use some butane or carb cleaner around all vacuum hoses make sure your done have a vacuum leak.any change in idle indicates a leak. if idle drops it means your running too rich

 

As I said, they are in the manual (spelled out very clearly); straightforward enough, but they do require a multimeter.

 

Hey man, when your car is idling and you turn the steering wheel, what happens?

Does it stall, or do rpms go up or down? Your IACV controls your rpm when turning the wheel at idle.

 

Yeah I just did the ISC power then ground out the 4 contacts test but there was nothing I could really adjust unless I missed something. The TPS is adjusted within spec. Still having stalling problem but that's a whole other thread.

For those that removed your ISC, was the plunger black like a fouled spark plug? And did you clean it with something?

 

I seem to recall seeing a DIY from someone on another board....I'll look for it.



Here. I found this on an sc400. I can't recall if this was what I was originally thinking of, but I think it's relevant to the 300's anyway:

http://www.planetsoarer.com/IAC/iac.htm





.

 

wow that was an awesome write up! yeah this is for my 400 so that's perfect. I'll do those proceedures tonight before I reinstall it.

 

any updates?

 

yup did the iac check. motor seems good on the iac. maybe i need to replace the bearing but i have problems finding the big bearing. for the tps i guess i need to do the ohm test.

 

Our 92 SC400 is having idling problems also. I have IACV off to test & clean it. I cleaned it per instructions in planetsoarer link above. Bearings were is good shape, smooth motion when disassembled. At reassembly I thought to checked resistance per manual step 1 and every one measured ~22.5 ohms. Hmmm less than the spec, but is it actually bad? Need some clarification on step 2 of testing the valve. Manual says to apply + voltage to terminals B1 & B2 and repeatedly ground terminals S1-S2-S3-S4-S1 in sequence, and check that valve moves toward closed position.

I want to make sure I'm doing this right. So I have +12V (from battery) to B1 & B2 simultaneously. Then take - jumper from battery and connect it 1st to S1, then remove from S1 & move it to S2, remove from S2 & move to S3, remove from S3 & move to S4, remove from S4 & move to S1. Nothing happens. I did it multiple times & even backwards S4-S3-S2-S1-S4. Still nothing.
So any advice from someone that's actually run this test before?

Also, 18 years + heat has taken it's toll. 1st picture is what the plastic connector to IACV looks like. It was like this before I started & I babied if off to keep from doing any more damage. OK to use as-is? I expect I'll just wrap it with electrical tape. As long as electrical contacts are good I'm probably OK.
2nd picture is how my Engine Coolant Temperature (ECT) sensor connector came off. With barely a nudge on removing the connector it broke in two. The new one's a bit more sturdy for now.

 

OK so I tried the sequential voltage test again & now it's working. Before I was expecting to see the shaft move the entire stroke. My mistake. It only incrementally moves a small amount for each - sequence S1-S2-S3-S4.... Initially barely noticable unless you mic the displacement or run the sequence multiple times 123412341234... After reassembling the IACV connector I taped it up & it looks good enough. For those of you working on these old engines, be gentle on the plastic connectors, as they can easily fall to pieces.

 

CRuby, thanks for this 4 year old post. I just pulled my IACV off again to check resistance (all four checks are right around 23 ohm; spec is 10-30 ... my two spares (long story) test identically) and was moving on to the battery powered open/close test and was similarly confused by the manual's instructions. I hadn't seen it covered anywhere else. Your clarification helps a ton.

 

Having the same problem. Anyone ever figure out what was wrong?