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Thu Dec 31, 2020 6:20 pm

Lurked for a long time but this is my first post. I have a 87 Westfalia with a gowesty 2.2l motor, installed in 2004. Has been a bit of a project for a while because I haven't had to use it other than to live in it. Now that Im not living in it Ive been doing the maintenance and motor work. Its been a slow decline but ive isolated a few things.

Wondering if anyone has come across this before. Trying to get the van to run proper but seems to want to sputter and die after it runs for a couple minutes. If i turn the key off then back on it will start and run for a few minute then sputter out and die.

Curious thing is that im getting 7.7v in the green COAX from the ECU o2 signal wire disconnected from the o2 sensor. Checked the terminal 2 and got 7.7v, checked my ground shield and it was reading 8.8v. Checked the terminal 19 off the ECU and getting 8.8v.... Terminal 19 has a white jumper to the coax shield and the brown wire leading to the harness. Snipped both at the ECU and the ECU is still throwing voltage through what should be a ground signal. ECU has power and a good ground to it, o2 green wire reading 7.7v and terminal 19 reading 8.8v.

Take apart ECU and find that a small resistor has some brown entry points to the board. Has R66 next to it on the board and the bands say its a 1.05k ohm resistor. Brown/Black/Green/Brown/Red followed by TY1 on the board.

Am i in the right ballpark to think the ECU is bad/ resistor only showing 3.5ohms, should be 1.05k

Thu Dec 31, 2020 6:54 pm

Can you post the part numer of your ECU. If it is a D version I might be able to help.

Thu Dec 31, 2020 6:58 pm

ECU is a Bosch 0 261 200 284/285
Made in Germany
04.03.97
26SA0000
1010 0019

Not the stock VW Ecu

Thu Dec 31, 2020 7:09 pm

Thu Dec 31, 2020 7:34 pm

You may have misunderstood Pin 19 and the function it serves.
That other end of that brown wire is supposed to be grounded on engine metal, to provide a reference ground TO the ECU.
The O2 sensor only has 1 signal wire and it uses the exhaust and engine as the return path for that signal. That brown wire is used by the ECU to measure the O2 sensor reading accurately.

Mark

Thu Dec 31, 2020 7:35 pm

tocsem wrote: ECU is a Bosch 0 261 200 284/285
Made in Germany
04.03.97
26SA0000
1010 0019

Not the stock VW Ecu

Where did you get it from? What car did it come out of? If it’s not a stock VW ECU then what is it?

Thu Dec 31, 2020 7:39 pm

A bad ECU is usually a fools diagnosis. I would say 95%bof the time

Here , though, your pins on the power transistor look to be cracked on the solder pads. I would recommend finding a Ham radio club nearby and finding who does boardrepairs for the club

Minimal cost and will know far more than any mechanic. S/he will also know things like how not to torch your unit from static discharge

Thu Dec 31, 2020 8:05 pm

The R66 resistor is surely a 215 ohm 1% resistor. I would disconnect it from the thyristor (I assume that's what TY1 is) before measuring though [1]. It would be very unlikely for that to dive to 3.5 ohms.

[1] Check what else is connected - how many layers to that printed circuit?

Thu Dec 31, 2020 8:13 pm

Abscate wrote: A bad ECU is usually a fools diagnosis. I would say 95%bof the time

Here , though, your pins on the power transistor look to be cracked on the solder pads. I would recommend finding a Ham radio club nearby and finding who does boardrepairs for the club

Minimal cost and will know far more than any mechanic. S/he will also know things like how not to torch your unit from static discharge

I was going to comment on those transistor (FET ?) legs. But if solder joints are ok at underside (they appear to be, maybe), IF fault at ECU, issue might not lie at solder joints?

If someone with basic soldering skills chose to float those joints, should they put a heat sink at each leg as they go?

Neil.

Thu Dec 31, 2020 8:20 pm

zoti wrote: tocsem wrote: ECU is a Bosch 0 261 200 284/285
Made in Germany
04.03.97
26SA0000
1010 0019

Not the stock VW Ecu

Where did you get it from? What car did it come out of? If it’s not a stock VW ECU then what is it?

Is a later version of the "D" version ECU - identical inside

Thu Dec 31, 2020 9:55 pm

crazyvwvanman wrote: You may have misunderstood Pin 19 and the function it serves.
That other end of that brown wire is supposed to be grounded on engine metal, to provide a reference ground TO the ECU.
The O2 sensor only has 1 signal wire and it uses the exhaust and engine as the return path for that signal. That brown wire is used by the ECU to measure the O2 sensor reading accurately.

Mark

So if I was to run a ground to the brown wire from the engine and bypass the old one, Then when I plug it in should it be reading a ground signal and not the 9v correct.

In regards to what the ecu output on the o2 signal wire would be without the sensor actually hooked up. I thought was to be around 5vs

Thu Dec 31, 2020 10:00 pm

I wonder if the R66 resister has not already been replaced at some point. Had it gotten hot it should show signs of heat, but instead both solder joints appear to have been hot while the resister proper does not.

A mentioned having voltage on a disconnected ground wire doesn't tell you much.

A properly working O2 sensor can seem to cause problems when there is a persistent misfire from a bad plug, wire, vacuum leak, or injector on one cylinder, the solution is to figure out the reason for the misfire.

Thu Dec 31, 2020 10:11 pm

Wildthings wrote:
A properly working O2 sensor can seem to cause problems when there is a persistent misfire from a bad plug, wire, vacuum leak, or injector on one cylinder, the solution is to figure out the reason for the misfire.

Im curious as to why it will die the way it does, loses power starts spiting black smoke and dies if you try to rev. Only the then refire and be totally fine for a minute or two, I thought that was the van resetting and trying to learn the ECU, or maybe just leveling out till the misfire is. Ive replaced with new injector rings, fuel lines, vacuum lines, plugs cap wire, and set to base timing, new coolant temp sensors, and oil pressure sensors(had to turn the Christmas lifts off). Still same symptoms with or without o2 sensor connected. Starts right up warms up a bit then dies out.

Thu Dec 31, 2020 10:22 pm

tocsem wrote: Has R66 next to it on the board and the bands say its a 1.05k ohm resistor. Brown/Black/Green/Brown/Red followed by TY1 on the board.

My information says it is Red/Brown/Green/Black/Brown - 215 Ohms 1%

I don't think this is your issue. It is part of the 5V circuitry and your engine wouldn't run if you didn't get 5 volts to the 6811 processor.

As far as I know, pin 19 at the ECU connects to nothing inside the ECU (dead ended) - it is not the source of your voltage reading

If the power wire for O2 sensor heater shorts to the signal wire for the O2 sensor it will cause the ECU to dump a lot of fuel - very rich. Shutting off the ECU and re-starting then delays the influence of the O2 sensor reading based on code in the ECU. Look at this post on O2 voltage to ECU.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9018074&highlight=#9018074

Thu Dec 31, 2020 10:50 pm

DigiMatrix wrote:

As far as I know, pin 19 at the ECU connects to nothing inside the ECU (dead ended) - it is not the source of your voltage reading

If the power wire for O2 sensor heater shorts to the signal wire for the O2 sensor it will cause the ECU to dump a lot of fuel - very rich.

Thanks for the link. Looks like my high voltage on the o2 signal is causing the fuel rich symptoms. Im gonna dive into the pin 19 wiring tomorrow and see where that voltage is coming from because that pin ties into the COAx with a white wire and reads the same at the engine side.

Thu Dec 31, 2020 11:16 pm

tocsem wrote: Wildthings wrote:
A properly working O2 sensor can seem to cause problems when there is a persistent misfire from a bad plug, wire, vacuum leak, or injector on one cylinder, the solution is to figure out the reason for the misfire.

Im curious as to why it will die the way it does, loses power starts spiting black smoke and dies if you try to rev. Only the then refire and be totally fine for a minute or two, I thought that was the van resetting and trying to learn the ECU, or maybe just leveling out till the misfire is. Ive replaced with new injector rings, fuel lines, vacuum lines, plugs cap wire, and set to base timing, new coolant temp sensors, and oil pressure sensors(had to turn the Christmas lifts off). Still same symptoms with or without o2 sensor connected. Starts right up warms up a bit then dies out.

The O2 sensor sees a misfire as a lean condition so the ECU signals the injectors to stay open longer causing a richer condition. Since this likely makes the original misfire worse and the other cylinders beginning to misfire as well the problem quickly gets worse and worse until the engine dies from running puke rich. Shut the engine down and it will take several seconds for the O2 ECU to begin to read the output of the O2 sensor again and for the problem to reappear.

Fri Jan 01, 2021 12:17 am

tocsem wrote: DigiMatrix wrote:

As far as I know, pin 19 at the ECU connects to nothing inside the ECU (dead ended) - it is not the source of your voltage reading

If the power wire for O2 sensor heater shorts to the signal wire for the O2 sensor it will cause the ECU to dump a lot of fuel - very rich.

Thanks for the link. Looks like my high voltage on the o2 signal is causing the fuel rich symptoms. Im gonna dive into the pin 19 wiring tomorrow and see where that voltage is coming from because that pin ties into the COAx with a white wire and reads the same at the engine side.

Also, once you find the source of this voltage on the O2 signal wire, make sure to check your oil. If you have run the engine this rich for any length of time, it is highly likely that your oil will smell of gasoline and be very thin. If it does, change it ASAP because it will cause damage to your cylinder walls and rings.

Fri Jan 01, 2021 6:08 am

Quote: Wondering if anyone has come across this before. Trying to get the van to run proper but seems to want to sputter and die after it runs for a couple minutes. If i turn the key off then back on it will start and run for a few minute then sputter out and die.

Specifically , have you covered replacement of plugs, wires, cap, rotor, inspection of the Hall effect sensor? Follow this by measuring fuel pressure at the fuel rail on cranking and idle ?

Finally, what is the general condition of the wiring on the AFM?

Fri Jan 01, 2021 9:25 am

[quote="Abscate"] Quote:
Specifically , have you covered replacement of plugs, wires, cap, rotor, inspection of the Hall effect sensor? Follow this by measuring fuel pressure at the fuel rail on cranking and idle ?

Finally, what is the general condition of the wiring on the AFM?

AFM has the correction pigtail installed, the wiring looks good but going to be diving into it this morning.

Replaced cap, rotor, plugs, wires, vacuum lines, fuel lines, fuel filter, injector orings, oil pressure sending units, cts, hall effect sensor tested ok

Fri Jan 01, 2021 10:23 am

tocsem wrote: So if I was to run a ground to the brown wire from the engine and bypass the old one, Then when I plug it in should it be reading a ground signal and not the 9v correct.

In regards to what the ecu output on the o2 signal wire would be without the sensor actually hooked up. I thought was to be around 5vs tocsem wrote: Looks like my high voltage on the o2 signal is causing the fuel rich symptoms. Im gonna dive into the pin 19 wiring tomorrow and see where that voltage is coming from because that pin ties into the COAx with a white wire and reads the same at the engine side.
O2 Ground (pin 19) should be connected to the cylinder head (or engine block), as per the book. By floating it, the ECU internally pulls it up to that ~9V you are seeing. This also messes with the O2 sensor (pin 2) readings. Fix that before you move on.

Abscate wrote: Here , though, your pins on the power transistor look to be cracked on the solder pads.
Absolutely. Take a look at your transistor T4 solder issue.

I think the resistor R66 concern is a red herring.