Diagnosing D-Jet Problem...solution & update, All of a sudden...loss of power... |
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Diagnosing D-Jet Problem...solution & update, All of a sudden...loss of power... |
MikeInMunich |
Jul 6 2018, 08:13 AM
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#1
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Member Group: Members Posts: 392 Joined: 19-November 13 From: Munich, Germany Member No.: 16,674 Region Association: None |
Greetings once again from Munich gentlemen! (IMG:style_emoticons/default/bye1.gif)
It started with a thought and no wood to knock on, seriously! (IMG:style_emoticons/default/mad.gif) I was driving around Munich about 6 weeks ago and thought to myself, this car is running perfectly and needs nothing. What could go wrong? Then literally, less than a few minutes after that, it started. A light hesitation in the lower RPM range. Seemed like the car was choking a bit, or missing on once cylinder. I was at a D-Jet workshop last year with Dr. D-Jet. See https://oldtimer.tips/de/ Volker is a great guy and knows as much about this system as anybody. He tested the vacuum on my MPS last year and informed me that it was "borderline". So that was the main culprit. I took it out, sent it to him and this year it was indeed worse and thus the main culprit. Volker disassembled it and replaced the copper diaphram. Now it's tight like new. Some may be surprised that this is possible and / or where he got a new diaphram from. He had them manufactured or perhaps, I'm not sure, manufactured them himself. PM me if you want / need one and I'll send you his email address. So, with my restored MPS I hooked it up and, low and behold, the problem was quite the same, only about 10x worse! (IMG:style_emoticons/default/hissyfit.gif) Now, with the car immobile and Volker hundreds of km away, I'm practically on my own, with his and your advice, to try to track down the real problem. Volker thinks that because the MPS was operating sub-optimally previous to my purchase of the car that the mechanic or the P.O. had compensated elsewhere to get the car to run properly and that now that the MPS is sending a different signal to the CPU, things are off. More info: Just before the problem started my milage was really bad The CPU is the correct one for my MPS and working according to specs. Volker tested it. Engine has about 5,000 miles on it. Was rebuilt and running GREAT. Fuel pressure was set at 29 psi only about a year ago. I reckon it could have hardly changed on its own since then. (IMG:style_emoticons/default/idea.gif) The engine was originally a 1,7 but is now 2liters with a “proper FI performance Webcam” (as stated by the mech ic who rebuilt the engine) No adjustments were made to the FI to get it to run properly. It was running excellentwith a virtually perfect idle when warm and just slightly rough for the first 3 Miles or so. TPS plate and air temp sensor are new. What do y'all reckon could be the culprit? What should I be testing? I'm taking it to a place to tell them what to test, including: Fuel Pressure Plugs Compression CO value TPS setting Timing & dwell search for Vacuum leaks grounds Valve adjustment Fuel filter Relais Injectors... What else should I have them look for? Thanks for your input! With best regards from what was just ranked The Most Livable City in the World by Monocle Magazine, Mike in Munich |
rhodyguy |
Jul 11 2018, 09:41 AM
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#2
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,072 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
Perhaps a discussion of the engine spec is in order prior to a MPS refurbish.
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MikeInMunich |
Jul 12 2018, 04:21 AM
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#3
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Member Group: Members Posts: 392 Joined: 19-November 13 From: Munich, Germany Member No.: 16,674 Region Association: None |
Perhaps a discussion of the engine spec is in order prior to a MPS refurbish. Absolutely. Had I discussed or even mentioned this to Dr. D-Jet he would have been happy to not have anything to do with this case and not unhappy about trying to help where he otherwise would have chosen to distance himself. |
Dr-DJet |
Jul 13 2018, 06:57 AM
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#4
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Dr-DJet Group: Members Posts: 14 Joined: 21-May 16 From: around Frankfort, Germany Member No.: 20,021 Region Association: Germany |
Perhaps a discussion of the engine spec is in order prior to a MPS refurbish. Absolutely. Had I discussed or even mention this to Dr. D-Jet he would have been happy to not have anything to do with this case and not unhappy about trying to help where he otherwise wouldn’t have chosen to distance himself. Well after Mike and me agreed on real facts that he had told me it would be an original 1.7 engine and that both MPS (one originally closed with rivets, vacuum tight etc) do not work for more than cold start enrichment (800 meters) and that he has also tried 2 ECUs: I have references for 94% of all MPS, rough ones from Bosch and very precise ones measured myself. I always adjust MPS to references. And that is what makes cars going. To the opposite: A leaking MPS (and the first one was losing vacuum in 4 seconds) should create a very rich mixture with bad motor run in idle and part-load. If it was running well with that, then there were earlier other problems already. I cannot know the revised engine specs but I can tell you that the ECU is used both on 1.7 and 2.0 engine. But 2.0 engines were never equipped with this MPS. It was equipped with 0280100 037 (sorry I do not work with Volkswagen no.s) in combination with this ECU. As a registered user u find all that information on oldtimer.tips MPS list. Anonymous surfing gives u only limited info. So if we have 2 ECUs and 2 MPS not solving the problem, it is time to follow my original advice from the beginning when I learned it is a modified engine: 1. What specs is this revised engine? Bore, stroke, compression and valve timing. 2. If it is like original 2.0 engine, I would recommend to try 0 280 100 037 factory spec MPS. It is much richer than the 049 for 1.7 engines. 3. If it is not like original 2.0 engine, well then you have to do trial and error. Regarding detuning MPS: You might know type 3 MPS from Mercedes-Benz, Opel, late Volvo etc. with black cap. Underneath is an easily accessible screw. (this one has just one screw and not 3 as it has no diaphragm and no full-load transition. Full-load is handled via a contact in throttle switch). I see a habit in the US to detune them. And later they are sold as core in ebay or completely with bad running car to someone else. Many MB 450 SL make it to Germany like that. And it a nightmare to fix it. They have altitude compensation and need to be checked at 750 and 600 Torr environmental pressure with differential vacuum applied to that environmental pressure. Fortunately we do not have such a tradition of detuning MPS in Germany. I am doubtful that you can adjust all 3 screws on your MPS simultaneously while riding a car and watching A/F meter. That is why I recommend not to do so. Tuning screws on MPS are VERY SENSITIVE. Regarding swapping MPS from one engine to a different engine: Normally then MPS have different slopes in their curves and you cannot reach it via screw tuning. It would need a change of springs inside plus proper tuning. Hope that clarifies the subject and please apologize if I got disturbed by "alternative facts" as they were first stated by Mike. It is good that he has changed that view and I accept that. (IMG:style_emoticons/default/driving.gif) BTW: In April local Porsche 914 club had invited me to Karlsruhe for a workshop with 18 Porsche 914s teaching only D-Jetronic and engine testing. It was a lovely event and they have asked to have Obelix and me again next year in another region. (IMG:style_emoticons/default/beerchug.gif) |
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