The gm sensor arrived yesterday, more issues. The gm is 3/8 npt my Cherokee uses 1/4 npt threads. I did more research and a dodge neon sensor is 1/4 npt don't know if specs are the same. Heading to parts store will let you know.

 

Put the GM one in the air cleaner lid.......

 

Cruiser, its obvious that you know way more than I do, here is my thinking. If I put the 200 ohm resistor in my backfire (lean?) goes away, I think it tells the ecu engine is up to temp. The neon iat I bought caused my backfire to come back, (it must have different values than the stock iat) I put the resistor back in and it goes away. ohm meter reading the neon iat is too high at operating temp. I think if I put the gm iat in the air cleaner it won't get hot enough to get the resistance to 200 ohms. I connected the resistor in during the same test run. Thank you for your help

 

Well, It turns out the GM guy doesn't know the Renix system that well after all.(we can forgive him for that) A lousy "screen shot" but from the Renix fuel injection Manual> It does use the incoming air temp, cranking in open loop.

 

Ain't that something Pete? lerob 225, ohms is what I'm using. Around 500 ohms seems normal, which translates to the sensor reading around 160* there in the manifold. Cruiser is maybe.... mildly..... interested in my experiment.
"So Lerob, does the backfire go away if you just leave it unplugged?" , I asked back in post #22.

Do you have an exhaust leak? Like at the header pipe? Backfiring might be rich, with 02 there to "participate" in the bang. If your 02 sensor is getting air it will increase the fuel, (pulse width) to the injectors. Then the gas and air go down the pipe. (A bang might be expected there)

 

Could it be the EGR operation? I must be losing it - I thought Cruiser had suggested possible EGR issue on this thread but looking through I can't find his comment. The stuff below is from another source on the web:


EMISSION CONTROL

ECU controls EGR valve and fuel evaporative operation. By energizing the EGR/EVAP solenoid, vacuum is shut off, making this system non-operative. When engine reaches normal operating temperatures, ECU de-energizes solenoid. When de-energized, solenoid allows vacuum to flow to EGR valve. ECU will energize solenoid whenever EGR action is undesirable, during idle, cold engine
operation, wide open throttle and rapid acceleration or deceleration


I guess a test would be to disconnect the EGR solenoid and see if acts differently.


Maybe not the right issue.


Grasping at straws.

 

Try the resistor as a diagnostic tool if you can't get a good used IAT sensor.

 

Guess what the first 4 sensors in that scan of the manual share?

 

67 gmc, egr is stuck closed, I hooked up hand held vacuum pump and egr shaft didn't move and it held vacuum. I assumed stuck closed and no vacuum leak was good for this trouble shooting, but we know what happens with assumptions. I'm going camping for the week when I get back I'll continue on with the quest. Thanks for all the help everyone

 

fuel delivery

 

Guess again.

 

The same ground (sensor ground)?

 

we have a winner!!!!!!!!

 

Hey now, it wasn't a guess. They all affect fuel delivery.

 

Btw, Ed says in post #5 he "applied" Cruiser's tips... Maybe re-checking the sensor ground with a bettter handle on the meter would make sense though.