runpasthefence

iTrader: (2)

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.

moehorsepower

iTrader: (3)

Talks about lean, rich, Have you tried anything other than the IFR tables? going into the VE and or MAF just to see if things clear up?

JakeFusion

iTrader: (7)

You're in Charleston? It might be worth it to either make a drive to Vengeance Racing or Tick Performance and have them iron things out for you.

runpasthefence

iTrader: (2)

That's the eventual plan. I'm really just trying to get this thing in drivable condition, and then I plan on placing her in more knowledgable hands. This is in a swap vehicle, and it's not even in towable condition right now...

Made an attempt to log commanded AFR today. 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 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.

The process continues.

moehorsepower

iTrader: (3)

Again have you tried doing any adjustment with the fueling? just for S & G why don't you go into the IFR table and raise the values and see what that does?

3 window

iTrader: (1)

Not sure how the gm system works, but you should be able to see all the parameters or PIDS before you even start the car with the key on. Take a look at those and make sure nothing looks grossly out of whack. I do know back in the day when Ford first came out with DBW, the throttle body and the gas pedal PIDS were opposite and they averaged themselves. (Banged my head against a wall for a few days trying to figure that one out). Try and fine what the TPS should be before you start it and adjust it accordingly. From there, it's going to be timing and fuel during idle. Give the engine what it wants to run, not a number you think it should be. We've all had our butts whipped by this type of thing at some point. Stay with it, youve done great so far, you'll figure it out.

runpasthefence

iTrader: (2)

I got into that today. Keep in mind, I was seeing evidence of both lean and rich conditions. I'm trusting what I'm seeing on the spark plugs and I'm leaning toward a rich condition. So, I've started pulling fuel.

I started researching last night about IFR with boost/vacuum referenced fuel pressure regulators. 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. 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.

This I haven't done. I find it strange that after reducing the fuel pressure by nearly 20psi, and reducing the injector flow rate, I'm still seeing wet spark plugs with tons of carbon build up. Thanks for the encouragement.

JakeFusion

iTrader: (7)

Keep the fuel pressure constant... but you probably need to lean the hell out of it at idle if the IFR table is right. Unfortunately, that has to be right first. I think we can probably get the injector data on them if they are Ford-spec Bosch injectors.

Also, set all of your tables... EQ Ratio in Open loop to 1s across the board. Take all of the fuel adders out. All of the temp and EGT adders in PE, closed-loop, etc. Turn off long term fuel trims.. Only table you should be running any additional fuel is in the PE table. At least to tune your VE table and MAF (you have a MAF?). I'd kill that for now and just focus on the VE table.

runpasthefence

iTrader: (2)

Sorry for the lapse in response. I've been working with a guy on the hptuners forum in the meantime, but, unfortunately, we weren't able to make heads or tails of what's going on.

Today I made all of the changes you mentioned above, but I saw no change in the engine's ability to start or run.

A few days ago I conducted a short experiment. I reduced my IFR (my injector data says it should be set to 52lbs/hr at 43.5 psi) by 10lbs/hr and logged my results. I did this all the way down to 22lbs/hr. As I approached 27-22lb/hr, the truck would actually idle, but was very lean.

The two weird things I've been focusing on lately are my commanded AFR and pulse width. My logs are showing commanded AFR all the way down to 2.9 and pulse widths at idle near 50ms.

I've also switched to a 2bar MAP and have been setting this tune up as speed density.

I've attached two logs and my most recent SD tune. The ifr27 log file is an older log with IFR set to 27lbs/hr. The other log is set to an IFR of 52lbs which is the correct flow data from Five-O Motorsports.

Hart_Rod

iTrader: (3)

updates?

runpasthefence

iTrader: (2)

Hey there Rod. Always enjoy your builds. Glad to see your Burb is coming along.

Yes! I think it's safe to say the problem was a vacuum leak...which all signs pointed to from the get-go. I just couldn't find one, so I started blaming injectors.

I ended up removing and re-installing the blower, and replacing the Five-O injectors with Deka 60s. In the process I found a damaged brass plug that was the source of the vacuum leak.

Runs great now, but I've got a million other little things to finish before the truck is on the road.