W140 Limp Home Mode, but no ASR light - PeachParts Mercedes-Benz Forum

kustom81 · #1 09-21-2006, 08:00 PM

I know there is alot of ASR questions on here. However, I have a 93 500SEL w/ 140K miles. Today, I was on the highway for 20 miles, got off, and when I accelerated, it went in to what feels like the Limp Home Mode. (Had that problem with a 94 I had) BUT NO ASR LIGHT. I turned on and off the car. That would always reset my old car. I did go to a car wash today, could something have gotten wet? Des anyone know what else causes LH Mode, other than ASR? Car runs great otherwise, and has plenty of oil pressure, etc.

Thanks

pcmaher · #2 09-22-2006, 08:25 AM

There are many things that have to work in concert for this system to work properly. Model years 92-95 have a known wire insulation issue that could also be the problem. The insulation on the wires degrades over time, and it will crack and fall off. This causes shorts in the wires. I would suggest you first see if there are any fault codes stored. If not, check the wire condition of the Electronic Throttle Actuator and Air Mass Meters. There are also potentiometers in the ETA that can go bad over time. I'm attaching a few links for you to read...

http://v12uberalles.com/AMM_rewire.htm

http://v12uberalles.com/throttle_actuator_rewire.htm

http://pages.prodigy.net/jforgione/MB_asr.html

kustom81 · #3 09-22-2006, 09:30 AM

Thanks,
I just thought those things had to do with the ASR light coming on, and maybe this is transmission related???? I have a very good Indy in Cedar Rapids. I will get the codes read.

suginami · #4 09-22-2006, 12:41 PM

After reading those links, out of all of the things that could cause a limp home problem, you're wondering if it's transmission related?

kustom81 · #5 09-25-2006, 10:23 AM

Mechanic just called. He said the Auto Protection Switch on the Tranny was bad. It caused the transmission into the limp mode. ( Shifts bad, retards timing etc.) I also had a leaky trans line up front under the bumper. $400.00 bucks to fix. Better than I thought.

kustom81 · #6 09-28-2006, 11:11 PM

mechanic fixed the tranny stuff, but still starts up like there is a load on the engine. low idle rpms, and no peddle response. Any suggestions? Feels like limp mode, but no lights on on the dash.

JimF · #7 09-29-2006, 11:01 AM

Not sure it's "limp home" mode from what you describe, so here's a few observations.

1) LH forces the car to idle at 1000rpm.
2) The accel pedal does not respond as it does normally; you can press down and nothing happens until you get to a point where it will respond.
3) The car doesn't shift normally; it won't go into 4th gear when driving unless you get the "rpms" up using a lower gear.
4) The ASR light is on.

Are you experiencing symptoms like this??

kustom81 · #8 09-29-2006, 01:37 PM

Jim, thanks for your answer.
On start up, very low RPMs, feels like it is going to stall. But also feels like there is a load on the engine right away. Very hard pedal response. Crawls from a stop, and shifts are somewhat hard, but after awhile, I can get it up to speed through the gears. The tranny will shift, but I need to lift my foot off the pedal for each shift to catch. Can drive it on the highway at speed, with no missfire, etc. Pretty smooth actually, but if I let off the gas, it takes awhile to get back up to speed. I have no ASR or CEL light on. Like I said, I have had ASR faults on my 94 S500, so I know what that feels like. This feels close, but I am not sure. It has been awhile. I will try a tune up when the parts come in. I almost think it's tranny related, because of what I just had fixed, but why does is run terrible at start up in Park. Is there a tranny limp mode that does not cause the ASR light to come on? Could it be the crank position sensor? That 17 code would not clear, my guy said. I don't want to get into the whole ETA thing, but I thought that usually triggers ASR light, etc. So my fingers are crossed. Car has been pampered and you could eat off the engine. Wiring looks great, and spent its life in upstate NY, so was not subject to heat all year, every year, like in CA or FL MBs.

I have an '02 Mitsu Montero 4 wheel drive that I will drive for the winter. Nice car but harsh ride. I miss my MB, and want my 500 back!!!!!

Thanks for any advice
Eric

tower · #9 09-29-2006, 02:35 PM

Does the exhaust really stink? I lost one of the coils on my 95s420. No power, idled really smooth (incredibly). Ran as if no power. Had to have a long lane to get up to any speed. Sounds similar to yours.

kustom81 · #10 09-29-2006, 03:09 PM

I am not sure if the exhaust stinks, but I did smell gas under the hood once, while poking around. I will look at that when i do my tune up.

Actually, while I am doing that, is the best way to check the coil (like the old days), pull the coil wire and crank it see if there is a spark??
Thanks for the idea

pcmaher · #11 09-29-2006, 04:05 PM

Hmmmm...maybe a monster vacuum leak somewhere?

Brian McL · #12 01-17-2009, 04:03 PM

I now this is old BUT was this issue ever resolved?? I got it too!

deanyel · #13 01-17-2009, 04:25 PM

Better to start over with a new thread with a proper title, and a complete description of what you've got.

Brian McL · #14 01-17-2009, 04:40 PM

Yeah...I have posted it a couple times with no help. I was hoping to go to someone who has had the problem rather then have them come to me...if you know what I mean.