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 |
Dr-DJet |
Jul 10 2018, 03:53 PM
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#2
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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 |
Hi,
Mike did not mention to you and to me that he does not have the original engine installed. He had his 1.7 engine bore increased to 2.0l and changed cam to unknwon spec. (IMG:style_emoticons/default/WTF.gif) It is of course not possible that any open loop control ECU and MPS will notice that. Even a closed loop injection system would have trouble with that. His previous MPS lost vacuum and thus saw far too low vacuum enriching A/F mixture artificially. When it is back to factory spec what happens? Of course mixture is far too lean for an engine that has 25% more air volume and a total different volumetric efficiency and fuel need. Both are hard coded into each ECU and each MPS. I do not understand how Mike could forget to mention this fact (IMG:style_emoticons/default/confused24.gif) . If he is lucky he now has an engine similar to an original 2.0l engine. Then he could use components from that engine. But without knowing engine mechanics and his specific cam changes in detail, that is impossible to say. My weeks of support for this trouble case is over. I learned of the total engine changes today. I am surprised what speculations have built up here in 914world why a factory spec MPS should not fit a normal engine. Bosch has supplied 10s of thousands of MPS as spares (and 100s of thousands originally). How would Bosch workshops have survived if they would have had to retune each spare MPS in field? (IMG:style_emoticons/default/headbang.gif) Do not create such fairy tales. Bosch Classic delivers repairs of MPS to their spec until today for many car models with Mercedes-Benz still being the largest user of D-Jetronic MPS. So please do not base wrong speculations on such a case where someone tries to fit original components on a total different and unknown engine. Sorry guys, I normally do not write here, but this was just too much fairy tale on false ground. See you on oldtimer.tips if you like. Best regards, Dr-DJet |
MikeInMunich |
Jul 10 2018, 04:16 PM
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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 |
Hi, Mike did not mention to you and to me that he does not have the original engine installed. He had his 1.7 engine bore increased to 2.0l and changed cam to unknwon spec. (IMG:style_emoticons/default/WTF.gif) It is of course not possible that any open loop control ECU and MPS will notice that. Even a closed loop injection system would have trouble with that. His previous MPS lost vacuum and thus saw far too low vacuum enriching A/F mixture artificially. When it is back to factory spec what happens? Of course mixture is far too lean for an engine that has 25% more air volume and a total different volumetric efficiency and fuel need. Both are hard coded into each ECU and each MPS. I do not understand how Mike could forget to mention this fact (IMG:style_emoticons/default/confused24.gif) . If he is lucky he now has an engine similar to an original 2.0l engine. Then he could use components from that engine. But without knowing engine mechanics and his specific cam changes in detail, that is impossible to say. My weeks of support for this trouble case is over. I learned of the total engine changes today. I am surprised what speculations have built up here in 914world why a factory spec MPS should not fit a normal engine. Bosch has supplied 10s of thousands of MPS as spares (and 100s of thousands originally). How would Bosch workshops have survived if they would have had to retune each spare MPS in field? (IMG:style_emoticons/default/headbang.gif) Do not create such fairy tales. Bosch Classic delivers repairs of MPS to their spec until today for many car models with Mercedes-Benz still being the largest user of D-Jetronic MPS. So please do not base wrong speculations on such a case where someone tries to fit original components on a total different and unknown engine. Sorry guys, I normally do not write here, but this was just too much fairy tale on false ground. See you on oldtimer.tips if you like. Best regards, Dr-DJet (IMG:style_emoticons/default/blink.gif) Hi Volker and fellow teener fans! As one can see in previous posts of mine here I have only spoken incredibly highly of Volker / Dr. D-Jet. When an expert makes a false assumption, as Volker here did, by assuming that my engine was stock instead of asking me, and then blames it on the (often naive) non-expert car owner for not sharing all pertinent information when one may not even know what pertinent is, then I think that’s a bit uncool because miscommunications happen in human interaction. We all know this, and usually, to be fair, both parties are responsible when sub optimal or sub sufficient communication takes place, not just one. So, in response I want to make clear here that I don’t appreciate being blamed in an aggressive manner as if I were either some kind of idiot who deserves no respect or as if I had (stupidly) withheld information because I wanted to piss Dr. D-Jet off on purpose. In other words, please, chill out. Beyond this, I’m pretty darn sure I MUST have told Volker (Dr. D-Jet) last year at some point that the engine was indeed increased to 2.0 liters either personally or via his site Oldtimer.tips.de This new problem popped up AFTER the engine had been running FINE. The discussion about what changed didn’t include any questions or REPEAT of the information which should have in all cases been shared a year previously in Erlangen or via correspondence. So yes, as much as Volker ASSUMED that my engine was stock, it could also be said that I assumed that he knew it wasn’t because again, I’m pretty sure that that must have been clear and in any case, he as the EXPERT looking to help diagnose a problem should, as a professional, KNOW / ASK the (often naive) lay customer about such essential basic background information. I find the irate tone and the WTF actually embarrassing for Volker and encourage a retraction. On top of this, I described the recent symptom via email without reminding Volker that the car was a 2.0 or, possibly, without having EVER mentioned at all, which wouldn’t have been the case if he had ever asked, which he obviously should have at some point if not straight away when we first met in person at his clinic in Erlangen in 2017. After describing the new symptom the talk was about a prime suspect, the quality of the seal in my MPS. I sent it to him and he determined that the diaphragm was DONE and replaced it, for which I paid him. He also tested my CPU and determined what its model number must be based on values. This was necessary because my CPU has no number on it anywhere. He also sold me his CPU so I would have one while he looked into what was up with mine. At the time it wasn’t clear if mine was compatible with the MPs because it has no number on it. So he spent his personal time helping me determine that my MPS and CPU are compatible and was paid for the rebuild of the MPS, as mentioned. The next step was for me to install the rebuilt MPS, with his CPU, because he still had/ has mine, which we KNEW was compatible with BOTH MPS mentioned here, and for me to determine if things were now OK, which I did, but the engine was running worse than before. Volker also gave me an extra MPS to test when I bought the CPU from him in Erlangen a few weeks ago. The engine seemed to function better with this „extra“ MPS, but only until the engine started to warm up, which is apparently due to the cold start valve enriching the mixture very temporarily. After only a half a mile the symptom returned, and I reported this to Volker this evening. That’s where we were. Confused and trying to move forward. Then Volker heard from someone that my engine wasn’t a stock 1,7 and decided to get all bent out of shape with me, as you can see. So, for the record, this is all that occurred and there is little more to it. Volker, I like you and I’ve been very grateful for your knowledge and support. I’m really disappointed how you’ve practically acttacked me here personally and I’m sorry I have this far failed you as a student. (IMG:style_emoticons/default/sad.gif) Mike |
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