Re: ‘91 coupe quattro cold start problems

[DeWitt Harrison]

Is cold start enrichment in the '91 CQ completely controlled by the ECU as
it reads engine temperature? Or is there some other bit of hardware
involved such as the cold start injector in the old turbo motors? If engine
temp is the only relevant input to the ECU, perhaps it might be worth
measuring the resistance value of the temp sensor directly at the ECU
connector to check for an open in the wiring. (You'd think a code would be
thrown.) If an open circuit, pulling the temp sensor connector would make
no difference.
DeWitt Harrison
'88 5ktq
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On Wed, 23 Jan 2019 06:56:40 -0500, Christopher Gharibo  wrote:

My ‘91 CQ cranks fine but has difficulty starting when cold. Once it starts
the subsequent cold starts and warm starts are fine. About eight hours
later, cold starts are a problem again.

I changed the 20 year old fuel pump and multi function temperature sensor
without improvement. All the vacuum lines seem fine. I unplugged the
coolant temp sensor behind the block without improvement. The fuel
injectors are 034 and about 15 yrs old.

The car runs and accelerates fine otherwise.

Any other ideas would be greatly appreciated.