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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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 Posted: Tue Nov 29, 2022 12:53 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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With all 4 unplugged?, if one is still connected it'll backfeed power through the injector coil.
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Sickies Garage
Samba Member
Joined: August 10, 2020
Posts: 73
Location: Fort Wayne Indiana
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| Posted: Wed Nov 30, 2022 4:59 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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Found the problem…..I believe it’s the ECU. Installed mine in another VW and my controller created the same problem in his car. Somewhere in the controller it’s not sending the ground signal to the injectors.
I’ll start looking for another ECU tonight!
Thank you all for helping! |
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Sickies Garage
Samba Member
Joined: August 10, 2020
Posts: 73
Location: Fort Wayne Indiana
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| Posted: Wed Nov 30, 2022 5:39 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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It only ran on cold start…never made it to the injectors
| busdaddy wrote: |
| Sickies Garage wrote: |
| I’d like to test the coil wire that fires the injectors for continuity….Does the other end of that wire land at the ecu connector or the double relay? |
Terminal #1 in the ECU plug.
But as Lost and Jimbo suggest if it runs with the flap poked injectors and ignition are working properly, you have to find out why it can't make enough suck to keep the AFM flap off it's stop. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Nov 30, 2022 5:42 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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Wow, that's very uncommon, but not impossible. You didn't happen to try the other car's unit in yours did you?
Part numbers listed here: https://ratwell.com/technical/FISwap.html although I have seen a few bug units in buses and bus units in bugs, most ran OK(ish).
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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Sickies Garage
Samba Member
Joined: August 10, 2020
Posts: 73
Location: Fort Wayne Indiana
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| Posted: Wed Nov 30, 2022 7:27 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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I did not try that one in mine. Found one here on Samba next state over. Hopefully I’ll have it by Friday and it’ll run.
quote="busdaddy"]Wow, that's very uncommon, but not impossible. You didn't happen to try the other car's unit in yours did you?
Part numbers listed here: https://ratwell.com/technical/FISwap.html although I have seen a few bug units in buses and bus units in bugs, most ran OK(ish).[/quote] |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Nov 30, 2022 9:12 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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| Sickies Garage wrote: |
| I did not try that one in mine. Found one here on Samba next state over. Hopefully I’ll have it by Friday and it’ll run. |
Well you've done very well with the ruling out of other potential causes, you get a big pat on the back for jumping in and learning instead of just blindly shooting the parts cannon at it, fingers crossed that a different ECU is the magic bullet for it.
Please keep us updated regardless of what happens.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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VW_Jimbo 
Samba Member
Joined: May 22, 2016
Posts: 9967
Location: Huntington Beach, CA
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| Posted: Wed Nov 30, 2022 11:28 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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| busdaddy wrote: |
| Sickies Garage wrote: |
| I did not try that one in mine. Found one here on Samba next state over. Hopefully I’ll have it by Friday and it’ll run. |
Well you've done very well with the ruling out of other potential causes, you get a big pat on the back for jumping in and learning instead of just blindly shooting the parts cannon at it, fingers crossed that a different ECU is the magic bullet for it.
Please keep us updated regardless of what happens. |
x2.
Just to triple ask…..you are sure the ecu is receiving uncomprimised power and ground? If so, ecu it is!
_________________
Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
| 67rustavenger wrote: |
GFY's Xevin and VW_Jimbo!  |
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Sickies Garage
Samba Member
Joined: August 10, 2020
Posts: 73
Location: Fort Wayne Indiana
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| Posted: Thu Dec 01, 2022 9:36 am Post subject: Re: 1979 VW Convertible will start but immediately dies |
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It’s been a great learning experience for me. Yes the ground is good as well as the power to the ACU…thank you!
| VW_Jimbo wrote: |
| busdaddy wrote: |
| Sickies Garage wrote: |
| I did not try that one in mine. Found one here on Samba next state over. Hopefully I’ll have it by Friday and it’ll run. |
Well you've done very well with the ruling out of other potential causes, you get a big pat on the back for jumping in and learning instead of just blindly shooting the parts cannon at it, fingers crossed that a different ECU is the magic bullet for it.
Please keep us updated regardless of what happens. |
x2.
Just to triple ask…..you are sure the ecu is receiving uncomprimised power and ground? If so, ecu it is! |
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VW_Jimbo
Samba Member
Joined: May 22, 2016
Posts: 9967
Location: Huntington Beach, CA
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| Posted: Thu Dec 01, 2022 10:55 am Post subject: Re: 1979 VW Convertible will start but immediately dies |
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Good! I have only seen a few of the ECU go bad, like 2! I guess stuff does eventually give up!
_________________
Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
| 67rustavenger wrote: |
| GFY's Xevin and VW_Jimbo! |
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Sickies Garage
Samba Member
Joined: August 10, 2020
Posts: 73
Location: Fort Wayne Indiana
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| Posted: Sat Dec 03, 2022 6:08 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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| The verdict is in….new ECM did the trick. Fired right up and purrs like a kitten! My question is which relay test would have identified that, if any? |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sat Dec 03, 2022 6:36 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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Yay! 
As for relay testing I don't think any test would have exposed that issue, the relay can only supply power to the ECU and injectors, the pulsed grounding is all the ECU's job.
Go buy a lottery ticket, you are one of the very few where an ECU swap actually solved the problem. I shudder to think of how many have been needlessly swapped when it was really something else to blame, the supply is dwindling and the "no testing before swapping" crowd is mostly to blame.
Don't trash your dead one, one day soon somebody will get into changing transistors or whatever is bugging it and save other vintage FI owners from a parts crisis. There's a few who have done it for their own projects, but not many who will touch others at this time.
Can't wait for the test drive review!
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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Sickies Garage
Samba Member
Joined: August 10, 2020
Posts: 73
Location: Fort Wayne Indiana
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| Posted: Sat Dec 03, 2022 8:12 pm Post subject: Re: 1979 VW Convertible will start but immediately dies |
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Busdaddy,
Guys like you on forums is what is so valuable. Thanks for taking your time and patience with semi novices like me….it’s huge encouragement to keep trying. I was able to take it to a point where I felt comfortable enough to tap a local resource to test the ecm. I will buy a ticket and if it produces I’ll let you know! I’ll let you know how the first test drive goes. Thanks again! |
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Sickies Garage
Samba Member
Joined: August 10, 2020
Posts: 73
Location: Fort Wayne Indiana
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| Posted: Mon Dec 05, 2022 4:47 am Post subject: Re: 1979 VW Convertible will start but immediately dies |
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Car drives great! I pulled the electronic ignition out in the very beginning to eliminate that early on so I am going to check the points and timing. Then will install the factory exhaust that they saved to replace the ugly aftermarket exhaust.
After that should be ready to go!
quote="busdaddy"]Yay!
As for relay testing I don't think any test would have exposed that issue, the relay can only supply power to the ECU and injectors, the pulsed grounding is all the ECU's job.
Go buy a lottery ticket, you are one of the very few where an ECU swap actually solved the problem. I shudder to think of how many have been needlessly swapped when it was really something else to blame, the supply is dwindling and the "no testing before swapping" crowd is mostly to blame.
Don't trash your dead one, one day soon somebody will get into changing transistors or whatever is bugging it and save other vintage FI owners from a parts crisis. There's a few who have done it for their own projects, but not many who will touch others at this time.
Can't wait for the test drive review![/quote] |
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