issues with OBDII computer

[69camarokid]

im having some issues with my LT1 powered 69 camaro. The engine is out of a 95 Trans am. ive been having a bad idle issue since i installed the engine over a year ago. itll not want to idle when first strated, the idle will flucuate from 400 to 700 and swing around wildly. after 30 seconds or so it will jump to 900 and stay there.

This whole proceedure will happen everytime i push the clutch in and slow down. So after cleaning the IAC and MAF sensors to no avail i tried to hook the computer up to my uncles scan tool. this scan tool works fine on my cousins LT1s, but it cannot connect to my PCm for some reason. It has a mail in tune from PCMs4less.

any ideas whats happenein with with either the idle or my PCM? thanks

[LSXfan]

without looking at data it will be hard to troubleshoot, who ibstalled the engine/PCM wiring ?

[LSx_88_Ciera]

Have you disconnected the IAC to check base idle. IIRC it should be 650rpm when fully warmed up. It sounds to me as though you have a bad IAC cleaning them will only fix the issue 50% of the time at best and can actually make things worse depending on how harsh the solvent is. It is actually not recommended to clean them since they are only designed for air and virtually any solvent can cause damage. I am as guilty of cleaning them as the next guy but I read somewhere that it is a bad idea so I no longer do.
What kind of scan tool does your uncle have? If a snap-on some have a generic function which will attempt to communicate with the ecm without you entering vin data. This could be helpful since it is a custom program and there might not be any vin specific data anymore.

[MonzaRacer]

use obdII generic scan on reflashed ecms usually works, now you als need to make sure the power and ground are present at DLC connector.
Ill post up the pics of them.

[MonzaRacer]

While the iac reading should be in the 10-15 area, figure your short term/long term readings should not exceed 10% added or subtracted together(ie 2 positives add, one positive ,one negative subtract neg reading from positive)
Now at idle your MAF should read around that same grams per second as liter of engine, roughly.
Now also look at your primary O2 sensor(s) you want it/them ranging after warmed up, below 200 and above 800. if they are 1 wire O2s then rev engine up to about 2000 for 3 to 5 minutes then let idle and watch them.
Also look at your injector ms reading if its bottoming out its trying to close them down too far and you may need to adjust fuel pressure.
If O2s are working, MAF if ok, and IAC is working between 5 to 20 and you have no air leaks fuel pressure adj may be needed.
Also if the injector is working too hard it may need more pressure.
Email me if you have questions @ [email protected].

[ryeguy2006a]

Also remember that from 1994-95 the lt1 computers weren't OBDII, although they have the same ports. It is known as a hybrid, called OBD 1.5, it has the OBDII diagnostic port, with OBDI computer.

[ryeguy2006a]

Also, the OBDI computers cannot be reflashed