P38A DSE throttle response issue.

Hi, my p38 only seems to accelerate properly when it is on full throttle, anything before that and its really slow, nanocom indicates the potentiometer if reading fine, also once the tc locks up at 50 it then will only unlock once its on full throttle at which point it drops gears as if its in sport and goes ok, my mates DSE will unlock the tc at even 50% throttle so seems mine has an issue. I did a 0-60 and it's around 14secs so I'm not down on power at full throttle but definitely lacks power/ response low down, MAP readings seem to check out OK too and i have no fault codes, gearbox level is OK and colour is good, in tank fuel pump is also good, not sure what else to check.
Thanks

Check the vacuum pipes under the inlet manifold, they can split causing sluggish acceleration

stemac33 said:

Check the vacuum pipes under the inlet manifold, they can split causing sluggish acceleration

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That vacuum pipe is a pressure pipe from the manifold to the MAP but good call.

Yes that is all good and my map reading seems fine so boost seems OK, and I haven't got any black smoke.

So it is was thinking about different car where the pipe acuates turbo solenoid valve

It's also weird it dosnt want to unlock torque converter unless I'm on full throttle, does it look at throttle position or is it some sort of power calculation?

Also forgot to mention, EGR had been removed so not an EGR ussue

Mine will do that sometimes, almost reluctant to come out of lockup. Sometimes eagerly.. Put it into sport and it'll drop gear in the blink of an eye. If so there may be nothing wrong. A remap does a world of difference to the diesel engine.
In sport it'll use lock up on third gear as well.

Mark Piercy said:

Mine will do that sometimes, almost reluctant to come out of lockup. Sometimes eagerly.. Put it into sport and it'll drop gear in the blink of an eye. If so there may be nothing wrong. A remap does a world of difference to the diesel engine.
In sport it'll use lock up on third gear as well.

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Lock up on third also works when not in sport mode. A remap shags the auto box PDQ.
Check the modulation with engine hot and idling.

Modulation is around 70% so a little high but not the worst

Colleydog91 said:

Modulation is around 70% so a little high but not the worst

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At what engine temperature? Getting the modulation spot on made a marked difference on my project car which is now more responsive than my original P38 on which I have yet to sort the modulation which is 74% @ 95C temperature

Mine was at around 87c, modulation is worse on my mates one and that unlocks the tc at like 50% throttle

On the old engine I got the modulation spot on and it had the same issue, the pump was leaking so I put it down to the fip but the new engine came with a fip and still has same issue.

Colleydog91 said:

Also forgot to mention, EGR had been removed so not an EGR ussue

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Does it still have MAF connected . If so unplug and see if it makes a difference

I think I have tried that before but will make sure tomorrow and let you know

Colleydog91 said:

I think I have tried that before but will make sure tomorrow and let you know

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Are the pipes to the unit blanked off also

Yes pipe blacked off and manifold also

Intercooler nice and clean? (Inside). Pull the pipes off stick your finger in there see if there’s black. If pipes internally delaminate usually chokes when turbo spools, if intercoolers clogged chokes til you build revs.

Datatek said:

Lock up on third also works when not in sport mode. A remap shags the auto box PDQ.
Check the modulation with engine hot and idling.

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Ours was remapped in 2004 for a previous owner Keith, we're over 230.000mls and the gbox is original other than the sticking valve which I've caused... It does actually drop off the revs to allow the gbox to be eased into changing gears when you give it some beans.
I agree the tc can be locked in third with the lever in the third gear position.

Mark Piercy said:

Ours was remapped in 2004 for a previous owner Keith, we're over 230.000mls and the gbox is original other than the sticking valve which I've caused... It does actually drop off the revs to allow the gbox to be eased into changing gears when you give it some beans.
I agree the tc can be locked in third with the lever in the third gear position.

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That's a good remap if the torque reduction on shifts has been maintained.