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606 erratic idle
I just completed a timing chain replacement with a new tensioner. Everything lined up at TDC and I'm sure I didn't miss a tooth on the cam. At the same time, I replaced all six injectors with reman Bosch units ( I still have the old ones with Bosio nozzles but well worn at 120K on them.) The injectors nail worse than the previous ones, despite me bleeding the lines several times yesterday and today.
After getting everything buttoned up, primed and driven briefly, the car has now developed the infamous erratic low idle problem. I've searched the forum archives but can't find anything related to the w124 1995 606 engine on this subject. When I first got the car 6 years ago, I replaced the ELR module behind the battery to solve an erratic idle problem. The ELR unit on the back of the IP also got changed out. At the same time, all the vacuum hoses were changed; an EGR bypass was performed with a bb and a copper freeze plug in the EGR tube attached the exhaust manifold, so there is no coke in the intake manifold causing any restrictions that could cause surging. I pulled the ELR module behind the battery and cleaned the contacts, then reinstalled it; no change in the symptoms afterwards. The erratic idle problem seems to only rear its head after I start the car and blip the throttle. When I shut off the engine and restart it, the idle evens out again. I disconnected the two pin connector at the top of the ELR module in the IP and it drops to an even 500RPM; upon reattachment,the RPM jumps back up to 650-700ish then starts loping. There is consistent light grey smoke coming from the tailpipe, suggesting an IP timing problem. Any suggestions appreciated, I'm at my wits end. Last edited by clickclak; 08-19-2014 at 03:13 PM. |
#2
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Any air bubbles in the clear fuel lines coming off the fuel filter mount?
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CENSORED due to not family friendly words |
#3
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Try adjusting timing with engine running and see if it gets better? Might not have missed a tooth on the cam but maybe on the IP? My bet is on the remans... Did you check for leaks? Cracked injectors tried to isolate?
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http://superturbodiesel.com/images/sig.04.10.jpg 1995 E420 Schwarz 1995 E300 Weiss #1987 300D Sturmmachine #1991 300D Nearly Perfect #1994 E320 Cabriolet #1995 E320 Touring #1985 300D Sedan OBK #42 |
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Hmm, didn't check those. I'll do that shortly. I did replace them 2 years ago but they could be cracked again due to heat.
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#5
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I don't know how to adjust timing on the IP, guess I'll have to check the FSM for that. I did check the for leaks on the injectors and attempted to isolate but found none so far, I'll check again.
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#6
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Update:
I just got back from errands and performed an italian tune up. Freeway speed on the interstate (70-80ish), followed by in town stop and go driving. The injectors have quieted down a lot. The erratic idle goes away after I get the speed up, and it stays level after coming to a stop for the most part. But the moment I come to a stop and put it in park or neutral, say to go in to get the mail, leaving the engine running (doors locked of course), the loping comes back. When I shift to drive and go again then come to another stop light/sign, it sometimes stays level, other times it lopes a little then evens out. |
#7
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After injector replacement it needs a hard run to settle things down.
Adjust the IP timing after checking the manual from the procedure and we'll go from there. |
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Thanks, I figured it had to be something related to the IP. I just checked all the clear lines coming from the filter housing to the pump; no sign of bubbles or cracks, nothing at the injectors. I just started it again after letting it sit for 20 minutes; the rpms came up level, but the moment I pulled the throttle lever and blipped it, the loping came back.
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#9
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Well, I checked the manual for the IP timing procedure and it involves getting several MB only electrical connectors, a digital meter and following the RIV method. Having never done this before, I performed a search here but came up with only hits on older 616 and 617 engines. Are there any references someone could point to that give the A-Z on how to set IP timing on a 606?
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#10
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you dont need any fancy connectors, all you need to do is to remove the locking pin plug from the injection pump governor housing, rotate the engine to 15 ATDC and look for the slot in the hole, it should be perfectly in the middle of it. If its not then you can rotate the injection pump to align it back.
My car once developed this loping issue which was resolved by fresh O rings on the clear pipes on the IP.
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2012 BMW X5 (Beef + Granite suspension model) 1995 E300D - The original humming machine (consumed by Flood 2017) 2000 E320 - The evolution (consumed by flood 2017) |
#11
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Are you certain you have the vacuum lines at the crossover and IM reconnected properly, and that there are no leaks?
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Terry Allison N. Calif. & Boca Chica, Panama 09' E320 Bluetec 77k (USA) 09' Hyundai Santa Fe Diesel 48k (S.A.) |
#12
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I'm a bit confused here. What year 606 is this? NA or Turbo?
The 97/99 pumps aren't electronic. They are mechanical pumps WITH electronic control. 97 and up diesels are drive-by-wire systems. List in your signature what year and model MB this is for future reference. |
#13
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Quote:
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#14
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Yes. I took several pictures and double checked them. As for leaks, not 100% sure, I replaced all the vacuum tubing six years ago. I'll have to visually inspect again, it could be a bad piece of tubing.
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#15
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Quote:
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