2.5 Turbo Boost problem. - Page 2 - PeachParts Mercedes-Benz Forum

DieselDummy · #16 01-03-2006, 11:43 AM

OK, I read the codes and had 2,3,8,9 and was able to clear all codes with a little work and have now gone around 150-200 miles with No Codes showing, but the car still runs poor and only has the limited boost (5-7 psi) all the time.
Again if I activate (2nd gear on only) the Cruise Control ACCL lever it instantly gets full boost (12-13 psi) for 5 sec. then drop back to the limited boost state. The EDS obvisously see's a single from the cruise circuit when activated. IMO.
What Now ?

pmari · #17 01-04-2006, 12:56 AM

#2) fuel rack position sensor (L7) or control rod travel sensor (i wonder if the CC over rides this for a moment?)

#3) Air flow sensor (B2/1)

#8) coolant temp sensor (B11/4)

#9) intake air temp sensor (B2/1a)

Give me a pm with an email addy and I'll send you the trouble shooting procedure for each code. Their in BMP format.

DieselDummy · #18 01-04-2006, 02:23 PM

Thanks PM sent !

These car suck without boost!

gsxr · #19 01-04-2006, 03:57 PM

Wow. You have some serious gremlins there. I'm really at a loss as to what would cause this. Worst case, you can always yank the turbo off, and replace it with one that has a pressure-operated wastegate, instead of the annoying computer-controlled, vacuum-operated wastegate. That would be a bit extreme, but it would likely solve the problem permanently...

DieselDummy · #20 01-05-2006, 02:58 PM

I have only had one code return in 250 miles (#3) and it still runs poorly all the time.

Brooksie43 · #21 01-05-2006, 11:38 PM

I had a problem which I think was similar to yours. Do a search of this site (surging) and look at the thread "surging at highway speed" you will see a number of good suggestions and how the problem was actually solved.
John

pmari · #22 01-06-2006, 12:25 AM

I don't think it's surging, it's got no turbo. Does a 87' have a EDS?

Quote:

For what it is worth, I solved my surging problem by bypassing the overload solenoid. Problem solved. The pressure switch was OK but the solenoid (switch over valve) must have been fluttering. This is the forth control system I have discarded on my engine only to see it run better. I have a wastegate and a boost gauge to control boost pressure; this was overkill. I hope this helps someone else.
John

There is a TSB for the surging...

Quote:

As of February 1992, a modified vacuum transducer has entered production. The new part can be identified by a black ring, however, the part number remains unchanged. In case of customer complaints of engine surging at approximately 50-60 MPH, smoking rough idle after start, or poor power output on vehicles with earlier production dates, the tests in this bulletin should be performed; see Testing.
Pressure control flap test (engine 602 only)
1. Connect vacuum tester to vacuum actuator (arrow, Figure 1).
2. Apply vacuum slowly until lever (a) contacts stop (b).
3. Vacuum reading should be 385 +/- 5 mbar. If necessary, adjust by loosing screws (c) and sliding vacuum actuator (100) in the slots. Release vacuum and repeat test if needed.

Vacuum pump test
1. Connect vacuum tester (019) to accessory connector on vacuum pump (arrow, Figure 2).
2. Disconnect main vacuum hose (B) from brake booster (A) and plug.
3. With engine idling, reading should be 700 mbar after 30 seconds. See barometric (altitude) correction table in this bulletin.

Barometric (altitude) correction (see chart)

Readings must be adjusted according to the prevailing barometric pressure to compensate for differences in altitude (deviation from sea level). When performing the vacuum pump test, reduce the reading obtained according to the altitude dependent value in the chart.

Vacuum system and consumer test

1. Using a Y-connector, connect vacuum tester into consumer connector on vacuum pump.

2. With engine idling, check that reading is at least 600 +/- 30 mbar.

3. If vacuum is below 570 mbar, check the following for leakage: line to vacuum control valve (65) (transparent), line to consumers (grey), vacuum transducers (Y31/1 and Y31/5), as well as the black/white vacuum supply line. To check, disconnect and plug lines at T-connector or double T-connector (arrow, Figures 7, 8, 9, and 10) one by one.
4. If vacuum is greater than 650 mbar, check for possible leakage in the vacuum line system.

Vacuum transducer test (Y31/1, Y31/2, Y31/3, Y31/4, and Y31/5)

1. Using a Y-connector, connect vacuum tester to consumer connector on vacuum pump.

2. With engine idling, disconnect connector VAC from transducer Y31/1 and plug line. If vacuum reading is below 650 mbar, replace vacuum transducer Y31/1. Repeat procedure for vacuum transducer Y31/3 (124.128 model year 1990-91) and Y31/4 (140.134)

3. On engine 602 only, with engine idling, disconnect connecting line VAC from transducer Y31/2 (model year 1990/91) or Y31/5 (starting model year 1992) at the Y-connector black/white line and plug. If vacuum reading is below 650 mbar, replace vacuum transducer Y31/2 or Y31/5.

Model years 1990/91
Engine 602.96 Model 124

Y31/1 EGR valve vacuum transducer
Y31/2 Pressure control flap vacuum transducer
Y31/3 Wastegate vacuum transducer

Model years 1990/91
Engine 603.970 Model 126

Y31/1 EGR valve vacuum transducer

Starting model year 1992
Engine 602.96 Model 124

Y27 EGR switchover valve
Y27/4 Boost pressure control switchover valve
Y27/5 Pressure control flap switchover valve
Y31/1 EGR valve vacuum transducer
Y31/5 Boost pressure control/pressure control flap vacuum
transducer (not visible, located under air cleaner housing.

Starting model year
1992 Engine 603.971 Model 140

Y31/1 EGR valve vacuum transducer
Y31/4 Boost pressure control vacuum transducer

DieselDummy · #23 01-06-2006, 02:41 PM

Thank you !
No it's not a surging problem, but I happy to consider anything.
And No the 87 does not have a EDS along with all the other troublesome parts. I had 2 87's (300) that if I would of spent a little time on I would of kept at least one.

With 3 vacuum Transducers on the 90/91 I'm thinking of a 92 system conversion(only 2 transducers) at over $100 per Vac. Trans. Also My Pressure Control valve leaks pretty bad and cost around $200. I don't want to just start replacing expensive parts hoping something helps. I can only imagine how much a new AirFlow sensor cost, which is the only code to come back (#3).

gsxr · #24 01-06-2006, 02:55 PM

Actually, the 1987 300D does have an EDS, but it's very basic - it only controls the idle speed, and the pollution junk (EGR and ARV). The 2.5T has a much more complex EDS that also controls boost. You can disable all the emissions stuff on the 1987 without affecting engine performance, but it's a LOT harder to do that on a 1990-up model.

Anyway, this is a really long shot, but have you checked your timing chain stretch? There's a TSB (see PDF attached below) for certain engines in the early 1990's that had defective chains. I don't think it would cause the problems you are having, but it wouldn't hurt to take a peek if you have the time to check.

EDIT: This forum's RIDICULOUS limit of 65kb won't let me attach the huge, enormous 70kb PDF file. So here's a direct link to the file on my website:
http://www.w124performance.com/docs/mb/OM60X/OM60x_Timing_Chain_TSB.pdf

DieselDummy · #25 01-06-2006, 04:14 PM

Quote:

Originally Posted by gsxr

Actually, the 1987 300D does have an EDS, but it's very basic - it only controls the idle speed, and the pollution junk (EGR and ARV). The 2.5T has a much more complex EDS that also controls boost. You can disable all the emissions stuff on the 1987 without affecting engine performance, but it's a LOT harder to do that on a 1990-up model.

Anyway, this is a really long shot, but have you checked your timing chain stretch? There's a TSB (see PDF attached below) for certain engines in the early 1990's that had defective chains. I don't think it would cause the problems you are having, but it wouldn't hurt to take a peek if you have the time to check.

EDIT: This forum's RIDICULOUS limit of 65kb won't let me attach the huge, enormous 70kb PDF file. So here's a direct link to the file on my website:
http://www.w124performance.com/docs/mb/OM60X/OM60x_Timing_Chain_TSB.pdf

My Bad on the EDS, I guess I was thinking about boost control.

The local MB shop said it was my timing chain because it was 3 deg. retarded and wanted $900 to fix it. I wasn't about to pay for something that wasn't the problem, if the chain was the problem it wouldn't run the same all the time. It was a waste of time and money to pay him $300 to tell me the wrong answer. I told him it was a boost control issue when I dropped it off, because it ran great when it boosted. This is a 29 year Master MB Mechanic that "made his living on Diesels". I hate knowing so little and more than the "Pros". I did fix the problem (timing chain) myself to see if it made a difference and no, Zero difference( he said it would make a huge diff.). The Mech. said replacement spec was 3-10 deg. retarded. Injec. pump was dead on 14.5 deg.
I did have two loose injectors that they tightened, but when I got the car back it ran worse. I found a main vacuum line disconnected, a loose bolt on the valve cover, and they didn't bother to replace the injector dust seals or replace the valve cover gasket that now leaked like a siv.

dataiv · #26 01-06-2006, 04:37 PM

Quote:

Originally Posted by pmari

There is a TSB for the surging...

Does anyone have the full TSB with the figures/pictures referenced in the TSB that was posted to this thread?

That sounds like a problem I used to have (surging) until I just disconnected the flap it talks about (with no power loss by disconnecting it on my car) and I'd like to see the full TSB if possible.

Is it available anywhere?

DieselDummy · #27 01-06-2006, 04:57 PM

Quote:

Originally Posted by dataiv

Does anyone have the full TSB with the figures/pictures referenced in the TSB that was posted to this thread?

That sounds like a problem I used to have (surging) until I just disconnected the flap it talks about (with no power loss by disconnecting it on my car) and I'd like to see the full TSB if possible.

Is it available anywhere?

I would be happy to mail you a copy, that's the only format I have. I do have it on CD but not sure how to capture it and send it to you ?

gsxr · #28 01-06-2006, 07:38 PM

Yeah, the actual timing chain replacement spec for "good" chains is 4 degrees or more. Mine was at 4, I changed it, and saw very little (if any) change in anything (noise, power, MPG, etc). For the batch of 'bad' chains, the spec was 3-10 degrees but I still wouldn't bother until it reached 4 (which could take another 50-100kmi!). Sorry you had to go through that hassle, and also that you can't seem to locate a competent MB mechanic...!

pmari · #29 01-08-2006, 03:23 AM

code1470

pmari · #30 01-08-2006, 03:26 AM

code 1470