Idle Speed and Air Temp/Humidity Options

[StarBear]

@wonkipop @Van B @clayperrine
UPDATE #2:
1. Found the hose on the back (rear) side of the throttle body was a bit loose. Put some sealer on the nipple and put hose back on. Nice and tight now.
2. Found the lever connected to the spring (see pic) doesn't pull back all the way when not running; there's 2-3 degrees of play where the spring doesn't fully reset the lever backwards. Weak spring (replaced it only a few years ago) or sign of the worn throttle body? Shot in some silicone spray and will let soak in; maybe do another test drive this afternoon.
Onward!

[Van B]

Update: Had a nice 30+ minute run today including highway. Air temp in mid 70s; a bit humid but not yet oppressive.
Car started at 1000 rpm then by 2-3 blocks rose to 1600 (my new seasonal initial preset). After 10+ min idle had dropped but only down to the desired 1000 rpm. Stayed in that mode until after highway and full time.
So, a) tightening the oil filler cap seems to have helped things from being so extreme and b) can live with a minor seasonal manual adjustments until a more permanent problem identification and solution.
(IMG:style_emoticons/default/dry.gif)

That sounds exactly right. I suppose after 50yrs of heat cycles, the spring steel in that AAR loses a bit of its action. Which would be most readily observed at the margins of its movement i.e. it doesn’t open all the way or close all the way without being really cold or really hot.

[Van B]

What I previously described is my method to see if the throttle plate is seated properly when the throttle is closed. And is best done when the car is running so you can hear a change in engine speed vs detecting 1-2mm of travel with your mits.

Springs and levers and such can get dirty and gummed up which obviously make for stick points in the travel.

But I say get the car up to temp and idling steady and then try to push the arm “more closed” and see if idle drops, even a little. If it does, it means your throttle plate and bore have worn. That’s what’s wrong with mine and will require a rebuild.

[StarBear]

Solved, I think/hope.
Did the TB test suggested by Van. No stalling or change. Van, maybe we can chat during the upcoming Gathering to make sure I did it correctly.

The hose going into the back of the TB is nice and snug.

Drove for 20 minutes and the idle didn’t fall off from the preset slightly higher idle the entire time. So , have backed off the higher idle a bit and will retest tomorrow morning.

Still begs the answer to all our questions about if/where our 1.8s have a Temp Sensor I.

Onward!

[ClayPerrine]

Still begs the answer to all our questions about if/where our 1.8s have a Temp Sensor I.

It is built into the air flow meter. You cannot replace it.

Clay

[StarBear]

Still begs the answer to all our questions about if/where our 1.8s have a Temp Sensor I.

It is built into the air flow meter. You cannot replace it.

Clay

Hmmmm and suppose no way to test it separately, either?

[Van B]

Resistance figures outlined in the manual are all we get.

[ClayPerrine]

Resistance figures outlined in the manual are all we get.

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[StarBear]

Resistance figures outlined in the manual are all we get.

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Ok; thanks!!!

[wonkipop]

you might have fixed it @StarBear .

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a throttle not fully returning would certainly do that trick.

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re the mysteries of the L jet AFM.
nihil44 has just come on that other thread about Air Fuel Ratio for L Jet.
has posted some fantastic images of all the guts of the different AFMs.
the temp sensor is definitely there in the 74 but there is no visible wiring in.
so its some kind of direct connection that is integrated as clay perrine states and as i surmised.

http://www.914world.com/bbs2/index.php?sho...60274&st=40

its just for curiosity value @StarBear .
guarantee its not your temp sensor playing up.
did a bit more reading on that and if it was a defective temp sensor the car would be running badly all over the rev range and in extreme cases might not even start and run.
if you are the least bit worried just do the test i posted on page 2.
you cannot isolate out the temp sensor but i guess given its part of it all if the test values don't come out good it means it could be the villian and there is not much you can do about it.

i've been trying to find factory manual info on the 75 and can't find anything.
was thinking there must be a test for the sensor for that one given its wired in separate.
but nothing in the literature i have. (IMG:style_emoticons/default/beerchug.gif)

[Van B]

I wouldn’t take those pics of the ‘74 as certain @wonkipop . Not the same as mine and both mine are identical.

[wonkipop]

I wouldn’t take those pics of the ‘74 as certain @wonkipop . Not the same as mine and both mine are identical.

yeah i noticed looking at the one you posted up you can see two wires there that are black coloured and fit snug down. maybe yours is a rebuild?
also the counterweight!!!!!

i could crack mine open and we would know.
its original from the factory.
but i'm not going to. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)

what i will do is undo my aircleaner etc and peer in there at the intake.
the temp sensor should be visible hanging down.
no spare time at the moment and not urgent.

main thing - we know its there (somewhere/somehow) and there is farken well narthing you can with one if its cactus! (IMG:style_emoticons/default/sad.gif)

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i did poke around in 912 universe,
sure enough you can test for temp sensor I
must have been able to do same test for the 75 914s?
just not in the copy of factory manual we have.

[wonkipop]

@StarBear .

just noticed something about your T/B looking carefully at the photo at top of page.

the throttle body gasket looks a bit wonky.
you can seen how its got a ripple in it where the little formed ledge looks to have moved away from the T/B edge.
maybe its not sealing well?

i had a problem with a gasket that had gone hard a couple of years ago and it sent the idle mental.'
worse than what you have been describing.

maybe make sure its still seating in nice.

[StarBear]

@StarBear .

just noticed something about your T/B looking carefully at the photo at top of page.

the throttle body gasket looks a bit wonky.
you can seen how its got a ripple in it where the little formed ledge looks to have moved away from the T/B edge.
maybe its not sealing well?

i had a problem with a gasket that had gone hard a couple of years ago and it sent the idle mental.'
worse than what you have been describing.

maybe make sure its still seating in nice.

Yes; will do cold and hot test on pins today. Might have a photo of my AFM internals from when I had it open a few years ago.
The TB gasket should be fine; finally replaced it about 2 years ago but will recheck and tighten to be sure.
In the home stretch! (IMG:style_emoticons/default/smile.gif)

[StarBear]

Update 2:
+ did the pin tests in cool garage with 6-9 at 324 ohms and 7-8 at 164 ohms, both within spec. Will check again after a drive and warm day air and engine.
+ @wonkipop Good spot on the TB gasket! Maybe some fine hair gaps on the edges. Temp fix with fill in with black RTV. Will let set then do another test drive. If needed, I have a spare new TB gasket.
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[StarBear]

Second test run for 20 min done.
Pins 6-9 at 324 ohms before starting. At end ohms varied widely, 961 to 1005 to 324 to 201 about 20 secs apart. Sometimes no reading at all, even after relearning pins.
Pins 8-9 very steady at 154 and 164 ohms, as before, about 20 secs apart.
Idle Behaving better but still not to my satisfaction. Looking at replacing the TB gasket. (IMG:style_emoticons/default/dry.gif)

[nihil44]

Apologies to the group for posting photos of what I believed to be the AFM from a 74. @Van B alerted me to the possibility that the photos were incorrect. I believed it to be a genuine 74 AFM as that was the AFM that came on the car when I got it.
I popped the top of the AFM which is on the car and indeed it is quite different inside. I don't know where the other AFM came from as the black plastic cap bearing the part number has been lost. Updated photos below. There are 2 black wires coming from the position of temp sensor ‘1’
I looked up PET and the change over point for the different AFM and ECU is the same – engine # ECO 037 551. 6 to 7 pin change over. No surprises there

[Van B]

Yeah that is definitely the ‘74 AFM right there!

[wonkipop]

Yeah that is definitely the ‘74 AFM right there!

yes
more like what i thought it would be.

i would say that counterweights on the units that @nihil44 has posted in the other thread are due to them being rebuilt units? the counterweights don't appear to be stock? the unit above looks stock.

it seems to me on the 74 that the temp sensor is feeding into pins 9 and 8 on the plug socket - as much as i can tell anyway and its modification of the signal is fed out via that circuit to the ECU.

the later ones in 75 are using pin 6 and an additional pin 27 added to the plug and ECU.

would suggest you might be able to test 74 AFM by taking the top off and testing at those two electrical connections from temp sensor I? if you had test reading data to check against? dunno. only ever found that 912 test.

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not sure what to make of @StarBear test above.
seems like his AFM is correct when tested cold.

can't really think what to make of his warm test or the why of it.
the AFM is sheltered from engine heat. isolated via intake boot and plastic air cleaner casing from direct engine heat conduction and is perched high in engine bay. i guess electrical circuits are all warmed up. but don't know what to make of it. don't think it matters. his test would seem to say his AFM is ok. (IMG:style_emoticons/default/confused24.gif)