LSx OBD2 Readout. Help Please

ckruzer

ckruzer

Infidel
Joined
Jul 2, 2015
Location
asheville nc
Ok. Looking for some expert input. Now that have ran the engine for prob 300 miles or so, pulled all the computer stuff with a reader. Looking for some help understanding, dissecting and making necessary changes (if any)!

YJ. 5.3 truck engine. ax15. return fuel engine, but blocked; tables adjusted. emissions deleted.

Readings took with engine off, key on.

THANKS FOR THE HELP!!!!

DTCs

172, too Rich Bank 1
175, too Rich Bank 2
550, MIL (not hooked up yet)

FUEL
Fuel System 1 Status - OL
Fuel System 2 Status - OL
Short Term Fuel Trim B1 - 0.0%
Long Term Fuel Trim B1 - (-)1.6%
Short Term Fuel Trim B2 - 0.0%
Long Term Fuel Trim B2 - (-)1.6%

Short Term Fuel Trim B1 to S1 - 0.0%
Short Term Fuel Trim B1 to S2 - 99.2%
Short Term Fuel Trim B2 to S1 - 0.0%
Short Term Fuel Trim B2 to S2 - 99.2%

OXYGEN
(only have pre cat o2 sensors. computer guy supposed to have deleted or turned off downstream)

Oxygen Sensor Output Voltage B1 to S1 - 0.000v
Oxygen Sensor Output Voltage B1 to S2 - 0.440v(+/- 0.005) < engine is off...?
Oxygen Sensor Output Voltage B2 to S1 - 0.025v(+/- 0.005) < engine is off...?
Oxygen Sensor Output Voltage B2 to S2 - 0.0440(+/- 0.005) < engine is off...?

OTHER

Intake Manifold Absolute Pressure - 94.0 kPa
Ignition Timing Advance on #1 Cylinder - 0 Degrees
Calculated LOAD Value - 0.0%
 
Running the wix filter reg in the back

If you mean I still have this (pic), then yes

e1ecbb7f3e9996a4f100b982cd84a4eb.jpg
 
You don't run the corvette filter/reg with that setup. You need a fuel pressure regulator and a return to the tank. Or you need to ditch those rails for a set without the return.

I would also throw those blue adapters in the trash. I have seen two come off. One could have burned a rig down with me underneath it.
 
rockmafia said:
You don't run the corvette filter/reg with that setup. You need a fuel pressure regulator and a return to the tank. Or you need to ditch those rails for a set without the return.

I would also throw those blue adapters in the trash. I have seen two come off. One could have burned a rig down with me underneath it.
Click to expand...

I reckon I'll need to look for some rails. Help me understand please. What's the issue specifically?

The rails connect via quick disconnect fittings. That's what they do. So you suggesting to make my own line or something? They ain't cheap fittings either. They are the russels AN fitting. Just Like Stock. What's the issue you're trying to point out?
 
ckruzer said:
I reckon I'll need to look for some rails. Help me understand please. What's the issue specifically?

The rails connect via quick disconnect fittings. That's what they do. So you suggesting to make my own line or something? They ain't cheap fittings either. They are the russels AN fitting. Just Like Stock. What's the issue you're trying to point out?
Click to expand...


I've seen two come loose under pressure.

We started using these at my shop and at MandM. They are all metal, no plastic BS.

Russell Push-On EFI Fittings 644123
 
rockmafia said:
You don't run the corvette filter/reg with that setup. You need a fuel pressure regulator and a return to the tank. Or you need to ditch those rails for a set without the return.

I would also throw those blue adapters in the trash. I have seen two come off. One could have burned a rig down with me underneath it.
Click to expand...

Tried to use same thing on my yj.

Couldn't get them to stay on the rail once the pump primed.

Ended up just shoving the line over the rail nipple and hose clamping it.

Good to know that someone makes an all metal one
 
Russel are cheap fittings imho. Not in cost but quality.

Other than that..I'd echo just what Jim (@rockmafia ) said. Almost sounds like he has done this once before
 
I agree! Did t know these all metal ones existed. If you've put these on you can't deny how sketch it "feels". Sad to hear it's for real, but no biggie to replace after I find some more rails.

I may find a used aftermarket set of rails with injectors. If the injectors are not stock will the ecm need to updated?
 
Yeah, you'll need a re-tune with different injectors.

I may have another set of non-return rails out in the shop, I'll look. I'm thinking the issue comes from having the vacuum referenced fuel presure regulator still operational, but being fed from an already regulated fuel source.

Personally, I like return style setups. They're way easier to tune in the injector tables and I don't have to depend on a fuel filter to regulate the fuel pressure.


- Your fuel trims look fine, but if you really want to know what they are you need to read them while it's running.
- The 02 sensor voltages almost seem like they're backwards...if the rear two are deleted, they shouldn't read any voltage. The ones you're using are a square-ish plug, right? Not a flat one with 4 or 5 wires?
- I feel like either the 02 sensors or the combo of both fuel pressure regulators is more than likely what is causing the rich condition. I'd make sure he deleted the rear ones and not the front ones. You could also verify fuel pressure at idle and under a load and see if it changes.
- MAP will always read 94 or 95 kpa when not running...that's a little less than atmospheric pressure
- Ignition advance and calculated engine load are zero because it's not running, obviously :D

It would be nice if you could data log it with a wideband 02 sensor...I'd offer to do it for you, but I'm a long ass drive away from you! It would let you see what everything is reading and doing while running in relation to the air/fuel ratio and probably make it easier to pinpoint the issue of it running rich. If everything looked good in a data log and a/f ratio, then it would just be a matter of disabling a few DTCs so they didn't keep popping up.
 
Yes get rid of those fittings. Use the screw together ones like in the link, never had an issue with any of those and I have used a lot of them.

I believe you can still use the return style fuel rail if you are already using a corvette filter regulator. BUT, you will need to remove the vacuum reference so it keeps constant pressure and doesn't vary with vacuum (essentially turning into a returnless rail). You will also need to make sure the tuner used fuel injector tables from a returnless setup, if not the ecm will think the fuel pressure is lower when vacuum is presesnt and base injector on-time on false data causing overfueling at cruise and idle.

Key on engine off data is going to tell us next to nothing. It won't tell us fuel trims, timing, airflow, etc. All this tells us is that your MAP sensor appears to be working and reading proper barometric pressure.

He has no codes for the rear O2 sensors, so I would imagine they are tuned out properly. The ECM will show approx .440-450v on the O2 sensors if there is nothing plugged into the sockets, so if they are deleted from the harness or left off, that reading is correct.
 
NC-V said:
Yes get rid of those fittings. Use the screw together ones like in the link, never had an issue with any of those and I have used a lot of them.

I believe you can still use the return style fuel rail if you are already using a corvette filter regulator. BUT, you will need to remove the vacuum reference so it keeps constant pressure and doesn't vary with vacuum (essentially turning into a returnless rail). You will also need to make sure the tuner used fuel injector tables from a returnless setup, if not the ecm will think the fuel pressure is lower when vacuum is presesnt and base injector on-time on false data causing overfueling at cruise and idle.
Click to expand...

He did. He confirmed he adjusted the tables to account for it. I inquired about it after the first time when you mentioned it! Thanks again! Just to confirm, with the ecm flash correct and tables adjusted, youre saying to plug the vaccum? Or leave it and do what?

NC-V said:
Key on engine off data is going to tell us next to nothing. It won't tell us fuel trims, timing, airflow, etc. All this tells us is that your MAP sensor appears to be working and reading proper barometric pressure.
Click to expand...

Haha yeah I see that now. Going to get a buddy to drive while I monitor and log. My reader is a simple one and doesnt store the data for me. It has graphs and usb hookup, so maybe with the right program it will? Idk. Ill find out by wed for sure.

NC-V said:
He has no codes for the rear O2 sensors, so I would imagine they are tuned out properly. The ECM will show approx .440-450v on the O2 sensors if there is nothing plugged into the sockets, so if they are deleted from the harness or left off, that reading is correct.
Click to expand...

Ah gotcha. Glad to know! Was curious why the voltage was there with engine off. Did not catch the forward/rear aspect! Nice catch!
 
Croatan_Kid said:
Yeah, you'll need a re-tune with different injectors.

I may have another set of non-return rails out in the shop, I'll look. I'm thinking the issue comes from having the vacuum referenced fuel presure regulator still operational, but being fed from an already regulated fuel source.

Personally, I like return style setups. They're way easier to tune in the injector tables and I don't have to depend on a fuel filter to regulate the fuel pressure.


- Your fuel trims look fine, but if you really want to know what they are you need to read them while it's running.
- The 02 sensor voltages almost seem like they're backwards...if the rear two are deleted, they shouldn't read any voltage. The ones you're using are a square-ish plug, right? Not a flat one with 4 or 5 wires?
- I feel like either the 02 sensors or the combo of both fuel pressure regulators is more than likely what is causing the rich condition. I'd make sure he deleted the rear ones and not the front ones. You could also verify fuel pressure at idle and under a load and see if it changes.
- MAP will always read 94 or 95 kpa when not running...that's a little less than atmospheric pressure
- Ignition advance and calculated engine load are zero because it's not running, obviously :D

It would be nice if you could data log it with a wideband 02 sensor...I'd offer to do it for you, but I'm a long ass drive away from you! It would let you see what everything is reading and doing while running in relation to the air/fuel ratio and probably make it easier to pinpoint the issue of it running rich. If everything looked good in a data log and a/f ratio, then it would just be a matter of disabling a few DTCs so they didn't keep popping up.
Click to expand...

THANKS for the info man! Ok, hopefully returnless rails would fit with the injectors I have now then? Which also points out another issue, if i did go to the returnless rails, would not the injector tables need to be adjusted again? @NC-V

Lemme know if you got em! I appreciate that! When i did some googling, the trim was not exorbiant from what I could understand. Some of info was saying that even a sticky injector could cause some negative trimming?

Yes! I want to get some wideband ones put in to a f/a/r gauge, but with the price Ill need to get a speedometer first. Been using my phone and a speedo app for now. lol.

Thanks for the input man!
 
You will only need widebands for initial tuning. After that there is really no reason on a stock or even mid built engine to run a wide band all the time.

If you get a returnless rail, you should not need to change anything unless you also change to different injectors (with different flow rate values). Otherwise unplug the vacuum line to the rail and plug the other end at the manifold so there is no vacuum leak and no vacuum to the diaphram.

Not sure on those codes, but usually to set a rich/lean code the long term fuel trims have to be +/- 25% for a period of time. That is a good bit off, but you will need to datalog to find that.
 
@DSM Turbos my engine is a 2001 Tahoe truck engine, right now has the return style rails on it. Its being proposed that they need to be swapped for returnless and the ecm reflashed for it...
 
NC-V said:
Otherwise unplug the vacuum line to the rail and plug the other end at the manifold so there is no vacuum leak and no vacuum to the diaphram.
Click to expand...

in that regard... why not just unplug the vacuum regulator now... wouldnt that be the same as a "returnless rail" that wouldnt have to pay for?
 
You could just unplug it and put a cap on the manifold, but if the diaphragm starts leaking in the regulator...whatcha gunna do?

FWIW, 2003 was the start of the returnless. It was the first year of the DBW throttle bodies, but I've seen return style and returnless fuel rails used on 2003 vehicles. The rails and injectors all interchange between truck/SUV stuff...they're all the "short" injectors. The car injectors were quite a bit longer.

You also don't need both rails, just the driver's side.
 
Is there some sort of plug readily available for the hole where the regulator goes?
 
Croatan_Kid said:
Is there some sort of plug readily available for the hole where the regulator goes?
Click to expand...

I don't know but that would be the way to go. May be able to make something if not. But there is really no more of a chance of the diaphram leaking than there would be on a stock vehicle...
 
I get that, but they do eventually go bad. That was my concern. I try to minimize possible leaks.
 
Ok. Ran the reader while driving.

Long terms were (-)14.8% at highway speeds. Come to a stop from that and goes to around (-)10%, idle from there long enough short and long balance out or whatever and idling i can be like -2 to -4 just depending on the conditions.

It was all kind of unsafe to read while driving, so I apologize about all the loosness here. haha.

Hmm. Whatelse. Coolant temps gave me a surprise. The autometer appears to be pretty heavy on the needle. When I get warmed up Im at 189 (i thought 200 by gauge) and when fan kicks on its at 200 actual. Very cool as thought was ranging 200 to 210.

Plugging the oem regulator now, and will redo the data stream here in a couple hours.

im not an expert like you guys, but im gunna try this air filter first. spectre garbage im thinking.

there is also a suspected vacuum leak as i reused the intake gaskets.
 
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Croatan_Kid said:
Is there some sort of plug readily available for the hole where the regulator goes?
Click to expand...

i plugged the intake nipple and the regulator connector hose, and they are still connected in the event of any failures.

This did not reduce the fuel trimming at all
 
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