for a couple seconds, then mess again and so on and so forth with an occasional small backfire. Runs totally fine otherwise and the ECM light isn't on and there are no other signs of trouble. From what I can tell, the turbo sounds like it's spooling up normally. When I parked the car, popped the hood and revved it at the throttle body and held it at high RPM, it sounded totally fine.

The only thing I can think to start with is the fuel filter and plugs and wires, despite the fact that the plugs and wires have probably only 30k on them and it doesn't really seem like they would be the problem. I'm not sure if a clogged fuel filter would cause this either and I'm trying to remember if I also changed that 30k ago. I did the timing belt, drive belts and water pump a couple months ago, btw. Any ideas??

Thanks,

Dave

[LegacyT]

When it misses is it abrupt? when did u last change plugs.

Mark,

[Gus]

Yeah, it is abrupt. I think the plugs and wires were changed around 30k ago. I'll have to check my records. The wires may be older, but I think I did the complete 120k service on it, including the plugs and fuel filter, a few years ago.

[boostjunkie]

Like everyone said, check your ignition components (plugs, wires, and coilpack). Then check the alternator for proper output. You could be experiencing that "hesitation" issue I used to experience before my alternator went kaput.

[Gus]

It's only under load though? Also, shouldn't a misfire trigger the ECM light on OBD I cars?? I know it doesn't take much of a misfire at all to trigger the light on my OBD II Sube.

[THAWA]

Well, there are a lot of different reasons for hesitation if that's what you do have. Mine would hesitate even w/o being under a lot of load, just normal accelleration. though it wasn't nearly as bad as when I went wot. Our ecu doesn't throw a code for a misfire. Also 30k seems like a long time for spark plugs, least to me. I'd go ahead and change those, it's only a couple bucks for all 4 so why not right? Plus you can see if there's anything abnormal going on in your engine.

[Legacy777]

It sounds like his problem is the car cutting out....not a slight hesitation.

I'd definitely check all your ignition stuff, plugs, wires. You may want to spray a fine mist of water around the coil pack in the dark and see if you see any sparks.

You may also want to visually inspect the knock sensor.

I'd probably replace the fuel filter for the hell of it. it's not too expensive, and you could've gotten some bad gas.

[Gus]

Yeah, I'm definitely going to change the plugs. I should do that on a couple cars, actually. I'll do the wires too once I find my cheapest source on those. This car has always ran great and never had any hesitation, so something is definitely wrong. The fact that it's doing it only under load is what's throwing me off here though. Knowing that the ECM won't trigger a code for a misfire now though is helpful. That was throwing me off too. Thanks for that tip.

Thanks,

Dave

[Gus]

Hey Josh,

The knock sensor is also around 30k old. I had to replace that right after the 120k service (which I think was closer to 130k). I'll take a look at it though to make sure it's not cracking like the old one did when it failed. I know that will trigger a code though (actually two since it triggers the cam angle sensor as well). And it doesn't feel like the hesitation and general sluggishness as it did when that failed. This is definitely cutting out.

I'll do the plug, wires, and fuel filter and go from there. It probably is bad gas. I love how this crap always happens on the way to work so I can trip on it and blow it out of proportion all day. I just figured I would throw it out at the experts here in case there was a more common and less obvious possible cause than the plugs, wires, etc.

Thanks,

Dave

[boostjunkie]

Again, have the alternator checked. When I first picked up the car it ran ok. The plugs (champions) put in the car were making it hesitate and bog only on load. I changed the plugs and the hesitation/bogging went away . . . then it started up again just before my alternator died.

What type of plugs are you running anyway?

[Gus]

Ok, I'll put a meter on the alternator while I'm at it. In all my Subes though, I have never had the original alternator fail, except for the recalled one in my '98.

Good question on the plugs. I can't remember which plugs are best for Subes. I know Bosch Supers are preferred in the Porsches. What do you guys run??

Thanks,

Dave

[boostjunkie]

Ok, I'll put a meter on the alternator while I'm at it. In all my Subes though, I have never had the original alternator fail, except for the recalled one in my '98.

Me neither. But this one failed. You never know. And it's better to be safe than sorry.

As for plugs, DO NOT USE BOSCHS in the subies! Honestly, I've never had anyone comment good things about Boschs in any car, but to each his/her own.

Use NGK v-powers (copper plugs). You won't be disappointed.

[Gus]

OK, NGK V-Powers it is. Those good for all Subes, or just my Turbo Legacy? I'm heading over to Autozone soon. If for some reason they don't have them, what's a good runner up?

Btw, I do recall seeing complaints about Bosch plugs on here before, so I knew I needed to get something else. No idea what I have in the car now. Probably Bosch Supers.... and therein may lie the problem. Heh.

[LegacyT]

If its really abrupt check the vaccum lines going in and out of the boost solenoid. Also check the lines from the wastegate and turbo outlet. Its possible one of these is cracked and leaking. Also check that your wastegate isn't seized. Any of the above would cause more then normal boost and freak the ecu out, making it implement fuel cut.

Mark,

[Gus]

That's more along the lines of what I was suspecting this morning. It has more of an abrupt fuel loss feeling to it than misfire, but it could be either. Hard to tell. It did have a couple small backfires though. I'll check out the turbo.

Thanks,

Dave

[Gus]

Autozone was out of the V-Powers, so I didn't get anything. The problem seems to have quietly gone away for the time being though. I ran the sh*t out of it while I was out and it seemed fine. Perhaps it's bad gas or a dirty fuel filter after all. I'll change the plugs whenever I can find them and will be back here if the problem resurfaces.

Thanks,

Dave

[georryan]

I've had the same problem as you have had. Although I've never had more than one abrupt hesitation like yours. I once felt very serious lack of power under full throttle and then after I left it floored it had the seriously abrupt loss of any acceleration like a misfire and a backfire that almost sounded like it was from the engine, and then I let off. After that though it seemed to accelerate fine. I've had the problem reacure and go away.

I have yet to check my battery and alternator, that is on my list of things to do.

Have you noticed what your tank level is at when you get your loss of power? So far I've noticed that when my tank is low it is more likely to happen, but I'm not sure if there is a relation yet since it is happening less often.

-Ryan

[Gus]

I think I may be experiencing the same thing as you then. It started cutting out again on the second half of my drive home last night and the more I stood on it, the more it would go away. When I parked it, I brought it up to redline a few times, then held it there and it never missed or backfired. This morning it ran fine all the way to work. Perhaps it just needed a good flogging. I'm thinking it's bunk gas or something in the tank or filter. When this started it was at half tank and now it's at quarter. I still plan on doing plugs and possibly wires and fuel filter this weekend. Oh yeah, and a new tank of gas. It's sad when the new tank of gas will cost me more than the plugs, wires and filter.

Thanks,

Dave

[Gus]

Hey guys, quick question in regards to the Bosch Platinum plugs. I had a friend pick up a set of plugs for each of my Subes and he came back with the V Powers for my turbo, but platinums for my '98GT. Will those be ok in that car or do I need to find something else for it?

No news on my original problem. Haven't really driven it much since it started acting up, much less have had time to work on it. It wasn't too bad this morning. Going to get fresh gas for it today and maybe get to the plugs tonight.

Thanks,

Dave

[vrg3]

The Bosch platinums might work okay, but if you can return them and get some NGK coppers you'd probably be better off. You may have to come up with the NGK part number yourself, since I think even NGK specifies platinum plugs for EJ25s.

[Gus]

Well, I can't really return them, so I guess I'll give them a shot.

Thanks,

Dave

[mTk]

Aren't bosch platinums guarenteed to make your car run better? Just tell bosch they didn't and try to get your money back. I know the +4's have this guarentee

MK

[Gus]

I'll just be like the dude wanting his refund on his 100% gauranteed breakfast on Fast Times at Ridgemont High. This was not the best breakfast i ever had. I want my money back. Mister, if you don't shut up, I'm going to kick 100% of you ass!

Dave

[mTk]

good movie. But you don't have to be an asshole when you try to get your money back

MK

[Gus]

For some reason that scene just popped in my head when I thought of trying to get my money back for the plugs. Must be sleep deprivation.

Btw my car ran like hell this morning. I really need to find time to work on it.

Dave