MY04 Liberty GT - FrankenStien - EOI welcome / FS

[dr20t]

Yes I should clarify that if I'm driving up a slight hill at very light throttle (sub 15%) then its fine even at that rev range. But load is obviously lower. So if I stay off boost at this rev range its fine. No stumble or any of the issue described above.

As soon as I give it a bit more throttle (say 20-30%) then boost comes up to 1-2psi. If I hold throttle at that point boost fluctuates between 1-2psi (struggling to boost) and then the stumble happens and afr goes wonky (out to 14.5:1 I've logged) and it just refuses to rev.

If I drop a gear, and revs and boost picks up to say 4-5psi, its fine.

Like I've said it's only at 1900-2500rpm at 1-2psi which equals load of 1.6-2.0 g.

Its not speed related

[dr20t]

Map sensor seems to be fine as I've logged manifold relative pressure and absolute and they both are in sync with my boost gauge, hks boost controller display and what my tune is aiming for at those load ranges

I have messaged Matt some time back asking for confirmation that this is the only way to check map sensor but no response

So unless someone tells me another way to test for map sensor then I'm assuming its ok

[Newbie GT]

Mick flame me of you wish

I insist its a vacuum issue / leak

[dr20t]

Mick flame me of you wish

I insist its a vacuum issue / leak

No flaming mate - it potentially could be. Smoke test is happening this weekend

[jslayz]

how is your target boost at that throttle n rpm?

Car perhaps not wanting to let you boost over the target boost but turbo trying to?

J

[dr20t]

how is your target boost at that throttle n rpm?

Car perhaps not wanting to let you boost over the target boost but turbo trying to?

J

Maybe

I don't have ecu controlled boost so its independent

If its related to what you're saying then it would be a maf or map sensor issue (or various gearbox switches) as these are the only things that help in determining engine load.

So engine load calculation would be out if the issue your describing is the issue.

Maybe this is impacting / overiding some fuel / timing tables at that load/ rev range

Another thing I've honestly been thinking about is maybe some of the invisible tables Matt has been playing with (calculated engine load and requested torque etc) are having a detrimental effect on some other parameters ?

Not pointing finger at Matt here but maybe there is something else going on that isn't being detected. Actually a way I can check this is flash the old tune done at insight with Matt in August 2013. Will see if this changes anything

Mick

[Newbie GT]

how is your target boost at that throttle n rpm?

Car perhaps not wanting to let you boost over the target boost but turbo trying to?

J

Maybe

I don't have ecu controlled boost so its independent

If its related to what you're saying then it would be a maf or map sensor issue (or various gearbox switches) as these are the only things that help in determining engine load.

So engine load calculation would be out if the issue your describing is the issue.

Maybe this is impacting / overiding some fuel / timing tables at that load/ rev range

Another thing I've honestly been thinking about is maybe some of the invisible tables Matt has been playing with (calculated engine load and requested torque etc) are having a detrimental effect on some other parameters ?

Not pointing finger at Matt here but maybe there is something else going on that isn't being detected. Actually a way I can check this is flash the old tune done at insight with Matt in August 2013. Will see if this changes anything

Mick

This is a great idea but what invisible tables ? Can you load a base tune say from scott to test this ? If you go back to a 2013 tune were the mods not different then ?

[jslayz]

Keen to hear your results.

[kennysti]

Same, very keen to hear results. Just this same little set of symptoms at basically the same point on a few modded and tuned cars now.

[dr20t]

Same, very keen to hear results. Just this same little set of symptoms at basically the same point on a few modded and tuned cars now.

Interested to hear about these other cars

Any links or details ?

[kennysti]

Same, very keen to hear results. Just this same little set of symptoms at basically the same point on a few modded and tuned cars now.

Interested to hear about these other cars

Any links or details ?

Myself to start with! let me do a search and I'll find a few

[kennysti]

False Knock causing symptoms?
viewtopic.php?f=56&t=17726
Boost actuator and fuel filter
viewtopic.php?f=10&t=22901&start=75

Just a few to start with

[dr20t]

Thanks for the links

Anyone know whether target boost tables have an influence on dbw / throttle maps when I'm running stand alone ebc?

I'm just building on my listof things to check

Will definitely be checking all mechanical first

Uppipe flange
Tial wastegate
Intake leaks
Coil fouling (doubt this)
Maf
Various transmission sensors and NSS
Then tune related stuff if the above doesn't fix the issue

[bigBADbenny]

Can you temporarily bridge the comp cover to the waste gate pressure signal port and log it just at waste gate pressure?
If possible that could rule out a lot of contributors on the boost control side.

[alexeiwoody]

Thanks for the links

Anyone know whether target boost tables have an influence on dbw / throttle maps when I'm running stand alone ebc?

They do. However not in the way you're concerned about.

You won't experience boost fluctuations or engine misbehaviour, it will only affect your TCU, ie gear shifting.