1990 300D 2.5 Running Rich - PeachParts Mercedes-Benz Forum

mcguirjf · #1 09-04-2007, 02:51 PM

Greetings,
I'm currently finishing the engine installation in my 1990 300D and have one problem left. Black smoke!

The car runs very very very rich. So much that I'll make your eyes water.

I even ran a separate container of fresh diesel just to make sure that I don't have bad fuel in the tank.

I replaced the timing chain. Cam marks align with TDC indicator. I've installed the IP with the locking tool at 15 deg ATDC. I used the allen key to adjust the timing within a certain range with no change.

I cracked each injector line individually with the same loss of cylinder affect and no change in smoke content.

The air filter is a K/N and is clean and not over oiled! I have also run the car with the air box disconnected from the air filter. There is no appearance of air restrictions.

Also when giving the car gas, if I don't let off the gas pedal slowly the car stalls. Example - Rev to 4000 rpms and let the rpms fall and the car stalls. If I hold the pedal a little the car's idle will fall slower and then regain idle.

From other posts... the vaccum controlled valve located after the turbo is suppose to move with actuation of the throttle this does not happen.

I'm going to perform a compression test later this week. I should have codes pulled this week. Any other suggestions on how I should trouble shoot this problem? Can the EDS alone cause a rich condition or does it just control idle?

sailor15015 · #2 09-04-2007, 04:09 PM

I don't know much about your model year but if the computer is holding the wastegate open, you won't get any boost and there won't be enough air to burn the supplied fuel, resulting in black smoke. A stuck open wastegate shouldn't cause stalling though, just a lack of power.

2.5Turbo · #3 09-04-2007, 06:53 PM

Quote:

Originally Posted by sailor15015

I don't know much about your model year but if the computer is holding the wastegate open, you won't get any boost and there won't be enough air to burn the supplied fuel, resulting in black smoke. A stuck open wastegate shouldn't cause stalling though, just a lack of power.

Yeah, but the ALDA keeps the fuel down when there isn't any boost. If the wastegate was open, the ALDA wouldn't get any pressure, so it wouldn't enrich the fuel to the point of black smoke. That is if the ALDA is unmolested, working and installed properly.

Make sure your EGR and flapper valve on the intake are both working and not stuck open or closed. Also check the two transducers that control these just behind the airbox. If you need to test them, there are three on this car and they're all the same part number and are interchangeable. This is how I pinned down a bad turbo wastegate transducer; I replaced it with the flapper valve one which was known to work.

You're also absolutely sure your intake isn't gunked up with that evil mix of EGR soot and oil from the breather?

mcguirjf · #4 09-05-2007, 10:10 AM

The ALDA is unmolested with the original black cap on top.

I will check to see if the egr is stuck. The intake runners only have 90K miles on them with very little sludge inside.

What is the part number on those transducers?

If there are error codes, could that result in car running in safe mode (shutting down the transducers) resulting in this rich condition?

I'm hoping my compression values are good and this is nothing more than a computer issue!

2.5Turbo · #5 09-05-2007, 04:36 PM

Quote:

Originally Posted by mcguirjf

The ALDA is unmolested with the original black cap on top.

I will check to see if the egr is stuck. The intake runners only have 90K miles on them with very little sludge inside.

What is the part number on those transducers?

If there are error codes, could that result in car running in safe mode (shutting down the transducers) resulting in this rich condition?

I'm hoping my compression values are good and this is nothing more than a computer issue!

The transducers have gone through revisions over the years. The one I got had a totally different part number and was smaller, but it works just fine and mounts up to the bracket perfectly. Don't know the PN off the top of my head, but you might have some luck discussing it with Phil on fastlane.

You can test the vacuum operated gadgets with straight vacuum. If you hold the wastegate closed with straight vacuum, be careful not to drive it too hard or you'll risk damage from overboosting. It would be good to have a boost gauge hooked up while doing this testing so you know you're not boosting to dangerous levels.

Error codes will hold your wastegate open. What is the power like? Is your 0-60 18-20 seconds? If so, your wastegate is not closing. If the EGR isn't working (transducer or valve itself) you may have an EGR transducer code. If something is wrong with the EGR system you may also get the airflow meter code. If you haven't built one already, build a code flasher/clearer. I've posted the link numerous times on here, so a quick search should turn it up. Costs about $20 in parts from Radioshack and a bit of time to solder it all together.

Also, the only thing the EDS does on the IP is control idle speed. The rack is controlled through the cable and linkage by your right foot. I don't see how the ELR actuator could create an over rich condition.

One more thought...if the ALDA went bad somehow and allowed full enrichment all the time and the turbo wasn't building boost because of error codes, you would have one hell of a smoke show. Are we sure the IP and ALDA on this new engine is good? Check and see if there are any extra shims under the ALDA as well...simply looking for the protective cap on top does not guarantee that it hasn't been tampered with underneath.

Hope you can get this sorted out without too much trouble...I have pretty much memorized the systems of the 602.962 by troubleshooting and working on mine. Currently my 300D is at home 2500 miles away

mcguirjf · #6 09-07-2007, 10:22 AM

Well I couldn't get her started last night as the battery has finally died. I was able to check for codes with the new scanner I built. Only had a code 7 which is ok since the car wasn't running.

Just to clarify for others #4 is where the signal output is located, and #1 is where the Ground connects. It took me an hour to figure out why the damn light would stay on because I had them reversed!

I checked the ERG Valve and it opens when vacuum is applied. And is closed with vacuum off.

I'm going to do a compression test when I get home today. Pending the results, I either have a compression problem or a fuel problem.

Stay Tuned!

777funk · #7 09-05-2007, 10:33 AM

As far as stalling when you let off the pedal. That could be your linkage/bowden cable not being tight enough.

Unplug the electronic idle (ELR) plug on the back of the pump. If your engine kills at idle then you have a mechanical adjustment problem. The ELR maintains your idle electronically. So if it kills without it, you've got linkage etc. to tighten. Most likely it's the bowden cable needs to be tightened. Try that first.

Simple test. Just start the car and unplug that ELR. If it kills you have the mentioned things to adjust.

mcguirjf · #8 09-05-2007, 11:02 AM

Which is the bowden cable?

The cable to the accelerator pedal or the cable to the transmission?

Are you refering to the solid adjustable linkages on the injector pump?

iceman805 · #9 09-05-2007, 12:46 PM

I have to say it is a privilege to watch how some members on this board work through issues...amazing. I hope I can learn half of what some of you have forgotten.

I saw this post and figured I could contribute from my service CD.

mcguirjf · #10 09-05-2007, 02:18 PM

OK! So the bowden cable referred to is the one connected to the accelerator pedal.

I found 07.1-2006 Testing Electronic Idle Speed Control in the FSM.

I also see listed 07-2053 as listed for Preceding work: Testing and Adjusting Idle Speed (07-2053).

There is enough slack in the cable so the spring stop is fully seated. I don't want to pull in the slack in the gas (diesel) pedal to raise the idle.

I see that there is a screw with a lock nut located to the side of the EDS on the injector pump.

I think I should solve the "rich" condition first before adjusting the idle.

Keep the Suggestions Coming!

sixto · #11 12-18-2008, 12:24 AM

14* ATDC

Sixto
87 300D

mcguirjf · #12 12-19-2008, 01:08 PM

Went to go pick up the new O ring to seal the IP to the crankcase and the wrong part was ordered. Damn it! Now I have to wait till next week. I'm going to throw it in tonight just to see what happens.

If I get the same results what should I do?

If the IP is too far advanced wound it knock badly?

When I had her at 34 degrees BTDC I heard one knock at start up and then nothing. It sounded quiet and smooth like my 1987 300TD and a 1995 S350D I test drove. It drove great too! It would break the tires loose from a stop!

Before it sounded like a OM617 at idle

and had a slight shake to her.

I may do another compression test, but I haven’t noticed anything different from the engine since I did it last year.

Should I get a second opinion on my IP? There is Yankee Diesel in Newtown, CT. Is there anywhere else in the CT area for IP testing / timing?

What is the pop pressure the injectors are supposed to be set to? I had all the injectors pop tested and set last year. Could the pop pressure being set incorrectly cause my condition? Lets say that if the injectors are supposed to pop at 120 psi and they are set to pop at 140 psi, that would cause my late condition, right? I see that they all popped low prior to being rebuilt??? Hummmmm! Interesting!

mcguirjf · #13 12-23-2008, 09:59 AM

I just got the IP back from the shop and was told the timing indicator in the IP was off 5 degrees. It was at 12 ATDC and is now set at 17 ATDC.

I installed it last night with the IP lock and the engine at 14 ATDC and the car runs! It does have some klack to her and I have heard quieter MB's.

I'm going to pull the injectors and have them re-pop tested and spray pattern checked.

My concern is that he retarded the timing in the IP, but for me to get it running before the repair I had to advance it when installing it in the engine???

I bet if I advance IP about 5 degrees she'll smooth right out, but I don't want to. I don't want to touch the IP anymore.

Suggestions please and Happy Holidays!

VegStew · #14 12-23-2008, 11:11 AM

After my injector pump rebuild on the 300d, it had a noticeably louder sound to it. I think its just the difference between a fresh new pump and an older worn in pump.
Mine quieted up in a month or so.

gsxr · #15 12-23-2008, 08:24 PM

Uh - this may be a stupid question, but:

What exactly are you using to read the numbers on the balancer? I'm wondering if you are looking at the wrong spot on the indicator. You should be looking at the passenger side of the triangle shaped tab, not the round hole with the threaded shaft near it. This might explain the numbers being so far off. The TDC indicator bolts to the timing cover, and is adjustable over a 3° range total, but normally this isn't touched.

Timing spec for your car is 14° ATDC, +0.5, -0. But I still don't know what the shop meant by your injection pump being off by 5 degrees. That is not adjustable... the tang is part of the camshaft inside the pump. See photos below.