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240 distributor terminal fault

no, the measurements are correct. center pin to right outer pin as pictured (4 to 5) is 21.8 ohms; center pin to left pin as pictured (4 to 3) is 41.7 ohms, across outer terminals (3 to 5 and vice versa) is 20ohms.

am I misunderstanding the measurements?

i have the IPD flame trap relocation kit installed, so that big hose runs to the intake boot right by the throttle body.

the air intake has been taped for as long as I've had the car so while I admit it's not ideal, i don't think it's causing this idle problem since two years prior it never caused a high idle.

Well, I'm confused. You have the odd-ball '85 LH 2.0 setup, not the '85 K-Jet turbo or later LH2.2. I thought the IAC was the same "T" style used by LH2.2, and I'm sure that the LH2.2 IAC center pin to either side pin is ~20ohms. The LH2.2 center pin is wired to +12v, and the other 2 pins go to the ECU. What's the history on your IAC? Is it known working good?
 
wow, I thought I had LH2.2? I figured that since my manual says LH2.2. started in 85. What might indicate the difference betwen LH2.0 and 2.2 - My distributor?

pin 4 to 3 (center to outer left) is reading 41.8ohms on my meter, which is out of spec. you are right - it is supposed to be 20ohms, but mine is off.

I've had this car about 3 years now; drove it one summer for work, then had it full time daily driver since fall of 2018. in that time period I had no known issues with the IAC until just recently. I wonder if maybe I damaged when grounding it to adjust the idle bypass screw or something?
 
I guess I shouldn't trust my memory - I thought '85 was still LH2.0 and '86 went to 2.2. If yours is LH2.2 (check the MAF part number), the IAC center pin to either side pins should be ~20ohms. Yours sounds like it was mis-wired from the factory (pins 4 & 5 swapped?), but I wouldn't expect it to work that way. I can't think of a reasonable way that a properly built IAC could fail as you've measured.
 
yeah seems pretty strange.

what i cant figure is what started this high idle in the first place? I installed a new engine harness and hall effect sensor. and cleaned the throttle body. then the high idle was present. trying to troubleshoot that, i cleaned the IAC and reinstalled. Still present. Now I got the check the piston and resistance measurements and it appears faulty - but for years it was fine?

OR could it be that I failed to properly ground the IAC test lead when adjusting the idle bypass screw, thus shorting out the IAC and creating a high idle situation???

if I look at what changed, I am less inclined to think that the IAC failure is causing it. if i look at when the high idle first appeared, I'd think I did something wrong with the throttle body. But I can confirm the butterfly valve is closing all the way... so on the other hand, i don't know where else to look, save an air or vac line leak.

it's not the intake gasket, as that was replaced with the manifold re-install...
it's not the throttle gasket, which was also replaced after cleaning....
i doubt it's the duct-taped air boot, since for years it didn't cause the high idle.....
\
 
Since it was working OK, I'd search for an air/vacuum leak. Carb or brake cleaner sprayed judiciously around the intake manifold and vacuum side of the throttle body can help. Look carefully that there's no pinched wires between block/intake and intake/throttle body.

Failing to ground the test lead won't damage anything -- all it means is that the ECU will try to adjust idle while you're changing the butterfly. If it's not grounded, you may have a hard time getting the low idle.

I'd also keep your eye out for a replacement IAC. Yours is certainly not right.
 
So i adjusted the position of the IAC piston component within the metal sleeve and was able to get the resistance values right. there are two marks on the piston component that suggest some sort of alignment, but i couldn't find any corresponding marks on the metal sleeve.

in any case - reinstalled with the IAC correctly adjusted and the idle was almost normal - fluctuating around 35Hz = ~875rpm. bit high but much better. idle was still fluctuating and choppy, so i sprayed around with cleaner and I think the trouble is my duct-taped air boot - spraying around there increased the idle slightly. at least compared to elsewhere - intake gasket, throttle gasket, vac lines - where the spraying had no effect.
 
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LH2.2 doesn't cover up air leaks like LH2.4 does and can result in a high idle
 
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alright, so now the car won't start or crank even. i checked the battery, it was at 11.5V, which is fully drained. tried jumping the car, though, and it still won't crank at all. Now battery is <11V. Did I totally screw something up? what does it mean if you jump the car and it still doesn't start? i hope it's not the alternator... just my luck it probably is.

i think that, with the IAC piston incorrectly inserted and wiring bad, it must've been drawing from the battery the past week or so and drained it bad. that's the only explanation that comes to mind, as everything was working fine before.

maybe I should just buy a camry and/or stop working on this thing... lord i cant catch no luck it seems. i appreciate all yalls help.
 
11-11.5v sounds low, you might have a bad cell, how old is the battery ?
Remove battery and charge, then check voltage again(iirc batt should be between 12.2~12.4v)

* you can have the battery tested at most auto supply stores


;-)
 
battery is maybe 6-8months old? starting to think the shop that sold it to me knew it was a dud. it doesn't have a date on it. i put a charger on it and didn't seem to be taking any charge. hopefully i just need a new one
 
Did you accidentally swap the TPS & IAC connectors?

^^

If someone did this, even though it was later wired correctly, one of the ECU's idle air control driver transistor is likely damaged. This is a well-known result of swapping the connectors, and the result is very high idle.

Also, I believe those resistance measurements on your IAC valve are indicating it is wired wrong inside. LH2.2 (1985) has power to pin 4, center pin on a brown wire, and alternating grounds from the ECU on pins 3 and 5, BR-W and GR-R respectively.
 
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I am still curious about this battery situation. why did it run down so suddenly? it is plausible to suspect that incorrectly inserting the IAC piston into the sleeve - causing the backwards resistance issue I was measuring - could have been draining the battery? that the IAC miswiring caused it drain current despite the car being off? I know I didnt leave any lights or anything on, and I am confident my alternator is good since I recently drove a 12hr trip and then a subsequent 2hr trip with no electrical issues.

i will probably get a new battery today and see.

I am certain that the TPS and IAC were not mixed up - they are and were wired correctly.

Art, you were suggesting my IAC is in fact just wired wrong to begin with, but are you describing the IAC terminals OR the harness terminals? I was measuring resistance across the IAC itself. apologies for my confusion here. but even fater adjusting the piston inside the sleeve has corrected this issue and the resistance is now at spec, you suspect that the IAC may be faulty regardless?
 
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Do a parasitic drain test. Use a jumper wire, or special tool, at first to take the load so it doesn't blow the fuse in your meter.

Google it.
 
I use a Fluke meter ($400) and an special tool ($80) that goes inline of the cable and has a current shutoff knob. The knob also has a couple of pins to conveniently clip the meter leads to. It doesn't arc and I don't blow the $20 fuse in my meter. Trying to hold a meter lead to a battery post can be tricky and you cant walk away and come back later and check the readings.

Learn to setup your meter to Amps, install a jumper wire, connect the meter, then pull the jumper wire.
 
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...
Art, you were suggesting my IAC is in fact just wired wrong to begin with, but are you describing the IAC terminals OR the harness terminals? I was measuring resistance across the IAC itself. apologies for my confusion here. but even fater adjusting the piston inside the sleeve has corrected this issue and the resistance is now at spec, you suspect that the IAC may be faulty regardless?

If you were accurate about the readings you quoted earlier in the thread, you were looking at an IAC valve internally wired so the common of the two coils appeared on an end pin (pin 5) instead of on the center pin (pin 4) as I believe it should be. I included the wire colors so you could double check.

I'm not following you with the "piston in sleeve" and how that could correct any resistance readings.

The IAC you have pictured looks new or freshly cleaned up, so I give the possibility it is miswired some credence, even though most likely event is faulty notes.

None of this has anything to do with your battery going dead in any way I can imagine.
 
So i adjusted the position of the IAC piston component within the metal sleeve and was able to get the resistance values right. there are two marks on the piston component that suggest some sort of alignment, but i couldn't find any corresponding marks on the metal sleeve.

in any case - reinstalled with the IAC correctly adjusted and the idle was almost normal - fluctuating around 35Hz = ~875rpm. bit high but much better. idle was still fluctuating and choppy, so i sprayed around with cleaner and I think the trouble is my duct-taped air boot - spraying around there increased the idle slightly. at least compared to elsewhere - intake gasket, throttle gasket, vac lines - where the spraying had no effect.

When you say you adjusted the position of the IAC piston, do you mean that you reached in through the hose nipple and moved the center rotating piece? Normally, that center piece rotates back and forth providing a bigger or smaller air passage. I'm not sure on the 3-pin T-style IACs, but on the 2-pin L-style IACs, the center piece is spring loaded and should return on its own to the default position. If it's sticky, cleaning is needed. Rotating it won't change the coil resistance measurements.

Where are you measuring 35Hz, on the coil? If so, 2 sparks per rev and 35Hz gives 35*60/2 = 1050rpm.
 
If you were accurate about the readings you quoted earlier in the thread, you were looking at an IAC valve internally wired so the common of the two coils appeared on an end pin (pin 5) instead of on the center pin (pin 4) as I believe it should be. I included the wire colors so you could double check.

I'm not following you with the "piston in sleeve" and how that could correct any resistance readings.

The IAC you have pictured looks new or freshly cleaned up, so I give the possibility it is miswired some credence, even though most likely event is faulty notes.

None of this has anything to do with your battery going dead in any way I can imagine.

The IAC basically has two parts, the bronze metal sleeve and the internal piston, which is where the hoses connect at the top as well. mine has metal tabs holding the internal piston in place, which, if pried back, allow the piston to be removed from the sleeve.
s-l1000.jpg


so i removed the top part from the sleeve with the Bosch stamp on it, and i think I did not have the alignment right when re-inserting the top piston part.

while i am here, the arrows on the IAC should be pointing towards the intake manifold/engine block? just want to confirm.

i must have either been misreading the resistance across the terminals or, as i suspect, I did not re-insert this metal piston part back in properly. as it stands, with the IAC reinstalled, my resistance readings are to spec.

does that make sense? I apologize for the confusion and i appreciate everyone's thoughts, help and patience.

I did a quick static current draw test with my dead battery and my meter is indicating 1.84-2mA, which is in spec (0-200mA per Bentley)

and yes, i measured Hz on coil. i did my math wrong.... again, my apologies....
 
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