MY04 Liberty GT - FrankenStien - EOI welcome / FS

[dr20t]

Spam away mate I always enjoy hearing bout your developments

On another note - this issue with the stumbling on spool is doing my head in

Any ideas?

Could a pre turbo leak at 3 bolt uppipe cause this (and therefore will me changing to v band fix it or am I wasting my time here?)

Could a bad maf do this even though I've cleaned it?

I don't want to be replacing parts as a guess to fix this.

Insight would be appreciated

Mick

[bigBADbenny]

With the car on stands, cold, spray the uppipe etc with soapy water, get a mate to start it, keep spraying till you see bubbles, or not, or the pipes get too hot.

[dr20t]

Thanks Benny

Done that already. Established it's leaking slightly.

My question is more around whether this is enough to cause the issue ive described with the lean stumble as soon as I hit positive boost, which then goes away after 5psi.

My thinking (which may be wrong hence why I'm asking) is that the leak gets worse as it makes positive boost (possibly due to pre turbo backpressure rising as boost rises), but then once enough pressure builds up, it seals / covers over the uppipe leak.

Can someone tell me if this does or doesn't make sense and if they feel its enough of a leak to cause the issue I'm describing

Mick

[senator]

Mick

Are you using any flex joins pre turbo????

If so might, be time to have a closer look………..

[dr20t]

No flex joins pre turbo - only in the wastgate vent pipe to dump pipe

[bigBADbenny]

Got the HKB alt diode?

Did you run heavy ga wire to the FPCM or any other pump related upgrades?

[bigBADbenny]

Also with the car in neutral, get someone to rev it whilst touching each coilpack in turn.

If you feel it ticking or get zapped...

[dr20t]

Got the HKB alt diode?

Did you run heavy ga wire to the FPCM or any other pump related upgrades?

Great thinking Benny -

I checked the diode yesterday. Its fine. Changed it to the standard 7.5amp fuse and still no change (so put the diode back)

I get the line you're taking though (fuel pump cycle). I've checked all that out. Its fine. Voltage at pump is fine. Even upped fuel pump duty cycle to 100% full time to see if it fixed it and it didnt.

Also measured fuel pressure at positive boost and its fine (not dropping fuel pressure)

Really fkn stumped now.

Has to be pre turbo exhaust leak, maf, map or mechanical issue

Can't be injectors as afr's are fine and car drives normal after 4-5psi

Mick

[dr20t]

Ah yes good idea with the coils. Will try that

Funnily enough this is how I diagnosed my dad's misfiring problem last week on his vz v6

[bigBADbenny]

Check the gearbox sensors - neutral pos switch etc is a classic WTF FU.
Could be a wire bending on take off, then reconnecting when speed is maintained.

[dr20t]

Another one to check thank you.

It only happens when loading it up in 3rd/4th at boost threshold

[bigBADbenny]

Hang on: it only chokes when you're about to give it?
Vehicle speed?

[dr20t]

Hang on: it only chokes when you're about to give it?
Vehicle speed?

When its at 1900-2500rpm and 1.6-2.0 load range - irrespective of speed

Mick

[bigBADbenny]

Now I have to google what exactly a load range is...

IIRC its in the Tune FAQ

Screen Shot 2014-09-30 at 12.59.48 pm.jpg (123.33 KiB) Viewed 4044 times

[bigBADbenny]

Spec C ignition system (lower heat range plugs, high CDI coil packs)
ID2000 injectors
HKS EVC 6 Electronic Boost Controller
HKS Ezy writer add-on (full EVC boost tunability by rpm \ load reference)
Omni 4 bar MAP sensor
Speed Density \ Blended MAF Tune (mafless)

Theres a lot going on here^.
Tried a different MAP sensor? (seen plenty of mixed results with those on the interwebz)
Send me a log of this event as it would be fun to look at it in MegaLogViewerMS: the 3D graphs especially.