Hey all,

Just pulled the Iac valve from my 82 with b21-LH1.0 and it looks to be stuck wide open and pretty gnarly inside. Does anyone know if there is an Iac comparability chart somewhere or could tell me what the next best option would be for an 0 280 140 500 Bosch?

Thanks!

hi zachary,
not to change directions on your question, but i believe you can clean the iah with spray cleaner, if only the cause is petroleum goo-related.

if i remember correctly, hold the iah in such a way where the cleaner drops down and away from any iah electronics.

if that does the job, keep it as a spare on the shelf.

regards,
byron golden
86 245
92 245
94 940

Hi,

I think in your case can use any IAC that has three pins in the connector is usable.
The three pin allows adjustment by the ECU to move the vane open and closed.
I don't know if it uses a steady current flow to open it or pluses it more open.
I can only imagine three pins ones pulse the polarity "X" amount each way.
Doing this requires using the center pin to be an electrically ground or a common pin.
This will cover up to LH 2.2 or around 1988 model cars.

On the LH 2.4 starting around 1989 they changed over to a two pin connector and it utilizes an internal return spring.
The two pin model powers only in one direction against the spring. It is more of a fail safe model to always close down to a closed/off idle throttle position.

If there are other differences, I'm not aware of them.
So between the two models, you have to pick the one that matches the connector your system has.

So an idea of my own, would be to test the possibility to use a two pin IAC in only one direction as well?
Modifying a wire here or there might be a thought. This means matching up the two pin model, to get the vane to work in the right direction.
This may end up to being a desperate action in the years to come.
I've stashed away a few of both styles for my future desperations.

Phil

It sounds like everyone has a little 240 secret stash...

What I don't quite understand is- is the IAC a simple open/closed only sort of thing, or is it translating a signal to be a RANGE of openness. If it's just simple open/shut, then it would be a pretty fun and totally doable project to make a 3 > 2 connector for allowing the use of newer IAC's (something I would totally be interested in doing)

My biggest issue beyond the IAC is finding new hose- Volvo is charging 35$ for my one-off model year specially formed IAC hose... EACH. Is there any way to build a new IAC hose from thick braided hose (with like... 15 MM ID :) ????

The idle valve in your car is adjusted by the ECU by alternately grounding outer two pins while the center pin is provided battery. Varying the ratio of time between the open and close pin gives a range of valve opening. This happens at a fixed 100/sec rate accounting for that throb you feel in a properly operating idle valve.

A common trouble with LH2.0 and 2.2 idle valves occurs when someone mistakenly swaps the connector with the throttle switch, ruining one of the two transistors driving the idle valve. The symptom, I hear, is constant high idle. LH1.0 is a left coast thing -- only ever seen one, in a junkyard -- I don't know whether it is even possible to mix up these connectors on yours.

Getting around the price of the molded hoses is the interesting thought here. I often wondered if anyone has success taking stock straight hose and keeping it open through tight bends with a tape wrap. Just choosing the hose and tape sounds challenging beyond $35, but a look at how these silicone hoses are bent up seems to shed light on the process:



--
Art Benstein near Baltimore

What's the fastest liquid on earth? Milk, because it's pasteurized before you see it.

It is a range of openness, the signal is a buzz.

As written above, any three wire IAC from an LH 2.2 car should work.

15mm is close to 5/8". See if you can find a piece of oil resistant 5/8" hose to substitute. All the hose does is provide an air passage.
--
john

https://www.brickboard.com/RWD/volvo/745194/220/240/260/280/iac_valve_part_numbers_dates_used_bosch_500_501_520_516.html


Bosch 500: 240 '81-'82 and 240 Turbo '81-'83.



If you can't find a affordable replacement my thought would be to put an ad up on Row52.com they they have about 7 currently in yards where you can request a part and a independent puller will pull and ship it. Labor shouldn't be much and the part is not going to be more than any other IAC valve. I think you have to put an ad for each car/yard. Trouble would be knowing which one is worth pulling.