Impossible... is it? new guy tuning issue.

[natek]

Hi Guys, I just want to thank you in advanced if you make it all the way through this post. I am at a loss of what is happening.

I am very mechanically inclined. I have successfully done my own engine swaps, diff swaps, head swaps, starters, clutches ect. I have no clue about tuning...

I have a very modified 2004 corvette, I bought it already modified and I am just learning about the car. I have had it for a few months and it has been running great. My last cruise with it was fine, nothing out of the ordinary and as usual after the drive I park it in my garage. The next time I go to take it out, I start it up, everything normal, I go to back it out of my garage and the shifter doesn't work. I quickly trouble shoot it and find the linkage at the shifter has broken and popped off. This is a simple fix for me. The whole point of this trip was to go to a car show with my son, so we missed out on that one. Anyways, I order a new shifter linkage cable and when it arrives I start to do the swap. This was done relativly easy aside from the long tube headers and typical exhaust issues pulling it out. The car has 3 02 sensors on it (no cats). The 02 sensors are the 2 upstream ones and one for the AFR wideband gauge.
I finished up the linkage swap and put everything back the way it was....(While I had it apart I disconnected the battery so I could pull in a stereo wire while i was working on the car anyways...) here is where the problem starts.

I go to start the car and it now runs super rich and wont barely idle, its stalls out and wont run and smells like a ton of fuel. I am puzzled. I rip it all apart again (relative to what I worked on) and i find that the o2 extension wires have been pinched as if the torque tube cover maybe pinched the extension wires. I know this wasnt caused by me because I clipped and stuffed the o2 extensions in after I tightend all the torque tube bolts
I go ahead and ordered new o2 sensor and extentions. pulled the exhaust off again and replaced them.... Carefully put everything back together and that still has not fixed the problem. I have tried switching the o2 sensors, i have checked all the fuses,
The car will not stay running.

My thoughts are, either the tune was lost while I had the battery disconnected... or the tuner tuned it with pinched o2 wires and now that i have fixed that and they arent pinched it is out of wack. I have talked to a tuner to get it retuned, but He is busy for a while. I have orderd HPtuners 3 and am wondering how hard it will be to trouble shoot this problem

Open to hear any ideas you guys might have.

[Alvin]

It won't loose a tune by disconnecting a battery. You likely have something else going on.

[2xLS1]

I bet your O2 sensors are plugged in on the wrong side. It's easy to check if you have any type of scanner. Unplug the drivers side O2 and see if B1S1 O2 voltage goes to 450mv. It's kind of hard to explain but on a vette the front O2s plug into the opposite side harness and sometimes people will use the rears with adapters for the fronts with headers and they plug into the same side as the O2 location.

[natek]

I bet your O2 sensors are plugged in on the wrong side. It's easy to check if you have any type of scanner. Unplug the drivers side O2 and see if B1S1 O2 voltage goes to 450mv. It's kind of hard to explain but on a vette the front O2s plug into the opposite side harness and sometimes people will use the rears with adapters for the fronts with headers and they plug into the same side as the O2 location.

Thank you for that comment, I did try swapping o2 sensors and nothing changed. I didnt try reading the mv though when I disconnected them. I can try that. Any idea what it should read when it isnt running? I can't get it to idle lol.

[Alvin]

I bet your O2 sensors are plugged in on the wrong side. It's easy to check if you have any type of scanner. Unplug the drivers side O2 and see if B1S1 O2 voltage goes to 450mv. It's kind of hard to explain but on a vette the front O2s plug into the opposite side harness and sometimes people will use the rears with adapters for the fronts with headers and they plug into the same side as the O2 location.

That's a great point.. please check that

I see it often on trailblazers and some trucks too.. just for anyone else reading.

We made this so people can double check https://www.pcmofnc.com/2020/04/08/c...r-information/

[GHuggins]

Depending on the tune setup, you should also be able to pull codes for the one that's unplugged with just key on engine off. Driver's front for example should be B1S1 open circuit or high voltage.

[natek]

Depending on the tune setup, you should also be able to pull codes for the one that's unplugged with just key on engine off. Driver's front for example should be B1S1 open circuit or high voltage.

Thank you this really helps me. You will get a high voltage signal if it is unplugged? I will check this tonight. I wasnt sure if the connection point is criss crossed or what. by that i mean. there is a connector on the drivers side and a connector on the passenger side of the engine block, i assumed the drivers side connector went to the drivers side o2.

[2xLS1]

Read my post again. It will read 450 mv unplugged, not high voltage.

[GHuggins]

Read my post again. It will read 450 mv unplugged, not high voltage.

Might want to read my post again It sets a CODE/DTC for high volt/open circuit.....

Either way, it sounds like might have gotten hooked up backwards. Once found and corrected, reset your fuel trims in the scanner and go from there.

[2xLS1]

I wasn't replying to you. But what code number combines high voltage with open circuit on a 04 Vette?

[GHuggins]

I know, but it might have been misleading... The reason why I pointed out the DTC part was because unless an O2 is allowed to heat up - especially when one is as cold as it's going to be now for the OP - all O2's will read around 450mv with initial key cycle - at least until the heater gets it up to temp then the ones working will drop to 0mv. Just wanted to clarify that and point out that checking the dtc's are sometimes the easiest way to go if the engine won't run anymore and the dtc's are actually allowed to report - so OP may have to change the dtc status for them to report. Either way the OP should be able to figure it out...

[natek]

hmm ok... All o2 sensors are reading .440 to 445.... whether they are plugged in or not. doing more searching on my end.

[natek]

Depending on the tune setup, you should also be able to pull codes for the one that's unplugged with just key on engine off. Driver's front for example should be B1S1 open circuit or high voltage.

Thank you this really helps me. So it doesnt seem to change whether i have the b1s1 b21s1 plugged in or not, they both read about .440v. when i unplug them they do seem to steady out to just .440, then with them plugged in they go from .430 to .460.

still unsure what is happening

Measureing 6.1v on black and red with ignition on at the o2 sensor connector

[GHuggins]

Make sure the codes correspond - this is why I said it's better to check codes - if heater circuits are down or anything like that they'll always show 450ish mv's... Check your heaters to see if they're getting power - should be 12v unplugged or plugged in. Make sure all of your fuses are good. Possible something pinched fried something, but really hope not, so check all of the basics first

[Alvin]

All this unplugging and plugging in talk..

It would be so easy to check the wire colors to know for sure

https://www.pcmofnc.com/2020/04/08/c...r-information/


O2 codes won't show up immediately. Usually takes a couple key cycles.

[natek]

Thanks everyone, I beleive i got it figured out. i think it had somthing to do with the short term fuel trims being reset. or both short and long. I forced it to start with the gas peddle and eventually it found its stoich and idles properly on its own. now it does have a problem when i go for a drive and give it some throttle. wondering if that needs to relearn also.

[mbray01]

It shouldnt have to relearn in order to work. Sounds to me like its not actually tuned, and whoever did all the work was being lazy and didnt tune it. Fuel trims should as close to zero as possible at all times

[natek]

Anyone bored and want to take a look at the original tune and data log i just made??