What about the EHA? Has that been checked? I have a friends 300e that does not want to move fast because of a leaky EHA

Sorry to hear of all your troubles

Forget symptoms and what happened to someone else. Go back and look at cause and effect. The car ran fine until you changed the plugs and wires. These cars are notably finicky about their plugs and less notably but more finicky about their wires. Phil's part number for the proper Beru wires you need is W0133-1609626. Plugs have been debated here endlessly, but as a guideline, Bosch H9DC before 5/88 and H9DCO after 5/88.

Could you have killed a sensor by putting one tank of 87 octane in the car? Of course its possible but not as likely as by substituting proper parts with known cheap substitutes which provide the wrong resistance at the wrong place in the electrical circuit. Start with the plugs and wires. I will leave others to comment on cap and rotor, but believe you will find the first two items will resolve the bulk of the problem.

I thought about this too after reading yesterday. The only issue with this is that it would not run like it is. I am replacing with MB recommended parts next week. I really think that the Cat is clogged. I am going to disconnect it this weekend and see if it changes anything. If it does I am going to punch it out and replace the entire exhaust next month. Thanks for the advice and I will post what I find.

Oxygen Sensor
 

My car had the same issues and were resolved by replacing the oxygen sensor. You state that the car idles fine when cold (oxygen sensor running in open loop until heated) but after the car warms up it will start to stumble (oxygen sensor in closed loop).

I believe I read in one of your earlier posts in this thread that the car will stumble unless you go WOT (again oxygen sensor running in open loop).

The wiring for the oxygen sensor enters the vehicle cabin right in front of the passenger seat. Lift up the mats on the passenger side, move the seat all the way back and look for the connector there.

Unplug the connector while the car is acting up and see if that clears up the stumble.

Do 93 400 SELs have an OVP problem also ? I have intermittent stmbling upon aceleration at bewteen 1400-1800 RPM . Could this be that OVP that everyone is talking about.

My mechanic said there was a lot of rust in the battery well in the trunk and he was suprised to see that

IIRC, MY '93 V8 motors no longer had OVP relays, and even 6 cylinder motors were phasing them out.

IIRC what does that mean ?

UPDATE
 

Well today I drove 25 miles on a highway ( LIE) to go change caps/rotors. Got caught in traffic for the last 10 miles so engine got to around 98 C (I Use K6JRF a/c diagnostics to display engine temp in a/c window) and it missfired pretty hard 2-3 X. Actually sounded like a backfire .

Got to the mechanic who swore without seeing car that it was caps and rotors that were the problem. He changed them and said the old ones were bad. I took them with me to look at . Dont ask me what I am looking for , but you can tell me what to look for ,and he said they were bad.

Drove the car all around long island for 30 minutes and it hesitated a few times but for a much shorter duration and less frequently than before , at least in my mind thats what I thought.

I drove back to the new Mechanic and told him it is better but still not right. He said its not the MAF, as I had that in mind to work on next . He says it prolly is the suppressors on the spark plugs. I told him I should change wires totally and he said just change suppressors. I told him his ex boss at MB dealership , who is shop foreman of mechanics, changed 3 suppressors and said if that did not solve it, plus changing all the plugs that the dealer did, I should change wires next . New mechanic said wires in my model car do not go bad. Grrr . Opinions

The new mechanic said also to change fuel filter when I change wires, to protect against bad gas . I might just change filter and give that a shot before I spend $$ money on wires. Does anyone think that could be the cause ?

I thought maybe give the sensors time to acclimate to the new rotors and it seemed better for a about and hour in stop and go, start and restart. After 45 minutes driving I accellerated quickly from a toll station and it stalled for a fraction of a second as opposed to 1-2 seconds as before.

Then I got into NYC and drove around in traffic and the hesitation although "MAYBE" not as severe is still there . Obviously the car gets warmer in NYC traffic and thats where I really have to be able to have the car run perfectly, to say it is fixed.

It looks like this is becoming a parts changing , guessing game for me .
I thought I would do the MAf cleaning but this mechanic says that stuff is garbage . So many mechanics, so much disagreement .

I am going to look tomorrow night at the wires to see if they are arcing and MAYBE disregard what he says and do a MAF cleaning . Or I could just change the fuel filter, unless I have an obvious arcing that I can see .

Again the problem happens and gets more frequent the warmer the engine is . Grr .Is there no way to diagnose this problem without just changing parts arbitrarily? He did not put a diagnostic tool on the car and I will call him tomorrow and ask him why not .

What should I look for on Caps /rotors? I am getting a daily headache from this.

The only good news is that this guy is very fair, pricewise and seems very honest .

Any other thoughts guys. I am going to take 2 tylenol .:)

Insulation does not last forever, and if you have no evidence that the wires have ever been changed, at 15+ years of age, they are highly suspect. If you have a record that they have been changed within the last 10 years, verify that they are OEM replacements (dealer or Beru), and then move on to something else. If original, arcing is an obvious sign, but they are past their useful life prior to that point.

I am the second owner and bought car in 1995 with 30K miles on it so I know for certain that they are original . I have all the service records from 116 miles till now.83K

So all the other possibilitys , CTS sensor pippettes , breather hose , hose to regeneration swithover valve, loose or worn injector connector, wire to CTS sensor, fuel filter, MAF I have read about are not the likely cause.

I guess I was hopefull that it would be something less expensive and more definitive as I have been told that the problem is coils, caps and rotors, plug suppressors , plug wires and plugs, and possibly injectors, all by either current or past certified MB mechanics.

I have changed plugs and 3 suppressors by MB dealer , then caps and rotors by ex dealer mechanic. So I have spent $700 so far and nothing is better . In your opinion regardless of arcing or not, I should change the plug wires.

I will check tonight for arcing but I will buy the Beru plug wires for $304 from ******** AZ . They are OEM . If this does not solve the problem I will commit suicide :)

Then I have to change brake booster hose, do a tranny fluid /filter /gasket change ,fully charge the a/c (I have had the evaporator etc changed 4 years ago), and possile motor and tranny mounts.

So I am trying to spend my $$ on the most urgent things first and as I only drive about 4K miles a year , do them as needed.

The truth is I really hate to spend money on something that is not positively identified as the culprit. But I guess we live in an imperfect world


P.S my new mechanic recommends Lucas Power steering sealant fr my PS which I forgot to mention. He also said he uses Lucas tranny something when he does the fluid flush filter change
Thoughts anyone

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.

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 :)

new info
 

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 ?

clean your air mass sensor, change your gas filter, and check the pressure on your fuel pump. disconnect your negative only, and let sit for 15 minutes. Put your key in the ignition turn it on, and then connect the negative, turn your car on

So what did you find?