What did we screw up?? - PeachParts Mercedes-Benz Forum

psaboic · #1 02-20-2011, 11:40 AM

Well, I have errands to do today, but as soon as I get the chance I will go over and look at the car. I'll check the ALDA lines and other vacuum lines. If that doesn't pan out we will go over the valves again. By the way, he pulled all three vacuum lines out of the black box on top of the valve cover before I got there and wasn't sure if he put them back in the correct spots. Does anyone have a good picture of where they go? That could be an issue as he said the tranny now shifts WAY smoother than it used to.

Would a mis-adjusted valve allow it to only miss under heavy load but no stutter or miss just cruising along?

vstech · #2 02-20-2011, 11:56 AM

Quote:

Originally Posted by psaboic

Well, I have errands to do today, but as soon as I get the chance I will go over and look at the car. I'll check the ALDA lines and other vacuum lines. If that doesn't pan out we will go over the valves again. By the way, he pulled all three vacuum lines out of the black box on top of the valve cover before I got there and wasn't sure if he put them back in the correct spots. Does anyone have a good picture of where they go? That could be an issue as he said the tranny now shifts WAY smoother than it used to.
the black box controls the EGR. if it's getting vacuum under load, it might be dumping exhaust when it's not supposed to.
follow the lines from the box and see where they connect to the vacuum source, and plug both lines. they are not important to the ability of the car to function.
see if that improves the miss.

Would a mis-adjusted valve allow it to only miss under heavy load but no stutter or miss just cruising along?

yes. this is exactly what a tight exhaust valve would cause.

psaboic · #3 02-20-2011, 08:28 PM

I will dis-connect the vacuum lines as you said and see what happens. I also would like to swap the fuel lines as mentioned here on the forums to rule out the fuel tank filter screen. What is the best way to do that? Can I swap them where the rubber hoses (from the IP and plastic fuel filter) meet the hard lines in the engine bay, or do they have the to be swapped somewhere else.

To all, Thanks for the help with this so far

Junkman · #4 02-20-2011, 08:48 PM

Quote:

Originally Posted by psaboic

I will dis-connect the vacuum lines as you said and see what happens. I also would like to swap the fuel lines as mentioned here on the forums to rule out the fuel tank filter screen. What is the best way to do that? Can I swap them where the rubber hoses (from the IP and plastic fuel filter) meet the hard lines in the engine bay, or do they have the to be swapped somewhere else.

To all, Thanks for the help with this so far

If the car ran before the valve adjustment, the problem is something done in the process. Perhaps continue that track until issue is resolved. You don't want to further complicate things.

psaboic · #5 02-23-2011, 01:03 PM

Ok, found the problem (sort of)

On a whim, I decided to see if the reason the car was running like crap was fuel related and not valve related. It sort of acted like my TDI when I had a bad filter.

Anyway, today I went over to the car and played with the fuel system. I took a spare fuel can and ran a hose from it directly to the IP input(no filter), and then ran the return hose from the spin on fuel filter housing directly back into the fuel can. So in effect, I isolated the car's fuel system, except for the spin on filter.

Took the car out on the road and Holy Crap Batman!!! It ran like a scalded dog. No stutter, no high speed miss, hit 80 MPH like it was not working hard at all. In essence, running fantastic.

Hooked up the regular fuel system lines again, and the car could barley hit 40 MPH floored and stuttered and missed at speeds above 30 or when pressed hard.

SO......Based on what I discovered, There is either a bad primary (plastic) fuel filter, a clogged tank screen, or both. Since I ran the fuel from the can into the IP and the return came from the spin on filter housing I'm assuming the spin on filter was still in the system, and since the car ran great that way, I can assume the spin on filter is OK.

Funny thing is my buddy just changed both fuel filters at the same time we did his valves.

So, what would you do next? I'm telling him we should plan on draining the tank and cleaning the tank screen this weekend and also changing the plastic fuel filter again as well.

Any other ideas?

Thanks,

Glenn