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Re: CIS ill on '87 4kq

I'll go ahead and place a bet on a failed coolant temperature sensor.  They are
supposed to have about 3K ohms resistance when cold and very little (<100 ohms)
when hot.  If it fails shorted, the computer will never know the car is cold and
won't enrich the mixture - resulting in a car that barely runs until it is
somewhat warmed up.  Once the engine warms up, it doesn't need the extra fuel
and runs fine.  It also seems that your open loop mixture is set a little too
rich since CIS-E is supposed to run quite lean if it looses computer control.


Luis Marques
'97 4kcsq

James Marriott <marriott@micron.net> wrote:
> Symptoms:
> 1) Driving in a parking lot yesterday (after sitting for 90 minutes).
> Had run for ~30 seconds. Seemed to be "out of gas" for about 8
> seconds. Fixed itself. Ran fine afterwards.
> 2) Leaving hospital today after a visit, (mom & kid doing fine, BTW)
> car starts & runs like crap. Attempt to drive. No power at all (weak
> like 6.0 compression, sputtering, etc). Open throttle by hand.
> Acceleration attempted, but not really past 3k, and accompanied by
> large quatities of black smoke. Disconnect cold-start electrics (been
> running for 90-120 seconds); no change. REMOVE CIS fuse. Runs much
> better. Drive home (~15 mins). Runs OK on the way, but down on power
> (like 7.5 compression) and has lots of popping on overrun (rich
> because of loss of "no-fuel" action, right?).
> 3) Get home. Engine now good and hot. Reinstall CIS fuse. Runs like
> new. 
> 4) Bentley is about zero help here.
> Details. ~10 dC/52 dF. ~Full tank of Mobil 87 (with OEM Techron! ;-)
> from four days ago.
> Ideas? Thermo time switch, O2, ruptured diaphragm, etc.
> tia,
> James