I drove to the country to check. We pulled the wire covers off and looked at idle , revving under load, when warm , NADA. My dealer mechanic had checked them and changed 3 suppressors but in his opinion the wires were ok


A mechanic in another forum PMd me this comment in regards to whether the EGR valve could be causing my problems and I quote him


"Of course.... the Exhaust gas recovery system can cause havoc with the Intake and idle/acceleration, especially with a sufficient leak to ambient pressure and temperatures... remember the gas recovery system is trying to pump the recovered gases back into the intake for extra fuel economy... this can especially foul up the air/fuel mix... perfect is .460 volts (actually called 460 milli volts) not rich and not lean....
But actually falling into Lean territory due to emission standard... but the leak throws it off and really fouls up acceleration and cause missing and stumbles..

Good Job! Great diagnostic effort... kudos all around for you! Hope you feel good! You never gave up... keep a close eye on those vacuum 1/8" vacuum rubber lines connecting the 1/8" nylon color coded lines... all extremely important as well as the secondary air injection system and Exhaust Gas Recovery valve and tubing as you have discovered... all are important and I cannot stress this enough... ALWAYS keep eye on these systems for maximum performance! "

Its really difficult to believe a 50 cents piece of hose could be the problem, after spending $700 on 2 mechnanics and parts.
I only hope he is correct and I will be driving around the city today 2-3 times and I will post back my results. Time will tell

I have not checked for DTCs but my Dealer mechanic said it showed no codes. Maybe I should make that reader and not beleive mechanics any more

When I turn engine to position #2 I see from left to right HIGH BEAMS, BATTERY,WASHER FLUID, RADIATOR, OIL CONTAINER , LIGHT BULBS HEADLIGHTS ETC,

Then on the right hand side of cluster ASR, ABS, A CIRCLE WITH BRAKE DRUMS AROUND IT BRAKE LINING LIGHT,PARKING BRAKE,SRS, SEAT BELTS, for a total of 12 lights believe there is another on top in center for ASR indicator .
There is a triangle with an exclamation point in the middle of it , in the cluster above the center where it says MPH not a ASR warning or it may double as an ASR warning as I remember seeing something when driving in snow

Is this what you are referring to as a Check Engine Light ? I am not familiar with what it looks like. In my wifes Mazda it is an engine bock that flashes

No CEL

Well Eric you are right again. I drove this AM for 30 minutes and it drove without a hiccup. 2 hours later I took it for another extended city drive and it takes 25 minutes or more to get to over 80 C. Then i drove it up a few hills and it stumbled again albeit for a much smaller period of time.

It seems to be getting better and maybe something in the gas is causing these problems like someone stated. How long should it take in city driving to get to 80C. If I get on a highway ,temp drops back to 70C. Is this a sign of something bad. I just had my coolant flushed and refilled with Benz coolant around september .

Just remember this car only has 83K miles on it and a dealer mechanic who looked it over for 2 hours , thought the wires were fine when he changed 3 suppressors and 8 spark plugs

Tomorrow I am going skiing and its about a 70 mile drive. My first experience with the problem was after a highway drive and then getting into stop and go driving .

I will replicate those conditions tomorrow two times, and report back .
I guess it was wishfull thinking that the broken EGR hose could have been the source of all my problems . Grrr

I think you should be able to see the writing on the light cover without the key being on. I just checked mine and I can see it. It should say Check Engine. Mine is all the way to the right. I can't imagine yours not having one. https://docs.google.com/leaf?id=0B-WRh0Hf7VdZMmQ3YTgwYjUtYTRkZC00YTY2LTk2YWQtNWM4NmY3N2E5OGZh&hl=en


It is possible that the prior owner disconnected the light and tried to hide the lens cover. Build the code reader and see what codes you're getting. This may point you in the right direction.

__________________
1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

The large variance in highway to city temperatures are likely caused by a failing fan clutch. I have replaced a few. Here in the desert, there's no such thing as a "close enough" repair to the cooling system. Every part is tested in normal driving every day and it has to be perfect, including the radiator cap.

As for the hesitation and stumbling, I, like Eric400, would be very suspicious of the engine wire harness. Not the spark plug wires, but the engine wire harness. I think 1993-1995 were the affected years for this biodegradable insulation, which if I read correctly somewhere else, was the doing of the German government environmentalists. Yippee for government intrusion!

But I digress. Any time I have suspected wiring issues, I, if possible give the harness a push/tug while the engine is running. If there's a problem, it'll likely show up. The reason I'm suspicious of this is not just the year, but the symptoms. If the harness is bad, get out your wallet.

Also, when checking the plug wires in the dark, even if you're under a street light, the dancing voltage can be seen and is more likely to show up if the high tension (spark) wires are introduced to moisture. What I have used in the past is mother's plant spray bottle. If you don't have one, I'm sure you can pick this up at your local Wal-Mart. With the engine running, simply spray the wires with a fine mist of tap water and look for the dancing arcs. If they're not there, its not your problem.

I think 1992 was the last year for CIS-E, but I'm not sure. If yours has a different style fuel injection system, then I don't know much about it. However, one question came to mind as I was reading through this entire thread was; what about the throttle position sensor? If it has a dead-spot, then wouldn't that cause an issue?

Fuel additives do little to curb this kind of hesitation/misfire, but do wonders to the upper cylinder and valve area inside the engine.

Moisture (water) in the fuel is a possibility, but unlikely to be consistent and RPM specific. Though it wouldn't hurt to drop a bottle of HEET into the tank every now and again, just for peace of mind.

That's about all I have to offer. Good luck!

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

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My cluster is different from the one you posted . In the far right of the cluster is a seat belt icon and the light bulb icon is on the left side of the cluster . I listed them in exact order from left to right and mine has ASR first and I cant see what yours has there due to flash .

Your right side does not have the same order as mine that much is certain . Oops I just saw yours is and E series and mine is a S series so yours has a different cluster .

I have to make the code reader if I cant get my mechanic to draw codes. When I told him caps and rotors did nothing he siad bring it in tuesday for him to check out , he had some other ideas .

I assume the scanner he has , will draw the same codes as the LED I should make ? Correct? Or is the LED better ?

I think the dealer's scan tool is much more sophisticated, but does not give the codes as we DIY's know them (the number of flashes on our LED testers). I was talking to my tech about a DTC 19 and he looked at me like I was an alien. Apparently theirs tells you in English what's wrong. You should keep looking for your check engine light though. It's got to be there somewhere--even if it's an S-Class.

Here's a link to Jim Forgione's home brew tester. Scroll down to the bottom of the page.. http://www.k6jrf.com/MB_X11.html

The thought just occurred to me: have you checked to see whether you have an aux diagnostic X11/21 switch with LED in your engine compartment, like the one in the picture in the link above? At least you could check the Diagnostic Module codes with this.

__________________
1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

Spark plug wire arcing will not be visible unless it is totally pitch black unless the wires are really bad.

Your M119 W140 is definitely a LH-SFI not the CIS-E. Same would be true even if it was a 92.

While you are on Jim F's site, you should read about and then do his "cool harness" mod. He tells you how to do it yourself (It's very easy) or you can buy his plug in kit. I swear by the mod and many guys who are way more knowledgeable than me swear by it too.

California cars got the self diagnostics system and the "Check Eng" light that goes with it before the rest of the country did so it's possible that your car didn't come with it especially if your car is an early 93. All 92 and later 500Es supposedly got this system regardless of whether or not they were Cali cars but my buddies 92 500E doesn't have it. It is an early 92 BTW. The point is if your car doesn't have it, it doesn't mean something is wrong.

Another crazy thing that has popped in my head is the possibility that the cats are beginning to plug up. I don't think this is "it" but it's something to keep in the back of your head if all else fails.
Regards, Eric

__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.

Ok I am going on this one day ski trip today which will only cause the same problems anyway.Grrr I am going to make Jims or one of the testers I have instructions for a Radio shack version and I positively do not have the LED light in mine , it should be right next to the CAN and I have checked 3 times .

I will wait till engine is really warm to test, as I am quite certain dealer mechanic did not wait 25 minutes for engine to get up to 80 + Celsius when he ran his tests.

Thanks

P.S. By the way did you find Jims air conditioning page . I had printed it out about 5 years ago ,and I cant find it now in my bookmarks or on his site .

He had the DTCs you could get my manipulating the buttons in certain positions at certain temps . That is what I have been using for my coolant temperature reading, which is more accurate than guessing what the cluster gauge says ( I HOPE )

This sound like degraded fuel, we see this a lot. Runs ok at lower rpms, then when asking for more, they stumble...

The original poster and I have the same car, NO Check Engine Light. I believe it only exist with California Models with the Diagnostic Modules.

thx
chedeng

Well I am glad we cleared that up . Chedeng I have Pmed you .

Here is todays diary entry Grrr

Well I just finished my skiing day trip. First of all engine temp stays around 71 on highway. At good speed without traffic (55-65 MPH with outside temp 1 C ) stays between 67 to 71 . After getting closer to ski mountain drove at lower speeds for about 25 minutes , the traffic for a few minutes and temp got to 82C and then a couple of stop and goes and got no stumble.
I was in a rush to ski so I did not do excessive testing.

On the way back to city, engine temp stayed around 70C on the road ,in the city it got to 98C and then stumbled at 1500 RPM. Then I drove to a small hill with temp of 99C no flat spot.
Went around again to same hill at 96C stumbled for a fraction of a second.
Maybe this is off the wall , but should temp be that low at highway speed 70 C and then fluctuate so quickly to 98C when I get into city traffic, and then drop to below 70 on the highway again. If not could this be sending some wrong signals to some sensoors ?
I have never had an overheating problem till this summer when coolant low sensor went on, but car temp never got to RED line in brutal heat.
Could a fautly temp sensor cause any problems like the ones I have? Or a thermostat or anything not ignition related but more cooling system related. I have been monitoring engine temp like a cardiologist monitors blood pressure etc , and maybe there have always been these fluctuations , and I am first noticing them ?
Bottom line is the stumble/hesitation when over 80C is still there , but not as often nor as severe.

If your freon is low, it will cause the low speed fan not to come on when the temp starts to creep up (in city driving). It sounds like an unconnected issue though.

__________________
1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

I just went out and drove around in this storm with the car both cold and warm. On flat spots and up hills. Both feathering the throttle and mashing it .

First of all the car NEVER stumbles when cold , under load (hill) aggressively, under load (hill) practically full throttle , under load (hill) feathered throttle like pressing on an egg etc., on flat ground under all conditions imaginable, IT NEVER STUMLED COLD !

It also idles perfectly regardless of temperature.

It stumbled one time when warm (over 70C) and stumbled fairly consistently once it was over 80C when I tried aggressive acceleration, over flat ground or hills . The more throttle I gave it te more likely to stumble. At WOT it took 2 tries to get the engine up to speed .

There are 2 constants , that can be considerd constants, as part of an intermittent syndrome in my mind .

#1 It will never stumble COLD regardless of throttle pressure .
#2 And it will not stumble loaded, unloaded , hot or cold , as long as I feather the throttle.

Someone suggested the fuel pressure regulator because it only happens when I try rapid acceleration , and that takes more vacuum . Does the amount of vacuum vary with engine temperature?

When I say cold, I mean from first starting out with engine running less than 45 seconds in 35 degree outside temp (below 40C bottom of temp gauge ) straight up thru approx 70 C .

And if it stumbles on quick start at 70-72 it is only once in ten tries.

What varies exclusively with temperature. I do not know at what engine temp car goes from open loop to closed loop but I think that at 65-70C after 3-4 minutes of driving it is prolly closed loop.
Still no problem till it hits at least 80C usually. And the hotter it gets , the more likely it gets that it will break up on hard acceleration, regardless of hilly or flat.

And why regardless of everything else, very light feathering does not create a problem ?

I asked the new mechanic again today, and he said he pulled the hose on the fuel pressure regulator and said it was OK. I think he said it did not leak . Does fuel pass thru it ?

Any new theories anyone ?

My mechanic is tryng to locate a used injector rack to throw on for a test