M119 LH Slight “drop-outs” or power reduction, especially when using cruise control

[phoenix217]

Hi, a quick technical question about my W140 S500.

My other M119s don't have this "problem" so I don't know where to start troubleshooting. But bear in mind that this is my only M119 with LH.

Same phenomenon under two conditions:

1. When I use the cruise control for a steady speed, I have a short drop out every 30-60 seconds. It feels as if an ECU is minimising or cutting off the fuel supply for a short time. Possibly to avoid exceeding the set speed. Can anyone confirm this? Preferably with a comparison to the 210 or 211 where this is not noticeable (in relation to cruise control).

2. Every now and then, when I am not using the cruise control (usually at half throttle, if I am observing correctly), the engine has a brief interruption. This feels similar to what I described above.

What has been done:

- Both distributor caps and distributor fingers are new (OE and Bosch)
- Spark plugs are new (OE)
- Ignition cables are new (Bosch) *to be fair, two are still "old" from 2020 (NGK)
- LH module converted to 5L (same problems with 4.2L module)
- EZS converted to 5L (same problems with 4.2L module)
- Crankcase breather and all other rubber parts (OE)
- New timing chain (OE)
- New upper chain guides (OE)
- Inspected cylinders (very good condition for 345,000KM)

The E-Gas module is still the original. Would that be an option?

I also thought about the engine wiring harness. However, it is not crumpled or damaged and has been renewed in around 2010.
The knock sensors also work and the harness looks good so far.

Thanks in advance!

 

[R129 UK]

Does the car have any kind of aftermarket alarm / immobiliser etc.?

 

[phoenix217]

Does the car have any kind of aftermarket alarm / immobiliser etc.?

Nope. All original and the EDW is deactivated/defective per HHT. Never confirmed if it's installed at all.

Would that have any impact on driving?

 

[lowman]

its probably the Egas module that is acting up. Pretty common. Had the same symptom on my old 1992 500e. I replaced mine,and it fixed the issue.

 

[R129 UK]

Nope. All original and the EDW is deactivated/defective per HHT. Never confirmed if it's installed at all.

Would that have any impact on driving?

I know of a car where the fuel cut-off for the immobiliser was intermittently causing the fuel pump to be momentarily shut off - it took a huge amount of fault finding.

I also had a car where the cruise control was affected by an electrical gremlin which took years to identify.

 

[gsxr]

What you describe is unlikely to be related to the ignition, or even fuel control. The new upper harness won't fail again unless damaged and is also unlikely to cause what you describe. If there's no fault code for the knock sensors, or the E-GAS, those are probably fine (and are NLA anyway).

1) Are there ANY fault codes on any modules which recur?

2) What is the age of the ETA? If rebuilt or replaced in the past, how many km's are on it? The ETA can cause all sorts of weird problems. Usually there are fault codes, but not always. Failures of the E-GAS module itself are, IME, very rare.

3) I've encountered similar hesitation to what you describe, although at a shorter fixed interval (i.e., maybe every 10-15 seconds, not 30-60). This could be related to a vacuum leak, only effective way to find one is via a smoke machine.

 

[phoenix217]

1) Are there ANY fault codes on any modules which recur?

There are no fault codes.

2) What is the age of the ETA? If rebuilt or replaced in the past, how many km's are on it? The ETA can cause all sorts of weird problems. Usually there are fault codes, but not always. Failures of the E-GAS module itself are, IME, very rare.

I replaced the E-GAS module with a different one from an S420 - seems to be better but the fault still occurs. Today we have high humidity and it's raining. Could be related.

As I do not know the history of the car itself and especially the engine swap, I have to assume that the ETA has 340,000KM or more on the clock.
I know that these can wear out apart from the internal insulation breaking. So I'm probably looking at a rebuild for 500 Euros from MKB.

Do you know if I can mix 420 and 500 ETA's? Or are they the same?
Edit: I just checked. Part numbers are identical. My car has ETS - do you know if I need an ETA with or without ASR?

3) I've encountered similar hesitation to what you describe, although at a shorter fixed interval (i.e., maybe every 10-15 seconds, not 30-60). This could be related to a vacuum leak, only effective way to find one is via a smoke machine.

While checking the transmission fault (which is diagnosed, transmission is rubbish) I checked the vacuum system. No leaks there.

 

[gsxr]

Your car has ETS? Was it a diesel originally, prior to the engine swap? AFAIK the 140.04x had ABS standard with optional ASR, and 140.05x had ASR standard... but neither had ETS available.

There's a date code on the ETA label, see what that shows. It's unusual to have an ETA failure with no fault codes and no limp mode, but it is possible.

 

[phoenix217]

Your car has ETS? Was it a diesel originally, prior to the engine swap?

Nope, some gasoline pre ESP W140's came with ETS. I had to check with some people before buying differentials.
Part number for the ETS/ASR module is A0024319812.

AFAIK the 140.04x had ABS standard with optional ASR, and 140.05x had ASR standard... but neither had ETS available.

I have an ABS and ASR light in the dash. ASR = ETS in my case. So I probably need an ETA with ASR.

There's a date code on the ETA label, see what that shows. It's unusual to have an ETA failure with no fault codes and no limp mode, but it is possible.

I'll check at the next oil change in a couple of weeks. The car is still very driveable (aside from the transmission, but thats getting swapped to an 722.6 either way).

 

[gsxr]

I think your car has ASR, not ETS. The hydraulic unit under the hood is shared between ASR and ETS systems, but I suspect it should have an ASR control module in the CAN box, and should not have an "ASR" warning indicator in the instrument cluster with ETS. Also, the EPC shows the "ETS" module grayed out for the 140.04x chassis. I'm only seeing ETS as available with either diesels, or the 6-cyl cars.

The ETA is completely different between ASR and non-ASR cars. The ASR ETA has a white decal and the throttle plate will only open half way. Non-ASR ETA has a green decal and will open fully. They require different control modules also, ASR uses E-GAS, non-ASR uses T/LLR. (ETS uses yet another module.)

I believe ESP was not available until the facelift cars, along with the 119.98x engine and 772.6 transmission.

Check your datacard, look for either option code 471 (ASR), or code 212 (ETS).

 

[phoenix217]

I think your car has ASR, not ETS. The hydraulic unit under the hood is shared between ASR and ETS systems, but I suspect it should have an ASR control module in the CAN box, and should not have an "ASR" warning indicator in the instrument cluster with ETS. Also, the EPC shows the "ETS" module grayed out for the 140.04x chassis. I'm only seeing ETS as available with either diesels, or the 6-cyl cars.

The ETA is completely different between ASR and non-ASR cars. The ASR ETA has a white decal and the throttle plate will only open half way. Non-ASR ETA has a green decal and will open fully. They require different control modules also, ASR uses E-GAS, non-ASR uses T/LLR. (ETS uses yet another module.)

See the pictures attached. I have an ASR/PML module + ETS hydraulic block - is that the reason for the ASR indicator in the dash?

I believe ESP was not available until the facelift cars, along with the 119.98x engine and 772.6 transmission.

That's what I found as well.

Check your datacard, look for either option code 471 (ASR), or code 212 (ETS).

I have neither.

 

[gsxr]

Your car definitely has ASR, not ETS. The reason for no code 471 in the datacard is likely that when it was produced, ASR was standard equipment. All E500E's also do not show 471 in the datacard, for the same reason - it was standard, you could not order one without ASR.

So yes, you need an ETA for ASR (white label) and it must have the correct / matching connector type (likely the late-style "tubular" connector, not the big old pancake connector).

 

[phoenix217]

Your car definitely has ASR, not ETS. The reason for no code 471 in the datacard is likely that when it was produced, ASR was standard equipment. All E500E's also do not show 471 in the datacard, for the same reason - it was standard, you could not order one without ASR.

So yes, you need an ETA for ASR (white label) and it must have the correct / matching connector type (likely the late-style "tubular" connector, not the big old pancake connector).

That explains a lot. Thank you!