2 Merc Questions for the Price of One

[Tepper]

I've recently bought an '89 Mercedes 190e, it's a 2.0 automatic. Which should be slow, but not 'can't keep up with traffic' slow.

The engine seems sweet enough and starts and idles very well when cold, it also seems to have the power it should do just after you start it from cold. However, very soon after it starts to warm up, it seems like it doesn't pull anywhere near as well as it should (it's much, much slower than my old 1.8 190). It can hesitate, especially as it revs past about 4,000 rpm. We have checked the induction system over for air leaks and reset the position of the airflow metering plate - everything seems fine to me. The car has had a service recently and most of the ignition system seems to be new. There is a fair bit of pressure in the breather system but it doesn't smoke, not sure if that has anything to do with it. So... any ideas?

The second question - can anyone recommend a good dent/scratch removal place in Reading/Berkshire? I backed into a post in the dark that I made a point of looking out for...
Alternatively are there any good products or methods for polishing out scratches on painted plastic bumpers?

Many thanks.

[chairchild]

No idea on the second point I'm afraid - but does the metering head have electronic controls going to it, or is it a nice purely mechanical setup?

If mechanical, it sounds like it may be over compensating when the engine's warming up? Quick way to tell, is to unbolt the warmup regulator block thingie from the engine (there's no coolant flow going through it, just heat from the block) Without this warming up, then it can't reduce fuelling when the engine's warm.


Obviously it's not ideal - but may help to diagnose the fault, and find the actual problem

[fred]

May be your auto box bands slipping or low on trans fluid

[Tepper]

Thanks for the replies people, always helpful.
The injection system is interesting in that it should/can run without any of the electrical bits. The metering head does have a plug on the side of it, which I believe is for the electro-hydraulic actuator. This changes the mixture according to a signal from the ECU. This forum post has been very helpful to me so far: mbworld.org/forums/e-class-w124/400937-ke-jetronic-diagnosis.html

I think the problem might lie with the EHA (the Merc troubleshooting manual describes my exact symptoms and says to check the EHA), or possibly the lambda sensor, but for now I'm quite confused. I don't want to just start replacing things to try to sort out the problem! I'm going to poke at the car with a multimeter this evening to see if that sheds any light on the situation...

Good idea about the transmission but I've just changed the fluid and it all seems fine to me.

[TurboDieselWeasel]

Hi!

There's sort of a fault code that can be read, have a google for 'duty cycle', but your multimeter needs to be ableto measure duty cyle or at least dwell angle. This allows a quick diagnosis

Suspects are water temp. sensor, air intake temp. sensor, lambda sensor and the EHA of course. Also the throttle position sensors can be faulty. Read a bit into it, if you'r handy with the multimeter I think you'll find the error soon. For the KE the fuel pressure values are also very important - if you can, get a reading of the fuel pressure!

Don't be tempted to fiddle with the mixture screw on the metering head; this should be the very last option on a KE-Jetronic

And last but not least; check the lobes of the camshaft! They are known to wear a lot, they'r too soft. As far as I'm aware, this problem was not resolved untill the end of '89, so your car might very well have that failure...

Next on the list; a faulty Over Voltage Protection (OVP) relais can cause funny behaviour of the whole system...

And then the 'standard stuff: How's the fuel filter? Split fuel lines? Broken vacuume tubes? Etc.

[Tepper]

Thanks for that DieselWeasel, I have read about the fault code system but my car (1989) doesn't have pin 3 on the diagnostic connector, which is the pin that outputs fault codes so far as I know. It also doesn't have an air intake temp. sensor, or a lambda sensor - I had a look under the car and also under the carpets to see if I could find the wiring. Is there any way to get fault codes from the car without pin 3? Or do you know what any of the other pins do? There are 9 pins in total.

I think the OVP is okay, because cold starts aren't a problem and the idle is usually fine, which I *think* indicates it's working? I'll check the camshaft soon as I'm planning on doing the rocker cover gasket, the thermostat is currently stuck open as well so I'll be changing that too. I haven't checked the fuel filter yet or the fuel lines, but we have checked for vacuum leaks.

My gut feeling is that it must be something related to the temperature of the engine, because when you start it up first thing in the morning it has much more power than usual. Also, the fuel consumption is pretty awful and there seems to be a lot of white smoke from the exhaust. Keep the suggestions coming...

[TurboDieselWeasel]

Oh weh... Does it have a cat converter?? Resp. is it the 118 or the 122HP engine? Sorry, I'm not familiar with the cat-less KE at all...

[Tepper]

I don't think it does, there is definitely a box of some sort before the final silencer but I don't think it's a cat, plus the ignition control unit isn't marked 'KAT' or 'EZL'. I think it's 122HP but I'm not sure. I think I'm just going to have to check all the sensors against spec. one by one.