Thank you for your help! Will let you know what trail I take.

Every mechanic I talk to, despite the feedback that I convey from what I learned on this forum all say that, no way, the potentiometer is hard to put in by itself and they will not do it. They also have said that anyone on this forum is just simply very talented and ingenious.

I hear you and I understand that you have done it successfully.

Yes, all new parts have been thrown at it except the fuel distributor and air flow meter. They also said that I have good compression and was happy about that for it has a ton of miles. I wonder if the putting in the two new fuel pumps temporarily somehow made something worse? Can increased fuel pressure further damage a failing fuel distributor?

All 3 techs have said that there is only so much one can test the air flow meter and the fuel distribtor and the only real way to know what to replace is to go by a hunch through experience.

What is frustrating is that 1 tech has one opinion (AFM), another tech says fuel distributor, and another tech say could be either.

Hey Matt, Check something for me. I just got done undoing this one. The 560 shop car needed a chain soooooo, I rolled a new chain and guides in it. In the process of 458 distractions I missed the l/h cam by one tooth. Car idled a lot like yours once warm and ran a lot like yours hot. Once I took and popped the valve covers off and looked I just dropped the tensioner and moved it a tooth. Runs like a top now. (hey we all have our moments)

It would be worth a look anyway. Just pop the valve covers, put it on TDC and see where the cams are in relation to the tdc marks on the bearing towers. Might be the culprit. I still dont think the car needs a fuel head.


Joe

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Acme Automotive Inc.
Raleigh NC
919-881-0364

One of the MAESTROS in the forum have spoken

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
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The latest is that the original tech put in a used fuel distributor and another set of wires. The tech says that the stumbe at idle is gone, but there is a "miss" on cylinder #5 and that it there is a 1/2 sec stumble during acceleration. He is still working on it.

The last tech said that my compression was around 150 psig on all cylinders, but the original tech that the compression is much lower than that due to mileage.

look here for the potentiometer:

Source for Airflow Sensor Potentiometer

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2012 E350
2006 Callaway SC560

Started it last night and ran it for a few minutes. It is a lot better. Not sure though if it is at 100%. I found out also that the fuel distributor was replaced with a used one (it was not rebuilt). He said that is is due to the two cyliders having lower compression - will see.

In any event , I think the car is as a good as it is going to get at this point. Perhaps that slight hesitation could not be felt before because the fuel distributor was so bad.

It definately does not shake as it used to.

Good news Matt. So I take it that it was the fuel dist and not the wires that where the problem.
m

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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)

For the most part, yes Martin, you are correct, it was the fuel distributor that was the bulk of the problem, not the air flow meter/potentiometer.

However, the original tech did admit that he put on the wrong wires when he put on the first new set. The correct set is on now. It is hard to say how much the wrong set of wires contributed to the problem as a result of the Fuel Dist. being so bad.

When I did a quick and short test drive, it ran pretty good while cold. The big test will be driving around when the engine is warm and when there is hard acceleration.

Thanks for your help. It was starting, idling, and running so bad after I let the 2nd tech look at it, I was really worried.

I drove it today for several miles and the first good news is that the incredible shaking at idle is totally gone. There is a quiver at acceleration, but I think that may have been there before and may be due to the high mileage as the tech mentioned.

My 300 has the same mileage and it is as smooth as ice. The 420 is still pleasurable to drive, it is just not as smooth as the 300. I guess I have to finally come to terms that one day I would have to deal with the engine's high mileage. It turned 236k, but still runs very strong for a 15 year old machine.

Overall after a 1 month fiasco and being in the shop for 2 weeks, I finally got the car back!!

Damn. maybe I could visit my sister in Charlotte and we could ALL get together. My dad's 300E has that problem. It was partially solved when the mechanic here put a shim in cylinder #4. That fixed part of the idle problem. I think the rest is the pot, but my dad won't buy the $42 part just to SEE if it works. Then again, the same mechanic bought a $92 OVP relay to see if it fixed the ABS problem. It didn't. I told my dad about the sensor, but he was determined to have am mechanic tell him, not me. Sorry to ramble. Let me know when you guys are doing that and I could maybe talk my mom into visiting my sister while I meet up w/ you guys for awhile.
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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Could it be injectors that he needs? There is a guy here who said that fixed the problem on his 300E. I know, different cars. BUT, maybe thew injectors are getting dirty?
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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