The bad news is all the rubber/plastics under the hood which perform a sealing or insulating function is approaching or past serviceable life. The better news is that many of these parts are relatively inexpensive, at least compared to sensors/mechanical components.

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1988 300E
1993 300SL
1994 540i

If I have a problem with my Mercedes, I go to MercedesShop. If I have a problem with my BMW, I go to BimmerNut.
If I have a probem with my Dell, I reboot it. I was an engineer for them for 10 years and we blamed everything on Microsoft.

Well waited till dark and after dinner me and my cousin opened up hood to see if there was any arcing.
We took off air filter housing and removed drivers side plug cover, no arcing. Decided to pull passengers side plug/wire cover off , absolutely no arcing.
Was sure to wait till engine temp got to over 8O Celsius no arcing . Looked at the wires when at idle, and loaded engine in gear no arcing .
I saw the 3 suppressor wires that dealer/ mechanic had said he changed, they were red colored caps so now at least I know which cylinders he thought might be suspect. Plug wires looked really good , even my cousin said he was surprised that after 17 years they were supple not dried or cracked or anything. No arcing at all
Looking around engine compartment to get an idea if anything else was obviously wrong and we found a vertical plastic hose coming out of a bundle that went in to an L shaped black rubber hose that connected to what looked to him like an EGR valve that is aprox 8-10 inches in left hand corner in front of the throttle body.

It is seen in the front left hand corner of the second photo of post #9 in

http://www.benzworld.org/forums/w140...nder-load.html


In case the photo does not come thru I will describe it as best as I can.
The part that the broken hose went in to was approx 1 3/4 inches in diameter and looks like a flying saucer .

Well since the plastic hose was broken off about 1/4 inch from where it went in to the black rubber hose we pulled the broken plastic part out.

There was not much play left in rubber hose but it seemed we were able to reverse the L shaped hose, and sorta stretch it and get it back on the valve. We thought we found the problem . Drove the car and it made no difference .

My cousin was not sure that the stretched hose was making a good connection and allowing the vacuum to function, so we left the hose off the valve entirely and I drove home 25 miles. Car drove perfectly without hose attached at all, and did not exhibit any hesitation, when I got back to city upon aggressive accelleration. I did not expect it to ,as highway driving kept engine temperature around 60C and it usually only happens after 80 C is reached.
It is possible that the repair we made stretched the hose so the vaccum could not function properly , but if that in case, is not the fact, then what is this valve that made no difference being unattached ?
So no arcing, and since it is past midnight , I will buy a new L shaped hose and attach it tomorrow and hope that is the problem.

It also is possible the 2 mechanics messing around in the engine compartment changing plugs ,and then rotors broke the hose/plastic piping .

What is that vacuum part called, and what does it do. Is it possible to be my problem?

Still lost

I put on new hose to EGR valve and drove around for 40 minutes in city traffic . Up hills and not a stall at all . Engine temp got to 98C and I drove up a 15% hill to really put it under load and it drove fine.

Then I stopped for a cup of coffee and after 15 minutes started her up and without waiting 30 seconds, pulled away on a flat road, and it hesitated again at 84 Celsius . Drove for another 5 minutes and it did not happen again . Drove for another 10 minutes after 30 minute break and it did not happen. Went to dinner and after 80 Minutes drove for another 10-15 minutes (engine was warm @ 80 C ) and it drove perfectly again.

Thats a total of one episode of bad performance in 5 different quick tripstotalling about one hour of city driving .

Do you think the hose made it better and the computer has to relearn something now?
I will be driving it again soon and see how it is

As to whether the EGR valve is functioning I have no clue how to check that and I am not concerned with it either. Only care if car runs well and does not hesitate / bogg down upon hard accelleration between 1400 - 2000 RPM, and is it possible by replacing the vacuum line to the EGR this is the result ?