Ok, this is a bit of a long story so please bear with me.

I picked this up for $500AU not going. Its now a daily driver but still has some issues I need to sort out.
The engine is the M104 IL6 3.2L engine with HFM injection and VDO ECU as found in 90's E320 et al. The engine and power train in these cars are 100% Mercedes Benz and not 'license built' copies, they are genuine Benz right down to the part numbers so I use MB parts if I buy new stuff (partly because the only Ssangyong dealer in the state is next to useless for parts.)

The original 'not going' problem was due to the infamous OVP relay having internal dry solder joints. I repaired these and the vehicle started immediately. 1st win. Windscreen wipers didn't work, was about to replace the motor when a fellow Musso owner suggested that if it had been standing a while (it had) good chance the linkages in the air intake box under the windscreen were seized. Drowned them in WD40 and they started to work. 2nd Win. There were a few minor issues with door switches, interior front light switches etc that responded well to WD40 and patience.

Prior to my getting it, it had dropped the timing chain and had the head rebuilt by a Mercedes mechanic, new valves, chain, guides, cam sensor etc. Aside from one slightly noisy hydraulic lifter, the engine is mechanically excellent, not a trace of smoke and uses virtually no oil.

Otherwise, mechanically it seems fine (though the front CV joints are getting clicky and will need replacing) and the brake pad warning light is on so need to do them soon too. It's done around 215,000km so far, about 2000 of those since we got it. Trans seems fine, no leaks, no overheating etc. Shifts are a bit rough when the engine is missing or otherwise misbehaving, but smooth when its running well (when cold in other words) AC works good, interior is good and all the lights, bells and whistles etc seem to work fine.

Now to the existing issues.

Problem 1. Missing. Seems to be an 'under load' thing. Back off the throttle a bit sometimes and it will run evenly again. I have changed coil packs which seemed to improve it, but it's still doing it. Once you get to cruise speed it seems to settle and not miss, even at fairly high speed, load it up by putting your foot down and it will usually start missing until you back off the throttle.

Problem 2. Won't increase power from idle, particularly under load. This can make it 'interesting' to drive as you try to take off from an intersection and it will barely increase the revs from idle, so you find yourself idling across an intersection with traffic bearing down on you... You can hear the change in intake sound from the throttle butterfly opening, but no increase in power. As it very slowly picks up, it will get to around 1500/2000 rpm and then it will pick up more or less normally.

Problem 3. Cam sensor error from read of computer. The original sensor was smashed when the cam chain let go. It was replaced with a new one at the time, however the computer says it's not there. I've measured 2mv pulses that look right at the computer and the sensor was again changed with one from a working Musso M104 with no change to the outcome. I have checked the spacing from the cam shaft tooth and it's within the specified .5mm. I fully expected changing the ECU to fix this problem but it made no difference, so I suspect it's a problem in the cable somewhere. The Musso doesn't seem to have the 90's wiring harness degradation issue - not sure why, but suspect the harness might be Korean rather than Mercedes made, but not sure, regardless all the wiring looks good.

The first two problems are not present when the engine is dead cold. It doesn't miss and the it accelerates from idle normally. After about 5-10 minutes running the problems appear.

So far, I have replaced the following components trying to sort this:
1. Cam Sensor (Twice)
2. Throttle body. (replacement used but had around 99,000km on it)
3. Coil Packs. (Used but supposedly good from a working engine)
4. ECU (Used but supposedly good from a working engine)
5. HFAM Sensor New aftermarket unit put on before I got it - but after reading about issues with non Bosch ones, replaced it with the original, which appeared only to need cleaning. Did that and it seems fine. Computer says it's ok so it's in the vehicle for now. Disconnecting the HFAM does not alter the miss/no acceleration issue one way or the other.

5. Crank sensor (unrelated to the stated problems, engine stopped and refused to start after a week or two of intermittent 'sudden deaths', which I suspect were an intermittent fault in the sensor. Replaced with new, no further issues in that area. Car starts almost instantly regardless of temperature.

I am now considering fuel injectors. These have been replaced prior to my buying the car, not sure when, but they appear to be used. I only know they were changed because the old ones were in a box in the back.
I changed the throttle body thinking that the throttle position sensor might have been crook. It did seem to improve it a little, so perhaps it was on the way out, but I'm pretty sure the sensor in the replacement is fine, as I said, when it's all dead cold, it runs fine.

I am going to change coil packs with brand new ones on general principles but I don't think they are the problem to be honest, so I will try injectors first.

Aside from the cam sensor fault, the computer is not showing any fault codes. Clearing it still sees the cam fault come back after one run of the engine.
I'm going to try running a length of RG58 from the sensor to the ECU and replacing the existing coax that goes to pin 8 and pin 19 on plug 2 of the VDO ECU.

I am using a clone Vag-Com USB cable, appropriate adapter to the 14 pin round plug on the Musso and HFMSCAN on a laptop to read and clear error codes.

I've considered sending the old throttle body and ECU away to have them rebuilt just to be certain, but there is no one in this country that seems to do that. I've messaged a couple in Europe, but they don't seem interested.

So, my questions are:
1. Any ideas about any of these faults?
2. Any ideas about somewhere I could get throttle body or ECU rebuilt?

ECU is standard as fitted to E320 et al. Marked '3.2l 6 Zyl' Numbers below from HFMSCAN.

System: HFM
Manufactured: VDO
Ident: M0 32853 VR0
ECU Nr: 162 545 30 32
Hardware date: 00/00
Software date: 04/97
Diagnosis index: 45/01

Any ideas or hints very much appreciated. I've never owned or worked on a Merc system before - so I'm learning as I go. I really like the car and thinking our next vehicle will be MB all the way - local mechanics seem to hate them with a passion (which I find hard to understand as they seem to be pretty straight forward once you understand how they work) and there is no local MB dealership anyway (nearest is 225km) so need to sort it myself really.



Regards

Geoff
Port Pirie
South Australia