https://www.ford-trucks.com/forums/s...d.php?t=108536

 

What? The computer is bypassed when the engine is in closed loop? What do think is controlling the engine while it's warming up? Firing injectors, reading sensor data (like the TPS), controlling idle speed, etc.?

I don't know what that will do.

 

Back when my truck (87 F250 with EFI 302) was quitting like you describe, it turned out to be the front tank lift pump went bad and shorted out my wiring between the tank selector switch and fuel intertia box. Check the wires and report back.

 

blacksmith, the ECT resistance sounds good. Before running a KOEO test, make sure the engine is warmed up...otherwise, ECT will fail.

RC Dan, in 'open loop', the ECM ignores readings from the O2 sensor. Once in 'closed loop', it reads them. The ECM is always in use.

 

ok - I swapped the ECT tonight and started the truck up, after 15 mins it was up to temp and it died while idling.

AndyM - I pulled a plug and you had it , no spark. I am baffled now.

So far I have replaced the following: ECT, IAC(that was bad) FPR, purge canister solinoid(that was bad). I pulled the codes and am getting 11's -

Any ideas out there? help a brother out!!

 

Hmmm since yours is a 90, there was a problem with the TFI module failing due to heat. If it fails, this equals no spark.

Someone, please correct me if im wrong.

 

Memorex,

the heat failure with the TFI, does it let you start after it cools off? I could spray it with some freeze and see if the spark comes back - is there a test for the TFI other than swapping it?

Will it failing throw a code? I am getting and 11, I think that is a system pass ok -

Thanks to everyone who is helping me out -

 

I dont believe there is a TFI failure code. Try cooling it, see what it does. I can't think of a test for the TFI.

 

is the heat failure covered by any recall thru ford? this is a $60 hit to replace. Is there any reason not to get one out of the bone yard?

 

I don't know if Ford ever recalled this. If you can get one out of the junkyard, go for it.

 

bump - any more ideas while i'm trying find a TFI ?

 

My bad, sorry. I was given some incorrect information myself. Sorry if I caused any confusion.

 

Just for an update - I started it up and in 15 mins it died again - I popped the hood and gave the TFI module a good shot of can freeze (canned air held upside down) then tried and it started right up.

- This morning I got an autozone TFI (only place near that had one) and I installed it with a slight mod that might help with the heat. I placed a 3x5" piece of aluminum between the dist and the TFI. All contacted pieces had the conductive grease on them.

I started it up and it has not died while idling or when warming up - drove around for an hour and so far ok.

Does anyone have a prob with the heat sink idea? I figure it has to help somewhat -

Thanks to the guys who steered me towards the no spark check - that was a biggie!!

 

Glad to hear it man. A heat sink is always good. Nice job

 

Here is a follow up on the 15 min stall problem - It looks like the TFI was the reason for the no spark after warmed up problem. When I gave it a shot of freeze the truck would start ok - replaced the TFI and installed a homemade heat sink and drove it 75 miles in Illinois yesterday, air temp 100 degs. No problems so far - Thanks again to all who took the time to post a reply -