'86 runs bad till it's warm - then it's great

[Tan Van]

For 13 years my 1986 has run poorly (hesitant, etc.) while it warms up -- but once it warms up it runs really great ... what are the main culprits ... (I have put up with this forever and, now I just want to be able to get in the van "cold" and go (without warming it up for a full 4 minutes first) -- thanks

[ninz30]

It may be as simple as a vacuum leak. Since or vans have an idle speed control valve which bypasses our throttle body during warm up. A vac leak in conjunction with an open isc valve can allow an excessive amount of air into the engine making it idle poorly. Once the engine coolant warms up the isc valve will close and the throttle body is the only inlet for air.

[gushaman]

Also check the coolant temp sensor that to the ecu

[Tan Van]

Also check the coolant temp sensor that to the ecu


interesting - I just replaced the coolant temp sensor with a new one (clearance from Rock Auto, I think) ... My initial post neglected to include that I broke my original coolant temp sensor in August and then replaced it with the aftermarket one ... I also had my first ever "check engine light" coincide with the broken sensor ... after replacing the sensor (and clearing the code by pulling the 15 A EFI fuse) - I STILL have the check engine light...AND, further, in conjunction with all that, I now have difficulty cold starting the van (which never used to be the case) ... ...SO, perhaps the new sensor is junk ??? do you all think I should arbitrarily replace it - and while I'm at it, chase around looking for a vacuum leak ?? Anything else you can think of ? thanks, Phil

[djshimon]

I am confused because in the first post you say, "For 13 years my 1986 has run poorly (hesitant, etc.) while it warms up" and in the last post you say, " I now have difficulty cold starting the van (which never used to be the case)" . So which one is it? Am I missing something?
When my temp sensor plug falls off the van starts poorly cold, and when I plug it back in it starts up cold beautifully.

[Tan Van]

I am confused because in the first post you say, "For 13 years my 1986 has run poorly (hesitant, etc.) while it warms up" and in the last post you say, " I now have difficulty cold starting the van (which never used to be the case)" . So which one is it? Am I missing something?
When my temp sensor plug falls off the van starts poorly cold, and when I plug it back in it starts up cold beautifully.


I said it ran poorly till it warms up - NOT that there was ever any trouble starting the van (that was always easy) ... but now- the van also is difficult to start (takes 2 to 3 tries till it stays running)- this is a recent problem... ...

... on the other note, my temp sensor plug does not seen very tight, and, I don't have the little metal clasp on the plug any more, either... so, I'll look at it more closely and more often - thanks

[djshimon]

Oh sorry I wasn't reading that right, I getcha now- definitely make sure that plug has a good connection. Mine had the plug but the metal inserts had almost pulled all the way out-I had to replace the plug and metal insert/clips.
I can't help with the slow start up period as I've never had to deal with that.

[ninz30]

Check the resistance on the temp sensor, before you think about changing it again. Is the check engine light code for the temp sensor?

also check for a vac leak.

[Tan Van]

Got It ...the van now starts on the first key turn (like it always used to) ...The problem WAS the Coolant Temperature Sensor ...also, now the check engine light is OFF again! (Great !) ... it's amazing how important that part is