Bucket o' turbo lag

[benchrisfennell]

There's a governor that limits the engine to 5000rpm which is a reasonable maximum for our engines with our fuel's combustion rate. Higher cetane rated fuel may allow for a slightly higher RPM and I believe that the Audi TDi race cars rev to around 5500rpm, but with a burn rate as slow as diesel is, revving it any faster would cause the fuel to still be burning forcefully as the exhaust valve opens (there's always some residual burning).

With that said, I agree with you. 4500rpm is a lot - and to get those revs, you're dumping a considerable amount of fuel into the motor. I'll take a look at mine later and see if I can get a reading on fuel rail pressure and flow rates at those RPM.

In this situation, I wonder if any DTCs are being generated? Does the CEL come on?

True tony. I rev mine around 2000/2500 for gear changes, maybe 3000 max if i have ever had to do a quick overtake. Even at 3 grand i. Cringing my teeth.. Then i pat the dash and say good girl. My truck i drive at work a 60 series detriot is screaming at 1900 rpm lol pull 60 + tonne no drama

 

[bods]

True tony. I rev mine around 2000/2500 for gear changes, maybe 3000 max if i have ever had to do a quick overtake. Even at 3 grand i. Cringing my teeth.. Then i pat the dash and say good girl. My truck i drive at work a 60 series detriot is screaming at 1900 rpm lol pull 60 + tonne no drama

Those detroits love their revs... We've got a truck at work with a semi auto series 60 detroit and it will go to 2000rpm between changes if you stick the boot into it hahahah

Still doesn't move anywhere though lol

 

[nuckin futs]

we had detroits on a couple of the pumps on the drilling rigs a few years back. rev their rings out and man, did they pump water

 

[benchrisfennell]

lol wish I could put a detriot in the nav

 

[bods]

You can keep your detroits hahahha.. give me a cat.. so much nicer to drive..

 

[MC_D40]

OK first post here, and this is the issue I'm having aswell.

so to bring you up to speed with my Nav..

2007 STX T/D, Manual - Spanish Built
Plazmaman hotside pipe
EGR Block Off
K&N Panel Filter (For Road Use - switch it when going off road ie Hardly ever)
YD25 Double Row Timing Chain
Direct Clutches H/D Clutch and SMF

the Car started having the boost issue this afternoon (was fine this morning)..
picked the kids up from school and on the M1 noticed that it was like driving a 12A with a TA51 on it (yeah I'm a rotorhead among other things). except it didn't kick you in the back and wheelspin down the highway at 160kph...

In the previous week popped cooler pipes off on 2 seperate occasions... replaced hose clamps and haven't had the issue since.

Boost guage was creeping up and peaking at about 15psi... nothing more, car was still able to rev but restricted/constipated.

So what I've done so far...

Checked actuator.. seems to be moving as per normal.
flushed intercooler and dried
cleaned MAF sensor (was still mint from clean a month ago)
cleaned air cleaner (as with MAF, still clean)
Cleaned throttle body with T"body cleaner and let dry out
reinstalled all parts that I removed/cleaned

about to kick it over and see what happens while warming it up.
from there if it seems ok will do a reset on the ECU.

fingers X'd, here I go

 

[Old.Tony]

Welcome to the forum!

I'm guessing from reading your post that you're experienced enough to know about over-oiling a K&N and what that can do to a MAFS, so you don't overoil it.

For the readers who don't know: too much oil causes the filter to shed droplets of oil, which are normally combusted by the motor and unnoticed, but every now and again one falls inside the MAFS. This is where it gets tricky.

The MAFS works by measuring resistance across a hot wire. As the passage of air cools the wire down thus changing the resistance of the wire, a change in that resistance means a change in air volume passing the sensor. Oil landing on the wire will burn and form a nice hard black shell that won't always wash off (destroying the MAFS, effectively) and won't be visible as soot when you clean it.

When you say "car was still able to rev but restricted", do you mean that it seemed like there was a limit to the RPM? Or did it rev freely, but took some time getting the revs up?

If it freely revs and takes its time it's likely to be air delivery. If it's limited in RPM, it could be the SCV which will inhibit engine performance. We've also seen similar responses with crushed fuel hoses (from tank removals) and dirty fuel pickups inside the tank.

Air delivery - a lot of the things you've checked, but also pay attention to how good your brakes work (vac leak in the brake booster), how firm/brittle the vac hoses are (can cause small vac leaks = poor response). If the actuator looks like it's moving in and out the solenoid is probably ok, but a reduced vacuum would result in a reduced change in the vanes = less air.

I doubt the ECU reset will do a great deal if your peak boost is only 15psi, but it's always worth trying and always harmless unless you've lost your radio PIN!

 

[MC_D40]

Cheers for the warm welcome Old.Tony,

Yeah well aware of the effects of over oiling and am very careful of it for that reason.

it seems to rev freely, but restricted.. which led me to think it was intake side or possibly blockage in the exhaust, but that seems unlikely.

I'm yet to start it after doing what i had previously mentioned as I'm just cleaning up some wiring that was already in there, but should be firing it in the next 30mins..

I'm inclined to replace all the vacuum hoses before I consider looking more deeply at the turbo, as I see all those factory heat shields and they make me cringe. (pet hate when I was working in the automotive industry)

I'll diagnose further and let you know what comes up..
I considered that it could be the SCV, but from my readings it doesn't seem to be the case.
although it's once again something that I will visit before replacement turbo is considered.

 

[Old.Tony]

The SCV usually presents itself in an unannounced limp mode - you can't do more than 2000rpm/80km/h but no CEL. If you DO suspect the SCV, cleaning it would be the first step.

Does it blow smoke? That will help. At night you'll see SOME smoke in the headlights of the car behind but those cars shouldn't disappear in the cloud. If there's a lot of smoke and/or you can smell diesel in the exhaust, I would suspect air delivery. If there's not a lot of smoke, the air could be fine and it could be fuel delivery.

Now, that could also happen if the CAS was slightly out of alignment. How does she idle? Easy start + smooth idle = highly likely the CAS is good.

 

[MC_D40]

OK, here's where I'm at thus far.
rewired the spot lights and everything re-installed.

fired up and checked.. W/G actuator now is NOT moving (bobbing away like usual)

went for a drive around the block regardless.
found that it will willing rev to 4000rpm, but will only hit max 15psi boost.
this should negate the SCV and the CAS. (car starts and idles beautifully)

As per afternoon drive after checking the I/C pipes, it blew quite a lot of smoke, more than usual (it's actually not very smoky at all with the EGR block off and Catch can installed)
unable to see this evening as no cars to gauge from, but imagine it would have been the same as it was behaving the same.

Tomorrow after doing the school run (in the astra). I'll go and get some new silicone vacuum hoses and replace them all.

I have seen forefront industries sell a Billet compressor wheel turbo, but I still view this as something that I will only do if completely necessary along with a new intercooler, 3" exhaust and tune (do it right, and get the results).

 

[Old.Tony]

Definitely sounds like air, and definitely sounds like turbo vane control. Don't worry about wastegates, the D40s use a variable vane turbo - no wastegate. The actuator controls the vanes, which direct/deflect exhaust gas as needed to change the speed of the turbine.

I'd replace the vac hoses first too, even if the turbocharger is replaced those hoses won't be wasted. From memory you need about 3m or so, the solenoid is attached to the back of the intercooler's hard intake pipe, the line runs up and over the engine to the vac pump and there's a hose that attaches to the brake booster too.

 

[MC_D40]

OK, remedied..

replaced the vacuum hoses and all is well, actuator was working fine again..
on inspection of the original hoses found that none were obviously split but they weren't in great condition.

Hope that my little adventure and diagnosis will be of help to some others..