Car won't stay running with coolant temp unplugged...WHY?

[89ShelbyGuy]

Hey guys, every time i want to time the car, i will unplug the coolant temp sensor like you should but the car refuses to stay running...i will have to adjust my adjustable fuel regulator really rich to keep it idling insted of dieing.....anyone have an idea on why it won't stay running?! i am thinking i have a fudged up sensor somewhere else??!

Thanks

Tom

[wheming]

Are you running a cal?

[ShelGame]

Hey guys, every time i want to time the car, i will unplug the coolant temp sensor like you should but the car refuses to stay running...i will have to adjust my adjustable fuel regulator really rich to keep it idling insted of dieing.....anyone have an idea on why it won't stay running?! i am thinking i have a fudged up sensor somewhere else??!

Thanks

Tom

The default coolant temp is set too low. It causes too much enrichment when the sensor is unplugged...

[Vigo]

I think your base timing is not close enough.

Unplug CTS, loosen distributor, have someone crank the motor while you turn the distributor until you find a spot it will stay running in, and THEN set it with the light.

[ShelGame]

Try this, Tom - http://www.turbo-mopar.com/forums/sh...=1#post1013269

[89ShelbyGuy]

To answer everyones question...Yes i am running a Boost button cal. I will try and change the default temp....it was set to 149...i upped it to 200...i will test later...Thanks for the help guys!!!!

Tom

[Reaper1]

Something else to check:

make sure the reluctor under the HEP isn't moving all around. On my car I used to wonder why I had an intermittent miss under light load and when I would unplug the CTS to set the timing, the timing mark was all over the place and the car ran like crap. I always just figured the car had an attitude! LOL Well, I found out that the reluctor had wallowed out the roll pin hole and was able to alter its timing! :O I'm lucky I didn't blow the engine sky high for all the years I ran it like that!

[5DIGITS]

Try this, Tom - http://www.turbo-mopar.com/forums/sh...=1#post1013269

Rob,
Please avoid changing the default temp, for cases where the coolant temp sensor actually fails or becomes intermittent.

There is an injector PW offset used when setting the advance and the coolant sensor is unplugged.
This is indirectly whats being addressed by raising the default coolant temp - it leans out the engine.
This becomes an over-rich condition when it isn't adjusted for larger injectors or 2.5, 3, or 4 bar MAP sensors are used, due to the decline in resolution.
It's typically $1A - $34 and an open loop enrichment factor scaled to a % by multiplying by 256.
It's located not too far down from the idle map PW table and should effectively be zero'd.

Thanks

[ShelGame]

Rob,
Please avoid changing the default temp, for cases where the coolant temp sensor actually fails or becomes intermittent.

There is an injector PW offset used when setting the advance and the coolant sensor is unplugged.
This is indirectly whats being addressed by raising the default coolant temp - it leans out the engine.
This becomes an over-rich condition when it isn't adjusted for larger injectors or 2.5, 3, or 4 bar MAP sensors are used, due to the decline in resolution.
It's typically $1A - $34 and an open loop enrichment factor scaled to a % by multiplying by 256.
It's located not too far down from the idle map PW table and should effectively be zero'd.

Thanks

Thanks, Ken.

I do rescale that value for injectors.

In this case, I think the difference is due to having the charge temp sensor code turned on, but not having a charge temp senor. By turned on - I mean that I added all of the IAT calibration values (where they were previously zero'd out in the 2.5 cals); and I added an option flag to that will then bypass the IAT read/filter code when it's 'turned off'. This makes it easy to turn 'on' or 'off' without having to copy 3-4 tables. Running, it works exactly as expected; but I've had many issues with the base timing setting due to this change.

I noticed all of the IC cals use a much higher value for the default coolant temp. That's why I suggested it be changed...

[5DIGITS]

Thanks, Ken. I do rescale that value for injectors. In this case, I think the difference is due to having the charge temp sensor code turned on, but not having a charge temp senor. I noticed all of the IC cals use a much higher value for the default coolant temp. That's why I suggested it be changed...

I understand.
There were also differences between banked and SFI and in many cases these default cals were typically the last to be done, if they were done at all.
They were a function of whoever did the preceding set-up and IC vs Non-IC were two different groups along with the subsequent groups that completed the default values.
As a result they were kind of all over the place with no rhyme or reason and some would clearly idle better than others but when all else was equalized, the coolant temp found it place near or at 70F.
It was always thought a better approach would have been to make the byte 'signed' so increased adjust-ability could address all of the preceding variation without affecting additional parameters.