95 E320 Wagon Erratic running
 

I have a 95 E320 Wagon with 122,000 miles. recently and intermittently it has started cutting out at 1500 rpm. this will only happen 1 time out of say 50 starts. what happens is as i accelerate, when the tach reaches 1500 rpm , the engine appears to cut out and then comes back at approx 900-1000 rpm. Even if I stop the car and push the accelerator it will not cross the 1500 rpm barrier. when I stop and restart the car sometimes it will repeat the same problem until after a few more tries it runs normal again. other times it will immediately run normal. seems to me that something has an occasional short somewhere which is causing this. As I said befor this may happen once a week or once a month. very frustrating. Anyone got any ideas or previous experience.

Sure I have had the same..., read my thread; Third summer in limp mode.

I have still no clue what is causing it, can be many things, mainly electric as I understand it or possibly vacuum leaks?

The "limp home mode" as it is called is to protect the engine from damage by cutting the revs at 1.500, thus also protecting you from getting totally stranded.

Read also JCWELLS thread on throttle actuator, giving the same problem.

The wiring harness is the no 1 suspect in our model years, but I have checked mine for any faults without finding any. Should be that the plastic insulation deteriorates since it was made by an environmentally friendly composition. It is not known however if this was the case on all markets.

So, my only hope is that me, you and jcwells soon will find out the cause and post it here for us and others to benefit!

L.

Yes, I am currently experiencing similar problems, 1500 must be the max RPM in limp mode.

To begin the diagnosis:
Is the check engine light on?
Have you made the code reading tool that will allow you to extract the error codes from the various engine modules? (Check the archives)

That would be a starting point.

John

With the lack of other symptoms, the miles and year of your car I would investigate the wiring harness first. Many, many go bad (mine did) in the M104 engines. Search 'wiring harness' and put aside a few hours to read all the posts.

Did you ever fix this problem, or find the source of it? My car has this exact same symtom. It seems to occur more the day after it rains (maybe a result of the dampness causing a short somewhere). I am having my throttle actuator replaced as we speak, due to a surging idle/low idle/stall/etc. problem, and hopefully the problem that you describe will go away. I had my wiring harness replaced a year and a half ago, so hopefully the throttle actuator will fix it.

Matt
'94 E320 158k

Actually no.

I didn’t have time to trouble shoot the problem over the summer and after learning you just had to turn the car on and off a few times to get it out of limp mode I figured my wife could use it till I get around to it. Actually the next project is to put her 82’ 240D back on the road (paint job) so I have a reliable vehicle to give her when I start digging into the 320.

Over the last 2 months it has gone into limp mode 1 more time.

I believe my next step will be to replace the harness, eliminating this known issue.

John

Matt, How much was your throttle actuator job? Curious so I can plan ahead.

I'm not sure of the exact amount yet, but I'm pretty sure that my mechanic paid $1050-1100 for the part from the dealer, and he told me it would take 2 hours of labor to put in. So, he will probably charge me $1500. But that's just a guess/estimate.

Matt

Matt

Please keep us posted on whether this cured the problem.

Thanks,

Haasman

Ok, throttle actuator was replaced, and the car ran great for the first day and today, the third day.

The second day, I took a trip (350 miles) and the idle was too high. The cruise control did not work on the trip, and the car idled between 1300-1800 in Park, and 900-1000 in Drive. I hit some traffic along the way, and I had to constantly have my foot on the brake; the car just wanted to move, as if the throttle was stuck open. If I took my foot off the brake, the RPMs would increase slowly as the car picked up speed (this is with my foot off the accelerator). Without touching the brake or the accelerator, the car would go about 10-15 miles an hour on level ground. And since it was raining, I can't help but link the wet weather to the car's quirky behavior.

Is there any other device that would cause the cruise control not to work (besides the fuse, which was ok)? This is my main concern, because I thought that the cruise control was linked directly to the throttle actuator.

Could the throttle actuator be defective?? Maybe the Mass Air Meter is bad? Could the wet weather cause some kind of malfunction in the electronics? What about the computer (is it called the ECU?), could it be defective?

I appreciate the help.

Matt
1994 E320 158k