The old limp home mode again

[sssstew]

yep agreed with mutley (as usual )

taking away the crank case breather involves using a catch can, have a search back through for this as its been discussed alot before, in the tdi and tdi tuning sections.

 

[Robb1990]

cheers. dont know if its placebo, but it does seem quicker with the swap over of valves. Going to get the wastegate free'd off next and see whats what.

 

[Muttley]

I'm probably nitpicking, but you don't have a wastegate, you have a VVT turbo which varies the inlet geometry instead. They are sized to allow max boost at max rpm with the inlet vanes wide open, and the vanes close down progressively at lower revs to keep the gas speed up (and thus the turbo speed as well) so keeping the boost at or near max over most of the rev range.

 

[Robb1990]

Yeah shouldnt of said wastegate really. Should of said vane actuator.

 

[davered]

Hi I started this thread about my car it’s been running great for about a week now after a couple of hiccups in the first few days, the last thing that was done was a new map I don’t know if the last couple Times it happened have down to me over revving in 3 rd gear trying to get the problem to reoccur. Anyway I see somebody on about a vvt turbo variable vane turbo if been told by various mechanics plus the vw specialist that fit my new turbo my car Leon tdi 110 se y reg 2001 defiantly does not have one of these it has a standard turbo

 

[Muttley]

Oh, yes it does. Typo on my part, mind you - that should have been VNT turbo, but my description, variable inlet geometry, is correct. This is the distinguishing factor between the TDI 90 and 110 which are otherwise very similar non-PD engines. No wastegate, variable inlet geometry.

VVT is usually taken as Variable Valve Timing, which the TDI's don't have.

 

[davered]

I was told by the mechanics it doesn’t have any vanes it has a waste gate actuator on the turbo this sticks and rusts up from lack of use driving round like a nanny or age, I freed mine up a few times by going up a hill getting in to 5 th gear and flooring it then taking my foot of the accelerator causing the valve to fully open and then close but it just sticks again now have a new turbo on

 

[Muttley]

This is the kind of turbo you and I have on our TDI 110 engines.

The animation at the bottom shows better than any description how the vanes close up the inlet geometry while keeping gas flow well streamlined.

Now, if you have a wastegate turbo then you have a TDI 90 engine, not a 110. What is your engine code? Should be AHF or ASV for a 110, AGR or ALH for a TDI 90.

The "Italian tune-up" process you describe is often effective in freeing up stuck vanes, it gets the turbo good and hot and can burn off enough soot to get rid of the problem. One thing to note, though: The vanes are closed at low revs, so that the lower volume of exhaust gas is forced to speed up, spinning the turbo faster, fast enough to give significant boost. The extra back pressure is more than compensated for by the power boost from the turbocharger. As revs rise, more and more exhaust gas is produced and the vanes open up to keep the turbo spinning at the right speed to give full boost for the inlet gas flow.

Wastegates, on the other hand, stay closed until you reach higher revs, then open to spill some of the exhaust around the turbine and avoid overspeeding it.

Both systems are actuated by vacuum servos which look very similar.

 

[davered]

This is what it says at front of my inspection and maintenance plan book (1M1 524 LEON 1.9 TDI SPORT ASV EGS) I believe you I have seen the animation before as I have been looking in to all this for over twelve months now, what can I say where do you find a mechanic that's not just interested in taking your money?

 

[Muttley]

Me personally? The Motorist Center outside Canterbury, former SEAT dealer now independent. Small operation, know the blokes to talk to, used to get my Ibiza serviced there in preference to the SEAT dealer in Maidstone. Bought the Toledo from there.

The two-man village garage 10 minutes walk from me is good for general servicing (anything that needs a ramp and/or special tools), MOT's and the like. Again, I know the guys, they live in the village.

 

[Janimal]

has anyone actually managed to fix this over boost problem?? I have it too on my 2001 se110 and have taken it to a tuners and was suggested a remap to cope with overboost. BUT will this actually fix the problem or just hide it for a while????????????? I want a real perminant fix!!! ANY REAL IDEAS? However since taking the turbo off to have it clean a few months ago (did nothing still have the problem) I did see that the inlet manifold was full of sticky black gunk! Did my best to clean it but did not clean the egr valve. This maybe needs a clean and maybe will sort out the problem. Read Muttley Catch that diesel!


Join Date: Mar 2006
Posts: 483 Sticking EGR valve and clogged inlet manifold.

Crankcase breather vapour (oily, fed into the inlet system just downstream of the MAF) combines with exhaust gas (hot, sooty) to gradually cake the inlet system downstream of the EGR with a sticky coating that builds up. This on its own restricts the inlet manifold and makes for higher inlet pressures as the system tries to deliver the correct mass of air through a smaller set of tubes. The clag builds up on the EGR valve too and causes it to stick instead of shutting as revs rise. This allows exhaust pressure into the inlet at higher revs. which the ECU reads as overboost

 

[Robb1990]

To do a proper job everything needs cleaning imo. Clean the EGR, Inlet manifold and the inlet ports. its time consuming, as you have to go to each cylinder, get it to TDC so both valves are closed, clean the carbon out and then blow ALL the loose stuff away with an air line. Then you have to go to the turbo side, give that a clean up. Then the intercooler should really be cleaned out to prevent any more oil residue coming back along.

Id then do the CCV mod, to take away the oil vapors, and either turn the EGR right down, or take away the VAC feed. which may or may not bring on CEL, my ASV engine doesnt bring on CEL after removing the connector to the N18 valve so id assume if i block the VAC feed to it, CEL wouldnt appear, but im yet to try this.

Carrying out both of those will see a dramatic improvement imo. obvously, if the CCV and EGR are left, then the oil/soot will build back up in time and need to be re-done.

 

[Janimal]

Thanks for the answer but now I feel a wee bit dim - what is TDC and CCV. Also is there anything I can put into the air flow that would help to clean the insides?

 

[Robb1990]

Top dead center, refering to the piston position in the engine. CCV is crank case ventilation, this is the small breather/diaphragm that sits on top of the rocker cover and vents blowby gasses back into the intake to be re-burnt. Due to its position, it just clogs everything up including the intercooler, turbo compressor vanes, boost pipes inlet manifold and EGR.

Ideally you will want some kind of catch tank to replace this system, so just take a pipe of similar diameter to the outlet of the diaphragm, send it into the top of a plastic/metal canister, you will also need another hole in the top of the canister to attach a small filter, this will prevent excess pressure building in the crank case bust still allow the oil to be collected. Then with the remaining hole on the intake pipe, use a rubber bung and clamp around that to seal off any unwanted air into the intake pipe.

 

[Janimal]

Finally managed to get my leon 110tdi on a rolling road and measured 122 bhp not having had it modded. I'm presuming that this is the cause of my 'limp mode'. Have changed the N75 and N18, MAF and MAP and had turbo cleaned by turbo technics twice!!! Have given the inlet manifold a 'rough' clean too and we're still going into limp mode and the 3000 rpm marker. What do you think would be next best step? Thorough clean or engine eMapped?

 

[sssstew]

122bhp for a 110 on the rollers is normal, i know an old ibiza 110 that got 128 on the rollers as standard. The old non PD TDIs always did more than they said on the tin.

If its still going into limp mode after all youve done then a remap wont help, the standard map will be fine, your going to have to look for other reasons like split boost pipes perhaps.