Robert and others, This is Jason from pacfab. I was made aware of this thread last night by a friend. I am here to respond and add info to the thread and hopefully get it cleared up for Robert.
No C2-53 either?
It sounds like they ran all of your o2 controls into 1 pin, but the wrong pin. I wonder what would happen if you moved C2-52 to C2-74
There are something like 8 different 02s from 98-current ls engines. Early one 98-2002 can be several different plug ends and case grounded or isolated grounding. The isolated grounded o2s share a ecm ground wire to all 4 02s (if you have the rears installed and wired), whereas the case grounded 02s use a ground wire to the chassis. Its not a year thing as which o2 is used, it can be different from USA, Canada, or Mexico built vehicles and the OS in the ecm all with in the same year.
There are a few things there which are wrong.
A 2004 and early 2000 ECM / harness are different. The operating systems are totally different and the ECMs are different in total memory size. So you can not, without make a good door stop, burn an OS cross memory size platform. Yes they look the same. One is blue/red and the other is blue/green. One is basically a half meg system while the other is a whole meg. 2004 would have been blue/green 1 meg drive by wire. Which you can convert to drive by cable if the ecm still retains the IAC driver on board. Which would require a different OS that supports drive by cable, like a van. Which then leads to the next thing....
A gm 4 wire O2 can have a different plug but they are the same as long as the pinouts are the same. What changes is how the O2 heaters are controlled in the harness and ECM.
If I read correctly this is a stock engine with an older intake.... The dying thing is not correct and bumping the idle is masking something else. Could be bad injector data, coil dwell time wrong, incorrect IAC scaling.....
Not point fingers here, just a lot of incorrect data that does not progress the understanding of how to swap an LS.
Could you verify what ECM you have, color wise at the connectors?
You are correct. While the engine was a 2004 unit, he wanted it to be cable driven so the harness was spec'd as an earlier unit. At no time was a blue/green os flashed into the red/blue ecm. Or the other way around. I dont believe the intake was changed, only the throttle body.
So with that said, as long as it was read blue the whole time there was no way to build an 04 harness for you.
With a manual tune how the idle air is controlled is different. What a lot of companies do is burn in a car tune then basic modify for a truck. Thats not the best way as airflow calculation is very very different between an LS1 and the LQ4. Starting with a proper truck manual tune would be best. Those are hard to come by as you can't just get them off a forum.... There are ways around it with the correct software and/or tuning knowledge.
Also, are you running a manual? This goes back to the airflow calculation when coming down to low RPM. If you are running a manual then you want the manual style tune in it but then again if you want full engine braking or decel fuel cutoff you would need speedo to trigger that. With an auto you have to account for the extra load the pump puts on the engine, that equals added airflow. With a manual, you get it...
Has the main base airflow been setup. As in adjust the throttle blade until the correct IAC counts have been set?
A dying issue in LS engines is usually a lack of airflow all of a sudden. The air demand is greater than the airflow base command and the IAC can't react that fast. An idle command bump would open the IAC further but you are still relying on a system that takes time to react and adapt. There is logable idle trims for airflow correct, with a stock engine if these are not ZERO then you do not have enough base airflow. All of this is amplified when larger cams and displacement comes into play.
Ever notice how some LS engine run awesome wide open and then have issues down low. Idle hunt or the awesome engine die when you get in and out of the throttle quick. It all translates to base incorrect setup mechanically and electronically in the tune. Thats why the last thing I ever tune on an engine is the idle air and idle control. You have to have everything else dialed to even receive accurate logged info at idle.
Original tune/os was 2001 silverado. This application was never a car tune then modified to truck specs. But yes that is common. Currently it should be a 2002 silverado, with the auto trans changed to manual. It is not an original manual tune. As stated these are hard to find and while I do have 2 of them neither match the current os and cant guarantee o2s would work currently as but are different os. The only thing changed from the stock tune is deleting unneeded stuff per swap. Like rear o2s, smog stuff and so on. We dont do any "tuning" to the take out engines. We recommend dyno tuning if you are seeking more performance or catering to your swap setup. Air intake tubes, lengths, placement, headers, exhaust and drive train loss are all things that can play into how well or bad it runs and in our opinion best dealt with on a dyno and not guessing prior.
With that said Im always open to learning and improving my knowledge. If there are somethings that can be improved upon between the manual and auto tunes Im all ears.
Well then my idle air and idle control must not be set right. Yes, it would die if I blipped the throttle as it was returning back, and almost back down to an idle. It would stuter, drop rpm way down, and then would normally recover back to 600rpm, but sometimes it would die completely.
I am supposed to be running a manual tune because I am using a 700R4 auto. Isn't a manual tune always used when using an older non electronic trans?
Regardless, it's running damn good. Drove it to work this morning and watching my Edge CS Evolution switch from loop status "open" to "close" was a sight for sore eyes. It wanting to die after a throttle blip is gone now, from the raised idle.
Only issue I am having really is that at full throttle in the upper RPM's Im getting a few pops. PF thinks I am running out of fuel and thought I mounted my inline pump too far forward, and that moving it back really close to the tank should solve it.
Robert, did you ever move the pump like recommended? Ever put a fuel pressure gauge on it and test? I wish we would have spent the few minutes and done this. If I remember correctly you have a factory blazer tank in the back and the pump/regulator setup half way up the frame, basically under the drivers seat? In our experience fuel pumps work better as pushers then suckers and its having to suck a ton of fuel before it can push it. Add in that its an unbaffled tank that may have debris inside and you can see where we can have a fuel delivery issue.
So when guys talk about using a manual tune they should be talking about the tans segments only but 9/10 times thats not the case.
Pops huh...... Can you verify fuel pressure? If thats fine then its time to look at the tune setup. Injector data, VE table, PE command, timing...... All can be a part of those symptoms if the injectors and fuel are in mechanical order.
That should have been looked at and addressed on your road test/tune.
All the tables are stock. Every time I have come across how it was running on the top end it has been a fuel delivery issue. I wish had saved the log file from the test drive so you could see what keyed me into that besides how it was acting.
Can you tell us when the Pops are happening? High rpm, throttle position, trans gear?
I ask because of way the above is worded, its very scary from a tuning knowledge aspect.
If I remember correctly, under heavy acceleration, wide open throttle, vehicle moving, in gear.
No biggie on the IAC stuff.
Now about the full throttle situation. What you are describing could very easily be way too rich in power enrichment..... In PE there is no feed back as to fuel correction. Yes you can see injector duty cycle and pulse width. NEITHER one of those will show any kind of OFF fuel condition when in commanded fuel, PE. PE is open loop commanded fuel. It takes the open loop commanded value and the PE commanded value, then uses which ever one is richer as the final commanded fuel when in PE. There are ZERO fuel trims at this point making what the "injectors are doing" a commanded value with no correction. So whether or not you have enough fuel will make zero difference in commanded pulse width.
Will it pop revving the engine in park?
Thought the popping was only happening in gear and moving. But I dont want to speak for Robert if this isnt the case.
Team208, if you have any insight as to whats creating the popping issues Im opening to trying. I would like to verify fuel pressure before changing anything. Robert Im more then happy to help you get this resolved, I do understand the time and distance though. I also understand if you choose to work with team208 and not us. But we are here to help and fix any issues on our side.
If either of you need to get ahold of me:
[email protected]
408-600-0122
If its a simple fix, I'd be happy to point it out though.
