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  #46  
Old 05-17-2003, 01:57 AM
Rohin99
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Same problemo

Hey guys, I have been following your post because it is the ESACT same problem I have, and it only started about a week ago, if that. So we are trying everything yu guys have mentioned and will see if there is a development for us too. But your guys info has been excellent. It shows us that we are on the right path. BTW, does the fuel pump relay have anything to do with this dilemna, mine smells like it is burning, however the relay itself is still working. And also, is your crusie control working quite erratically, b/c that is what has started with mine. It will either not go on at all or kick in while going steady a high speeds. Your input is greatly appreciated.

Cheers

1990 300SE
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  #47  
Old 05-17-2003, 07:05 AM
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Join Date: Mar 2003
Posts: 64
I've read over the posts again. Have you checked the coolant temperature sensor?

The AFM pot will only influence the ECU same as the temp sensor. I think it might be time to check for continuity from the ECU to the EHA. ECU to AFM. Coolant Temp sensor to ECU. Also measure the resistance at the pins of the ECU plug per the manual for each sensor.

You should not have a rough idle with the EHA disconnected, in fact if anything in a good condition engine the idle could be even smoother (at running temp) as there is no closed loop control and no (very) minor fluctuation in idle as you see with rich/lean correction. This of course is only if Lamda is set correctly mechanically.

Besides cold hard start, I imagine cold rough idling. You must make the measurements at 80 deg C with respect to duty cycle. Are you seeing a fixed number now or is it fluctuating? How about general driving, is it still stalling? Car will stall if the mixture is badly adjusted or the Zero position/Basic position of the AFM throttle plate is incorrectly set. Have you checked that?

HTH
Neil
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87 190 E
89 190 Sport Evolution
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  #48  
Old 05-17-2003, 10:47 AM
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So what is your EHA current? is it the same with the O2 sensor disconnected?

The airflow pot only has a small capability to affect EHA current. A quick voltage change from low (less than 1v) to high (above 3v) will cause the acceleration enrichment function to act. This adds at most 5-10ma.

The main defect I see with the airflow pot is the lack of proper idle speed control.
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Continental Imports
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33 years MB technician
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  #49  
Old 05-17-2003, 11:15 AM
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did you search???

I had the same problem... did you check my thread?

look for Hesitation = history

xp
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  #50  
Old 05-17-2003, 02:19 PM
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Location: Colorado Springs
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Ukevo, I have not checked the temp sensor yet.
The idle is only marginally rough and i have great acceleration. There is still an almost imperceptable stumble when first accelerating from stop, this is most obvious when cold and it will occasionally stall if it is cold with the eha disconnected. With eha connected the car will stall completely on acceleration everytime.

I can not do a duty cycle measurement as I just get a fixed reading.

Xp190, It was your thread that got me on to the potentiometer. I still needed to replace mine as it was worn out but I am now trying to figure out why I do not have a good electrical connection or closed loop.

Both xp190 and UKevo brought up the zero position on the aitflow. I have ignored this as I thought I would stumble all the time and would not run as well as is it does.

Steve my current is identical to what it was before. I will check the current with the o2 sensor disconnected

Robin99, Actually my cruise does work fine. keep me in t he loop if come across anything.
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #51  
Old 05-17-2003, 05:51 PM
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follow up to steve

Steve, With the O2 sensor disconected the eha goes from 1.6 to 2.6 ma. No fluctuation.
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #52  
Old 05-17-2003, 07:21 PM
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it should go to zero ma. How does it run there?

What happens when you plug the O2 back in?
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Continental Imports
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Bosch Master, ASE Master, L1
33 years MB technician
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  #53  
Old 05-17-2003, 07:40 PM
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Hiya,

I'm guessing the mixture is set too rich to compensate for a failed sensor or incorrectly set AFM plate. Too much fuel when cold will give you a rough idle, bom-bom-bom sounding exhaust and a tendency to stall with EHA connected on acceleration as current is altered to initially richen the mixture. Disconnected there is no enrichment so you have less tendency to stall than when it's connected. Just a wild guess...

Right first check the temp sensor. Do you have the values?

What is the fixed value you get at X11? It will indicate a fault code.

Don't ignore the Zero position it's a 5 second visual check and it's critical to correct mixture adjustment at idle. If zero position is out your mixture will be out at idle and it can definitely cause the stumble you speak of.

A few simple steps. Make sure your Zero position is correct (see previous posts). Lean the mixture out counter-clockwise until your basic position is at the very bottom of the vertical cylinder. Likely it won't start here. Richen it approx. 1/8th of a turn until the engine will start and hold a cold idle - this is just to get you in the ballpark. Wait till 80 deg C and you should go into closed loop mode and see fluctuating duty cycle at the pin 3 x11. Tune it by duty cycle and/or EHA current. If not and the duty cycle is fixed check the fault code it will likely pinpoint the problem.

You say the EHA current goes from 1.6-2.6ma. When is this happening? At idle, is the current moving up and down constantly or is this a one off event at some point? Can you elaborate?

Cheers,
Neil
--
87 190 E
89 190 Sport Evolution
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  #54  
Old 05-17-2003, 09:32 PM
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neil

the mA read on the eha is engine on reading with O2 sensor connected 1.6 without O2 is 2.6. The X11 is either 50.4 or 98.6 nothing in between.


Stevebl
It runs but it always stumbles on acceleration, once past accelration she is fine. with O2 reconnected it goes back to 1.6 and stays there.

I will check the Zero position, What is the 5 second check?
m
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #55  
Old 05-17-2003, 11:34 PM
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Your ma readings don't make any sense.

How many milliamps do you read with the key on engine off. Most cars should be 20ma, some are 10ma.

Before the readings can be interpreted they must mean something. If you can't get any of these numbers I suspect your technique.

Since I can't use your EHA current I would suggest to disconnect it. With it disconnected, any mixture under the sun can be hand taylored. Can the car be made to run right with manual mixture correction.. If not you are looking in the wrong area fooling with electric controls.

This should be the first test always. That is to see if basic mixture is the problem by manual adjustment with ALL electrical out of the picture by disconnecting the EHA. I see a lot of chasing one's tail on the issues.

Remember, the system can be adjusted to run just fine without the EHA connected so if you are sure its an electrical control problem thats the way to prove it. It should run great adjusted up.
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33 years MB technician
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  #56  
Old 05-18-2003, 02:00 AM
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Steve,
I totally agree, it is running fine right now I have driven the last 500 miles without the EHA connected for this reason. Without the electrics she is running fine just a little hard to start when cold. Gas mileage is down from 16 to 15 now, but not horrendous for a 560. The only time the car struggles is on cold starts and on acceleration right after the colds start after that she has been running great. However, I would like to get the electrics back. I agree my EHA readings are way off, that is why I posted the pictures to confirm that I did indeed do them correctly. So I know this is electrical and it is something that happened literally overnight about 2 months ago now. The car was adjusted by my local mech to its exhaust gases as we have no lambda, he threw an ovp and oxygen sensor at it still no luck, I have replaced the potentiometer and still no luck, am trying to do some more diagnosis before I throw more parts at it. It is indeed frustrating. I am going to try and figure out the zero tomorrow make sure it is good.
One other thing if I rich up the mixture it overcomes the stall on acceleration with the eha connected, but it is really running rich to do this. Exhaust gases where horendous when we tested it, it only does the stall when the exhaust gases where set to normal.

thanks again everyone for thier time.
m
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #57  
Old 06-13-2003, 01:36 AM
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Join Date: Oct 2002
Location: Colorado Springs
Posts: 481
I am back

Hi all. I am back from from 5 weeks of trips and vacation. Had sometime to think and tried some stuff out. I have discovered the sears ammeter does not close the eha circuit with the testing cable on in ma mode. Hence my screwy numbers. So with the duty cycle at between 45 and 55 the eha is reading (with the old trusty analog ammeter) is +2-4ma. So I believe the eha is doing the job. Now my problem is why do I have the stall from stop when the eha is connected to the system and only a small stumble when disconnected. I understand that the circuit is open when the EHA is disconnected. But why would it stall with it connected what is happening in the system to cause that?
When I accelerate from stop the eha reading drops to close to zero. When I release the accelerator it goes to almost 7ma then comes back to the 2 range, at a steady 40 it is almost zero. On an Acceleration that results in a stall the eha goes down at first as in a normal acceleration but, as the engine starts to stall the reading increases up to @7ma I guess trying to enrichen the engine.

Key on engine off showed a -75ma

Any pointers would be appreciated.
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)

Last edited by mhingram; 06-13-2003 at 01:50 AM.
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  #58  
Old 06-14-2003, 09:01 PM
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Join Date: Oct 2002
Location: Colorado Springs
Posts: 481
almost there

I have have narrowed it down and thanks to steve now have a good number for the eha and duty cycle. My stall is still there but only when the circuit is closed and functioning, although i have to set the duty cycle to about 40% (rich) before I disconnect the system and can drive without stalling. SO now I need to determine the cause. I believe it is the air mass flow. I replaced the potentiometer, but the ohm reading I get is the same with either the new or the old one at just above idle between 3.98and 4.01 k ohm the ammeter loses the continuity then it picks it up at just above 4.02. It is indentical on both potentiometers. Could someone out there with a 560 test this on thier's. I am measuring the 1 and 2 pin from the top. If yours does not do it I have found the problem. Then I just need to figure out how to fix it.
thanks in advance especially to steve for all his patience as i figured out the electronics.
m
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #59  
Old 06-25-2003, 11:28 PM
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Join Date: Oct 2002
Location: Colorado Springs
Posts: 481
AFM same as mine

Okay so i think I was barking up the wrong tree. I bought a used AFM on ebay, it gives the same reading as mine(assuming it does not have the same problem as mine!). So now I am back to square one. I stall on acceleration from stop with a closed circuit warm or cold. With an open circuit and slightly rich (40% duty cycle) she is fine except when very cold, and hesitation is still noticable. If I richen up the mixture completely so she smokes black smoke the stall goes away even with a closed circuit.

So for some reason I am not getting enough gas on acceleration this is exacerbated in closed circuit. Once I am moving all is well. Temp sensor and idle control valve are fine and EHA reading is in bounds.

In previous discussions it has been mentioned to check the AFM is positioned correctly to start with, does anyone know how to do this or know where there is some reading material on it. I am getting a tad frustrated because I thought I had found my problem but now am lost.

thanks for any help.
martin
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #60  
Old 06-26-2003, 07:37 AM
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Posts: 64
I posted a heap of info on this in another thread do a search on my username + zero position. I also made reference to a book on bosch FI which will show you how to set the AFM up in pictures.
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