Not going into closed loop

[tblu92]

I am tuning a 2001 LS1 Firebird A4---The owner bought the car with an aftermarket MAF--looks like a SLP---
Whats happening is that the computer never goes into closed loop---It starts in open loop as it should but never changes--The LTFT's are not reading so i can't adjust them---However when flooring it the AFR does change to the commanded 12.7 that I've tuned in--
I can't tell what the actual AFR is because the 02 voltages are not oscillating either and are stuck around .450 millivolts at WOT
Any ideas or suggestion where to look for a problem or where to start ????

[5.7ute]

Post up the tune file so we can have a look.

[hquick]

I don't know if it's relavent. Everything I've heard about aftermarket Maf's is bad!
Apparently they are designed to mostly 'trick' the PCM.
I reckon I'd be getting an OEM MAF and sticking that in there as a first step.

[joecar]

Post the tune file and any log files.

[tblu92]

will post tune today--THKS guys !!!--------

The Maf is working --i am getting a Lbs. per min. reading when it's plugged in--the callibration i'm sure is way off--I suspect the 02 sensors--

[Doc]

What kind of ECT readings are you getting?

[tblu92]

What kind of ECT readings are you getting?

The coolant temps are in line--runs about 180*--has a 160 thermo--I have the closed loop timer set at 90 seconds and the activate temp at the stock 92*

Replaced the 02 sensors today ---and still only .440 milliv. on them--not oscillating----no closed loop---- So---not the 02's---

Checked the "engine Sens " fuse today--was good----ALSO tried a stock MAF and same thing

[tblu92]

The coolant temps are in line--runs about 180*--has a 160 thermo--I have the closed loop timer set at 90 seconds and the activate temp at the stock 92*

Replaced the 02 sensors today ---and still only .440 milliv. on them--not oscillating----no closed loop---- So---not the 02's---

Checked the "engine Sens " fuse today--was good----ALSO tried a stock MAF and same thing


UPDATE--- RESOLVED --Trans shop had reversed the 02 pigtails--connected the rear pigtails to the front 02's !!!!!!!!!!!!!!

Still they read .450 millivolts interestingly ----disconnected !!

[joecar]

Cool... :cheers: ...it pays to pay attention to where all the wires go.

Yes, the PCM biases the O2 signal wire to 450mV wrt to signal ground, and the O2 sensor rides its AC-like output voltage waveform on top of that.