88 300E Sputtering Problem
 

Please excuse the charaterization of what it is doing. The car will run great for about 15 to 20 minutes. From a stand still will run fine. After about 15 to 20 minutes it will sputter off the line where you have to play with the gas peddle to get it going and even flor it to get off the line. I have just replaced the fuel filter as I thought that might have been the problem. The one I took out was original and had water and ugly stuff coming out of it. Just put in a new battery in last week because other one was 6 yrs old and failing. Pulled the ovp behind the battery and the fuse was good but changed it anyway. The check engine light is on. How can I check why it is on to start with and what might me my problem. As usual this site is great for help and would expect nothing more.

Thank you for your help in advance.

I am having the exact same issue...My guy tells me the cat converter is shot...so I am waiting to get it in the shop...it is like when it is cold no prob...did you also notice that if you shut it off and then re start it after a few seconds it reverts to the same stumble until u floor it again? I am watching this post for more possibilties...

Sounds like a plugwire issue.

check the ignition coil - if it is original replace it (won't hurt anything anyways). My 87 had the same sort of problem and the coil was the issue.

usually when the cat goes bad, it creates a restriction in the exhaust and things heat up rather fast, and it runs hotter then before. Does your engine get to it's normal operating temperature? 15-20 mins sounds like the time it would take to come off of a cold mixture, and lean down to the normal run mix.

wow great advice----coil sounds like a good idea...it may have gotten wet fro FAY out here in SFLA...coils really go out tat ways? I am nuts too...There is just no possible way that a fuel system would allow a car to run, and then just like crap out and let it stutter and bog. I am gona get a coil...will report back....

There are a lot of threads on here that detail this problem and other possibilities. The coil wouldn't just die because it got wet, but apparently when they do fail its on a partial fail basis. Something to do with the inside of the coil and the way it works - beats me though.

Another thought, check the dist. cap/rotor and the wires and plugs. Again, same thought as the coil, if you haven't replaced them, it might be the problem, might not, but in either case it will only make the car run better.

If you search, there are threads that also reference the temp sensor on the engine (I believe) and the crank position sensor as possible problems, along with vacuum leaks.

There is also the possibility of carbon build up on the back of the valves, in which case you should run some injector cleaner and drive the car harder.

Last but not least, it could be the fuel injectors/fuel injector seals. Apparently if these are bad, the result could be a similar problem to what you describe.

Hope all this helps. Its not as detailed as other posts on here, but it gives you a starting point to search out the more technical answers. Good luck w/ the coil.