Engine shutters and shakes at idle, CEL is on

[Craig Mack]

Hey guys.

I have almost 61k on my '97 Cobra. About 500 miles ago I got a complete check up. I got the oil changed, new plugs, new filters, completely new spark plug wires ($$$) etc. The car was running in tip top shape. All of a sudden today, my check engine light came on. I didnt hear anything out of the ordinary...

My car has always shuddered at idle. Every few seconds the seats shudder, you can feel it pulsating from the engine. I never thought anything of it. But since my CEL came on today, I popped the hood with the engine running at idle. The engine would shake noticeably back and forth lopey like, then stop and be calm for a few seconds, then shudder back and forth again. Should I be worried about this?

I took my car to Autozone to have the code scanned but they didnt have the scanner with them. The car just had its major check up and everything is supposedly running awesome, except for this engine shudder and newfound CEL.

Any advice is greatly appriciated.

 

[5.0's 4 ever]

First off you need to get the code pulled and find out what it is. Second does the car have a miss under acceleration?

 

[Craig Mack]

First off you need to get the code pulled and find out what it is. Second does the car have a miss under acceleration?

I Know, definately gotta get it pulled. I'm going out tommorow again to try and find some autozone type place that will help me. The ECU is under the drivers seat, right?

What do you mean "miss"? It accelerates normally, but I haven't really pushed it since the CEL came on. I had to drop it into 3rd while merging on the highway tonite to pass some broad in a minivan before the lane ended, and the car felt slower than usual. Other than that, I haven't noticed any unusual blunders during acceleration.

Sometimes, with the A/C on, the car will studder at mid/high 2k rpm when I casually accelerate in 2nd gear, but its always done that. WOT has always been generally smooth though.

 

[black98snake]

Could be dirty IMRC's. Crankshaft position sensor could be bad if you are having a hard time starting the car. Dirty IAC or MAF sensor.

 

[Craig Mack]

Could be dirty IMRC's. Crankshaft position sensor could be bad if you are having a hard time starting the car. Dirty IAC or MAF sensor.

I'm not having trouble starting it, although it studders a few times before turning over, but I presume its normal. Also, can I see the IMRC's if I take off the intake? When I did, the entire throttle body was SQUEEKY clean.

Would dirty IMRC's trigger a CEL?

 

[missouri_guy197]

Yep the IMRCs could trigger a CEL, but it wouldn't cause the car to have a miss like that...sounds like you have a problem with a spark plug or wire...

Go to another Autozone and have the code scanned before you go and try diagnosing anything more...

 

[Craig Mack]

Alright...i'll get it scanned and let you guys know what it shows up as.

 

[Craig Mack]

Well, something wierd happened. On the way to work while sitting at a stop light, as the light turned green and I accelerated, the CEL all of a sudden went off. ~4 hours later coming back it is still off.

Weird. I hope to God this isn't related to my MIL eliminators again. That was such a PITA. We'll see though.

 

[Tat98Cobra]

With the cel on, you'll be in limp mode so it will be sluggish no matter what. If you cant get it scanned, try resetting the battery, then drive it again. See how it drives before the CEL comes back on. Sometimes, bad gas can trigger a CEL (usually show a lean condition from one or both front 02's) and clear itself after a new tank. Definately get it scanned though - sounds 02 related to me.

peace

 

[Nicks98Cobra]

mine does the exact same thing yours is doing. Mine is caused by the air pump being bad. It sounds like a miss at idle but its from fuel building up in the cats and them causing a mini explosion. How much are new air pumps anyway?

 

[Craig Mack]

mine does the exact same thing yours is doing. Mine is caused by the air pump being bad. It sounds like a miss at idle but its from fuel building up in the cats and them causing a mini explosion. How much are new air pumps anyway?

But I don't have any cats.

 

[Nicks98Cobra]

Hummmmm. Well I hope you figure this out before I go buy a new air pump so Im not wasting my money.

 

[Craig Mack]

Hummmmm. Well I hope you figure this out before I go buy a new air pump so Im not wasting my money.

lol, well I dont know if I should scan it unless the CEL comes back on. Maybe I have a retarded computer or something.

 

[CobraSusie]

Hey guys.

I have almost 61k on my '97 Cobra. About 500 miles ago I got a complete check up. I got the oil changed, new plugs, new filters, completely new spark plug wires ($$$) etc. The car was running in tip top shape. All of a sudden today, my check engine light came on. I didnt hear anything out of the ordinary...

My car has always shuddered at idle. Every few seconds the seats shudder, you can feel it pulsating from the engine. I never thought anything of it. But since my CEL came on today, I popped the hood with the engine running at idle. The engine would shake noticeably back and forth lopey like, then stop and be calm for a few seconds, then shudder back and forth again. Should I be worried about this?

I took my car to Autozone to have the code scanned but they didnt have the scanner with them. The car just had its major check up and everything is supposedly running awesome, except for this engine shudder and newfound CEL.

Any advice is greatly appriciated.

possibly a coil pack?

 

[doogz]

Hummmmm. Well I hope you figure this out before I go buy a new air pump so Im not wasting my money.

The air pump won't cause any drivability problems. It'll throw a code if it's unplugged, but you won't notice a difference without it on. I simply unplugged mine and left it hanging there. No harm, no foul.

For the bucking problem, the MAF may be dirty or my bets are on the IAC being dirty.

 

[Craig Mack]

Can't be the coil packs, they were replaced when the car got a tune up less than 1,000 miles ago.

So, even if I take off the intake and look at the Throttle body, which was extremely clean, the IMRCs could still be gunked up? A dirty MAF is another possible solution. Maybe the shop got their greasy hands on the screen and didn't clean it off or something.

Two things though: The code is still off and hasn't reappeared, and the car runs smooth at WOT. Is it possible that whatever the problem was, the car corrected it by itself?