What’s the solution to this?? Idle adjustor

So I went to adjust my idle on my 90 suburban and found the adjuster like this!

You have to drill that cap out to get to the screw.

the cap will come out with a small screw driver or a pick. you shouldn't need to drill it out.

better question is - what are you trying to accomplish by adjusting the min idle air screw? the IAC controls the actual idle speed.

gmbellew said:

the cap will come out with a small screw driver or a pick. you shouldn't need to drill it out.

better question is - what are you trying to accomplish by adjusting the min idle air screw? the IAC controls the actual idle speed.

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Sorry for the late response I’m trying to lower the idle on start up, I’ve replaced IAC but it is still a bit high.

Would be better to properly diagnose the problem. Really need to know the IAC counts. If you close the throttle plates to fix a cold start issue it could have a sticky throttle or die when warm. The IAC can only adjust so far then other undesirable things will happen. Some possible suspects are a vacuum leak, timing advanced too far, TPS out of adjustment or bad.

fast 99 said:

Would be better to properly diagnose the problem. Really need to know the IAC counts. If you close the throttle plates to fix a cold start issue it could have a sticky throttle or die when warm. The IAC can only adjust so far then other undesirable things will happen. Some possible suspects are a vacuum leak, timing advanced too far, TPS out of adjustment or bad.

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How you FIND the IAC counts? Mine always wants to idle at about 950, it will start off with a nice low idle and then as you sit at a light it will slowly start to idle up to around 950 and never go back down until you turn off and on again. Someone before me had already removed the cap and presumably played with the screw underneath before I got the truck, probably trying to solve the same problem.

Need a scanner or equipment to access the ALDL data.

YakkoWarner said:

How you FIND the IAC counts? Mine always wants to idle at about 950, it will start off with a nice low idle and then as you sit at a light it will slowly start to idle up to around 950 and never go back down until you turn off and on again. Someone before me had already removed the cap and presumably played with the screw underneath before I got the truck, probably trying to solve the same problem.

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Theres a procedure that doesn't actually rely on having any data to reset the idle. Get the vehicle nice and warm and then shut it off.

-Jumper the A and B pin on the ALDL connector.
-Turn the key on without starting the engine for 10 seconds to allow the IAC pintle to fully close.
-Turn key off.
-Unplug the IAC valve and remove the jumper from the ALDL connector.
-Start the engine and let settle on idle(you probably will need to give it a little throttle to start it and then slowly let off the throttle to get it to settle).
-You will need to have a timing light with a tach function connected.
-Adjust idle RPM set screw until it is ~125rpm less than warm idle RPM(usually 500-600rpm)
-Turn engine off and re-connect IAC
-Start engine and let idle for 5 seconds, turn off engine and let sit for AT LEAST 30 seconds.
-Start engine and verify that idle is now correct.

If your idle is still high or intermittent, verify that timing is set correctly and there are NO vacuum leaks. If that is all good, then check the resistance on the CTS near the thermostat housing. That sensor tells the computer what your engine coolant temp is and will drive both a rich condition and high idle if it thinks the engine is cold.

fast 99 said:

Need a scanner or equipment to access the ALDL data.

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Is there any current source to get one of these? Has some sort of copyright/intellectual property dispute made then illegal? The only references I can find are to people or companies that seem to have vanished a decade or more earlier. A tool like that seems vital to really solving issues with TBI, but there is no one making them.

YakkoWarner said:

Is there any current source to get one of these? Has some sort of copyright/intellectual property dispute made then illegal? The only references I can find are to people or companies that seem to have vanished a decade or more earlier. A tool like that seems vital to really solving issues with TBI, but there is no one making them.

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There's a ton of them out there. Autel, Snapon, Innova, etc... all make various models that are capable of accessing the live data and doing various things. You can also just get a simple ALDL cable for cheap and use Tunerpro to read the data.

Here's one of the "covers all" solutions: https://www.autozone.com/test-scan-...V6yitBh1GJCz-EAQYBCABEgKHCfD_BwE&gclsrc=aw.ds

And here's one of the cheaper Tunerpro solutions: https://reddevilriver.com/home-page/ols/products/gm-12-pin-aldl-scan-bluetooth

Bextreme04 said:

There's a ton of them out there. Autel, Snapon, Innova, etc... all make various models that are capable of accessing the live data and doing various things. You can also just get a simple ALDL cable for cheap and use Tunerpro to read the data.

Here's one of the "covers all" solutions: https://www.autozone.com/test-scan-...V6yitBh1GJCz-EAQYBCABEgKHCfD_BwE&gclsrc=aw.ds

And here's one of the cheaper Tunerpro solutions: https://reddevilriver.com/home-page/ols/products/gm-12-pin-aldl-scan-bluetooth

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Will that Innova one from Autozone read the live data from OBD-1 or just the error codes? The RedRiver bluetooth option looks really nice but since its listed as an "LLC" I'm expecting it to be an overseas purchase so that might not work. I've seen the various units at Autozone but always assumed they were code-only readers for OBD1 and real data on OBD2 - if they can do real data on OBD1 I may be picking one up this week....

YakkoWarner said:

Will that Innova one from Autozone read the live data from OBD-1 or just the error codes? The RedRiver bluetooth option looks really nice but since its listed as an "LLC" I'm expecting it to be an overseas purchase so that might not work. I've seen the various units at Autozone but always assumed they were code-only readers for OBD1 and real data on OBD2 - if they can do real data on OBD1 I may be picking one up this week....

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Supposedly both the Innova and Autel options will read live data from ALDL OBD1 applications. I've been thinking about getting one to read live data on my 93 Honda civic.

The RedRiver one is supposedly just some car guys in New York... but they are notoriously bad at communication. They have been around a while and are known to eventually deliver the product. Theres also version on that website that is just a cable to connect to a laptop and will work with tunerpro. The bluetooth versio nI linked is nice to use with an android tablet or phone running ALDLdroid.
https://www.thirdgen.org/forums/dfi-ecm/783254-red-devil-river.html

The other very well known cheep ALDL option was Moates, but they have discontinued their ALDL reader. BoostedNW has a version that is exactly the same and is known to work.
https://boostednw.com/Datalogging/gm-datalogging/boostednw-aldl-12-pin-gm-datalogger

Sometimes those caps for the base idle adjustment are a royal pain in the a$$ to remove. They are very stout, they kill drill bits and they sometimes fit very snug into the throttle body. Iirc, the later ones are stronger than the earlier years of TBI.

Bextreme04 said:

Supposedly both the Innova and Autel options will read live data from ALDL OBD1 applications. I've been thinking about getting one to read live data on my 93 Honda civic.

The RedRiver one is supposedly just some car guys in New York... but they are notoriously bad at communication. They have been around a while and are known to eventually deliver the product. Theres also version on that website that is just a cable to connect to a laptop and will work with tunerpro. The bluetooth versio nI linked is nice to use with an android tablet or phone running ALDLdroid.
https://www.thirdgen.org/forums/dfi-ecm/783254-red-devil-river.html

The other very well known cheep ALDL option was Moates, but they have discontinued their ALDL reader. BoostedNW has a version that is exactly the same and is known to work.
https://boostednw.com/Datalogging/gm-datalogging/boostednw-aldl-12-pin-gm-datalogger

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I downloaded and read the manual for that Innova3170 which Autozone offers, and according to its instructions it only retrieves the codes on GM vehicles, it doesn't seem to have live monitoring capability so that might not be overly useful since the codes are easily available through the SES light with a jumper.

Thanks for the info about BoostedNW's device, it looks like the only option (and less expensive as well) available. All the Autel ones which mention OBD1 capacity in any form seem to be close to or over $1000 which puts them out of range for people not actually earning money from their use.

YakkoWarner said:

I downloaded and read the manual for that Innova3170 which Autozone offers, and according to its instructions it only retrieves the codes on GM vehicles, it doesn't seem to have live monitoring capability so that might not be overly useful since the codes are easily available through the SES light with a jumper.

Thanks for the info about BoostedNW's device, it looks like the only option (and less expensive as well) available. All the Autel ones which mention OBD1 capacity in any form seem to be close to or over $1000 which puts them out of range for people not actually earning money from their use.

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I occasionally see old OBD1 and OBD1/OBD2 diagnostic scanners for sale on Craigslist. Prices vary, but I've seen them for a few hundred bucks or less.