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Hot Start problem 1985 1.9 Vanagon
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Gruppe B
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PostPosted: Thu Jul 19, 2012 9:31 am    Post subject: Hot Start problem 1985 1.9 Vanagon Reply with quote

Hey guys,
I have recently purchased a 1985 1.9 Vanagon Westy and have been trying to fix a serious hot start issue that had stopped the previous owner from driving.

The van will start perfectly when cold and idle at 900rpm smoothly. Driving is good with excellent response and no hesitation. When I turn off the engine however it will not restart until dead cold.

The vans starter works fine and turns over the engine fast however there is no firing of any sort during hot start. After trying to start the engine again and again I can smell raw gas. Once cold the van will start instantly as if nothing was wrong. Evil or Very Mad


Last edited by Gruppe B on Thu Jul 19, 2012 9:43 am; edited 1 time in total
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Gruppe B
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PostPosted: Thu Jul 19, 2012 9:36 am    Post subject: Reply with quote

Things I have done to fix the problem
After reading the numerous hot start threads here is a list of fixes that I have done.
-Swapped a new Temp 2 sensor (no change)
-New plugs, cap, rotor, wires (no change)
-New Oxygen Sensor (no change)
-Fixed all exhaust leaks (no change)
-New grounds (no change)
-Tried starting with ether starting fluid during hot start (no start either)

I don't have a spare coil however I cant believe that a coil would be bad if it runs great at full temp.

Please help Sad
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Wildthings
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PostPosted: Thu Jul 19, 2012 9:37 am    Post subject: Reply with quote

Do the diagnostics of the ignition system according to the Bentley and you should have it in no time.
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Gruppe B
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PostPosted: Thu Jul 19, 2012 9:45 am    Post subject: Reply with quote

I'll crack out the Bentley and my multimeter and reply back with the results.
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ShultzRoadHouse
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PostPosted: Thu Jul 19, 2012 9:56 am    Post subject: Reply with quote

Unplug your cold start valve, worked for me and its still dissconnected. I will need to fix the real problem before winter.
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Ahwahnee
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PostPosted: Thu Jul 19, 2012 11:07 am    Post subject: Reply with quote

Wildthings wrote:
Do the diagnostics of the ignition system according to the Bentley and you should have it in no time.


Starting with what your nice new Temp II sensor says when the engine is hot. Reading that at the pins at the ECU end will take into account the wires involved.

Quote:
Unplug your cold start valve...


Do 1.9Ls have a cold start valve?
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Gruppe B
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PostPosted: Thu Jul 19, 2012 6:22 pm    Post subject: Reply with quote

Tested the temp2 sensor tonight.
2.2ohm at 20 celcius
0.2ohm at 100 celcius

In specification Sad

Will now check ignition system
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Ahwahnee
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PostPosted: Thu Jul 19, 2012 6:36 pm    Post subject: Reply with quote

One possibility that is harder to prove by test is a coil that only fails when hot.

Swapping on a fresh coil is possibly the easiest way to confrim this -- don't have to undo the old and re-mount the new -- just up a fresh cool coil and lay it there on top of the hoses.
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Gruppe B
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PostPosted: Thu Jul 19, 2012 6:55 pm    Post subject: Reply with quote

Does anyone know what VW coils are swappable with the1.9?
Do the the aircooled coils have the same output (have spares of those)
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Gruppe B
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PostPosted: Fri Jul 20, 2012 7:58 am    Post subject: Reply with quote

Coils are the same as the Aircooled Vanagons (as per Busdepot.com)
http://www.busdepot.com/00041

Will try a swap tonight
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Wildthings
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PostPosted: Fri Jul 20, 2012 8:17 am    Post subject: Reply with quote

I have swapped them with later Vanagon coils as well, just needed to change the end on the coil wire. I don't think there is anything all that special about these coils.
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Gruppe B
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PostPosted: Fri Jul 20, 2012 9:27 am    Post subject: Reply with quote

Thanks for all the help so far everyone!

Last night I had also double checked that the engine was getting fuel.
cranked the engine multiple times during Hot Start, fuel smell came back, and you could see smoke coming from the hot exhaust when not cranking (raw fuel burning/evaporating.

I also pulled a spark plug and could smell fuel, however it was dry due to the engine heat.

I can see the rpms bounce slightly on the tach when cranking during hot start, doesn't that mean that the Hall sensor is functioning?
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MidwestDrifter
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PostPosted: Fri Jul 20, 2012 11:09 am    Post subject: Reply with quote

Have you had a chance to swap the coil? Do you have spark when your hot start issue happens?

By your description it seems the engine isn't catching at all, which makes me think ignition system, so do the full manual check on it. Very Happy


I know this may seem a little basic, but whats your voltage during cranking as measured at the battery? It is unlikely, but you may have really low voltage when hot cranking. I think you need at least 10.5 volts, but i am not 100% on that number.
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Gruppe B
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PostPosted: Fri Jul 20, 2012 11:52 am    Post subject: Reply with quote

I haven't swapped the ignition coil yet but will try shortly.

The engine doesn't catch at all, but the starter cranks it very fast.
I agree, it's got to be the ignition but I can understand how an engine can run so well hot but once turned off, it won't start back up.

I'm running out of gasoline and can't fill up at a gas station without having to wait 5 hours to cool lol.
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MidwestDrifter
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PostPosted: Fri Jul 20, 2012 5:13 pm    Post subject: Reply with quote

Another option that I have seen cause hot start issues (in a different vehicle though) is relays that won't close/activate when they are hot. Sometimes the relay's internal coil has too high of a resistance when warm, and can't overcome the internal spring.

Question How to test? Follow the Manual sections for testing power supply to the ECU.

I guess there is no substitute for straight up troubleshooting Smile
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Gruppe B
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PostPosted: Fri Jul 20, 2012 7:47 pm    Post subject: Reply with quote

I really need to up my game from parts swapper to troubleshooter before my van becomes all new. Smile

My coil research didn't pan out. The 1980 Aircooled Vanagon is running a side contact type ignition wire setup while the 1985 has a center pin contact.

Dropping my 1985 coil on the ground during the swap didn't help either.

Time to hit the junk yard in the morning to find another coil

I'll run the tests on the relays in the morning as well

Thanks again everyone!
Chris
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Gruppe B
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PostPosted: Sat Jul 21, 2012 11:01 am    Post subject: Reply with quote

Went to the junk yard today to get a coil.

The same model coil for an 85 Vanagon was found on a Volvo 740.

Came home swapped the coil, started right up, took it for a drive, drove back home, turned off and then tried to restart.
No change, engine spins but no firing. Sad

On to the relay box next Rolling Eyes
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Wildthings
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PostPosted: Sat Jul 21, 2012 11:27 am    Post subject: Reply with quote

Are you still getting power to the coil when it will not start or not? Have you checked to see if you have pulsating power on the negative side of the coil when cranking?
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Gruppe B
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PostPosted: Wed Jul 25, 2012 9:52 am    Post subject: Reply with quote

Drove the vehicle for another test.
Got the engine to operating temperature, drove home, turned it off and tried to restart. Turns over rapidly but no signs of catching.

Replace both relays in relay box above coil, go to restart. Turns over rapidly but no signs of catching.
Let it cool off, and it started right up Sad

Next item tonight is to hard power the coil #15 to the hot alternater terminal for testing as per your recommendations.

Running out of time, if I don't track it down tonight, I'll bring it to the dealer tomorrow.

Place bets on the results, I'll keep everyone posted.
I'm putting my bet on the Hall sensor even though the tach bounces when turning over (everything else has been replaced)
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floggingmolly
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PostPosted: Wed Jul 25, 2012 6:09 pm    Post subject: Reply with quote

You may want to contact "thatvwbusguy" who sells a hot start relay to solve this issue. My wife had a similar issue on her old scirocco and it was the relay.
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