96 E300D, the motor runs good sometimes and other times it will not rev up over about 3000RPm with a load on the engine. It also sounds like there are marbles in the motor. The sound is not in the botom end but I cant be sure if it is coming from the injection pump or maybe even the injectors. It acts like it is not getting enough fuel although I do not see air bubbles in the lines. The injectors were replaced about 50K miles ago by the previoius owner

So far I have changed the fuel lines around the injection pump, eliminated the pre-filter going ito the fuel filter, and changed the fuel filter. I also chnged the fuel supply lines from the cowl to the pump. I thought I had it narrowed down to the fuel pick up O ring in the tank but it still does it when the tank is completely full. That O ring is partially down the tube so it should not suck air when the tank is fuiiled.

I have an intermitting check engine light from the vacuum transducer near the EGR valve but it does not seem to be related as it will act up with the light on or off.

It seems to be more consistant in running poorly now.

Any thoughts?

check filters, first and foremost

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

That transducer is for a throttling valve in the induction piping. It will act as you describe if that valve doesn't open. Fix that now! Otherwise the engine cannot ingest any air when it fails closed. This causes the cyls to flood with fuel, misfire, and then preignite in the following cycles. That preignition causes the "chewing on marbles" sound. Not particularly good for the engine.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

In addition to the above- you might check out the posts on "resonator/ resonance flaps," and if you haven't had your intake cleaned out- do that too. The wife bought some old nasty, stinky diesel in Chicago once that made our e300 noisy and run like crap too- and it took another complete fill up after running it through to straighten out...

With the flaps removed and I have good air flow on the intake side I am looking now at the catalytic converter being blocked. I removed the tube from the exhaust manifold to the EGR to relieve some pressure and took it for a quick ride. It seems to have better accelleration but it still gets to about 4200 rpm and levels out, then it will not shift until I back off the throttle a little. It seems to be better but I am not convinced yet. It also sounds better when I rev it up in the shop but I cant tell if the marble noise is less due to the exhaust noise. Are the converters a known failure on these cars.

Thanks for the help

The code you mention can be caused by any one of a number of sensors. There are the two sensors on the side of the air intake filter box which have the same part number. One controls the resonance flaps, and the other controls the egr valve. On my model, those two vacuum pressure transducers also receive a signal from an intake manifold sensor that is located on the left wheel well, and has a small black rubber hose attached to the intake manifold. Then there is the actual throttle position sensor itself located near the drivers side firewall. Along with checking the vacuum lines as already suggested, I would also remove each electrical plug, spray it with electronics cleaner, and reinstall it. Hope this helps...

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96 E300d

Thanks for the input,
I actually thought it felt like a restriction, I removed the flap itself from the EGR valve in case that was sticking closed and restricting fresh air. Again, the light comes and goes but when it runs poorly it may do it with hte light on or off. I also checked the vacuum dash pots that actuate the valves.

when the code first arrived, it was an EGR transducer code, I switched the position of the two transducers and when the code came back it two codes, and one of them was EGR and the other was something to do with the "resonsnce" flaps. I assumed at that point that the first one was bad but again it seems to be an independant issue with the poor running.

My thought is at this point, with the flaps removed the light may stay on but there cant be a restriction in the intake with the flaps removed. That brings me back to the fuel issue.

Tonight, I pulled the cross over pipe and removed that flap also. I will run it again and see how it acts. However, this flap only marginally block the air flow so I dont think I will see a difference. I will smoke test teh rest of these vacuum liines too and see if there are any other leaks.

I dont mean to be cheap but the transducer is close to 200.00 and if the pump is bad it may be time to quit on this car

Any other ideas?

CHECK FOR BROKEN WIRES BY THE EGR VALVE
SILVER

CHECK FOR BROKEN WIRES BY THE EGR VALVE
CONNECTOR
SILVER

I smoke tested the vacuum lines and everything is good, no leaks. I removed all the flaps and re-set the computer. It drove the same, lazy acceleration, marbles in the engine as the RPM cam up, maxed out are about 3200rpm as if it could not get enough fuel to turn any faster.

light came back on with one code for EGR control no diffence in performance light off or on.

I have gone over all the electrical conectors at the various componets and everything is good. My next step would be to trace continuity back to the computer. I am not as concerned about the light and the code at this point, it should run with that light on and this intake opened up

I am back to fuel in my mind. The injectors had been changed by a previous owner, can they be an issue if they were cheap replacements? I also thought about pump timing, is it adjustable, could pump timing have jumped?

thanks for the help

How many miles on the car?
How long have you owned it?
What part of the country do you live in?

How, and why, did you bypass the pre-filter?

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Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

I suggest bypassing the fuel heat exchanger. Just bypass it and see if it works any better. There is a tiny thermostat in there and maybe it has stopped working properly or is plugged with junk. This is the first place fuel enters the engine compartment after leaving the tank. This is a very simple test that can be done very easily with an old hard fuel pipe, some fuel hose and hose clamps. Also, make sure fuel pipes on lift pump aren't switched - the short pipe should be farthest away from the injection pump.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900