Stock 04 Suburban engine running like garbage

[FlatBlack]

Hello, I've got a 99 LM7 5.3L with a 04 L59 5.3L DBW Flex Fuel harness/injectors/FPR/etc on it. The engine was running great with the LM7 harness and ECU

I'm really not sure what is going on here, so here's my log of it idling in my garage, maybe yall can see if anything looks weird.

I drove it around and when I go WOT it's super rich (pegging the LC2 gauge at like 7-8 AFR but driving around/idling it's super lean (22.5 on the gauge)

I have the LC2 wideband signal going through the A pressure sensor wire but I couldn't figure out how to convert it to AFR so it's just in 0-5V mode.

Any thoughts?

240LSXFirstRunACAFR.hpl

L59FlexFuelECUstock.hpt

[5FDP]

o2 sensors aren't working and the commanded AFR is pegged at 12.4 the whole time.

That is something to look into.

[Nastruck]

Maybe start with logging long term and short term fuel trims. One o2 shows low voltage and the other one is maxed out.

Since commanded afr is really rich maybe set AFR 14.68 all the way across on the stoich table and disable fuel trims and see if it smoothens out.

[Nastruck]

I'm going to assume this is in a 240sx now. Going to take a guess that there's no flex fuel sensor on the vehicle for the pcm to pickup alcohol content. If that's the case. I'd disable flex fuel and set the Stoich AFR to 14.68 across the table and probably run a lot better with the fuel trims disabled till you find out why the o2 voltages are doing what they are doing.

[GHuggins]

You appear to be stuck in open loop because your O2's aren't working - could also be other things wrong, but this is the most currently obvious as already pointed out...

[FlatBlack]

I disabled the Flex Fuel in a different tune but I just went back to stock because nothing was working.

One of my O2 sensors isn't plugged in so I can run the wideband. Can I force it into Open Loop?

I will fix the Stoich tables and pull Flex Fuel off. Forgot to do that.

The engine is in my 1989 240SX and has been running for over a year. Just did the ECU/harness swap last week.

*edit* I'm a newb - where is the Stoich table? (Off to Google I go)

[Nastruck]

Fuel/General/ Stoich AFR

[FlatBlack]

Fuel/General/ Stoich AFR

The only thing I see in the Fuel/General tab is "Injector Control - Flow rate (Flow Rate vs. KPA button)"

Do I need to be plugged into the car?

*edit* The Stoich entry is there on my LM7 ECU file though.... weird

*more edit* There is no choice to disable LTFT on my L59 ECU either, but there is on the LM7. I'm very confused.

[5FDP]

Edit > view > advanced.

That will fix your problem for not seeing tables.

[FlatBlack]

Edit > view > advanced.

That will fix your problem for not seeing tables.

Thank you!!!

Look at all them settings

If I adjust the values at all in that table it says it's outside of the min/max limits. I was just going to make them all (0-100%) 14.681. Is that cool?

Ah, nevermind. That's a Flex Fuel thing. The Flex Fuel disable should fix the commanded AFR of 12.x

[Nastruck]

just set them all 14.681 flex fuel enable or not it wont change stoich away from being richer. stoich will always be commanded 14.681 except for coolant temp will change the afr till its at operating temp

[FlatBlack]

Just ran it with the FF disabled and got a commanded AFR of ~15 (Engine was only 100*)

I'll do a proper drive tomorrow.

[FlatBlack]

Took the car to work this morning. I just learned how to turn on histograms (after I got to work obviously) but if you look towards the end where I WOT (around 8:07) it was super rich ~10ish (commanded is 12.3) and even smoked a bit due to all the fuel.

Commanded AFR was around 14 every time I glanced over at the computer at cruise but the LC2 gauge was reading lean.

Tried to turn off Fuel Trims and force the ECU to run in Open Loop until I can get my new O2 sensors in. I don't know if it worked without putting it in some sort of limp mode or something. I have the black flat connectors for the 99 harness and I need the white square O2s for the 04 harness before I can run in Closed Loop. Alternatively I could run my wideband's spare outputs to the harness.

I've used MegaSquirt for years and this HPTuners/stock ECU stuff is pretty new to me. Should I richen up the MAF for the cruise issue and then lower the PE Enrichments for the WOT rich issue? Or should I be messing with my VE table instead?

The car has longtubes but the engine is otherwise untouched.

240LSXcommute.hpl

L59ECUstockFF_FTdisabled.hpt

[FlatBlack]

I feel like there's some weirdness going on here.

The tune still isn't good but it'll cruise normally (AFR reads around Commanded) sometimes but then go really rich on the AFR gauge with no change in input

The blue area circled here shows were the AFR gauge in the car was reading a normal reading then it 'switched' like something is getting unplugged or something and its going to full lean (22.5 AFR) on the gauge



Also when I go WOT around the 12:41 timestamp, my commanded AFR is low 12s and 11s, and I'm not sure where that is coming from. *edit* looks like that's the value coming from my PE modifier.

240LSXvitekMAFonlyfinallunch.hpl
L59VBMAFvalues90plusLM7VE.hpt

My intake is in the engine bay near the engine which is why the IATs are high