Problem

Having a strange problem with my Eaton M112 supercharged EF and hoping someone might have some ideas.

After a cold start, the car drives beautifully and goes hard on and off boost with perfect AFRs initially... love its guts... but after this period (depending on weather) the AFRs get leaner both on and off boost and it starts pinging.

In cold weather it has run perfectly for up to around 20 minutes and took lots of boosting to go bad, but in hot weather it can go bad within a 5 minutes. You can then turn the car off and start it again before it's cooled down and it will be lean straight away.

I've tuned the car with a J3 and Techedge logger/wideband. I'm fairly sure it is not the ECU or the tune causing the issue as I've disabled all temperature related modifiers such as cold start enrichment, intake air multiplier etc. I've also disconnected the IAT sensor and it made no difference. Nor does the problem seem to correlate with coolant temp. I only put the blower in recently and it has had this problem since. Not sure if it had the problem before the blower because I didn't have a wideband then.

Have also noticed more recently that around the same time as it starts going lean, it starts idling around 1000rpm instead of 800rpm. I didn't notice this symptom previously but that's not to say that it wasn't there... makes me think maybe a vacuum leak that gets worse as something gets hotter (there's no ISC in the car).

Info about the car

- Snort M112 kit running 10psi, 90mm throttle body
- 60lb Siemens Deka shorty injectors, billet rail and Turbosmart FPR 800 reg, Bosch 023 in tank pump
- Bosch black leads and NGK BCPR6ES plugs standard 1.1mm gap, standard coil pack
- Wade 1004 cam, heavy valve springs, AU MLS gasket
- J3 chip with boost mapped tune
- Turbosmart pneumatic Fuel Cut Defender (not yet adjusted, so MAP sensors are currently seeing full boost)
- Extractors and 2.5" exhaust
- Open pod in engine bay for now, soon to be in guard
- Standard EF bottom end

Tried so far

- Checked resistance of injectors hot and cold, normal
- Checked voltages at injector plugs hot and cold, normal
- Checked condition of plugs, look normal, only 5000km old anyway
- Disabled all temperature related modifiers defined for the tune in the available EF definitions
- Messed with base fuel and stabilised fuel tables in the tune, turns out it is not the ECU switching from base to stabilised table as first suspected
- Disabled MFA (lean cruise) mode in the tune
- Disconnected IAT sensor, still does it
- Pulled diagnostics codes from the ECU, only one about the disconnected IAT sensor
- Checked fuel pressure at the reg when running normally and when running rich, both the same (however only checked at idle)
- To check for vacuum leaks, sprayed carby cleaner around all mating surfaces and hoses I can get at while idling, noticed no change in revs, but haven't checked the underside of the blower yet
- Opened bonnet to let some heat out once running lean, continues to run lean (clutching at straws )

Any ideas would be awesome.
Cheers

Last edited by Tragilgas on Mon Feb 16, 2015 2:27 pm, edited 2 times in total.

whats your ve vs ACT multiplier? sounds like its leaning out due to higher ACT

I thought the same thing, so changed them all to "1", but it made no difference. Also disconnected the IAT/ACT sensor to be doubly sure but still does it.

Cheers

 

 

Attachments:

VE ACT Multiplier.jpg [ 51.27 KiB | Viewed 235 times ]

1 is bad for higher temps, try doubling it for the 123.3deg one maybe even more, to see if it changes it

Thanks mate, I agree it's looking like hot intake temps causing it, started logging temps and saw it get up to a max of 75*C after some sustained boosting on a 30*C day. When it gets up near those temps is when it starts dogging out.

I'll try increasing it and also moving the pod from the engine bay to the guard.

Will post back with results.

So I've found this problem doesn't happen if the coolant temp sensor is unplugged. AFRs stay stable as a rock.

Also unplugged the thermos to be sure it wasn't just the car running cooler because of the thermos running on high due to disconnected coolant sensor.

Have a new coolant sensor here to try, but the old T5 also happened to cark it today, so won't be testing it til I get time to put a new box in within a couple of weeks.

Will post back with results... just in case anyone else ever happens to have this weird a*** problem!

Just to follow up this old thread, the following change in the tune is what solved it:

Fuel Base Table before:
10.29 10.29 10.29 10.64 11.44 12.35 12.70 13.50 14.07 14.64
10.29 10.29 10.29 10.64 11.44 12.35 12.70 13.50 14.07 14.64
10.52 10.52 10.52 10.98 11.67 12.47 12.92 13.95 14.18 14.64
10.98 10.98 10.98 10.98 11.67 12.58 13.15 14.07 14.18 14.64
11.32 11.32 11.32 11.32 12.01 12.70 13.27 14.18 14.30 14.64
11.67 12.01 12.47 12.70 13.50 13.73 13.95 14.64 14.64 14.64
12.47 12.70 13.04 13.27 13.61 13.95 13.95 14.64 14.64 14.64
12.35 12.58 12.92 13.04 13.50 13.73 13.73 14.18 14.30 14.64
11.67 12.01 12.35 12.70 12.70 13.04 13.15 13.50 14.07 14.64

Fuel Base Table after:
10.29 10.29 10.29 10.64 11.44 12.01 12.01 12.01 12.01 12.01
10.29 10.29 10.29 10.64 11.44 12.35 12.70 13.50 14.07 14.64
10.52 10.52 10.52 10.98 11.67 12.47 12.92 13.95 14.18 14.64
10.98 10.98 10.98 10.98 11.67 12.58 13.15 14.07 14.18 14.64
11.32 11.32 11.32 11.32 12.01 12.70 13.27 14.18 14.30 14.64
11.67 12.01 12.47 12.70 13.50 13.73 13.95 14.64 14.64 14.64
12.47 12.70 13.04 13.27 13.61 13.95 13.95 14.64 14.64 14.64
12.35 12.58 12.92 13.04 13.50 13.73 13.73 14.18 14.30 14.64
11.67 12.01 12.35 12.70 12.70 13.04 13.15 13.50 14.07 14.64

From all of my testing it seems that changes to both the Base and Stabilised tables are reflected at the same time/under the same conditions, which goes against all I have read that says uses one or the other depending on ECT_STABLE_FLAG and WARM_EGO flags, but most info out there is re. American EECs so maybe it's different for our Falcon I6 ECUs.

The fact the problem didn't happen with the coolant temp sensor disconnected was the clue that lead to the Base table.

I live locally and would like to see your car some time.