Engine management problem 93 W124 220E 4cyl. - Benzworld.org

Guest (MBNZ) · 11-16-2001, 05:19 PM

Recently bought a 93 W124 220E with HFM electonic control system (at least I think it is- it has the Air Mass meter etc). Dont think this 4 cyl model was released in the US. I'm located in Australia. Am told no CD available and Haynes W124 very superficial. 
 
When I first drove the car it was good on the open road,stumbled a bit at traffic lights,and tended to surge from around 700rpm idle to around 850rpm whilst waiting.Couple of times didnt seem to respond to accelerator.Lately it tends to stall after very rough idle.Still fine when running at speed,but still sometimes completely non responsive to pedal. 
 
Had it checked out,scan said MB fault 009. Air Mass signal too high. Put in a brand new Air Mass unit - cleared fault history, retried scan said same thing.Went back to original unit Now says same thing also fault MB 023. O2 sensor voltage too high.That sensor is brand new- prepurchase inspection said the existing one was suspect. 
Tied new overvoltage relay no change.Cleaned every connection I could find. Still the same.Wiring all looks OK some looks new. 
 
Anyone got any ideas? All I can think of is the ECU.-that sounds like disaster costwise.

Guest (MBNZ) · 11-22-2001, 02:09 PM

Further to the above,I've got part way to solving the problem and this may interest others.It is not just relevant to this model. Pulled the lambda sensor. Not only did this turn out to be non original-it had 'Ford' on it. More importantly when soldering the wires to the sensor,the work had be sloppily done resulting in a short between sensor heater current (12/14 volts)and sensor output (around 1 volt?) No wonder the fault code said voltage too high! Moral of story, if you are going to use an aftermarket lambda sensor without the mercedes plug,be VERY careful with your soldering and DONT rely on heatshrink for insulation. Despite what I have read elsewhere on this forum I would stick with the mercedes unit with plug. Other fault still looks like ECU problem - possibly caused by sensor overvoltage.

Guest (MBNZ) · 11-30-2001, 02:32 PM

Hi there, I was reading your messages and thinking 'I'm not alone'. 'Down under' there are someone experiencing the same problems on their beloved Mercedes! I'm in Portugal, just across the planet, and my car's idle (a 1991, W124, 200 TE) is disturbing me. The engine never stalls, however lacks power (sometimes!) and the idle is always out of tune and in traffic lights goes down and down again to stop/wondering around 800 rpm. I've tryed everything but... the annoyance remains. Once, after a long 'web search', I found an Australian guy and his company INTERJECT. (http://www.users.bigpond.com/INTERJECT/product.htm) Apparently, he knows quite a lot of fuel injection systems. Since he's not represented in Portugal (there's a representative in Germany) why don't you try his expertise and products and then tell me if it works? All the best Paulo

Guest (MBNZ) · 12-05-2001, 10:44 PM

Many thanks for the reply Paulo. Been a week since I checked for messages my apologies for the delay.Certainly I'll try to contact INTERJECT. I did find a competent local guy here on the Gold Coast, but although he has all the gear,he doesnt run a website. It WAS the main electronic control unit-the one right at the back behind the battery with the double multiconnectors.Also somebody found it previously - it had 'AIRMASS FAULT' written on the back of it! Had to sent the ECU to Melbourne for possible repair- they found me an exchange unit for about US$500.00 not too bad.Relacing the ECU cleared everything except occasional engine cutout. Traced that to either fuel pump relay- the small green cube behind battery on LHS or the over voltage protection relay-tall aluminum relay (siemens) behind battery on RHS. Changed them both and now the car is running as it should. All up cost about US$1000.Going after shonky dealer and incompetent repair shop. It doesnt sound as though our problems were the same.No sure if the 91 &93 motors had the same HFM management system.The Haynes manual I have is very basic and not much help.I assume youve checked the obvious? I once found a plastic bag in my aircleaner blocking the intake! Dirty injectors might also give you the uneven idle but it sounds more like sensors. Best regards Adrian