any issues with running a 2002 5.3L w/ a 1998 firebird PCM/harness??
01-03-2012, 06:50 PM
#1
any issues with running a 2002 5.3L w/ a 1998 firebird PCM/harness?? I have a friend who had a 5.3L swapped into a jeep wrangler and the place that did it used a 1998 firebird PCM/Harness in which they flashed w/ a 5.3L tune (I think, or they just changed up the firebird tune to accommodate the 5.3)
anyways, after it was started up and went from open loop to closed loop - all hell went loose. The STFT would go + to -, back and forth very fast and the engine ran like complete ****, it would buck very very very badly if you tried to drive it. When we unplugged the front o2 sensors, it ran fine (in open loop)
now, recently the guy took it to a tuner who made it to where it constantly stays in open loop.
I want to diagnose the problem (turn the o2's back on -- or just flash the PCM with a stock 5.3L tune and go from there)
anyone see any issues w/ flashing the PCM with a 2002 5.3L tune and tossing the firebird tune? what would ya'll do?
anyways, after it was started up and went from open loop to closed loop - all hell went loose. The STFT would go + to -, back and forth very fast and the engine ran like complete ****, it would buck very very very badly if you tried to drive it. When we unplugged the front o2 sensors, it ran fine (in open loop)
now, recently the guy took it to a tuner who made it to where it constantly stays in open loop.
I want to diagnose the problem (turn the o2's back on -- or just flash the PCM with a stock 5.3L tune and go from there)
anyone see any issues w/ flashing the PCM with a 2002 5.3L tune and tossing the firebird tune? what would ya'll do?
01-03-2012, 09:09 PM
#3
I do have a complete harness and PCM off a 2000 Camaro, but the 1998 pcm/harness is already installed on the vehicle and I don't really want to take it all apart
do you suggest I just throw in the 2000 harness/pcm (scrap the 19998 pcm/harness) and tune the PCM to match that of a 2002 5.3? I'm reading through threads and finding that 1998 pcms cause weird problems
01-03-2012, 10:08 PM
#4
98 pcms are fine and can run a 5.3L with no problem. Don't believe everything you read about 98 pcms. Without posting the tune you are running now or some kind of data log, it's hard to say what the problem is. I've seen things like the O2 sensor wiring swapped L&R cause problems on transplants like you have.
01-03-2012, 10:52 PM
#5
98 pcms are fine and can run a 5.3L with no problem. Don't believe everything you read about 98 pcms. Without posting the tune you are running now or some kind of data log, it's hard to say what the problem is. I've seen things like the O2 sensor wiring swapped L&R cause problems on transplants like you have.
so what could be the issue with the wiring? What you have seen it was purely wiring, nothing to do with the tune?
01-03-2012, 11:12 PM
#6
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As far as I know they are completely different operating systems/setups. Remember the 98 was somewhat of an oddball year. So it would be nice to know what he changed right up front. I suspect with a simple keystrokes, the 5.3 would run with an almost stock 98 tune.
01-04-2012, 12:30 AM
#7
I'm thinking that the EASIEST option would be tossing the 1998 harness/PCM and start over w/ a 2000 PCM/harness
If the tune on the 2000 PCM is for a LS1/4l60e, would I just need to change the displacement of the engine or is there a lot more that would need to be changed for it to run the 5.3L/4l60e?
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01-04-2012, 02:04 AM
#8
A data log would be better than the tune. If it runs good in open loop, the problem is going to be somewhere in the O2 wiring, etc. I vote for th swapped L&R too. Seen it many times. The left O2 sensor is plugged into the right connector in the hanress, and vice versa.
01-04-2012, 12:40 PM
#10
A data log would be better than the tune. If it runs good in open loop, the problem is going to be somewhere in the O2 wiring, etc. I vote for th swapped L&R too. Seen it many times. The left O2 sensor is plugged into the right connector in the hanress, and vice versa.
sounds simple enough! hahaha
Last edited by TXjeepTJ; 01-04-2012 at 12:55 PM.
01-04-2012, 07:32 PM
#12
After researching some more, some people are saying that in order to run the 1998 harness/pcm you have to swap out sensors, meaning you have to use sensors specific to 1998 firebird
is this true? if so, that pretty much screws everything up as far as using a 2000 PCM and the 1998 harness that is repinned..
is this true? if so, that pretty much screws everything up as far as using a 2000 PCM and the 1998 harness that is repinned..
01-05-2012, 01:39 PM
#14
Alright guys I found out what the tuner did to disable the front o2s from ever going on-- he changed the values in the ECT vs IAT for closed loop all to 285 degrees Fahrenheit (meaning it will never go into closed loop)
I changed them to stock values and ran a scan of what the engine does at a constant throttle %. I used the default imperial .cfg for this
Anyone know what is going on? I checked the wiring to the front o2s and they are labeled correctly (bank 1 sensor 1 is on drivers side and bank 2 sensor 1 is on passenger side). Unless the wiring was messed up, as I think someone made this harness at home and tried to pass it off as a "painless" wiring harness
I changed them to stock values and ran a scan of what the engine does at a constant throttle %. I used the default imperial .cfg for this
Anyone know what is going on? I checked the wiring to the front o2s and they are labeled correctly (bank 1 sensor 1 is on drivers side and bank 2 sensor 1 is on passenger side). Unless the wiring was messed up, as I think someone made this harness at home and tried to pass it off as a "painless" wiring harness
01-06-2012, 04:26 AM
#16
If the constant 447 mV doesn't match the side of the sensor you unplugged, then they are swapped.
01-06-2012, 05:37 PM
#17
It's very easy to know if they are swapped. Unplug one sensor, turn the engine on and hook the scanner. Watch for O2 mV, you should see like 447 mV constants for the unplugged sensor, and variable readings for the other sensor.
If the constant 447 mV doesn't match the side of the sensor you unplugged, then they are swapped.
If the constant 447 mV doesn't match the side of the sensor you unplugged, then they are swapped.
Does anyone know what a vacuum leak will look like when being scanned? will the STFT's be going opposite of each other like on the scan I posted?
01-15-2012, 01:06 AM
#18
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What condition are your O2 sensors in? I had a similar situation where it would run normal while the car was cold / warming up, but once it went into closed loop it would run like ***. Smoothed out when I floored it though. threw a new set of o2 sensors in there and it ran like a champ.
01-18-2012, 04:34 PM
#19
What condition are your O2 sensors in? I had a similar situation where it would run normal while the car was cold / warming up, but once it went into closed loop it would run like ***. Smoothed out when I floored it though. threw a new set of o2 sensors in there and it ran like a champ.
I fixed the problem, not sure what is was, but I put 5.3L injectors back on it and replaced the 1998 PCM/Harness w/ a 2000 Wiring harness/PCM
Cranked it up, waited for it to go into closed loop and it ran smooth as butter. So the problem was in either the injectors, tuning or harness lol
