Glowing headers at idle on S197 3V Kenne Bell (and other issues)

[S-351R]

Helping on a nice project for a 2008 Mustang GT with big KB, 168mm Mammoth, built engine with Stage III cams, 4.5" HPX MAF, headers, hi-flow cats, etc...

Car has been a saga and full of head-scratchers on a couple of issues, but biggest one currently is that at idle, it will rather quickly start to glow the headers (1-2 mins) even though fuel Trims are dialed in. Noting that I am struggling to get idle from 1000 down to commanded 825rpm, so timing is pretty much at it's floor at 5* trying to reduce it. (Mammoth throttle body data from Jeff Evans, but haven't gotten it to idle down to commanded yet once warm)

Additional data:
- On 3rd PMAS MAF, 2 of which were HPXs, and all transfer function spreadsheets immediately required like 25-35% additional fuel. So 1000 rpm idle is at like 2.30 lb/min of 'airflow' to get trims in line

- On 2nd set of injectors, previously 80lbs Siemans with validated data, and now 95lbs matched with solid injector data from Banish

- Previous idle and parking lot logs showed a lot of Knock Retard at low rpms, load, even with low timing (one sensor seems to be sorta flat with low mv's too)

- GT500 pump has matching fuel pump data

Latest tune file is attached with last idle data log. The tune hasn't really gotten started to dial in as we have been methodically trying to eliminate culprits, but please at least take a look to see if there is something I have missed or where to troubleshoot first.

Thx2008 Mustang KB V10 MAF DD test.hpt2008 Mustang KB V10 Idle MAF DD test 2 glowing.hpl

[B E N]

Headers glowing at idle usually indicates retarded ignition timing. Your logs are showing 5 deg, it may actually be less. Try bumping that up to 15 deg and see how it responds, a little more probably won't hurt. Otherwise it's due to something in the ignition pickup setup.

[S-351R]

We finally got the timing verified and it matched what was showing on the scanner. BUT, disconnecting the MAF allowed the idle to drop down to commanded 800 (for a while before dropping lower), timing went back up to 20s, and glowing stopped.

So:
1. Was it reasonable that 5* would be retarded enough to glow at idle?

2. How might the MAF be the culprit? We have had 3 different MAFs and all ended up needing a lot more lb/min in trim despite decent Transfer function spreadsheets. Idle trims always got dialed in.

3. What do I need to do get this idle down to commanded (which is steady 1000 vs. 800) as the normal tables aren't doing it? This would at least help get timing off the floor.

4. My ETC errors are ~ -1.9, so I think the TB data is close, unless there is a trick to this Mammoth 168 elliptical. Any clues here?

Thx BEN, and any ideas where to chase next are appreciated.

[B E N]

Sounds like the MAF may not be closing enough, or the IAC is not functioning properly, more likely you have a vac leak.

On timing, it looks like you have way too much for a blower? I would back it down until you get it on a dyno, then work it back up.

I think your idle timing is so retarded because your IAT are over 100? and you have 50? retard built in to ECM 44587 (spark IAT correction base) at 100 deg.

[S-351R]

Thx BEN, yeah we will be able to do a smoke test on Monday and frankly hoping for a vacuum leak (the old carb cleaner trick revealed nothing though)

For timing, just to make sure we are looking at same stuff, my .hpt file shows IAT retard values starting only at 160* and -35. All zeros before that. Am I seeing something different?

After that, got a couple of MAF tests to do (factory MAF and small tube, etc), and then chase TB mechanicals next... Will see what we learn. Thx again.

[B E N]

For timing, just to make sure we are looking at same stuff, my .hpt file shows IAT retard values starting only at 160* and -35. All zeros before that. Am I seeing something different?
.

My bad, I was doing a compare with a stock tune and was looking at the stock tune. Your good on that. Verify your ECT, cold load and lambda adders are what you want before you start on boost runs.

I still don't quite understand why the car is pulling so much timing. Your actual advance is following MBT/borderline pretty much dead on but roughly 20 deg lower. I also don't see your AFR, maybe it's related to that... It could be your torque modeling is off, if nothing else works try multiplying the top 3 rows and column (9 blocks) by 1.5 and see if it changes, if that works go from there. Take a look at this thread and see if it's any help. https://forum.hptuners.com/showthrea...820#post690820 specifically post 22 and beyond.

[B E N]

Heres the channels I use if it helps, add on but try to keep it minimal, more channels means less logging resolution.

5 21 channels.Channels.xml

[S-351R]

Agreed on the why timing is being pulled like that unless it's tied to trying to hit target idle and pull down from its current high idle. I even reduced idle Airflow values, but did not really change anything.

Will have access to the car again early next week and will chase some of the Torque modeling recommendations with the other tests. Thx again.

[eficalibrator]

If your giant throttle bleeds too much airflow at the minimum setting, you will have higher idle airflow (also measured by the MAF) and the EEC will retard the timing a bunch in an effort to get down to desired RPM.

Unplugging the MAF just makes it default to your "Load w/ Failed MAF" table for airflow. If this wasn't recalibrated, it explains the difference in calculated airflow and ultimately spark.

I would start by running at known stock ETC and dialing in the MAF down low with that. After that, you can swap to the bigger MAF and dial in the ETC tables correctly, then also move on to LWFM.

All of this ASSumes that your injectors can reliably deliver the small fuel pulse needed to hit lambda=1.0 at idle. If you are riding the min PW or the injectors are "spitting" inconsistent amounts (common with SD80's), you'll get misleading wideband data when dialing in the MAF and ETC stuff. Misfires also lead to hot EGTs and glowing headers.

I have a bunch of Ford-specific training on my streaming site in my sig if you want more. I was a calibration engineer for this stuff in Dearborn once upon a time.

[S-351R]

Hey Greg, sorry for missing this earlier and haven't had time to mess with it much, but many thx for the input.

And yes, this does make sense given the combo. We do now have the 95lb Bosch injectors as I was pretty quick to blame the SD80s, but symptoms were nearly exactly the same.

May not be able to swap out the TB, but will certainly set target Idle to what seems to be the minimum for this giant and see if things are more consistent. If timing stabilizes, will move on to rest of the tune to see how things go.

Thx again

[S-351R]

Well, I matched Desired Idle with the min this TB was giving (~1050rpm) which allowed to spark to work around 10-15* doing typical idle trims. Fuel Trims and WB were consistent, and still glowing headers at idle.

Unplugged MAF and verified fueling on WB and it was very lean on the LWMF table (not dialed in yet, but had reasonable values from another SC car), fine but does explain that it was leanness that was dropping RPM idle despite the big TB.

Swapped in stock MAF sensor in same large 4.5 tube, scaled it, and trims were back to fine, MAF lb/hr dropped a little by about .2 (2.1 vs 2.3 at 1050rpm idle)

Idle timing good, still started glowing pretty quick.

2500rpm hold with solid 14.5's AFRs, 30s timing, and still glowing (even more) on both sides... With the timing high, and stable higher RPM fueling, what would cause this to get worse?

Timing was verified with light and even if ring had somehow shifted it was commanding plenty of spark.

Is cam timing the only thing reasonably left to verify? (Rather large cams, locked out...)

[B E N]

Cam timing too early or something else is hanging the exhaust valves open.

[veeefour]

You should at least run +10' of timing at IDLE, otherwise it will get hot, especially if you have no cats.

Or its the other way around, you cats are clogged or something else in exhaust blocking. I see no other reason.

[eficalibrator]

Well, I matched Desired Idle with the min this TB was giving (~1050rpm) which allowed to spark to work around 10-15* doing typical idle trims. Fuel Trims and WB were consistent, and still glowing headers at idle.

Unplugged MAF and verified fueling on WB and it was very lean on the LWMF table (not dialed in yet, but had reasonable values from another SC car), fine but does explain that it was leanness that was dropping RPM idle despite the big TB.

Swapped in stock MAF sensor in same large 4.5 tube, scaled it, and trims were back to fine, MAF lb/hr dropped a little by about .2 (2.1 vs 2.3 at 1050rpm idle)

Idle timing good, still started glowing pretty quick.

2500rpm hold with solid 14.5's AFRs, 30s timing, and still glowing (even more) on both sides... With the timing high, and stable higher RPM fueling, what would cause this to get worse?

Timing was verified with light and even if ring had somehow shifted it was commanding plenty of spark.

Is cam timing the only thing reasonably left to verify? (Rather large cams, locked out...)

Time to re-check the cams. I would want to see the as-installed ICL/ECL vs what's on the cam cards for starters. "Stage III" doesn't tell us much other than they are probably "big". It could be that they are either installed incorrectly or that there's just so much overlap at idle that you have a ton of unburned air and fuel passing the chamber and lighting off in the exhaust.

[shawnaj7731]

The maf curve looks like it needs some desperate attention to.

[shawnaj7731]

maf curve.PNG the curve is way off.

[S-351R]

Greg - yeah the Tech is chasing the cam card, and certainly agree.

Shawn - That MAF curve down is the result of what I felt were some unnatural adds in the scaling to get the trims in line, she just kept wanting more and more fuel beyond a triple checked transfer function from PMAS. Just didn't finish up curve largely because we haven't gone anywhere yet...lol

This has become one of those snails-paced projects, but appreciate everyone's input!