Tdi questions

[wagonwheels]

I've not long bought a 99 2.5d v70. It has sensible mileage,fsh and just had both belts done. It had no boost when I bought it but that's sorted with a fuse for the tcv.
Now it's boosting (had a new turbo fitted before i got it) I'm getting flat spots over 3000rpm. Changed a few hoses and swapped out the maf but no difference.
My question is can pump timing effect or give flat spots? It is out showing 1.37 on vida.

[Baffler]

You're a little advanced there so ideally you'd need to get it to the desired 0.5° sweet spot, although, I don't think being 1° advanced would cause flat spots.

A few things spring to mind. I know you said full service history but when was the fuel filter last changed?

Why did the TCV fuse blow? Try cleaning the TCV with carb cleaner and, once dry, get some PTFE spray through it to prevent it from sticking.

Did you check the condition of the rubber hose from the MAP sensor (located on the OS strut turret) to the inlet manifold and make sure, where it's connected to the manifold, is clear of carbon.

The replacement MAF sensor...was it new or second-hand?

[Martin Cox]

It certainly won't do any harm to get the timing correct although if it's starting well and otherwise running OK it can't be that far out. However it is quite critical and even small errors do have a noticeable effect on starting and performance. If you have software that can read the timing, it's not a difficult job to adjust it. To be honest I don't know if a timing error would cause flat spots or just an overall deterioration in performance.

Martin

1998 V70 Tdi auto 227,000 miles

[wagonwheels]

Thanks for the reply guys. The hose to the map was rotten so I changed it. When looking at requested vs actual boost the actual is lower and never makes target. I now have a roverron box on and it seems to make target and some (by product of extra fueling I guess)
I've a replacement map and tcv coming. The tcv fuse had blown because the intake heater device has died and runs the same fuse.
Because it has a new turbo fitted,is it precalibrated for boost or can it be adjusted?
Ive a dawes device that's going on but I'd rather it was running 100% regarding boost control before upping it.

The maf was secondhand and still has the slight flat spot (holding back) and seems to fuel harder too.

[Baffler]

It's not too far out by the sounds of it, as Martin has eluded to, but can you confirm the cam was set in relation to the crank when the cam belt was replaced?

The RonBox is probably compensating for the discrepancy you're seeing in boost and fueling so I'd certainly remove it temporarily, and any other upgrades, until you have it running 100%.

I can't remember now, me auld walnut isn't what it used to be, but isn't the RonBox fitted between the pump and the multiplug? The multiplug itself can create issues due to oil contamination so try some contact cleaner here an insure the sealing gasket is sitting square and plug goes all the way home.

Also check the condition of the wire going to and from the needle lift sensor on injector 5 as it can get damaged/worn against the injector pipes.

A new TCV would be a wise move and with regards to the MAF sensor on the MSA15.8...I'd be inclined to fit a new sensor here too, especially since you plan on upping the power, unless you can test your existing second-hand sensors on a fully functioning car.

Just a few things to keep you busy during lockdown

Oh and have a search for Martin R Smith's, Brickman and PNut's threads. The TDI Guru's

[wagonwheels]

Thanks Liam.
I may have to bite the bullet and get a new maf to be sure. I've got a tcv and map coming so I can rule them out and get the pump timing done.

[wagonwheels]

Small update. . I've fitted a replacement tcv and map with hoses. It now pulls very well and most importantly its smooth to the redline.
While testing full throttle boost in 4th and 5th I notice its boosting to 1.5bar! Requested was 1bar so somethings up. Ecm-0009 was the code from vida.

[wagonwheels]

New tcv , map and maf fitted along with new vac lines and its still hitting limp mode at 1.5bar above 3000rpm. Really annoying now... I did notice the new turbo has the old actuator/wastegate on it!! This was because (I have now found the other wastegate) that the nipples been snapped off the end of it that does to the tcv.
Tcv is operating as it should but under full boost its showing 97% duty but still the boost climbs.
I put a vac line on the wastegate to make sure I could hear it move and it can be heard moving...
Struggling for ideas now....would a partially blocked cat cause this?

[wagonwheels]

Thanks to baffler. I just checked the map pipe nipple on the end of the manifold to check for carbon....I though it would be fine but on carefully sticking a drill bit down it I found it fairly clogged with soot and carbon.
Interestingly the live boost data showed lower than desired boost on light throttle then higher once boosting hard...I'm guessing when pressure is forced into the map pipe passed the restricted nipple it can't back feed and gives a false high reading.
I'll drive it some more to test it out.