IDM

[TLS]

Where is the IDM located on a1987 bronco Ii.

UDATE :
I found the IDM and now need to find one or a replacement resistor to replace it.
I still get a continues code 18 when checking KOEO.
While searching the code definitions in the continues codes it says states causes could be the following,
( Loss of tachometer input/IDM circuit failure / SPOUT circuit grounded )
all wiring looks good so I’m thinking maybe the IDM is bad, I don’t know what else to check.
Any ideas or information on what I can do to resolve this code 18 are really much appreciated.
Thank you

 

[Uncle Gump]

There are just so many acronyms... I'm drawing blanks on IDM. What exactly are you looking for?

 

[Uncle Gump]

Try to cycle the key to ON a few times before attempting the start it. This will build fuel pressure in the rail. The pump(s) will pump for a couple seconds to prime the system. If it starts first time you might be having issue with your fuel pump. Have you verified you have the correct fuel pressure?

Usually and unstable idle is caused by a vacuum leak.

The engine coolant temperature (ECT) is what signals the ECM that it needs to go to cold enrichment and high idle.

 

[TLS]

here’s the latest.
I started over fresh this morning and still have the same cold start issues it it ran good after warming up as usual.
I retried reading the fault codes KOEO and got a code 18 in the continues codes.
this is the same code I can not get rid of.
In the definition section of the manual it states this code can be caused as follows.
( Loss of tachometer input/IDM circuit failure SPOUT circuit grounded)
I did find the IDM resistor over by the coil in a wiring loom and all wiring looks good. So I’m trying to find an IDM which seems to to be impossible, I was told it can be replaced by a 1W 22ohm resistor again which I cant find.
any ideas on what to do about clearing or fixing this code 18 issue are much appreciated.
thank you

 

[TLS]

Update:
Found an IDM in the good old salvage yard and also changed the IAT. After warming it up it ran fine.
Still have the cold start problem where it takes at least 3 tries to get it running then the rpm surges going from roughly 500rpm to 1000rpm for a few minutes until it starts warming up then it idles fine.
would the ETC sensor cause my cold idle problem even though it’s not throwing a code?

 

[Uncle Gump]

That is one of the reasons I like OBD II better... you can pull up a data and see what it is doing. OBD I requires way more effort.

Here is a resistance chart based on temperature. It's easy enough to put put an ohm meter on it and see where it is.

 

[TLS]

Got it andThanks again.
they sure buried he ETC but I going to try to get to it today.