Engine shaky/skips a beat/chugs along

[Bob K]

I have a 1997 Cadillac Seville. 80,000 miles.

I have this problem that's been on and off for a while now. I took it to the dealer, but the mechanics didn't solve the problem, all they did was change the spark plugs.

The problem is, that the engine "skips a beat". The problem starts for the first time when you first turn on the engine, not while driving, and it continues this engine shake. The RPM appears lower (dipping really close to 500 rpm at times). When in high RPM, the shake goes away, but still present when its low. The average MPG is lower by 4 mpg. When I go up an incline slowly, you can feel the car chug along, chug-chug-chug-chug. You can hear it when its in neutral. Its slight, but you can hear it and the minor engine shake.

Usually this problem goes away after 3 or 4 days, however this has been going along for a full week. The idiot mechanics only changed the plugs and didn't do anything else. Any ideas as to the cause and the solution to this problem? I hope I have been descriptive enough.

 

[codewize]

Well I guess I would give the car a good once over. Look for signs of a blown head gasket? coolant in the oil, oil in the coolant. Any smoking? If it's not that it sounds like ignition problems but I'm not familiar enough with the new engines to make stipulations.

I'm just going back to the basics. As it sounds like your mechanics did. If you can and you want to take the time you can idle the car and pull off one plug wire at a time. The one that doesn't drop the idle is the cylinder with the problem. If none of them seem to make a difference then the problem is NOT an ignition problem.

Just my input

 

[Bob K]

I talked to 2 guys already, and one says that it may be the fuel injectors. The other says the ECM.

As it turned out, they did more than just plugs, but ive misplaced the reciept, and I dont remember what they did. I've got to call them tomorrow and take a look at the last repair. As it looks, I may have to take it back to the dealer anyway. Just the thought that I have to pay more money makes me cringe. I already payd but the problem is not fixed.

 

[codewize]

LOL you weren't a member of the board when I had my rant. I have a repair list as long as my leg for things both from a dealer and private mechanic for literally thousands of dollars and still had the same couple problems I started with.

Not that that makes your problem any better. I could see that being a symptom of one injector being clogged or malfunctioning. As I said I'm not totally up on the new style stuff as far as having experience in diagnostics.

 

[Jibit]

I'm curious if its starving for fuel? Has anyone ran a test under load on the fuel rail? BTW, welcome, hope you can make it to our December meet.

 

[Bob K]

Thanks, ill look into that meet. If I cant fix the problem by then mayby someone else can help me.

Ok, I got a copy of the reciept this morning. This is all they did:
-Replaced plugs and wires
-Replaced fuel pressure regulator.

At the time, they pulled a misfire code p0300 #7 cylinder.

Right now, replacing the ECM for $115 sounds alot better than the $700 "repair" they made that didn't fix the problem. What do you guys think?

I like the older cars better. If they break, they are easy to fix yourself. Now GM packs everything so tight you have to have the dealer change the batter for you. :Bang

 

[Jibit]

Thanks, ill look into that meet. If I cant fix the problem by then mayby someone else can help me.

I'm sure there will be plenty of guys at the meet willing to help, or just stare and say "yep, I used to work on these things until they got computers!"

 

[huntz52]

The same problem was happening to my 2002 sts and it ended up to be a broken engine mount. it was an easy fix. and my car is running like new. It happened they said from shifting to much from 1st to 2nd and up like that. although i guess it could be something else.

 

[HappyMofo]

ya, I was thinking engine mount also... i had an 88 grand am and it had a broken engine mount and chug'd until it was fixed.... because the engine raises up when accelerating or idling on the side not fixed to the frame. I hate the dealers...80 bucks for a diagnostic for my tranny...f them

btw, when is the meet...what is it? srry im a newb on this forum, just got an sts 4 days ago...lol :waving: