I wanted to check to see if anyone could help with the hesitation and stumbling problem. This ia a 91 190E 2.6 having the problem. Start up is fine and taking off is good, but if you turn the air conditioning on after start-up and they try to move out it will hesitate & stumble. If you step down rather quickly it will die out. It could do this a couple of times. Once it's going a ways like a block or two with the AC still on and stop and re-start there is no problem. I've read a lot of problems with the threads on Climate Control, but didn't know if this was a possible cause or not. The R-12 is ice cold no problems there. The cooling from the R-12 refrigerant is hard to beat, I think. Any help to trouble shoot problem would be appreciated. Thanks

Sound more like a fuel mixture issue.

Most likely too lean, possibly the coolant temp sensor is out of spec when cold.

Also with 10% ethanol in most fuels...the issue can be somewhat normal.

Have you tried different fuel?

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
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27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thanks for the help on this. Beings you mention the coolant sensor, I wanted to air that sometimes after driving the car and stop & park. The coolant temperature on switch would be below the middle bar on a hot day. I would get back in it in 3 or 4 minutes & start it up. Then the temperature guage would be a ways above the middle bar & the cooling fans would come on and run till the guage dropped down below the middle bar. I didn't think this way maybe right?

Rebe, your last post is a bit cryptic, but if I'm following it, you are saying that after the motor has come up to operating temp and is then turned off, it will be hotter when turned on again after a short time. If that's what you mean, that's how mine is too, and I believe that to be normal. That's the effect of heat soak causing the engine to actually get hotter while it's not running because there is no air or coolant circulation during that time to keep the temp down. But that's only a momentary condition. As soon as the coolant pump is running again and there's some airflow over the radiator, the temp should come right back down to "normal" operating temp, about 85C or so.

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

Your car has several temp sensors, one for the guage, one for the fuel system, one for the cooling fans...they do not work in conjunction with each other.

So the one for the fuel system could be an issue.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Wow! there are several sensors that could be involved. My question is what kind of test gear can be gotten that will work on these old cars before the OBDII. I have noticed like referral to a Lambda tester?? Would like to be able to do scanning on it, without just throwing money at it. Thanks!