2.5TD powerloss

Hi all,

I have 2.5 D40 2007 STX Manual and suffering powerloss under heavy acceleration. I have chipit with EGT and was running tune 4, this was installed about 8 weeks ago and has been running really well, a couple heavy accelaration events saw massive powerloss at about 3000rpm. I was concerned and thought it maybe chip related so disconnected it but the problem persists.

Points to note include

- egr blank is fitted
- powerloss can happen in any gear at any speed but always under heavy accleration
- no engine light comes on
- if i get out of the throttle for a few seconds power returns but can lose it again
-it was quite random but is now happening regulary

I was thinking it maybe the fuel rail dump valve but not sure and cannot understand why this would happen on standard tune. Has anyone else experienced this with chips and on standard tune? Any theories? I know that chipit provide a magical washer to fit to fuel rail dump valve. Has anyone fitted this from a result of powerloss and corrected the problem?

Any thoughts appreciated

Thanks

could it be the mafs??

Try this: loosen the fuel cap and see if it still does it. We had a local Navara go into limp mode without warning lights. I found a P1272 error code and the fuel rail pressure was about 2,000kPa over.

You could have a fuel rail pressure sender issue, it could be the MAFS a little dirty (use electrical circuit cleaner, you could have air caught in the fuel pump, your turbo could be overboosting or the boost sensor is misreading things.

Now, the boost sensor is on the output of the intercooler at the front near the battery. I suppose it could get dirt/oil on it under high loads - remember your PCV is piped to the intake just in front of the turbocharger and the muck is fed into your intercooler where it collects. Catch can fitting is advised!

You need to find the DTC code first indeed, it could be 0089, 1272, or one or two others, but nearly always related to the fuel pressure relief valve opening.

Climate changes, and thus your air intake temp readings, vary, and adjust MAF signal, which is the single most important parameter for the ecu to ramp up fuel pressure.

Years ago I made the mistake of tuning a simple chip at night, and I would go to limpmode at full throttle at midday.

Bottomline: your initial tune may have been too aggressive for current climatic conditions.

Thanks, it is interesting you say that. It first occurred up on the Atherton tablelands which is probably 1000m ASL, it did it many times that day but when i returned to the coast the problem went away, however now it does not matter where I am.

I will have to get a scangauge to see what codes it is spitting out. Could it be possible that the fuel relief valve is getting weaker and easier to trigger? I imagine it is a spring setup and that with constant use (several times a day) it may be reliefing at potentially lower pressure that originally designed, does that sound feasible??? even on standard tune?

Thanks

I use an ELM327-compliant Bluetooth OBD adapter and some $5 softwaare from the Android market. It will pull the error code from the ECU and show things like boost levels, fuel rail pressure and much more in real time directly from the ECU itself. It's a worthwhile investment!

Thanks Tony, this data then displays on you andriod phone? Can you let me know where you got the adapter? I can boroow a scangauge from a mate for short term solution but long term like the sound of what you have, what is the app called?

crowe said:

Thanks Tony, this data then displays on you andriod phone? Can you let me know where you got the adapter? I can boroow a scangauge from a mate for short term solution but long term like the sound of what you have, what is the app called?

Click to expand...

Jason found this one, here's his post.

I should update another thread on this subject where I doubted the viability of this adapter. With the right softwaare it does work rather nicely.

I'm using Ian Hawkins' Torque application.

Hi all,

For those that care i have an outcome for this problem (nothing worse than unfinished posts).

1. I received scangauge and hooked it up, no error codes.... bummer!!
2. Thought it may be the scangauge so went for a drive and made it fault, still no error codes.
3. Pulled out fuel pressure dump valve with thoughts of using chipit limiter disc.
4. Didnt like the idea of limiter disc (I dont understand how it can still let fuel through when the rail pressure is truly exceeded from ligitimate fault).
5. Removed spring from dump valve and used 3 x 6mm s/s washers equating to 1.6mm thick behind where spring seats in valve (essentially spacing the spring out 1.6mm)
6. S/S washers still allow fuel to flow through valve.
7. Re-installed and tighthened.
8. Back to full horses on tune 5 and revs beyound 4K, no problems with power loss.

I hope that can help someone else out there.

Cheers

crowe said:

Hi all,

For those that care i have an outcome for this problem (nothing worse than unfinished posts).

1. I received scangauge and hooked it up, no error codes.... bummer!!
2. Thought it may be the scangauge so went for a drive and made it fault, still no error codes.
3. Pulled out fuel pressure dump valve with thoughts of using chipit limiter disc.
4. Didnt like the idea of limiter disc (I dont understand how it can still let fuel through when the rail pressure is truly exceeded from ligitimate fault).
5. Removed spring from dump valve and used 3 x 6mm s/s washers equating to 1.6mm thick behind where spring seats in valve (essentially spacing the spring out 1.6mm)
6. S/S washers still allow fuel to flow through valve.
7. Re-installed and tighthened.
8. Back to full horses on tune 5 and revs beyound 4K, no problems with power loss.

I hope that can help someone else out there.

Cheers

Click to expand...

Good stuuf, nice result. Heaps of instances of this kind of problem.
Don't spose you got any pic's of your mod?

crowe said:

Hi all,

For those that care i have an outcome for this problem (nothing worse than unfinished posts).

1. I received scangauge and hooked it up, no error codes.... bummer!!
2. Thought it may be the scangauge so went for a drive and made it fault, still no error codes.
3. Pulled out fuel pressure dump valve with thoughts of using chipit limiter disc.
4. Didnt like the idea of limiter disc (I dont understand how it can still let fuel through when the rail pressure is truly exceeded from ligitimate fault).
5. Removed spring from dump valve and used 3 x 6mm s/s washers equating to 1.6mm thick behind where spring seats in valve (essentially spacing the spring out 1.6mm)
6. S/S washers still allow fuel to flow through valve.
7. Re-installed and tighthened.
8. Back to full horses on tune 5 and revs beyound 4K, no problems with power loss.

I hope that can help someone else out there.

Cheers

Click to expand...

I am late to this thread and pleased to see you have fixed. It is a timely reminder to those using the Chip It chip that they do need to do undertake this mod if they intend loading high tunes.

where do u get the shim for this

You can easily have a fuel pressure valve shim made. If you (carefully) open up the pressure relief valve (it is held together with a crimp) you will find a shim, 1.5mm thick, that adds a preload to the pressure relief spring. You can either add another 2.0-2.5mm spring (what I did), or replace the stock shim with a 3.5-4.0mm, to increase the preload, and therefore the pressure relief threshold.


Reassemble (a vice comes in handy), and recrimp the open end.

Be sensible with the tuning (as you have indeed reduced that factory failsafe on railpressure), and keep an eye on your egt's.