85 380SE Idle problems - Page 2 - PeachParts Mercedes-Benz Forum

Monomer · #16 02-01-2006, 09:40 PM

Quote:

Originally Posted by derryb

to fill us in on this one. Seems like my indie (as good a mercedes tech I've ever met, spent many years as a master at the local dealer) used what looked like a HVAC vaccum line (small diamieter) for the mod and he knew right where to tap into the hoses for what looked like a small bypass for the ICV. Like I said if you look at a 87 or later V8 I think you will see this already done by the factory. What we need is a pic from someone who has the ICV with the small bypass tubing installed from the factory and one of our resident expert's take on the subject. Don't go drillin on no mercedes based on my say!

If you look it up on the mercedes site partfinder, it gives you a pic of what the new hoses look like.

Drilling into a couple of hoses is nothing, I can easily find a replacement for that locally if (when) I screw it up. I'm a machinest by trade, I'm quite handy with a drill (and LOVE to tinker)

A pic "under the hood" of the car that has the proper lines would be perfect.

Monomer · #17 02-03-2006, 09:49 PM

Had a talk wit Whunter yesterday:

-Might be a ground issue, between the tranny/engine ground (he recomended a jumper from the battery's neg terminal to a Solid engine ground)

-Could be as simple as a cold solder joint on the OVP (it's the relay with the red fuse at the top)

derryb · #18 02-03-2006, 11:35 PM

did you mention the jumper hose at the ICV that appears in 87 and later V8s? I'm curious about this one.

Monomer · #19 02-04-2006, 11:59 AM

Quote:

Originally Posted by derryb

did you mention the jumper hose at the ICV that appears in 87 and later V8s? I'm curious about this one.

I did not.

Monomer · #20 02-04-2006, 08:38 PM

A bad solder joint seems to have been the problem for me.

Take a look inside you OVP (the relay/fuse that has the red top/10amp fuse in it)

This also explains why some of the car's other functions werent working all to well...

Gary Ganaway · #21 02-06-2006, 04:50 PM

I have seen this bypass tube on my W126 CD but it is not on my 380SE. I too would like to know what puting one in would do..my two hoses on the idle control valve have the little extension where one of these by pass hoses could be put in but are sealed. Wonder what else was changed or added along with this by pass hose on the 87's 420's

Monomer · #22 02-06-2006, 08:46 PM

I lied....

still has problems.

Might be as simple as an O2 sensor

Gary Ganaway · #23 02-07-2006, 03:05 PM

Still investigating rough ilde until car warms up to about 60-80C Not as bad this morning even though it was 19 F degrees.

1. Would a "bad" tank of fuel be more noticeable in cold start than when fully warm?

2.Would fuel pressure regulator problem be more noticeable when cold?

Plugs, rotor, dist cap in good shape--rechecked condition yesterday.
fuel filter replaced this year.
New OVP and water temp sensor

Cleaned idle control valve and if I disconnect it engine revs increase so I don't think this is a problem. Wasn't very dirty either

Frequency valve buzzes so it appears ok.

Cannot find any vacuum hose problems.

Filled tank up yesterday and rough cold idle not quite as bad but it still somewhat rough till warm then car runs and idles like a dream.

Haven't checked cold start valve yet but it seems if this was a problem car would not start right up and run at higher rev abouat 1000/min then gradually drop to normal 500/min when warm.

thanks

derryb · #24 02-08-2006, 05:17 AM

and look for fouling. How many miles on the wires? I would put it new plugs (bosch copper, non-resistor) and try a set of new beru wires. You might be surprised, expecially if someone installed cheap wires or platinum plugs.

Monomer · #25 02-08-2006, 07:33 AM

Quote:

Originally Posted by derryb

and look for fouling. How many miles on the wires? I would put it new plugs (bosch copper, non-resistor) and try a set of new beru wires. You might be surprised, expecially if someone installed cheap wires or platinum plugs.

plugs were the first thing I replaced. I didnt use the recomend bosch plugs, but the ngk with the same specs as it.

plug wires and dist. are new.

derryb · #26 02-08-2006, 05:19 PM

started a new thread titled ICV jumper hose with a picture of that appears on V-8s starting in 1987.

Monomer · #27 02-08-2006, 08:17 PM

Quote:

Originally Posted by derryb

Lint to ICV at fastlane with pic:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1Q1172JL21Q216YDXW&year=1985&make=MB&model=380-SE-001&category=C&part=Idle+Control+Valve

The hoses on each end can be bought pretty cheap. Try:
http://www.mercedes-benz-parts-direct.com/

The jumper hose I referred to goes between the two hoses on each end of the ICV sort of like a bypass. Didn't have it on my 85 380SE. Indie added it by drilling into 2 hoses at each end of ICV. Improved idle. Last time I looked at a V8 (87 420 SEL) this bypass hose looked like it had become a factory stock item. If you look at the photos of the hoses for the ICV for an 87 420 SEL at:
http://www.mercedes-benz-parts-direct.com/
you can see the jumper (hose connector) and a photo of the two ICV hoses with a place for this jumper to plug in. I don't recall seeing this arranagement on pre-87 V8s. Its possible the 87 ICV hoses and jumper will give you the mod on earlier V8s. Was hoping one of our resident gurus would have popped in by now. I am not an expert on this. Just passing on what I have seen.

just ordered those peices + hose from fastlane.

will post when they're tested.

elolson · #28 11-02-2007, 08:23 PM

I had another post here but it was misleading in what it solved so I did not want to send anybody down the wrong path.

I too have a 1985 380se with an idle problem. When it has warmed up thoroughly, this is when it has the issue. It is clearly noticeable in Park or in Neutral with no load. In drive, sometimes it is there. Add AC to drive and I have never felt it. So no load is biggest problem, and the more load you add, the better it gets.

I bought a CIS fuel pressure testing kit. The warm-up compensator did not pass the cold pressure test. I replaced it, the new one is in spec. exactly, that was nice to see, but... all this did exactly nothing for my idle problem.

elolson · #29 02-01-2008, 09:37 PM

I did not thoroughly diagnose the system, but kind of launched into the idea that the brain was dead. This was due to the following observation. When warmed up, and doing the old funky idle mis-fire thing I would watch the on-off ratio. It would start at about 1.25 volts then drop down to 0.8-0.9, misfire, and then it would bounce back up to 1.25, the engine would rev up to do this as it followed the ratio back up. Then fall down again, mis-fire would occur and then it would center back up.

I got a rebuilt lambda control unit in, pulled out the kick panel, removed the old one, dropped the little nut down under the floor, got another nut, and installed the new unit. It most definitely stopped that hunting BS. I guess I was expecting a baby smooth idle like my 2003 VW, the miss is gone but it is still not as smooth as I was expecting. Tomorrow, I am going to try and fine tune the on-off ratio to see if I can help it a smidge.

Other thing I did was after initial brain transplant, I went ahead and drilled out the rubber couplers on the ICV and installed a by-pass shunt as was mentioned. For you folks considering such a move, don't bother, that does exactly nothing other than add another couple of holes in an already touchy system that is sensitive to vacuum. The closed loop ICU will keep the idle where it needs to be. I am now guessing that when they did role this change in they might have done some other electronic adjustments to take advantage of the air flow offset, that would not be in my 85, just supposing of course.

germanltd · #30 02-01-2008, 10:42 PM

starting problem issue is diferent at cold or hot engine start, when it hard to start cold engine you must check fuel pressure before starting the engine , if it is not sufficient your problem is in fuel pressure check valve at fuel pumps($30 each) , if the starting problem is at hot engine your problem is damper($180) , that is the cone type aluminium piece next to pumps. if you have one of this problems - it is real meaning that your fuel pumps are weak and need help , first remedy to it will be ATF to the tank to lubricate them.
irregular idling will be a different problem, but you can not jump to that before fixing fueling problem.
good luck