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-   -   M103 idle surge ... STILL (http://www.peachparts.com/shopforum/tech-help/373175-m103-idle-surge-still.html)

TnBob 11-04-2015 06:08 PM

M103 idle surge ... STILL
 
Still dealing with this POS.
Ohhh yes, the high idle was solved leaving behind the infamous 'surging idle'

There has to be a very special group of German engineers who gather at least annually to laugh at those they left behind to deal with their incredibly bs style of so called engineering.

Some background.
http://www.peachparts.com/shopforum/tech-help/369277-89-300e-w124-m103-high-idle-solved.html

ALL injector boots replaced. ALL needed it. Been all over the drivers side of the motor with a spray looking for any other vacuum leaks which many of the injector boots had. No additional leaks found anywhere.

Additionally, the OVP relay replaced with a 2 fuse version as was the one I pulled. NO CHANGE.

Distributor cap and rotor were also replaced. Both were needed.

From another site one suggestion I just got thru trying was to replace the AIR FLOW POTENTIOMETER which did not solve the issue. Spec is supposed to be 0.7mvdc +- 0.1mvdc.

At operating temp, voltage ranges from 0.3 to 1.8mvdc. Rpm's range from ~500 to 1100rpm.

Is there anyone here that has solved this issue ? By solve I mean had a M103 with a surging idle that something was done that actually left the M103 with a stable idle.

I have to express that I am not looking for guesses...just resolution.
Thanks


optimusprime 11-05-2015 04:59 AM

I did see a video on youtube on this fault .Thinking he changed the fuel relay Is this in a 260e? or 300e ? You wll find it at the rear of battery ,pull away the plastic membrain ,you will see another black box close to the ovp relay.It will be hard to remove as it as lugs on the side of the base that pop in to slots on the holder thats in there.This is if it like my 260e .Just another thing that can make these symptoms, look down on to the engine from the top with air box removed.Loook for this T shaped item with two hoses going to it and electrical connection on the rear. This regulates the air in to engine if its gummed up it will give fluctuation of engine speed.It is held in there with a plastic sadle just 2 bolts to remove it .Get it out and spray inside with carb cleaner ,shake it a little then tip it out. Do this few times.Refit , check for damage on the 2 hoses as you put them back on. Do let us know how it works out for you please..

optimusprime 11-05-2015 05:07 AM

TnBob this is what your looking for .

optimusprime 11-05-2015 05:10 AM

This is the item to clean .Sorry pictures not working

TnBob 11-05-2015 11:04 AM

optimusprime, the fuel pump relay is one of the few things I havent changed, yet.
Ive not only pulled and cleaned the IAV, but replaced it even after it checked good statically and on the car. Both the large vacuum lines including that absolute POS son of a bitxx one that goes to the block were changed. The one to the block was rock hard with the other one not far behind.

I somehow missed that youtube. Parts ordered

optimusprime 11-06-2015 04:57 AM

TnBOB do let us know how you get on please.

tilac1 11-06-2015 07:23 AM

I got so sick and tired of trying to get a decent, consistent idle, I removed the IAC valve and replaced it with a plumbing gate valve from home depot, I think it was 3/4" but I cant remember. It fit perfectly inside the hoses and secured with hose clamps. Air cleaner hides it. Set it and forget it. Low tech but works great.

Stretch 11-06-2015 09:30 AM

Quote:

Originally Posted by TnBob (Post 3536576)
Still dealing with this POS.
Ohhh yes, the high idle was solved leaving behind the infamous 'surging idle'

There has to be a very special group of German engineers who gather at least annually to laugh at those they left behind to deal with their incredibly bs style of so called engineering.

...

Quote:

Originally Posted by tilac1 (Post 3537209)
I got so sick and tired of trying to get a decent, consistent idle, I removed the IAC valve and replaced it with a plumbing gate valve from home depot, I think it was 3/4" but I cant remember. It fit perfectly inside the hoses and secured with hose clamps. Air cleaner hides it. Set it and forget it. Low tech but works great.

I too sympathise with the frustration of M102 / M103 idle troubles

Bob - when do you get the surging?

Does it happen immediately from cold?

OR does it happen after you've been driving?

Stretch 11-06-2015 09:32 AM

Quote:

Originally Posted by TnBob (Post 3536576)
...
From another site one suggestion I just got thru trying was to replace the AIR FLOW POTENTIOMETER which did not solve the issue. Spec is supposed to be 0.7mvdc +- 0.1mvdc.

At operating temp, voltage ranges from 0.3 to 1.8mvdc. Rpm's range from ~500 to 1100rpm.
...


But you did adjust it at operating temp didn't you?

I have alternative instructions for the fitting of this potentiometer that do not include the "live" with engine running method.

I'll dig 'em out and post them in a bit.

Benz Mondi 11-06-2015 10:57 AM

Dare I say it... send it out
 
For me, one of the few times it makes sense to send my cars to a pro and pay for one hour of their time, $120, is when I think it's going to cost me 2-3X as much time to figure it out.

Dare I say it...
send it to a pro and have him tell you what's wrong once and for all?

Stretch 11-06-2015 01:02 PM

Heretic!

Stone him!

TnBob 11-06-2015 02:44 PM

Stretch, surge commences 5/6 secs from startup
Adjustments made at bout 80c

tilac, IAC powered or not seems to make no difference. How bout necking down to 1/'4'' ??

optimusprime 11-07-2015 10:39 AM

Vacuum problem my be .

Stretch 11-07-2015 11:07 AM

Sorry Bob - I forgot to post this
 
1 Attachment(s)
http://www.peachparts.com/shopforum/...1&d=1446912077

And at the risk of being stoned myself

I hate to suggest it but perhaps you need to reconsider the water sensor and the resistor you installed?

I've got a list of the output values as they should be if you're interested.

My experience has shown that idle (before moving / driving the car) can be nice and smooth by making sure air idle control valve is working (so disconnect plug - idle goes up to about 1200 to 1500 rpm), making sure the air flow sensor is new without worn tracks, and replacing O2 sensor.

I get the impression that the pressure difference in the upper and lower chambers in the fuel distributor also need to be checked but so far I haven't found the correct adapters to allow me to check this measurement and adjust the hydro-electric actuator (back of fuel distributor).

w123fanman 11-07-2015 11:55 AM

Are there any fault codes?


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