Lean Condition and High Idle in Swap Vehicle

[C5 2000]

Check Your O2 if they working and look for burned or short in the wires. Also take a look at O2 fuse.

[nkautz]

You set it up like this , right? :

20150212_183143.jpg

[runpasthefence]

Yep, and like I've tried configuring the sensor manually using PLXs data. Got the same results for each. It's also hooked up like this - http://www.hptuners.com/forum/attach...6&d=1175327143

I haven't spent the time to check hardware yet. That's the plan for this weekend.

[nkautz]

Mine is PLX wideband , too... but it's hooked up a little differently. I don't use the cigarette lighter , I wired it into a switched 12v source in the passenger footwell. I forget exactly but I think I soldered it to a fuse or an accessory stereo wire. I think I ran the ground wire to the battery area. This is on a C5Z.

Here's the instructions I used:

SM-AFRGen2UsersGuide-1.jpg

SM-AFRGen2UsersGuide.jpg

[runpasthefence]

Yeah, sorry, I just found that illustration while checking my work. Mine is hard wired to a fused and ignition-switched 12v source and is grounded to the vehicle's accessory ground block. I'm sure it's hooked up correctly; I just need to go through and see if I've damage or burn any harness wires along the way.

[runpasthefence]

Well, no progress...only more questions.

I returned most tune values back to stock, and the engine still runs like crap. It sounded like it was firing on 3 cylinders. I was just about to start pulling the blower back off when I decided to pull the plugs to have a look.



That's far from being lean. Previously, readings from my O2s and fuel trims made me think I was running way lean. But I was having an intermittent problem with dropping cylinders occasionally. I'm wondering why my PCM is reading lean, but is pretty clearly inducing a rich condition by adding fuel.

Also, I went through my PLX wideband install. Everything is perfect. I checked continuity in the harness, pin assignment on the HPTuners plug, auxuliary PID assignment - it's all good. Could it have been reading correctly at 10.2x-10.3x all this time, and I've just been ignoring it because my O2 sensors are giving me opposite information?

Signs that point to rich fuel mixture:
- Fouled/sooty plugs
- Wideband reading is pig rich

Signs that point to lean fuel mixture:
- Backfire/popping when engine tries to run
- O2 sensors are commanding positive fuel trims

Not really sure where to go from here.

[nkautz]

Is your stoich afr set to 14.6-14.7? And o2 sensors are plugged in correctly ? I think its possible mix up pre cat and post cat o2s. your wideband might be right. Log your commanded afr

[runpasthefence]

Just checked, stoich AFR was set to 14.17. I'm only running one set of oxygen sensors, and the harness only has provisions for pre-cat O2s, so they're plugged in correctly. I just set up the scanner to log commanded AFR. I'll see what that gets me.

Thanks

[runpasthefence]

Made an attempt to log commanded AFR. Unfortunately, the injectors are dumping fuel so I foul plugs every time I try to start it. I'll pull out the fouled plugs, replace or clean them, and drop another 3-5 cylinders due to fouling. Plugs are soaked and covered in carbon. I'm going to try to pick up some hotter plugs tomorrow and see if that'll help. I'm currently running TR6.

I'm not sure how to interpret the AFR commanded data, but I figured I'll post it here while I read up on the topic.

AFRcommand.hpl

I'm still unsure about my wideband readings. There's very little fluctuation while the vehicle is running.

I'm also suspicious of my throttle body. It's still staying 18-20% open throughout the starting process.

[nkautz]

18-20% throttle at cranking/idle is not unreasonable. Your wideband might be ok , its just reading max rich which makes sense given how your plugs look. So the problem is probably your injectors are dumping fuel at a rate much higher than the commanded fueling. This is probably due to incorrect injector settings or MAF/VE being too high. I would start by putting the short pulse adder and offset tables back to stock. The data you put in those tables is adding fuel. If that doesn't help , try reducing your Maf and VE by 10%.

[runpasthefence]

Might be making some progress.

After doing some reading yesterday, I realized I might be entering my injector flow rate improperly. I'm using a return-style fuel rail with a boost/vacuum referenced fuel pressure regulator. I was wondering what effect that'd have on my IFR table, so I did some reading. I came away with the following changes.

- I used the IFR spreadsheet to determine my flow rate. I then entered the calculated value at 0kPa(MAP) for the entire IFR table
- I reduced my prime/idle fuel pressure to 40psi (I'd read this helped someone with a similar problem)
- Installed NGK TR5 plugs to prevent fouling while I figure this stuff out (had TR6)
- Short pulse adder and offset tables are stock, but have been for a couple of days now

Starting attempt is probably the best I've had in a while. Though, an inspection of the plugs still indicated a rich condition (wet, carbon). Wideband still shows 10.30ish, and I'm still not convinced if it's accurate. I went back and made some other recommended edits:
- Reduced VE and MAF tables by 10%

The engine will start and hunt for a bit, but it shuts off after a few seconds. While it's running it will respond to throttle. If throttle is applied, it will rev, and it sounds great. No popping, etc. However, regardless of throttle input the engine will shut off after a couple of seconds.
I'm unclear why it's shutting down. It almost sounds like some just turns off the ignition switch I tested the following:
- Fuel pump has 12v+ during prime, during cranking, running, and as the engine shuts down
- Fuel pressure doesn't drop at the fuel rail
- Noid light shows that injectors are still pulsing as the engine shuts down
- In-line spark tester shows coils are firing as the engine shuts down

Still trying to figure out what's going on there. Tune and log attached

LowerRailPressure.hplBBearStockhybridwVacRef10Percentoff.hpt

[nkautz]

Ok , set your IFR to 60 across the board. Then copy these values from my tune (2007 lq9) that I've posted below: Under Fuel -> General: Copy the Injector offset , short pulse adder , default injector pulse , and minimum injector pulse. (Don't copy my IFR, I'll explain that later if need be). Copy all of the cranking fuel settings. Copy the P/N Drive Enrichment tables. My car is manual and running 3bar SD (no maf), so many of the other values will not apply. But since you are blown , I would highly consider switching to 2bar SD os and disabling MAF because you will probably be maxing out the MAF at higher airflow levels, at which point you can look more closely at how I set that up.

2007 lq9.hpt

[runpasthefence]

Ok , set your IFR to 60 across the board. Then copy these values from my tune (2007 lq9) that I've posted below: Under Fuel -> General: Copy the Injector offset , short pulse adder , default injector pulse , and minimum injector pulse. (Don't copy my IFR, I'll explain that later if need be). Copy all of the cranking fuel settings. Copy the P/N Drive Enrichment tables. My car is manual and running 3bar SD (no maf), so many of the other values will not apply. But since you are blown , I would highly consider switching to 2bar SD os and disabling MAF because you will probably be maxing out the MAF at higher airflow levels, at which point you can look more closely at how I set that up.

2007 lq9.hpt

This is good stuff. I've done what you said, and I'll give it a shot in morning and see what happens. Going through your tune made me look at a few things that I think were probably leading to my shut-down issue.

My only question is about IFR. You said to set it to 60 across the board. Those values are usually in the 3-9g/sec range, so 60 would be huge. Do you mean to set it to the equivalent flow at 60psi at the rail? Not sure I follow.

Thanks for all of the help. I actually have a 2bar map sensor, and have been planning on switching to a 2bar SD anyway. I was going to leave that to a professional at the dyno to dial that in, but I've been working on a separate tune on the side for when I get these things ironed out. Once it runs and I trust my wideband readings, I'll probably give it a go.

[nkautz]

Setting it to 60 ifr will decrease total fueling, and the injectors are likely rated to 60lb/hr at 43psi fuel pressure, so its gonna be the correct setting anyways

[runpasthefence]

Setting it to 60 ifr will decrease total fueling, and the injectors are likely rated to 60lb/hr at 43psi fuel pressure, so its gonna be the correct setting anyways

Yeah, I'm a moron. I forgot that I can change the units of measurement for that table. My injectors are rated at 53lbs at 43.5psi and 62lbs at 50psi. I've set my fuel rail pressure to 43psi and entered 53lbs/hr into my IFR.

I copied over all of your relevant data, and, unfortunately, I saw zero change in the engine's ability to start or run. It was identical to yesterday's situation. It would start, hunt for idle, take throttle, the die almost immediately. I thought it sounded like a VATS issue, but without internet at my shop, I couldn't do much about it.

I'm at work now, and I didn't realize it's such a simple thing to remove. I just double checked my tune, and, sure enough, VATS was still enabled. I'll head back over there in the morning and give it another go.

[runpasthefence]

This might be adding to too many variables into this discussion, but just for shits and giggles I threw in a 2bar MAP sensor and tried to run my SD tune. It started and ran for longer than the standard tune, but it dropped 3 cylinders (plugs fouled again) and went into some type of limp mode. It continued to run in that limp mode (throttle disengaged, spark advance locked) while surging on 6 cylinders until I shut it off. I checked my SD tune, and VATS is also enabled on it, so it's hard to draw any solid conclusions from this experiment.

I thought I'd attach a log of this trial run for the sake of experimentation.

[gagliano7]

One thing you can try is up your spark advance at idle rpms. Yours is pretty low. I would think with all that fuel at idle you need more spark. Look at the spark tables on the 2007 lq9 file posted by nkautz.

[nkautz]

You still need less VE , can you post your latest 2bar tune and I'll revise it for you. See how your injector pulsewidth skyrockets as MAP increases even at low rpm? PW should be around 2 during idle and go up to maybe 3-4-5 with part throttle. I'm seeing 10 and 12 at 1200rpm

[runpasthefence]

One thing you can try is up your spark advance at idle rpms. Yours is pretty low. I would think with all that fuel at idle you need more spark. Look at the spark tables on the 2007 lq9 file posted by nkautz.

Another day, another set of spark plugs! My bike left me stranded at work last night, so I didn't have much time this morning to tinker with the truck. I switched back to my 1bar MAF tune since it's the one I've been revising from input on this thread. The SD tune needs to be brought up to speed (which I might do before I submit this post).

I did review nkautz's spark tables and revised mine a bit. This was also my first attempt with VATS disabled. Because I've been editing the initial blackbear tune, I had just assumed it was removed. Anyway, it didn't make a difference. The engine starts, runs/hunts for a few seconds then just dies. So, with a little time on my hands I started dicking around with my IFR table. For shits and giggles, I started removing 10lb/hr from the table, flashing, run/log, then remove another 10lb/hr. I started with 52lb/hr and worked down to 22. Attached, you'll find the log for an attempt at a run with an IFR of 27lbs/hr. Predictably, it's as lean as a butcher's dog, but it idles! I guess somewhere in the 22-27lb/hr range the low IFR counteracts the wide pulsewidths that nkautz mentions below and allows the engine to idle...kind of.

You still need less VE , can you post your latest 2bar tune and I'll revise it for you. See how your injector pulsewidth skyrockets as MAP increases even at low rpm? PW should be around 2 during idle and go up to maybe 3-4-5 with part throttle. I'm seeing 10 and 12 at 1200rpm

That's a generous offer. It's attached. I noticed from looking at my logs from my different IFR logs that those big pulsewidth numbers are only associated with higher IFR values. The log I've posted (27lb/hr IFR) shows pretty good pulsewidth. I'll have to do some research on the correlation.

[nkautz]

Ok,put your IFR back at all 52's and change the tables in the spreadsheet I've attached. You should be able to copy and paste everything:

I still think your wideband has it's head up it's ass, it hasn't budged since your first log.

VE.xlsx