When you say "stumble," do you hear anything that sounds like preignition when it's under a load? I'm talking about what it commonly referred to "valve ping."

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

I mean a flat spot, miss, stall, hesitation almost die out.I dont think it is anything like a ping from using lower octane gas, or bad timing etc.

It can vary from almost a hiccup , to feeling like the engine stopped completely for one second or more, if I do not back off on the pedal . It varies according to how aggressive I am on the throttle.

More gas when it happens, it almost dies totally. Less gas it hesitates/sputters for a shorter period of time. I think I just instinctively back off on the throttle when I feel it , so as not to cause any damage.

Feather the throttle and no problem whatsoever. I have become very proficient at feathering, and could probably drive witout breaking an egg on the gas pedal.

The few times I tried to power thru it by giving it more gas, the engine just felt worse and nearly died completely on me.

Do you get a puff of exhaust smoke when you start it after it has been sitting over night?

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

Now that you mention it , my first mechanic out of certified MB mechanics thought it was coils. His partner said caps / rotors. I replaced caps/rotors and plugs plus 3 suppressors .

Maybe I should change coils. They are not very expensive to do?

I wasn't really thinking coils. On my old 400E, I had a problem where the engine was severely pre-igniting under a load and it did not have any power at that time unless I backed off like you were saying you had to "feather" the engine.

It always occurred when it was up to temperature and under a load. What I think was happening was that the valve seals were leaking oil into the cylinder after I shut it down for the night and the oil was coking up on top of the pistons. Once the engine got up to temperature, I think the deposits were causing an independent source of pre-ignition. The ignition module has the authority to retard the ignition if it is pre-igniting and it will result in a loss of power like you described.

The good news: I ran two quarts of Chevron Techron through one full tank and it absolutely cured the problem. I couldn't believe it. I thought I was in for a new engine, but the Techron totally solved the problem.

It was either the coking of oil on the cylinders or a clogged injector that was leaning out and causing detonation. In either case, it is very cheap to buy this at Costco by the 4-pack. Make sure you changed your oil after you run through a tank full. Maybe it's not the problem, but it sure is cheap to find out.

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

I have run 2 cans of Techron thru in the last 2 tankfulls of gas. I am running a Lucas additive that is supposed to clean injectors as per my mechanics instructions.

But what you are describing is what my hesitation/ flat spot feels like. I have never looked at the exhaust when I first start it up in the morning , but from inside the car I have never noticed anything like that .

I will look when I start it tomorrow . Would I not be low on oil if I was losing it thru valve covers. I will check that also ,as I never check my oil level between changes , only when I dont trust the mechanic who last changed the oil/filter combo .

No one mentioned changing oil after either additive ?

Maybe the Techron is making it run better lately. I used two quarts of Techron to one tank. I saw a remarkable difference.

The oil usage from leaking valve stem seals was not even noticeable on my car because I changed oil every 2,000 miles anyway.

Someone on this forum suggested that I change oil after running a heavy dose of Techron because some of the carbon or gunk it breaks loose could end up in the oil. It sounded like a reasonable precaution.

Are you sure you're not hearing any valve ping at all when you first accelerate? The 119 engine has a pretty high compression ratio. If an injector was clogged and one cylinder was leaning out, I would think it could cause detonation.

Are you running at least 91 octane?

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

Yes, change the oil after the Techron treatment. I don't know about the Lucas, but the same probably applies. It's because some of that strong detergent ends up in the oil, compromising it.

What ever happened to the spark plug wires?
Regards, Eric

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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.

I just realized I did not answer this suggestion. I have had the air filter housing off 3 or 4 times. I have looked at breather hose and it looks OK and I mentioned it to my mechanic and he said it is OK .

I always run 93 Sunoco or BP . I dont know what a valve ping sounds like . Rememeber most of my tests are done in NYC and there is a lot of external noise . Is a valve ping loud?

One time I would swear I heard it backfire. Also when we were in the country checking for wires arcing it was 11 Pm and we did it on quit country roads. My wifes cousin who was helping me, used to build and race track cars (Mustangs ) and he test drove it and said it was dying, sputtering, but never mentioned valve ping.

These dam storms are stopping me from getting it on the road and burning that Lucas additive out Grr

Here is a link to a temp thread I started as someone said my temp fluctuations are abnormal and could be causing me problems

http://www.peachparts.com/shopforum/tech-help/272258-engine-temp-fluctuations-normal-not.html#post2413559

MY new mechanic test drove it when it was warm and breaking up under load , and changed his theory about plug wires. Now he says they are not the problem .

He made me use a Lucas additive and is searching for used injectors to swap out

Well I just went down and started the car which was parked overnight with a friend looking at the exhaust. When it first started it blew a whitish grey smoke he said. I turned it right off.

I switched positions and within about 30 seconds fired her up and I saw what looked to me like whitish grey smoke also.Turned her off .

I waited about 1 minute and had him start it up again. Whitish grey smoke for the first few seconds.

What relationship does this have to engine breaking up when warm and under load ? Does it have any connection with injectors that my mechanic wants to try/swap out with used ones?

I described the possible relationship leaking valve stem seals would have to your hesitation in the post above. You can live a long time with leaking valve seals, but if the oil accumulates on the top of the piston, it could give you detonation or preignition problems that would cause the ignition to retard under a loan. I don't know for sure if that's the problem, but I believe this is what happened to me and the Techron solved the problem.

I haven't read much about fuel injectors going bad on the 119 engines. I would ask your mechanic if he did a bleed down check on them first before he started swapping out injectors. The injectors expensive ($200 each). If he gets in there and disturbs the engine wiring harness (most of the wiring harness consists of injector wires), you could end up with more problems than you have now.

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

I misunderstood. You are saying the coking up could cause intermittent stalling under load when warm . I have been reading so much , I am having a tough time focusing .

Would the white smoke show up 3 times in a row, and not burn off in the initial start ? Its because I am not sure if it was white or grey or a combo of the two, and I have never looked at my start up exhaust before

I also spoke to a MB dealer parts guy , who has his job for 12 years and said the injectors were not particularly problematic in the 119s. He was going to swap them out with used injectors from another car. I am not quite sure if he was borrowing them or what ,as he did not mention money to me at all.

I will tell him to be carefull ,and watch that he be especially carefull when switching injectors if that is what he wants to try next!

I am sorta putting myself in his hands , with suggestions from you guys also to check out by myself if possible , or run by him .

Before I would let anyone start swapping injectors, I would build the code reader and pull the codes. I didn't read if you changed the fuel filter. If it's clogged, it could cause the engine to lean out and you could experience similar problems under a load.

You can either spend a lot of time and money throwing parts at the car, hoping that you get lucky, or you can pay to have a good MB tech trouble shoot it for you. Many of us here prefer not to take our cars to a tech because it's kind of like admitting defeat (at least that's how I feel).

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