My M119 Engine stuttering, not reving past 3000 rpm, and looks to be running rich.

[amerh]

Gents,

Having some engine problems, that to date my mechanic has been unable fix. Seeking any advice you can provide.

First some background.

Car was running well, but wouldn't rev past 4000rpm. Had my mechanic try to find the problem.

The error code that came up was: Code 4 Voltage at mass air sensor with hot wire circuit. Open or shorted circuit.

At this point, the mechanic looked at the upper wiring harness, and it was in bad shape. Had to order a new wiring harness for the car, which took about a month. In the meantime, most likely due to further shorts from inspecting the very bad wiring harness....the car would stutter, not rev pass 3000, and smoke was coming out the exhaust...car looked to be running rich.

So having installed a brand new upper wiring harness, the car still suffers from the same issues. Stumbling, not reving pass 3000, running rich.

When he checked the codes post installing the new harness, two codes came up. He managed to clear the injector code, but cannot clear the original code: Code 4 Voltage at mass air sensor with hot wire circuit. It will not change with the meter plugged in or not, won't clear.

Would greatly appreciate any help on this.

 

[amerh]

Trying to provide more clairty:

The code that first appeared and cannot be cleared is:


FAULT CODE TABLE

DTC Readout
4

Possible Cause of Failure
Voltage at mass air sensor with hot wire circuit. Open or short circuit

Just trying to get some insight into what could be causing this.

Thanks again.

 

[195910]

Why did he look at the MAF itself ?

 

[r44raven]

Sounds very much like my experience recently with a failed MAF - stumbling idle, reluctance to rev, masses of unburnt fuel out the back etc. etc.

I don't know what (if any) fault codes were present, but the problem was solved when a replacement MAF was fitted.

P.S. MAF NLA from MB - and I wasn't able to find any company that was able to refurbish my unit. I eventually sourced a good one from a 500eBoard member.

(What are we going to do when the source of used MAFs runs dry?).

 

[amerh]

Hope it is not the MAF....cheapest source seems to be $1000CDN for a replacement. Yes, those do sounds like the exact symptons my 500E is experiencing.

Anyone know a source for a rebuilt MAF? After having spent $900CDN for the upper wiring harness and install, need to find a cheaper alternative.

 

[r44raven]

I have obtained a spare MAF from:

AutoECMS, 124 Wynchurch Circle, Pittston, PA 18640.
www.autoecmstore.com

If I recall correctly, it was described as "refurbished", and cost me $225 + $100 core charge, refunded on return of old unit, plus shipping.

When it arrived, it certainly, for a "used" unit, was very clean, but I cannot be sure what actual work was done to qualify it to be described as "refurbished". I was just happy that, on checking, it was serviceable!

 

[gsxr]

AFAIK, it's not possible to "refurbish" the MAF anywhere outside a Bosch factory. Any claim by a seller along those lines probably means a good cleaning, and hopefully, a proper test via SDS.

 

[Duh_Vinci]

When I purchased my 1995 SL500, had the very same issue and the same black smoke, same codes, Socket 4: code 4, plus socket 19: code 10 "Voltage at Mass Air sensor too high/low (along with many others). Original owner had new harness installed, plus bunch of other things, along Bosch re-manufactured MAF. I ended up being a bad MAF, re-manufactured, but bad. Ordered good used from Ebay (with 100% money back guaranteed), same issues, sent it back, since at that time dealer had NO re-manufactured units or new units available at all! Found one through car-part.com - all codes cleared, no repeat of the same issues ever since! See if you could find a good used one?

Regards,
D

 

[amerh]

Thanks folks. Looking like we will need to source a new or good condition used MAF.

Anyone have an extra one they are willing to part with?

 

[195910]

Thanks folks. Looking like we will need to source a new or good condition used MAF.

Anyone have an extra one they are willing to part with?

Unfortunately, the MAF is NLA from both M-B and Bosch (both 0280 and 986 numbers) !!
I know because I bought the last Bosch unit in Europe (yes i called 7-8 different countries for the M-B or bosch unit) and I already checked in the US.

I do have a really clean one with only 30-35tkm. But do check locally first.