Solution to my limp home problem - PeachParts Mercedes-Benz Forum

anziani · #1 03-08-2011, 12:33 PM

The car is a Federal '93 300CE that I have owned for 2 years. It came with a peculiar problem in that it went into "limp home" at the start of each day within 1/4 mile of my house. No ASR light and stopping and restarting would clear it for the rest of the day. Changed all of the usual suspects: brake switch, OVP relay, micro switch on throttle linkage, 2 different throttle actuators, speed sensors front and rear, brake light connections and holders, ASR controller, new tires, new engine temp sender, all to no avail. Error codes still pointed to the ETA. Then the Cruise Control failed. Found a used "E-gas" controller although EPC calls it a "Cruise/Idle" controller. Installed it and the limp home has STOPPED. Didn't solve the Cruise Control problem but a new stalk switch should do it.
Anziani
'93 300CE 195K
'95 E420 122K

anziani · #2 03-08-2011, 03:08 PM

I SPOKE TOO SOON!!! Drove it this AM and limp home has returned.
Anziani

EricSilver · #3 03-08-2011, 04:30 PM

Battery? Believe it or not I still have not changed mine because it refuses to die, and I have been living with this intermittent issue for 3+ years.

At this stage, limp mode is triggered when the temperature drops below 50 or so. (In the summer high heat and humidity will cause the same).

You specifically said "No ASR light." Are you referring to the yellow one on the lower right of the IC or the one above the tach?

deanyel · #4 03-08-2011, 04:46 PM

With no ASR light what makes you think you're in the limp home mode? Are you saying you put in a non-ASR control unit? Anything named cruise/ISC would typically be a non-ASR.

anziani · #5 03-08-2011, 04:49 PM

Eric,
I think we are doomed! Let's keep the gas cap and drive a new car under it.

Anyway, it is the ASR light in the speedometer that doesn't come on. In fact, nothing lights up but all lamps are working and I can get the ASR light to fire if I take a corner with gusto.

My battery is new but the weather out here is in the 70's and the mornings are about 55F.

Can another CCU be in my future?

Anziani

anziani · #6 03-08-2011, 04:53 PM

Deanyel,
No it goes into limp home. RPM jumps to 1500, gas pedal to the floor to get it moving, all of the classic symptoms. Goes away with a restart.
No the E-gas controller is the correct part number for this car with ASR. I use EPC and Dave Hendy has been a big help in this.
Anziani

EricSilver · #7 03-09-2011, 09:19 AM

Quote:

Originally Posted by anziani

Eric,
I think we are doomed! Let's keep the gas cap and drive a new car under it.
Can another CCU be in my future?

Anziani

Your problem is still likely electrical in nature quite possibly in the computer.

Considering how much you have spent so far, and the likely upcoming costs, it might be worth considering a replacement. (Nice '02 E320's are about $9K now.)

anziani · #8 03-09-2011, 11:51 AM

Eric,
I have too much money in it now to sell it. During all of this, I needed a new head gasket and a starter. Car is an absolute joy to drive now. I've told my family that when I die, just dig a large hole here in the desert and bury me in the car.

I am the poster boy for:
"No hay nada mas caro que uno barato Mercedes"
Anziani

EricSilver · #9 03-10-2011, 11:10 AM

Quote:

Originally Posted by anziani

Eric,
I have too much money in it now to sell it. During all of this, I needed a new head gasket and a starter. Car is an absolute joy to drive now. I've told my family that when I die, just dig a large hole here in the desert and bury me in the car.

I am the poster boy for:
"No hay nada mas caro que uno barato Mercedes"
Anziani

I can definitely understand the sentiment. And | love how my car looks and performs, and will likely never get rid of it, but if an

expense larger than about $3,000 seems forthcoming I will opt for a new(er) daily driver.

EricSilver · #10 03-10-2011, 11:41 AM

On a stroll down Memory Lane I found the post with my very fist mention of the ASR issue, along with photos of my car, which I had forgotten I posted. Hard to believe it has been 3 years.

200K Miles, One More Time…

ohiomike · #11 03-11-2011, 07:17 PM

Some of these cars go thru O2 sensors quickly. It could that or a throttle control. Throttle controls are expensive at dealer so get a rebuilt one from Florida place that rebuilds them. (do a search)

deanyel · #12 03-11-2011, 11:09 PM

Quote:

Originally Posted by ohiomike

Some of these cars go thru O2 sensors quickly. It could that or a throttle control. Throttle controls are expensive at dealer so get a rebuilt one from Florida place that rebuilds them. (do a search)

He's been through two throttle actuators already. I've heard it's theorectially possible to be in the limp home mode without an ASR light but I've never heard of it actually happening, not once in thousands of LH mode instances. I would try to get someone to read the sub-codes on pin 14.

anziani · #13 03-12-2011, 01:10 PM

Deanyel,

I have no explanation for it but I don't get an ASR light. You mention subcodes. Is this a dealer visit? I didn't think the blinking light code system was that sophisticated.
Anziani
'93 300CE
'95 E420

deanyel · #14 03-12-2011, 01:47 PM

A dealer could do it but so could many independent shops. In other words you need more than a flash code reader. With the right equipment there's an additional level of detail available on several of the pins on the 16 pin port.

PS - when you say you have no ASR light we presume you mean your ASR light works and it doesn't come on, not that it doesn't work.

anziani · #15 03-13-2011, 01:20 PM

Yes, the ASR light does NOT come on. And yes the ASR light works on the initial start-up display of all lights. When I get on it on a cornering maneuver, it lights right up.
From the git-go this has been a strange problem. M.B. Doc thinks it is an electrical problem. Before I bought it, the car took a mild hit from the right rear. $300, a new tail light and some paint took care of it. We have looked at all of the wiring in the rear but nothing was out of ordinary. We changed out the rear speed sensors just in case. I have another CCU on the way. If this doesn't do it, I am running out of choices.
Arthur Dalton gave me a tip a couple of days ago. He suggested cleaning #5 and #7 fuses and pushing in the "snow chain" switch on the first commute. Fuses are all new but I tried the switch method yesterday and no "limp home".
Will see what today brings but tomorrow will talk to the dealer about a scan.
Anziani
'93 300CE
'95 E420