Thread: Is 0.58 bar turbo pressure at 3000rpm about right for a Td5?

Originally Posted by discorevy

If they'd set the clearance on the cam base they would be destroyed, as for the cam timing , I've corrected a few after others have had the head off and not lined up the crank locking recess correctly ...... you know the cam sprocket is slotted ?



worth a look re green tops fitted.
If there isn't enough fuel the airflow can read high but boost can be low

The method I use to calculate air charge uses both speed density and mass air,

I have simply been comparing the 2 readings provided in the log which shows that for the given "air flow" from the MAF calculated into air charge, the speed density air charge error checking I ran shows that the MAP/IAT is reading significantly lower than MAF.

One sensor reading is not independent of the other, the problem is, I don't know which one is incorrect!

A stand alone boost gauge would probably clear this up.

The most logical explanation would be that considering the MAP/IAT has been replaced, and it's STILL reading lower -- and taking for granted that some kind of bizarre electrical problem isn't at play... is that there is a boost leak between the turbo and inlet manifold.

This would give poor performance, and highly mismatched air charge figures between the 2 sensors as boost builds, which is exactly what exists.
I highly doubt that it would stop the engine revving past 3000 rpm though, that is most likely a separate issue.


Cheers
James

I've just had another look at the logs you posted, I would definitely be putting some effort into looking for a boost leak, that's the most logical explanation for the disparity in the readings.
Also interesting to note that everything reads the same until the boost level rises.

So that gives us some sort of baseline to say that the sensors are working reasonably well.

Cheers
James

So...have discovered two problems. As suggested above, there is a boost leak - a split along the welds on my aftermarket intercooler which is disappointing given that it is supposed to be a quality brand (Td5 Alive). But the more major issue is the fuel pressure which is only 23PSI just before the regulator and should be more like 65PSI. So Graeme Coopers were right in saying it wasn't getting enough fuel but kind of bizarre that they fitted an upgraded ECU to try to fix the problem rather than looking at fuel tank filter/pump... So some jobs to do when I get home in a few weeks but will be good to finally release the performance!

Originally Posted by feraldisco

So...have discovered two problems. As suggested above, there is a boost leak - a split along the welds on my aftermarket intercooler which is disappointing given that it is supposed to be a quality brand (Td5 Alive). But the more major issue is the fuel pressure which is only 23PSI just before the regulator and should be more like 65PSI. So Graeme Coopers were right in saying it wasn't getting enough fuel but kind of bizarre that they fitted an upgraded ECU to try to fix the problem rather than looking at fuel tank filter/pump... So some jobs to do when I get home in a few weeks but will be good to finally release the performance!

Well I'm relieved to see that you've found some logical answers, and that I hadn't lost my last remaining marbles.

Once you fix those things I think you'll be surprised how it goes!

A good workshop should not have missed those problems, and a remap should never have been suggested in this scenario, until the underlying issues were fixed...

Cheers
James

MAF and MAP are used by the ECU as part of the engine torque calculation which is fed to the Auto.


I've seen this issue with a blocked exhaust which was easy to find as the EGT's were through the roof.

you could also try checking the turbo, claggy bearings and seals will result in turbo drag meaning the engine never gets enough to respond to.

it wont be fuel pressure in the rail, so long as there is enough pressure to fill the injectors they'll fire a full load of fuel, Typically this results in a deminishing torque curve (fewer openings drawing more fuel at lower RPM for more torque typically uses less fuel over all than lots of smaller openings at higher RPM for not quite as much torque) this is easy to pick on a manual less so on an auto.

your auto could also be stuck in a loop asking the engine to reduce torque in preperation for a shift it doesnt actually want to make.

whats the boost do at full load at say 2250 RPM?

Thanks. It's a manual. Bruce Davis reckons you need about 65psi at the fuel pressure regulator. The fuel pump makes all the right noises and has been the same for 15 years...and I obviously don't want to stuff around with the fuel tank/pump if the fuel pressure isn't a problem...but surely 23 PSI is going to be marginal at higher revs? I basically have to ease the throttle on and cruise at lower revs...2000rpm feels ok...have to really push it to get to 2500rpm and flog it to get to 3000rpm...won't go over that.

I think the split in the aftermarket intercooler is a relatively minor problem as the lack of power/revability was there with the previous original intercooler.

Turbo spins freely, although I have a slightly modded new cartridge to go in at some stage.

Dump pipe studs look like they're going to be a challenge to remove to check that the exhaust is free of obstruction. Haven't checked EGT but the coolant temp on Nanocom is generally pretty good unless a really hot day up a long hill.

I've also heard that crank timing can result in a doughy engine but the mech didn't check that.

Originally Posted by Blknight.aus

MAF and MAP are used by the ECU as part of the engine torque calculation which is fed to the Auto.


I've seen this issue with a blocked exhaust which was easy to find as the EGT's were through the roof.

you could also try checking the turbo, claggy bearings and seals will result in turbo drag meaning the engine never gets enough to respond to.

it wont be fuel pressure in the rail, so long as there is enough pressure to fill the injectors they'll fire a full load of fuel, Typically this results in a deminishing torque curve (fewer openings drawing more fuel at lower RPM for more torque typically uses less fuel over all than lots of smaller openings at higher RPM for not quite as much torque) this is easy to pick on a manual less so on an auto.

your auto could also be stuck in a loop asking the engine to reduce torque in preperation for a shift it doesnt actually want to make.

whats the boost do at full load at say 2250 RPM?

So since my last post earlier this year I've replaced the split intercooler with a new one, fitted a new fuel pump, rebuilt the FPR and cleaned the mesh filter behind the FPR... The new fuel pump didn't improve anything but not surprisingly the new intercooler and rebuilt FPR made improvements to power and economy (FPR was leaking)...but I still have the fundamental problem of not being about to rev beyond 2500rpm easily or beyond 3000rpm at all. And a new problem that seemed to have been introduced since rebuilding the FPR but could just be coincidence...a kind of 'flaring' sometimes when I try to accelerate hard. It feels a bit like clutch slip but happens at lower (2000rpm) rather than higher revs. I think it's a bit worse when vehicle is cold. It's not a big problem as it's occasional and minor but it's a bit bizarre. The inability to rev out is a bigger concern, but even with that, the car runs great with the Storm Tuning map up to 2500rpm...very smooth and torquey, great economy and I can't get it to blow smoke even if I try.

I've attached another Nanocom log if that helps anyone with diagnosis...

Thanks

Originally Posted by feraldisco

So since my last post earlier this year I've replaced the split intercooler with a new one, fitted a new fuel pump, rebuilt the FPR and cleaned the mesh filter behind the FPR... The new fuel pump didn't improve anything but not surprisingly the new intercooler and rebuilt FPR made improvements to power and economy (FPR was leaking)...but I still have the fundamental problem of not being about to rev beyond 2500rpm easily or beyond 3000rpm at all. And a new problem that seemed to have been introduced since rebuilding the FPR but could just be coincidence...a kind of 'flaring' sometimes when I try to accelerate hard. It feels a bit like clutch slip but happens at lower (2000rpm) rather than higher revs. I think it's a bit worse when vehicle is cold. It's not a big problem as it's occasional and minor but it's a bit bizarre. The inability to rev out is a bigger concern, but even with that, the car runs great with the Storm Tuning map up to 2500rpm...very smooth and torquey, great economy and I can't get it to blow smoke even if I try.

I've attached another Nanocom log if that helps anyone with diagnosis...

Thanks

Can't be bothered re reading the whole thread! So even in neutral you can't rev past 3k ?

Does it rev freely up to 3k in neutral?

Cheers
James