Ok I tested it and found 1-2=36 2-3=36 1-3=68
4-5=36 5-6=36 4-6=68

what does this mean?

OK, I'm kind of confused. You said your original fast idle was around 2000 and you didn't like that. Eventually when your engine warmed up it dropped to ~900 rpm. You put your newly-acquired IAC in and now the fast idle is at 1500, which sounds about right to me. Did you let the engine warm up and see what the idle was when warm? It should be around 700 - 800 rpm.

In my '89, when the engine is cold, the fast idle is around 1800. It drops down gradually as the engine warms up. It should take your engine somewhere around 5 minutes to warm up to the point where the temp gauge is beyond the low line. If this is not happening you most likely have a stuck thermostat. Bottom line is that when the engine is cold, the idle is supposed to be high.

Eric W.

Thanks. I was quick to remove the 'new' one, maybe I should have left it in longer, but the idle was jumping around not smooth (I should have mentioned that).
When I tested the ohms on the 'new' one it was way different than mine. Don't know what that means, I do know that the 'new' one came out of a different year than mine (don't remember what year though)
The resistance on the 'new' 1-2=76 2-3=34 1-3=105
The second row seems normal 4-5=33 5-6=33 4-6=62


Eric; When I start mine (cold) it takes about 7-10 minutes and the temp gauge moves to almost mid point, at this point my idle is normal, and it runs good. During the 7-10 minutes it idles at 2000 and runs sluggish and surges.

Jon I think you have two IACs with blown coils. According to the FSM, looking at the connector-side of the IAC you will see six pins:

1 2 3
4 5 6

Measure the resistance between 1-2 and 2-3. Spec is 28-33 ohms.

Measure the resistance between 4-5 and 5-6. Spec is 28-33 ohms.

I think most IACs you'll get from the junkyard are going to be DOA. You can get a brand new one from dsmisc.com for less than $150. That's what I did when suddenly the idle would no longer bump up when the A/C came on. Popped the new one in, works like a champ.

Good luck! <img src="/forums/images/graemlins/kewl.gif" alt="" />

Eric W.

Oh, by the way, look at sooper-sekret-linky for Factory Service Manuals <img src="/forums/images/graemlins/wink.gif" alt="" />

While it is possible to "fix" blown coils with good coils from a donor unit, there is a risk to the ecu from a bad IAC. I'd buy the new style IAC from the site above and forget about the problem. I think I paid about $135 for mine. OEM mitsu part and box, looks diff but works just fine.

The 3.0 has two idle air controls.

One is the FIDLE valve, a thermostatic, unservicable initial fast idle valve that closes as soon as the coolant temp starts to rise. It's built into the TB, and you can't get at it. Bad FIDLE means new TB. The other one is the IAC/ISC, which you've had out already.

I'd reinstall the "new" JY IAC and disco the battery for at least 10 seconds to clear the ecu memory, then let the ecu relearn the new IAC and see if it settles down.

You may also have a failing ecu coollant temp sensor, and not be getting full cold start enrichment from the injectors. That would cause a lean stumble, and perhaps a hard start.

"You may also have a failing ecu coolant temp sensor"


If I do have this part failing, is it serviceable?

Yes. Fairly cheap and auto parts store available. Connector points forward on water neck below/left of upper rad hose connection to engine. Two wire connector, two sensor connections in T formation.

I thought you said in your other thread somewhere that you already replaced the coolant temp sensor <img src="/forums/images/graemlins/confused.gif" alt="" /> I explained where it was in another of your threads???

Yes the part that was just explained has been replaced. When he said 'ecu' temp sensor, I thought it was a different part.

well just for kicks I replaced the thermostat this weekend, and it runs the same. high idle for 6-10 min and sluggish, then it runs perfect after that.
I think I'll give up now. lol