Tormenting Problem with 95 E320 (Long)
 

Ok guys, I've scratched my head so much on this one that I'm starting to lose my hair, so I'm hoping there is a savior out there that can lead me to a resolution to this problem I have with my baby......

95 E320, 172k miles, has a stumbling problem that I can't find. Arthur Dalton and myself have troubleshot this problem until he's probably ready to start billing me:(

Here's the things we've eliminated:

1. EGR/Air Pump and Circuit
2. Cam Advance Magnet and circuit
3. Purge Valve
4. O2 sensor
5. Coils and resistor boots
6. Wiring Harness
7. Operating Voltage

So what I have to start with is a code 11 out of socket 14 which is a fuel safety shut-off signal code. That's the only code that seems to keep coming back after I clear them. My car runs fine except under a load, partial throttle, around 2000rpm to 4000 it will stumble like crazy acting like the cam advance magnet/curcuit is bad but it isn't. Also if I floor it, on occasion, it will hesitate big time around 5000rpm. And every now and then when I'm sitting at a stop light it will stumble. If you take off gently, cruising down the highway, and don't ever put the engine under a heavy load/downshifting into 3 - 1 gears you'll never know there is a problem. Cruise works great with no problems as well.

Engine temp. doesn't seem to matter, and this problem only showed up when it started getting hot here in Atlanta.

I've done some reading on the fuel safety shut-off signal but can't figure out where it is (inside the ISC unit?) nor how to properly test/fix it.

One note of interest is that I can make the stumbling go away if I unplug the cam advance magnet, that's what Arthur and I originally thought was causing the running problem until I ran some test on it per the manual and it checked out fine.

I'm getting really frustrated with this because I feel like I'm going in a hundred different directions and have yet to solve this mystery.

Someone please help me keep my hair and sanity:(

Oh yeah, I forgot to add that I replaced the OVP too with no help.

Fuel pump relay?
Injectors?

My '94 E320 is very fussy about gasoline brands. have you switched brands lately? Also, I put in some Valvoline fuel injector cleaner that caused skipping and rough running in my car. I stopped using it. When did it start getting hot in Atlanta? How long has the car run like this?

Is the air mass shot? Ea dirty?



Joe

Watch your air mass value in an actual values screen using an appropriate scan tool. The Air Mass should exceed 400kgh under hard accelaration, if not suspect the MAF. You can also connect directly to the the MAF meter with a Vantage/oscilloscope and watch the HFM voltage, you should capture something there for sure.

Update
 

Well all, the only component I hadn't closey looked at was the throttle body and guess what???? The wiring harness connected to the throttle body was shot!!! The insulation just crumbled on all of the wires when I cut open the outer wiring harness casing. So my baby is dead as a stone until I find another one. By the way I did find a used one in Michigan that I bought only to find out the harness on that one was shot too. Luckily they're taking it back and giving me a full credit.

So if anyone else has any weird running complaints or mysterious codes like I described in my original post, you may want to make a 3 inch cut in the wiring harness coming out of the throttle body unit and then cross your fingers your wires are ok because more than likely they aren't.

Oh yeah, I was qouted $1,080 for a new one and this is for a Non-ASR car!!! I'm going to keep looking but I bet I end up buying a new one because all of the used ones are going to have the same problem with them.

I have no idea of the detail of this assembly but is it not possible to resleeve all the wires with heat shrink or some such?. Probably laborious but once you get going should not take too long AND could work AND say you $$$$ (Or even rewire the whole bloody thing entirely?)

believe it or not Norman I did that, I re-wired the entire harness only to find out that the drive value potentiometer and the actual value poteniometer were bad as well. These 2 units were in a sealed unit which also contained the Fuel Safety Shut-off Switch. Bad news...........

Re-Wiring it was not a bad job, kind of time consuming but I'm guessing that when the bare wires were touching on occasion is when it fried the potentiometers.

Oh! ----sorry to hear that Dale, all that work and .....

- sheesh don't you just hate these 'sealed units'

Good luck in yr quest to resolve this one.

NormanB

PS: Have you tried a can opener? ;)

I'm still hunting for one Norman, I just got a reply from a used parts dealer that has one for $425, but the problem right now is I'm trying to get him to cut open the wiring harness to check the wires before I agree to the deal. He's very reluctant.......we'll see what happens. Thanks for everyones replies and ideas.

Don't feel too bad about having to replace your throttle actuator .

I had to replace mine, too, for the same reason.

The throttle actuators on 1993-1995 M104 engines and V12 engines seem to suffer from the deteriorating harnesses.

I would not recommend buying a used one as it will suffer from the same fate.

Just bite the bullet and get a new one.

I've just about came to that conclusion Paul, as a matter of fact I'm waiting to get one more qoute on a new one and then I'll buy it....

I bought mine from Phil here at PartsShop, and it was about $1060-ish, if I recall correctly.

Also, if you install it yourself, you can remove the old one and install the new one without removing the intake manifold. You have to move some things out of the way, but the manifold can stay in place.

I've had mine off about 5 times so I've got the removal down to about 10 minutes. Surprising easy to remove and install. I've got the price down to $1100 delivered to my house, that's the best deal I've found so far. I'll probably order one on Monday and get this ordeal over with. Hopefully from here I'll be in good shape to make my goal of 300k miles.:D After that I'm buying a diesel........