Previa D4D Acceleration Problem

[d4depressed]

Hi Everyone,

New to the forums and happy to join such an active community.

I need some help with a previa D4D which had an intemittent EML and loss of power, turns out it was the SCV's . Changed these and it was right as rain for about a week.

It then started losing power between 2000 and 3000 RPM. Mostly uphill, no EML. However the problem has gradually worsened and at one point the EML did come on fault code was P1251.

Problem is most severe when going uphill.

I would appreciate some pointers, thanks in advance.

[igormus]

Hi Everyone,

New to the forums and happy to join such an active community.

I need some help with a previa D4D which had an intemittent EML and loss of power, turns out it was the SCV's . Changed these and it was right as rain for about a week.

It then started losing power between 2000 and 3000 RPM. Mostly uphill, no EML. However the problem has gradually worsened and at one point the EML did come on fault code was P1251.

Problem is most severe when going uphill.

I would appreciate some pointers, thanks in advance.

hi matey

check with condition of an EGR -- it might be partly blocked with carbon deposits inside covering passing holes.

i do not consider issue with injection quality.

regards / Igor

[d4depressed]

Hi, EGR is clean, replaced the SCV's about eight weeks ago, the problem started about two to three weeks after the scv's were replaced.

However it may have existed before I replaced the scv's as the fault code was also in the ECU.

P1250. SCV code doesnt show up anymore and the starting issues have dissapeared. So definetly a different fault.

Mostly always in second gear and worst uphill between about 2200 and 3000 rpm.

I followed some of the other posts about the VSV on the turbo side. Resistant checked out fine, however when blowing air from E to G, the air travelled through.

Cleaned it with WD4 and then it stopped letting air through. So it may be the VSV, any idea what they cost new?

[darko1429]

Could be MAF sensor?

[Devon Aygo]

In your previous posts you mention both P1250 & P1251 these are Turbo charger faults being recognised by the engine ECU

P1250 Turbocharger System Malfunction

P1251 Turbocharger overboost condition

This is usually caused by sticking "variable vanes" in the turbo which usually requires removing and servicing/reparing or cleaning by turbo specialists such as turbo technics.

Because of the nature of the fault the ECU will illuminate the EML and put the car into limp mode the prevent damage to the turbo or engine by a overboosting turbo.

Devon

[treborzg]

P1251 is only connected with Turbo overload. It is very often problem in D4D-s.

Exchange VRV valve on efficient from other 2.0 D4D and check is the problem perish.

If not: clean steerings inside the turbo (do not move rotors !) and your problem will dissapear - practically proven.

[d4depressed]

Thanks for all your recommendations gents.

Just an update for anyone else who experiences a similiar issue

SCV's were faulty and the Turbo was overboosting. Got a recon turbo fitted by DPS and has been right as rain since.