At my wits end with high idle issues.

[bobby v]

Wow... Deja vu !! I'm gonna ride along with my ears and eyes wide open..lol

Not to hijack but I too am having the same issues. Though I was also having an issue of it dying whenever I mash the throttle whether it was on the TBI itself or from the pedal. Coolant Temp sensor fixed that but still having idling problems.

At times it'll idle (in park) at 750 then suddenly ramp up to 1200-1500 then idle down to 1000. It's so sporadic it's driving me nuts.

I've switched out every possible switch/sensor, install (soldered) a few new connectors, new vacuum hoses, new EGR,reset IAC and no improvement. Even pulled and re-installed the intake thinking I had a leak there, nope.

Installed a new adjustable fuel pressure regulator..nothing

I even bought the ALDL Scan Cable program (Red Devil River) from research and thought it was a simple plug and play and that I'd get my reading and make adjustments...lol, Well I'm finding that it's not that simple or I'm totally missing something with the installation of the program.

I can see that there's a wealth of knowledge here and I'd even pay one to resolve this. Wish one here was my neighbor...lol Harder to fix via the net vs seeing and hearing in person.

I hear ya on no one around to help cause Im still going thru the same as you, and done just about the same with no fix, still idles high. At start up its fine but then it starts to climb and stays there, goes from 750rpms to 1000rpms.
My closest help is TBI, desert old guy who sounds like he knows his stuff but he's like hundreds of miles away
Bobby V

 

[skylark]

I read this procedure. Really . Think I would convert the tbi to a carburetor. Plenty of instructions online.

By the time he deals with the fuel pressure being too high and the transmission not being able to shift without the computer, he is going to spend a crapload of money. Also his transmission is a 1995 which is a one year only transmission. Unfortunately I don't know if aftermarket controller would run it properly.

 

[Supercharged111]

Since the trans is shifting weird, I'd be looking toward the TPS. If the TPS doesn't tell the computer the throttle is fully closed it won't provide fuel, timing, airflow, etc for an idle either. A scanner would show this quickly. My truck had a recessed PCM pin that shorted an AC recirc 12V signal onto the 5V reference signal for the TPS and truck idled 1000+.

 

[sixteenacrewood]

+1 on what Big Dave said

did you use a digital multi meter and test the IAC plug?

I had the same idle problem and found out I had plugged the IAC plug in backwards

 

[deve05]

Following back on this post. I haven't been able to actually work on the truck because I've had construction going on at home and have been running back and forth getting materials. Thankfully ol' reliable pulls through every time. My 84 c10 that has never failed me lol

Anyways, thanks to everyone that chipped in. There's a lot of good info I just got done reading and a couple of them right up my alley. My IAC connector clip IS broken, so I'll definitely check if thats plugged in wrong. That right there would make me feel purty damn stupid lol

One question though, you guys keep mentioning scanners. My truck is an obd1. And believe me, coming from working on mostly obd2 cars, I LOVE scanners and programing tools and I'm very good with them. But when i bought this truck I looked for obd1 scanners and all i kept getting was this dumb tool with a light on it that all it does is mimic the flashing of the MIL.

Is there an actual scanner that reads commanded rpm, % of throttle, and tps signal etc like for obd2?

Sent from my moto g(6) plus using Tapatalk

 

[PlayingWithTBI]

Is there an actual scanner that reads commanded rpm, % of throttle, and tps signal etc like for obd2?

Yes there is ones such as the Snap On "Brick". Go on sleasebay and look. I use TunerPro RT v5 and an ALDL/USB cable to data log and monitor, plus a Moates Burn2 to flash 27SF512 chips.

http://www.tunerpro.net/
http://aldlcable.com/aldl.asp
http://www.moates.net/burn2-chip-programmer-p-197.html?cPath=94

 

[skylark]

Following back on this post. I haven't been able to actually work on the truck because I've had construction going on at home and have been running back and forth getting materials. Thankfully ol' reliable pulls through every time. My 84 c10 that has never failed me lol

Anyways, thanks to everyone that chipped in. There's a lot of good info I just got done reading and a couple of them right up my alley. My IAC connector clip IS broken, so I'll definitely check if thats plugged in wrong. That right there would make me feel purty damn stupid lol

One question though, you guys keep mentioning scanners. My truck is an obd1. And believe me, coming from working on mostly obd2 cars, I LOVE scanners and programing tools and I'm very good with them. But when i bought this truck I looked for obd1 scanners and all i kept getting was this dumb tool with a light on it that all it does is mimic the flashing of the MIL.

Is there an actual scanner that reads commanded rpm, % of throttle, and tps signal etc like for obd2?

Sent from my moto g(6) plus using Tapatalk

This is the snap on mt2500. It will do obd2 as well. I have cartridges for mine up to 2000 and I've heard rumors about them going to 05.
https://www.ebay.com/itm/Snap-On-MT...827082&hash=item23c14ad497:g:oxcAAOSwogNdK6j-

 

[deve05]

Yes there is ones such as the Snap On "Brick". Go on sleasebay and look. I use TunerPro RT v5 and an ALDL/USB cable to data log and monitor, plus a Moates Burn2 to flash 27SF512 chips.

http://www.tunerpro.net/
http://aldlcable.com/aldl.asp
http://www.moates.net/burn2-chip-programmer-p-197.html?cPath=94

Nice! I see the tunerpro is free to download? And aldl cable is only 60 bucks.... Not bad!

Sent from my moto g(6) plus using Tapatalk

 

[Darrell]

Nice! I see the tunerpro is free to download? And aldl cable is only 60 bucks.... Not bad!

Sent from my moto g(6) plus using Tapatalk

Here's a thread I started with great help. I bought the ALDL scan cable and I'm now reading lots of info from this thread.

ALDL Scan Cable, is there a "how to" on installation instructions for dummies ?

 

[Schurkey]

This is the snap on mt2500. It will do obd2 as well. I have cartridges for mine up to 2000 and I've heard rumors about them going to 05.
https://www.ebay.com/itm/Snap-On-MT...827082&hash=item23c14ad497:g:oxcAAOSwogNdK6j-

I don't know when Snap-On stopped selling the MT2500/MTG2500, but they ended support for them in 2009, so that's the newest VIN-specific software there is. Of course, generic OBD-2 would still be available--but who wants generic?

Mine goes to 2006 for domestic makes.

I have an extensive post about the capabilities of a "REAL" scan tool for OBD-1 on another site. Here's the link. Posts 14 and 15, especially.
http://www.automotiveforums.com/vbulletin/showthread.php?t=1146067