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You could swap injector #3 with one of the other injectors, if the fault follows the injector is faulty.
Let me know what those voltages are, then I will be able to advise further.

I wouldn't recommend replacing the harness with another 18 year old harness.
 

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Discussion Starter · #82 ·
You could swap injector #3 with one of the other injectors, if the fault follows the injector is faulty.
Let me know what those voltages are, then I will be able to advise further.

I wouldn't recommend replacing the harness with another 18 year old harness.
Hi Tom
I've got the voltages at the #3 injector and some other info. First the voltages. I didn't know which pin was #1 and which was #2 so I called them front and back, front being the one toward the front of the car.
KEY ON
Front pin: 3.5 volts
Rear pin: 0 volts
ENGINE RUNNING
Front pin: 3.7 volts
Rear pin: 14.4 volts

Two other items the significance of which I am not sure:

1. I tried to get the injector readings from measuring block #13 and it's reading nothing. I checked my connection which was good and some of the other measuring blocks were showing readings but not that one.

2. From a cold start when the idle is a little higher there's no miss. Engine runs as smooth as a baby's behind. As soon as the idle dropped down, BOOM the miss appeared.

I have a Bentley manual on the way. That will be a big help.
As far as the wiring harness I don't thing VAG is making them any longer so unless my Chinese friends have them it's going to have to be a used part if it comes to that. To me it doesn't look like wiring issue since voltage is getting through on both pins. Once my manual arrives I'll be able to check for continuity in all the circuits on that harness and I would do that before pulling one off of a junk.

Here are the fault codes - It was popping codes like nobodies business, I'm talking pages until I got the new ECU in there. Now it's three but all related to the same issue.
3 Faults Found:
17647 - Fuel Injector for Cylinder 3 (N32): Open Circuit P1239 - 004 - No Signal/Communication
16684 - Random/Multiple Cylinder Misfire Detected P0300 - 001 - Upper Limit Exceeded
16687 - Cylinder 3: Misfire Detected P0303 - 001 - Upper Limit Exceeded
Readiness: 0110 1101

Thanks so much for the help!!
 

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Could you do those voltage tests again, while it is mis-firing ?
This time check the voltages at all 4 injectors.
The pin numbers are marked on the injectors (as can be clearly seen in your pic) Pin #1 on all injectors has a Black/Blue wire connected,
Pin #2 has a different colour wire for each injector.
 

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Discussion Starter · #84 ·
Could you do those voltage tests again, while it is mis-firing ?
This time check the voltages at all 4 injectors.
The pin numbers are marked on the injectors (as can be clearly seen in your pic) Pin #1 on all injectors has a Black/Blue wire connected,
Pin #2 has a different colour wire for each injector.
Sure! I can check all the injectors but something is a little confusing. Can the voltage be checked without removing the lead to the injector? Is it possible for the cylinder to not misfire with the injector unplugged?
Thanks for pointing out the numbers. I would never have seen them in a million years.
 

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The cylinder would not fire with the injector unplugged.

For the test that I requested, all injectors must be connected.
 

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Discussion Starter · #86 ·
The cylinder would not fire with the injector unplugged.

For the test that I requested, all injectors must be connected.
I took a closer look after the #1,#2 discussion and I can now see that I can get to the leads without unplugging them. I'll get out tomorrow and get a full set of readings with all the injectors connected both with the key on and with the engine running, making sure to wait until it kicks down and the miss starts. It's a matter of a minute and it's impossible to not notice it.
THANKS again.
 

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" making sure to wait until it kicks down and the miss starts. It's a matter of a minute and it's impossible to not notice it"..........interesting.
 

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Discussion Starter · #88 ·
" making sure to wait until it kicks down and the miss starts. It's a matter of a minute and it's impossible to not notice it"..........interesting.
That's why I mentioned it. Since I got the ECU working I've only started it a few times so it may have been an anomalous event. I will observe more closely as I collect voltages tomorrow.
 

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Discussion Starter · #89 ·
The cylinder would not fire with the injector unplugged.

For the test that I requested, all injectors must be connected.
Strange turn of events. I uncapped the injector connections turned the ignition to ON and there was no voltage at any of the pins. Then I started the car and waited for the idle to kick down, When it kicked down it hesitated a bit, smoothed out and no discernible miss. I waited a few minutes and it's purring like a kitten. So I checked the voltages and all of the #1 pins read 14.2V with the exception of cylinder 4 which was within .02 volt [lower]. I let the car run and came in and got my laptop and cable, shut down the car, plugged in, brought up the VCDS, started the car and cleared the fault codes. I let the car run for an hour and the miss never reappeared and no CEL. It's running perfectly at idle and responds normally with no hesitation to a goose of the accelerator. Idle is dead on 800 Rs and smooth as can be. I didn't have time to put everything back together and take it for a ride to see how it does with a load. I can imagine a few scenarios but one thing is that before today I didn't run it for more than a few moments with the new ECU. I'll report on my road test.
 

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It appears that you have an intermittent bad connection in the injector wiring or one of the connectors.

I suggest you check the splices in the Black/Blue wires that connect from the fuse to pin 1 of each injector.
Also check the pins in #3 injector connector, and the wire from injector #3 pin 2 to the ECU.
 

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Discussion Starter · #91 ·
It appears that you have an intermittent bad connection in the injector wiring or one of the connectors.

I suggest you check the splices in the Black/Blue wires that connect from the fuse to pin 1 of each injector.
Also check the pins in #3 injector connector, and the wire from injector #3 pin 2 to the ECU.
Hi Tom
Your message was timely as today was the first day I could get away from work to pay attention to the wagon. I did a full set of voltage tests which are here:
103185


I observed and further tested the following:
I'd previously observed that, as you mentioned, the problem is intermittent.
The miss only starts once the engine has warmed up enough for the idle to kick down.
I had a day where I ran the car for at least an hour and the miss did NOT emerge,
Today I was able to make the miss stop [by letting the engine cool down for about 15 minutes] and therefore test the voltages both ways as you see above.
I also did this: I turned off the engine but left the key on while the miss was occurring. There was 3.5 volts in C3P2. If I turned off the engine while there was no miss the voltage was Zero.
Gently wiggling the repaired area of the wiring had no effect but once or twice wiggling the voltmeter probe while it was in C3P2 did make a change. I couldn't repeat the result consistently though. It would be really crazy if I went through all of this and the problem is a 50 cent connector.

I will check the wiring issues you mentioned. When you say check the wiring am I checking continuity? Physical inspection? Anything else I'm looking for?

Thanks as always for the help.
 

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Those voltages indicate that there is no problem in any of the wiring.
There is a fault in injector #3 or one of its connectors.
I suggest you replace both connectors on injector #3. (you can buy new connector pins with pigtails)

If that doesn't solve the problem, swap injector #3 with one of the others, and if the fault goes to that other cylinder replace the injector.
I suggested this early in this thread.

It appears that originally (when you took it to the dealer) this was the only fault, and there was no problem with the ECU.
 

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.

It appears that originally (when you took it to the dealer) this was the only fault, and there was no problem with the ECU.
I’m late to this thread, but that was my thought on post 1. The dealer sounded like an ass, ultimately probably trying to get you into a newer car. These cars don’t belong at the dealer anymore; their techs generally don’t know how to work on cars with old age diseases.
 

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Discussion Starter · #94 ·
Those voltages indicate that there is no problem in any of the wiring.
There is a fault in injector #3 or one of its connectors.
I suggest you replace both connectors on injector #3. (you can buy new connector pins with pigtails)

If that doesn't solve the problem, swap injector #3 with one of the others, and if the fault goes to that other cylinder replace the injector.
I suggested this early in this thread.

It appears that originally (when you took it to the dealer) this was the only fault, and there was no problem with the ECU.
It seems that taking it to the dealer was my big mistake. I get what you're saying about the ECU and the fact that the miss is exactly the same as it was with the dealer jumper wire and with the old ECU certainly points strongly in that direction. There is one difference: The old ECU was throwing scads of codes but now it's only throwing codes specific to the injector. That's based on idling for over an hour and I know that's not the same as putting a load on the engine. I'll look for those pins and replace them and if that doesn't do it we'll swap out the injectors.
THANKS as always and I will report back ASAP.
 

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Discussion Starter · #95 ·
I’m late to this thread, but that was my thought on post 1. The dealer sounded like an ass, ultimately probably trying to get you into a newer car. These cars don’t belong at the dealer anymore; their techs generally don’t know how to work on cars with old age diseases.
@Hirnbeiss After they told me that they "couldn't" fix it my thought was: What they were expecting me to say was 'What can I get on a trade?'. Had it played out that way how long before they the car would have been fixed and on the lot. Keep in mind this car is absolutely cherry in terms of the body, paint, interior, It has a new front end and less than 5,000 miles since timing belt/water pump replacement.
 

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Discussion Starter · #96 ·
Those voltages indicate that there is no problem in any of the wiring.
There is a fault in injector #3 or one of its connectors.
I suggest you replace both connectors on injector #3. (you can buy new connector pins with pigtails)

If that doesn't solve the problem, swap injector #3 with one of the others, and if the fault goes to that other cylinder replace the injector.
I suggested this early in this thread.

It appears that originally (when you took it to the dealer) this was the only fault, and there was no problem with the ECU.
Hi Tom
I replaced the dual connector on which one of the leads had been rewired by the dealer. There was no change in the behavior of the engine. Ran smooth on start up and then missing after kickdown. Then I noticed that you said to replace BOTH connectors. Only one dual wire connector is obvious to me. Is there another one?
Also my Bentley manual is being delivered. When it arrives I will swap out the injector and report my results.
I apologize that this process moves at a crawl and thank you again for sharing your knowledge.
 

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Hi Tom
I replaced the dual connector on which one of the leads had been rewired by the dealer. There was no change in the behavior of the engine. Ran smooth on start up and then missing after kickdown. Then I noticed that you said to replace BOTH connectors. Only one dual wire connector is obvious to me. Is there another one?
Also my Bentley manual is being delivered. When it arrives I will swap out the injector and report my results.
I apologize that this process moves at a crawl and thank you again for sharing your knowledge.
There is one connector with 2 pins.
 

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Discussion Starter · #98 ·
There is one connector with 2 pins.
OK Tom I think we've got our perpetrator! I switched the #3 injector to cylinder 2 and here is the result:
PREVIOUS SCAN
17647 - Fuel Injector for Cylinder 3 (N32): Open Circuit
P1239 - 004 - No Signal/Communication

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded

16687 - Cylinder 3: Misfire Detected
P0303 - 001 - Upper Limit Exceeded

SCAN FOLLOWING INJECTOR SWITCH
17646 - Fuel Injector for Cylinder 2 (N31): Open Circuit
P1238 - 004 - No Signal/Communication - Intermittent

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded
16686 - Cylinder 2: Misfire Detected
P0302 - 001 - Upper Limit Exceeded

Recommendations for a set of injectors? [I'd like to keep it stock]

After the injectors are in I'm going to switch the original ECU back in. If it works I'm also going to need a lawyer.
 

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Discussion Starter · #100 ·
I would go for a used one (or set) from a pick & pull.
If you want new, any OEM would be fine.
Thanks Tom. I will report back in about a week. I have a fairly minor hand surgery on Thursday. I'm finding pretty good prices on OEM [Bosch] sets so I think I'll go that way. I like the pick & pull idea but having the things show up on my door seems like a good idea right now.
 
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