FI wont run when outside air temp is below 55*

[BusKid231]

Alrighty I'm offcially back in the FI camp. Just picked up a 75 westy with a 2.0 swapped in the back full fuel injection hooked up. Its a frankenstine of an engine but all done professionally and seems to be in the right order. Done by the previous owner and sold to me in her current config. Came from south TX Shes a great van overall.

Except When starting I have to crack the pedal. Just a touch. Then I let her warm up a few min and if the outside air temp is warm. She takes off flawlessly. Runs for hours with no issues. But When its cold out, Like early morning (Yesterday to be exact) even after letting her warm up for 15 min in the driveway she will just spudder and die with any load or more then 1/4 pedal with no load.

I came back from work. Air temp was about 76. she started right up and we cruised for about two hours. its like two different vans!!! Ive read alot about cylinder head temp sensors and cold start valves but none quite fit what im going through. Any thoughts? Thanks in advance.

[busdaddy]

Have you done a smoke test on it?, much of what you describe could be caused by vacuum leaks.
Testing the TS2 ohms wouldn't be wasted time either.
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[SGKent]

[VWFIXER]

Do a correct compression test,
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[BusKid231]

[SGKent]

I don't think lack of compression is at fault here.
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[busdaddy]

I agree, it's either way too lean, or a component is breaking down when it gets cold.
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[cmonSTART]

I've personally dealt with this issue caused by both of the above (vacuum leak and TS2 issue) as well as bad electrical connections in and around the distributor (including the cap and rotor.)
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[VWFIXER]

[SGKent]

Certainly he has some things to check out. Compression is not temperature sensitive like it works at one temp but not 20 F degrees warmer. It is always worth checking on a tune up. So are a valve adjustments.

What is temperature sensitive is the air to fuel ratio. In the morning when it is dry and cool, the air is denser. In the afternoon the air is warmer and less dense. You need a little more fuel when the air is denser so if an engine was right on the edge of too lean, it could fall over in the denser air as it would run leaner.

Or if the condenser has failed, it could be temperature sensitive
Or if there is a bad connection with some corrosion or ground the temperature change
Or it could be random and just showed up that way so he thinks it is temperature sensitive.
Most of the AFM's have a temperature sensor in them. The TS1. Could that cause it?

He can also get a couple cans of freeze spray and see if hitting any of the components might cause it to fall over.
Heck it could even be a fuel pump that is ready to fail, that needs a little extra temperature to free itself to spin.
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[BusKid231]

Ok. Went though the vaccum lines and found two tiny leaks both sealed up with some quick gummy tape until I get to the auto store. S- boot was OK. No difference to start up and i didnt let it warm up to avoid working over a hot exhaust. Interestingly I found a II Temp sensor in the cook draw under the stove. It has an extension on it like the Vanagons. I attempted to track down the one that should be installed on cyl 3. No luck but it had gotten dark and I had started to pack up for the night. It very well could be relocated somewhere else on the engine. More digging tonight so long as the rain holds off. She slowly reveals her secrets to me as the nights go on.

[vwwestyman]

You can eliminate the TSII by grounding the wire that goes from it to the engine computer.

A smoke test on a cool day would be interesting-I kinda like the idea of there is a component with a leak or crack that opens just enough to cause an issue with the cool temps, and then in warmer temps things expand just enough to close that crack enough to let the engine run.

Will it run ok if you can manage to get it started at cool temps and idle long enough to warm the engine up?
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1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
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[BusKid231]

[busdaddy]

I'm curious about fuel pump power, a test light stuffed into terminal # 88d on the double relay plug would tell us if something like the AFM contacts aren't closing when cool, or the DR or it's plugs have issues.

Are you sure the AFM plug is fully seated in the unit?
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[SGKent]

I have seen intermittent fuel pumps in my life time. With low fuel pressure the engine might idle but fall over when it needs fuel. Likewise a bad double relay might do something goofy where the fuel pump gets voltage while starting but loses it if the double relay is acting weird. We've seen a lot of condenser failures lately and they can be goofy too.
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[busdaddy]

So you see where I'm going, it's like when you leave the AFM unplugged, it'll start and idle, but quits when you step on the gas.
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[SGKent]

[BusKid231]

update. replaced fuel pump with new bosch. no change. back to chasing sensors and grounds!

[SGKent]

to refresh the history. Have you:

done a smoke test?

sniffed the mixture to see where it is?
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[BusKid231]