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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?

TnBob 11-07-2015 06:54 PM

No vacuum leaks, been over everything with a spray can.

'89 doenst have codes. I think it was the last one not to.

Work currently aborted due to rain

''reconsider the water sensor and the resistor you installed'' reconsider what? It stopped the 1200+ rpm idle at ~80c

FWIW, the pot adjustment was made by sliding the full assembly up / down from the far right.
What does the itty bitty adjustment towards the center actually adjust ?

w123fanman 11-07-2015 09:41 PM

My car has a similar idle problem and the fault codes and these are what I had initially:

"7 TNA (Engine RPM) Signal
14 Road Speed Signal At CIS-E Control Unit
18 Current To Idle Speed Air Valve
27 Data Exchange Fault Between CIS-E Control Unit and EZL ignition Control Unit"

Cleared the codes and the only one that still comes up is 14. From what I have read, most common issue is the failure of the hall effect sensor that is on the back of the speedometer. Other potential issue is the CIS computer itself.

I have a likely good used one that is waiting to be installed just haven't been able to do that in the past 4 months. My issue really isn't that bad atm.

Part number is 0075422917, should be about $55 at the dealer.

TnBob 11-08-2015 01:15 AM

89 seems to be a production break point.
Your 93 electronics are different than mine but thanks

tilac1 11-08-2015 07:15 AM

Quote:

Originally Posted by TnBob (Post 3537460)

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

I believe the inside diameter of the mechanical valve is 1/2". The IAC is Normally Open unpowered, so that's why your idle is high. Try the gate valve idea, less than $10.

optimusprime 11-08-2015 07:18 AM

The potentiomiter
 
1 Attachment(s)
Potentiomiter may be the problem ,remove it and check out the carbon track if worn its shot.

Stretch 11-08-2015 10:56 AM

Quote:

Originally Posted by TnBob (Post 3537929)
...
''reconsider the water sensor and the resistor you installed'' reconsider what? It stopped the 1200+ rpm idle at ~80c

FWIW, the pot adjustment was made by sliding the full assembly up / down from the far right.
What does the itty bitty adjustment towards the center actually adjust ?

If you unplug your air idle control valve the revs should be about 1200 to 1500 rpm - do you still get that after your resistor modification?

As for the little adjustment thing in the centre of the potentiometer that's the fine tuning. "Everyone" says don't touch it.

Stretch 11-08-2015 10:56 AM

Quote:

Originally Posted by optimusprime (Post 3538087)
Potentiomiter may be the problem ,remove it and check out the carbon track if worn its shot.

He's already done that I think

Stretch 11-08-2015 11:00 AM

Quote:

Originally Posted by TnBob (Post 3538064)
89 seems to be a production break point.
Your 93 electronics are different than mine but thanks

If you don't have the ability to measure fault "blips" then I believe the fault codes are given in terms of on off ratio aren't they?

TnBob 11-08-2015 12:23 PM

Potentiometer is brand new, no change

I dont know bout the fault codes

tilac, sure cant hurt

optimusprime 11-08-2015 02:37 PM

Tnbob Take the vacuum pipe of the brake servo and check vacuum with a guage .And if it fluctuates with it off the problem is on the engine side. Blockthe pipe with a bung then If it is stable your brake servo is leaking vacuum.

TnBob 11-08-2015 05:02 PM

opti... thats one I actually havent tried yet.

optimusprime 11-09-2015 04:57 AM

tnbob let us know please how you get on with it .

TnBob 11-09-2015 04:53 PM

rain, wind and coool postponed work

TnBob 11-09-2015 06:48 PM

for new readers/problem solvers, here is a recap
New cap and rotor
New fuel distributor
new EHA, torx's replaced with flat head screws
new pot on front of FD
NEW vacuum hoses to and from the IAC, one to the block is a real (&^*(&^*
IAC replaced with used one, both tested good.
OVP relay replaced, no change
New injector boots
New temp sensor with resistor mod.
The temp sensor stopped the high (1200ish rpm) idle

Vacuum leak checked with carb cleaner spray. NONE found

Things to do:
Confirm alternator voltage regulator is working properly
Change fuel pump relay with new one.
Replace IAC with gate or ball valve setup
Start a mold for some type of as of yet unknown shaped charge

TnBob 11-09-2015 07:07 PM

I did find a nice pictorial of how/what/who the IAC is supposed to do.

http://www.k-jet.org/img/articles/diagrams/cis_system1.jpg

TnBob 11-10-2015 03:55 PM

Well well...
New fuel pump relay made a great difference ! Not perfect but much better.
Alternator regulator working great. 600 to 3000rpm = 13.88vdc +- ,01vdc

At cold start, no surge but by about 45/50c surge returned but not as radical.
Ranged from ~550 to ~900. popped the IAC connector and rpm instantly went to ~1000 and STABLE. Im guessing that even though very throughly cleaned both the original and the used replacement are failing. Both read correctly for ohm reading too.

At operating temp, 80C, idle surge remained ~550 to ~900 with the IAC connected and went to a STABLE 1000rpm with the IAC disconnected.

TnBob 11-10-2015 06:08 PM

Once again out of daylight.
$4.71 later I have a gate valve with 2 barbs

optimusprime 11-11-2015 11:02 AM

You will get there .

Stretch 11-11-2015 02:54 PM

Quote:

Originally Posted by TnBob (Post 3539041)
Well well...
New fuel pump relay made a great difference ! Not perfect but much better.
Alternator regulator working great. 600 to 3000rpm = 13.88vdc +- ,01vdc

At cold start, no surge but by about 45/50c surge returned but not as radical.
Ranged from ~550 to ~900. popped the IAC connector and rpm instantly went to ~1000 and STABLE. Im guessing that even though very throughly cleaned both the original and the used replacement are failing. Both read correctly for ohm reading too.

At operating temp, 80C, idle surge remained ~550 to ~900 with the IAC connected and went to a STABLE 1000rpm with the IAC disconnected.

It should idling a bit higher than that (from what I've read) when the air idle control valve is unplugged. I wonder if that's due to your resistor fix.

TnBob 11-11-2015 07:31 PM

Dont know ... wish now Id put a pot on that sensor rather than a fixed resistor.

Got some 0.1 ohm 5 watt coming in to get my resistor substitution box wattage upgraded. Will allow me 1 ohm steps from 1 ohm to 10 meg ohm with a 5 watt. $10 from our fav auction site: http://www.ebay.com/itm/1R-9999999R-Seven-Decade-Programmable-Resistor-Board-Step-1R-1-4W-F-/131647177301?

it was soooo nice to have a stable idle even if it was high

Stretch 11-12-2015 12:12 PM

Quote:

Originally Posted by TnBob (Post 3539510)
Dont know ... wish now Id put a pot on that sensor rather than a fixed resistor.

Got some 0.1 ohm 5 watt coming in to get my resistor substitution box wattage upgraded. Will allow me 1 ohm steps from 1 ohm to 10 meg ohm with a 5 watt. $10 from our fav auction site: http://rover.ebay.com/ar/1/711-53200...31647177301%3Fhttp://www.ebay.com/itm/1R-9999999R-Seven-Decade-Programmable-Resistor-Board-Step-1R-1-4W-F-/131647177301?

it was soooo nice to have a stable idle even if it was high

Well is seems from what you're saying the unstable idle can be fixed by disconnecting the air idle control valve and fit in that bit of plumbing. You could then tune the air flow potentiometer to get a lower idle and call it good.

BUT

I have a feeling that the O2 sensor and emissions might not be working as well as they could. You might also get other trouble such as poor fuel consumption / over heating.

##########

That's a bloody good price for a decade box.

optimusprime 11-12-2015 12:52 PM

1 Attachment(s)
No good hiding a problem to make another elseware.This chart might help you .

TnBob 11-12-2015 02:17 PM

The last one is sure the key.

The decade box is repeatable. Seller seems to always have them up.
The 5W Watt 0.1 Ohm 5% cost $0.18 by buying 10 so if you need/want one
pm me your addy. Gonna break the ground plane and install mine there.

Stretch 11-13-2015 07:22 AM

Very kind but I have a source where I can borrow one - thanks anyway

pmckechnie 11-13-2015 08:46 AM

Bob, could you explain this.
"Got some 0.1 ohm 5 watt coming in to get my resistor substitution box wattage upgraded. Will allow me 1 ohm steps from 1 ohm to 10 meg ohm with a 5 watt. $10 from our fav auction site:"
Where are going to put a 0.1 ohm resistor in the ground plain, and why.
I just don't understand.

PaulM

TnBob 11-13-2015 02:18 PM

The resistor sub board came with 1/4w resistors understandably.
Adding the 5w 0.1 ohm brings up my wattage level as watts in series
are additive. Technically my board will become a 5 1/4w sub board

pmckechnie 11-13-2015 03:30 PM

Bob, I don't think it works like that.

Power is calculated from the voltage drop across the resistor times the amps in the circuit.

The amps is calculated from the voltage in the circuit divided by the total ohms of all the resistors.

The voltage drop across your .1 ohm resistor will be very small compared to the lowest ohm you can get from the box.

We need an EE to jump in here.

PaulM

TnBob 11-14-2015 10:57 PM

"Wattage in a Series Circuit is Additive"
Wattage Series

Very good basic answer

optimusprime 11-16-2015 10:05 AM

I will let you carry on ,the way your going you will have more problems in the end .

Stretch 11-16-2015 11:03 AM

Quote:

Originally Posted by optimusprime (Post 3541343)
I will let you carry on ,the way your going you will have more problems in the end .

Bob's free to do what he wants. It is his car!

Don't take an apparent "refusal" to heed your advice personally.

Sit back an watch what happens.

I also think he shouldn't have rigged the temperature sender but I have learnt something => it looks like you can control the idle by changing the thermostat output. This is quite a nice experiment for the future when I borrow a decade box (perhaps next week); so I can try this myself and in some way or other and perhaps get a better understanding of what this crazy CIS system is doing...

...it is a big learning curve for us folks who are used to mechanical diesel systems - cut us some slack.

TnBob 11-16-2015 12:29 PM

"more problems" ???

Im to a point of popping the oil drain plug and locking the fuel feed to the max in an effort to find out which piston blows the furthest.

Stretch 11-16-2015 01:06 PM

Well that could be a release for the frustration.

Do you have a plan for the next thing to check or are you thoroughly pissed off?

Graham 11-16-2015 04:08 PM

Quote:

Originally Posted by TnBob (Post 3540963)
"Wattage in a Series Circuit is Additive"
Wattage Series

Very good basic answer

Just trying to recall the little I remember about what Stretch calls Electrotrickery :)

Lets say you have a 120v lamp with a 100W bulb. You turn it on and you get 100W output. From Power = V*I, I=100/120= 0.833A. Power also is (I^2)R so R=P/(I^2) or 100/(0.833*0.833)=144.11ohms.

Now you connect four 100W lamps in series and connect 120v across the string of bulbs. You do have a 400W system, but do you get 400W of output?

You get a current of V/R or 120/(4*144.11)=0.21amps. So each lamp puts out (I^2)R or (0.21*0.21)*144.11*4= ~25 watts. So string of lamps still provides about 100watts output. (probably in practice less)

If you want 400watts output, then you would need 4x120V=480volts. Then you would get 480/(4*144.11)=0.833Amps (each bulb gets same as single bulb on 120v!) Now you would get 400watts of output!

So Power may be additive, but Power Output only if current remains the same.

Don't know if this just confuses things. If so, sorry for butting in. (Gotta stop click on New Posts and reading stuff I am not concerned with :( )

w123fanman 11-16-2015 05:28 PM

Are you sure it's not the hall effect sensor? I replaced mine yesterday and it fixed my idle surging. Also made the cruise control work. The EPC seems to indicate that all 201s have this sensor, it's on the back of the instrument cluster.

TnBob 11-16-2015 08:12 PM

Mine ia an 89, Im not aware of one fanman.

4 100w bulbs WILL put out the same TOTAL lumens as a single 400w or quite close.
Never id an amp check on bulbs so Im not sure what they actually measured, in theory a 400w should draw about 4 amps.

stretch, the weather has me cooling off. Supposed to get ~3" over the next couple of days.


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