M102 running on 3?
 

Car was working fine, had been no problems for quite awhile, when I parked it in the garage a few days ago. Went to start it yesterday, and it starts up but feels like idling and driving on 3 cylinders. I replaced ignition coil, cap, rotor, plugwire set, and swapped out each plug in turn - no change. No conclusive change for the worse if any plugwire pulled - unfortunately I don't have the guts (or the right tools) to do it while running. I pulled the cam cover, but saw no missing or wobbly rockers or other obvious problems. No exhaust vapors of any kind noted while running in this condition, plugs all looked fine and about the same.

What are the odds for a clogged screen to one injector, or a sudden failure in the fuel system to cause this behavior? Is there any other place to look first? Looking for a direction here? Thanks for any help!

Steve

Did you check the compression. Either no fire, no fuel, or no compression will cause only one cylinder to skip or I forgot about this a vacuum leak on the affected intake rail

Unfortunately, I don't have a working compression gauge. However, I would think an improperly closing valve would get noisy (but maybe not with hydraulic lifters). Since this was sudden, no overheating or other associated events, I'm hoping compression is not as likely as simply a blocked fuel distributor port? Anyway, I'll have to get a gauge to be sure. Thanks!

Steve

Pull the coil wire from the distributor cap, let it crank for awhile. Take the spark plug out of the suspect cylinder. Sniff for fuel.


Hope this helps.

I would bet you have a clogged fuel injecor. I'd swap injectors with the suspected cylinder and I bet you the problem will move. I dunno why, but it seems that these fuel injectors get dirty really easily.

Yep if you have spark at all four I would look at the plugs first as described! It is easier than removing the injectors to check and make sure fuel is getting to the chambers. Pull the coil wire and crank her over a few times then check the plugs. That may help figure out if it is an injector and which one it is. If it is an injector I would pull all four and soak them in carb cleaner for about 15 minutes. Then wipe them clean! You can then spray them down with carb cleaner, then spray into them. I had done this before and noticed that one injector allowed the carb cleaner to go right through it. Once I was done with them none of them allowed the cleaner to go right through. If you indeed do need new injectors they are pretty cheap online, 25 bucks a pop roughly. I got four new ones and noticed no change over the old and was told by a few MB Techs that these injectors rarely fail and it is normal for them to just get gummed up. After all this if it is an injector you should dump a can or two of Injector cleaner in your tank! Good Luck!

Dan, Skiier, and Jamie, thanks for the posts. Great tip on plug-sniffing. This morning I tried that several times, but gas smell was weak at best by the time I would get the plugs out. Still, I never did smell it at all on plug #1, even though it was the first removed. Injectors and seals were quite new, as I replaced them less than a year ago after deciding spray pattern on some was not the best. That move did not cure whatever the issue was at the time, so I knew the old batch was still usable. So, I swapped out an old one for the current #1 injector, and that has solved the problem. I guess it is back to stocking up on Techron from Costco!

Thanks a bunch for the advice everyone, it has saved me at least a lot of extra fretting and wasted time before getting our car back on the road!

Steve

Yep probably had a bad new injector as well. Apparantly the QC on them Babie's is not what it used to be! lol