TBI 350 Target Idle Speed

[ralmo94]

Any updates?

[maronielb]

Hi i received the new prom chip on Monday but i have not had time to install it yet. Wheather been shitty, i will probably install it this Saturday. One thing i was thinking about the other day is if i do the IAC reset but leave the IAC unplugged then the truck shouid idle at the base idle speed correct? With the IAC unplugged the computer won’t be able to get the idle up to 1k. This will also be a dead give away to is there is a vacuum leak present. With IAC fully extended out and left unplugged the truck would idle at the base idle that was set at the factory since the cap has never been removed on this TBI. Should i try this before i switch the prom chip? Or am i just running in circles

[ralmo94]

With the IAC closed and unplugged, yes it should run at where ever the butterfly stop is set, but that still wouldn't tell you why the ECU is requesting 1k idle speed. It may be a worthwhile test to see if it will idle slow, but if it has a vacuum leak, butterfly open too far, it should still target around 550 to 650 rpm, after warm up.

[maronielb]

Ok i get what your saying, i won’t be able to install the new chip
Until Monday evening but I’ll let you know what happens. I really don’t think it’s the chip i think it’s something to do with the TPS sensor but idk

[maronielb]

OK so I installed the new chip in the computer today and I did not notice any difference in the idle speed or the way the truck ran or drove. I didn’t notice any difference the RPM needle still sits right around 1000 RPM and also ended up breaking one of the little pins on my old chip when I was trying to take it out of the casing so I can no longer use that. So now I’m stuck with the new one which is fine I mean the truck still runs the same exact so I’m sure it’s not gonna be an issue but when I took the old chip out I did notice that it said Delco on it so I’m assuming that that is a factory chip that was never modified or anything like that but yeah, I’m gonna lost now with this with this idle speed. I don’t know what else to do frankly, I mean I can try a new TPS sensor just for the hell of it but other than that, I really don’t know where else to look.

[MO LS Noobie]

Go to beginning of your post, start there.

[Resin]

Do you have your scanner hooked up constantly as you are testing?

Edit: I read more of the thread and answered my own question.

Check for resistance across pins A and B of your ALDL connector.

[maronielb]

I don’t have a multi meter to get resistance, what wouid that do anyway?

[maronielb]

You are essentially tell me to adjust the base idle speed manually lol