ISV/ICV replacement ('86.5)
06-02-2017, 09:37 AM
#31
Three Wheelin'
That is what the diagrams I have say should be there, but my splitter doesn't seem to have anything going to the EZF directly. I suspect something has been misrouted, or perhaps my car is a bit of a Franken-beast, with some of it containing earlier parts? Hard to say at this point.
My diagram does show an EGR and AC Kickdown but I read someplace else that those were not in use in the later years, and they do seem to have hoses going to the vicinity of that charcoal canister in the wheel well...I'll bet that's what those are, as you described.
My diagram does show an EGR and AC Kickdown but I read someplace else that those were not in use in the later years, and they do seem to have hoses going to the vicinity of that charcoal canister in the wheel well...I'll bet that's what those are, as you described.
There was a modified routing set up for the vacc lines that some people were doing, it was supposed to be more efficient. I never learned enough about it, but it may be that your PO has moved stuff around.
I'm always amazed that these engines can run as well as they do without the vacc system hooked in. When I got mine the EZF was not connected and the line to the EGR was chewed thru, etc.
While this part of the game is maddening, at least it isn't that expensive
06-02-2017, 12:01 PM
#32
Rennlist Member
Thread Starter
The frustrating part is that anomalies in this area that have been there since I bought the car can't be the cause of my recent problems. I see something and think "A-Ha!" only to learn that, right or wrong, it's been that way for a while.
06-02-2017, 03:21 PM
#33
Rennlist Member
Yeah, but just imagine how much better it's going to run once you re-route the vacuum the way it was supposed to be and your EZF starts advancing the timing based on engine load!
Might not be a bad idea if you pulled the rest of the manifold apart and pulled the vacuum system from scratch with new hoses and fittings. You can get the 4mm line from Belmetric at a decent price, and the U-connectors are cheaper from the Mercedes suppliers. Pain in the ***, but at least you'll know what you've got. No EGR on the 86.5. The lines from that side of the splitter only go to the EZF and the vacuum diaphragm that's mounted to the cross bar. (and your non-existent automatic transmission)
Might not be a bad idea if you pulled the rest of the manifold apart and pulled the vacuum system from scratch with new hoses and fittings. You can get the 4mm line from Belmetric at a decent price, and the U-connectors are cheaper from the Mercedes suppliers. Pain in the ***, but at least you'll know what you've got. No EGR on the 86.5. The lines from that side of the splitter only go to the EZF and the vacuum diaphragm that's mounted to the cross bar. (and your non-existent automatic transmission)
06-02-2017, 03:41 PM
#34
Rennlist Member
Thread Starter
That's a good point! I suspect in addition to this, I've created a fairly major vacuum leak somewhere with my ISV replacement...if I have to pull a bunch of stuff off anyway, I will definitely re-do that stuff from scratch. If I don't, I will try to get it back to being correctly routed, etc, but if I can't...I'll have to pull everything. I make a habit out of trying to get out of extra work like that, failing, and ending up doing it all anyway, so that would not be a shocking outcome!
06-03-2017, 01:51 PM
#35
Rennlist Member
Thread Starter
OK, I made some progress....with one exception, I believe I have the vacuum lines properly sorted (ie the start where they're supposed to start, and end where they're supposed to end...how they get there may be a different story 
). The one exception is the line from the thermoswitch to the vacuum valve by the coolant overflow tank...the nipple on the thermoswitch seems to be broken off. As an aside, if anyone knows how this thing is supposed to behave, please let me know. Does it open or close at operating temps? (I assume it's purpose is to cause that vacuum valve...which is attached to the exhaust gas recovery thing in the wheel well...to route those gasses wherever they're supposed to go, so the thermoswitch essentially turns the vacuum source on and off to that valve). I now get about 15-16 in-Hg at the EZF vacuum line, a bit low, but on the right track. Plugging the thermoswitch broken nipple with my finger didn't seem to improve this, fwiw, but I don't know if it was even connected to anything at that point, based on switch behavior and temps.
Note that my basic problem...extremely high idle....is still there, as expected. For the most part, these vacuum routing issues have been there since before my high idle and ISV replacement. The most likely cause is still me causing a vacuum leak somewhere, probably in the throttle body-to-large intake tube, or the intake tube to the boxes on the side. Testing that (smoke I guess...someone suggested spraying brake cleaner around and seeing where the engine reacts, but I'm not sure I want that stuff all over my intake) and checking the idle switch electrically are my next moves.
The funny thing is, other than the high idle, the car is driving great right now. On startup, it's not even that high...around 1000. But once you start driving, it will still do the RPM-dive-at-clutch-in thing, but they then shoot up to around 1600 and idle there, which is really disconcerting...
). The one exception is the line from the thermoswitch to the vacuum valve by the coolant overflow tank...the nipple on the thermoswitch seems to be broken off. As an aside, if anyone knows how this thing is supposed to behave, please let me know. Does it open or close at operating temps? (I assume it's purpose is to cause that vacuum valve...which is attached to the exhaust gas recovery thing in the wheel well...to route those gasses wherever they're supposed to go, so the thermoswitch essentially turns the vacuum source on and off to that valve). I now get about 15-16 in-Hg at the EZF vacuum line, a bit low, but on the right track. Plugging the thermoswitch broken nipple with my finger didn't seem to improve this, fwiw, but I don't know if it was even connected to anything at that point, based on switch behavior and temps.Note that my basic problem...extremely high idle....is still there, as expected. For the most part, these vacuum routing issues have been there since before my high idle and ISV replacement. The most likely cause is still me causing a vacuum leak somewhere, probably in the throttle body-to-large intake tube, or the intake tube to the boxes on the side. Testing that (smoke I guess...someone suggested spraying brake cleaner around and seeing where the engine reacts, but I'm not sure I want that stuff all over my intake) and checking the idle switch electrically are my next moves.
The funny thing is, other than the high idle, the car is driving great right now. On startup, it's not even that high...around 1000. But once you start driving, it will still do the RPM-dive-at-clutch-in thing, but they then shoot up to around 1600 and idle there, which is really disconcerting...
06-03-2017, 02:29 PM
#36
Rennlist Member
The fuel vapor purge is a two-step process. The coolant temp needs to be above a certain point and the engine needs to be running above idle. Hence the two diaphragms for it. The one closest to the fender runs off of the thermoswitch, which opens the vacuum flow when it hits its set temp. The diaphragm mounted to the crossbar is closed under peak vacuum, and opens up as vacuum drops when the throttle plate opens up. This overly complicated process prevents the fuel vapor purge from richening the mixture at idle when you first start the engine.
06-03-2017, 02:47 PM
#37
Rennlist Member
Thread Starter
OK, that all makes sense, thank you. I will order a new thermoswitch, along with whatever else I discover is needed.
06-08-2017, 10:25 PM
#38
Rennlist Member
Thread Starter
UPDATE: I bought one of those $76 smoke machine leak testers on Ebay. The good news: Very simple to use, and works great. The bad, although not entirely unexpected news: It looked like my car was vaping I apparently have more than one leak. The most obvious was from the driver's side coupling on the large T...not surprising, as I had to wrestle with that one, and it just doesn't seem wide enough, to me. There was quite a bit of smoke seeping up through the gaps in the pipe organ from below, I suspect the hoses connected to the ISV, or possibly the throttle body-to-T connection. It was dark though, so a bit hard to tell where it was all coming from...plus I couldn't see through all that smoke
I apparently have more than one leak. The most obvious was from the driver's side coupling on the large T...not surprising, as I had to wrestle with that one, and it just doesn't seem wide enough, to me. There was quite a bit of smoke seeping up through the gaps in the pipe organ from below, I suspect the hoses connected to the ISV, or possibly the throttle body-to-T connection. It was dark though, so a bit hard to tell where it was all coming from...plus I couldn't see through all that smoke
06-10-2017, 03:27 PM
#39
Rennlist Member
Thread Starter
OK, so my leak situation wasn't so bad, I must have simply curled the T coupling up under the tube, for a massive leak. Once I managed to get that coupling on properly (I still maintain that, at least on my car, those center T couplings are too short) I saw no more smoke! Woohoo! At least, not that I can see. I measure about 16 in-Hg at the EZF. That's still a little low, especially considering I was measuring over 20 at the brake booster. But, it's within view of the target, anyway.
Now...I think I will move further discussions to another thread, since the ISV replacement task appears to be concluded. I took some pics so I may add those the this thread at some point, in case they're useful to someone in the future. I will say that, with the air box and passenger side intake box thing removed, and the center T pulled up out of its sleeve a little, removing the ISV wasn't really that difficult. I used a combination of long screwdrivers and socket driver with extension and a u-joint, and was able to get to the clamps, etc.
Now...I think I will move further discussions to another thread, since the ISV replacement task appears to be concluded. I took some pics so I may add those the this thread at some point, in case they're useful to someone in the future. I will say that, with the air box and passenger side intake box thing removed, and the center T pulled up out of its sleeve a little, removing the ISV wasn't really that difficult. I used a combination of long screwdrivers and socket driver with extension and a u-joint, and was able to get to the clamps, etc.