Can anyone help?

[Pace 1989]

When going down the street, if I let off the gas the rpms drop to 500rpm and the car sometimes dies. When it doesn't die the engine acts like it catches itself and jumps back up. But the car dies frequently. I did get a code 45 once (the o2 sensor is almost new), and the idle is rough.
I can't find any vacuum leaks.
I changed chips from extender + with 3" MAF sensor to Joe Lubrant and stock MAF, and it still does it. I've adjusted the IAC to the normal parameters (10-20 in park), I've adjusted the TPS sensor to .44 at idle and 4.5+ at WOT.
How do I know what happens when an ECM goes bad?
How do I know what happens when the IAC motor goes bad?
Can anyone help please!

Ken

 

[Dan Thompson]

Your running a stock MAF with Joe Lubrant chip?

What are your mods?

What happens when you start the car and let it idle? Does it start easy?

Do you have a scantool?

Have you run lead fuel with the new 02?

 

[RobV6]

You also didn't mention what injecters you have. And fuel pressue..............I think it would help everyone if you listed your
parts.......

Trying to help

 

[Pace 1989]

Thank you for your responses!
It's a TTA if it makes a difference
Yes, now I have the stock MAF and JL chip in it.
Starts right up.
Idles like crap (I think it's running rich)
I use Turbolink as a scan tool.
I have never run race gas and the O2 sensor is less than 2 months old. (I have at least three good ones as spares)
Fuel pressure is at 45 which is what the Extender chip calls for.
Mods:
009 injectors
Rebuilt engine with TRW .030 pistons
K&N, MAF pipe
TA49
Power Plate
ported heads
3" THDP
adjustable fuel pressure regulator
adjustable wastegate

Ken

 

[Pace 1989]

Anyone?

Someone suggested to me that it might be the ECM. What happens when that goes bad?
Also when the rpms crash to 500, the IAC counts go to about 140.
What happens when an IAC motor goes bad?
Thanks for help in advance.

Ken

 

[Pace 1989]

O.K. I got an ECM from the boneyard today and will try it. Needed a spare anyway. But what else could this be?

Ken

 

[WarpSpeed]

Could be egr related,, might plug the vac line to the valve itself and see if there's a diff.
Actually it seems to me if the rpm goes to 500, the IAC should work like h*ll trying to correct, so the 140 may be right.
Are you using an AC delco O2 sensor?
What vacume reading is the motor pulling at idle?

 

[Pace 1989]

I am using a GM O2 sensor. What should my EGR readings look like? (at idle, part thorttle, WOT, etc.)
I had the EGR blocked (power plate) until recently when I drilled the hole. The car did this before I drilled the hole with the JL chip. Sounds like you might be on to something here, how can I check the EGR system?

Ken