Misfire at low RPM after warm

Hey guys

I have a weird problem. My car runs 100% fine and is a blast to drive. But after driving it for a while and its warmed up, it starts to misfire if I'm coasting at low RPM.

The check engine light starts to flash and I can hear and feel the engine is misfiring. If I pull over and shut the car off, then turn it back on its back to normal. Also if I drive at 3k or higher RPM I don't have this problem.

Anyone have any insight on this?

 

Have someone with an SD2 check her and they should be able to isolate the problem pretty quickly. Lots of possible culprits like leaking intake manifold gasket, vacuum hose leak, coil pack, etc.

 

if you have a generic scanner you should be able to figure it out on your own. Could be all that taz said. Considering you feel this only when warm would point more towards a coil issues. I see this very frequently on BMWs running bosch coils where it'll misfire once the car warms up. Not sure if you are mechanically inclined, but you can take a generic scanner and check the cylinder its misfiring on once you figure that out you can swap coils form another cylinder. If the issue moves to the next cylinder its a coil issue (Make sure to mark your coils). But yes it can be a ton of things and best bet would be an SD2 and someone knowledgable.

 

I had this same exact problem. I was getting a Cylinder #6 misfire code and the car would run real rough at idle once warmed up, but in all other respects she ran fine.

I replaced the coil and spark plug but that didn't fix the issue. It turned out to be a busted intake manifold gasket.

 

Thanks for the info

I'll read the codes and see if its specific to a cylinder and do a coil swap.

If problem moves, it should be the coil. If not, possibly spark plug/ intake manifold gasket?

Anything else it could be?

 

It would be helpful to fill out your profile with the model and year of your car. I believe the issue with intake manifold gaskets is more prevalent on early cars (2005/2006), than later years.

 

Simple solution. Drive the car in higher RPMs.

 

Actually it is not...since it is not possible to drive the car in higher RPMs at all times. The illuminated "check engine" light confirms things are not right.

 

Get a code reader (make sure you get one that reads all cars and not one that you have to enter the car's make and model as Ferrari is not listed).

If it is just one cylinder then it is probably a coil, plug or intake gasket. If it is multiple cylinders, then it is probably a MAF or intake gasket leak. Hopefully it is a MAF as that is an easy fix.

 

It was meant as a joke!!

 

Any visible moister anywhere? My dumb a** power washed the engine last night and flashing engine light misfires all over the place lol. I already knew what i was in for *Stupid* Drove it let it heat up, left it over night, all good this morning ahah.

 

Be careful with that method...once water gets down in the plug holes it is hard for it to evaporate completely out...you can end up with rusty and fouled spark plugs...seen it previously on my 308 and 355. My 308 needed eight new rubber caps for the plug holes, the 355 was missing the foam blocks at the rear of the cam covers (one for each cam cover). In both cases I had rusty plugs and a light misfire at idle that never went away until I replaced the offending plugs.

 

valid point, yea i had rust in the wells when i bought the car i noticed on my first plug change. Will not use that method again, had some beers and got bored..

 

Mine was leaky manifold gasket killed a coil pack.. Replaced coil and burnt out again. No idea how that happened but my mechanic took care of it and got a new coil too

 

+1.

 

Had the same symptom, fixed by replacing all the intake gaskets. If one is bad then the others just as old. FWIW


Jeff Pintler
89 348tb, 86tr, 99 360 3pedal, S-160 Bobcat

 

Thanks for the help guys

I swapped the coils between cylinder 2 and 3. Lets see if the problem moves over.

I checked for any signs of leaks in the intake manifold gasket, can't see any residue or anything, but I'm not ruling it out.

Will keep you posted