Stop Screw Adjustment 1749VC Hybrid

[S10EAT]

Another quick question for someone that might be able to shed some light on this.

I've been trying to adjust the stop screw on a hybrid 1749VC turbo.

In basic settings for group 11 between on and off for actuator test I get 984 vs 1128 so a 144 mbar difference.

My question is I have tremendous lag up until 3000 rpm, do I need this figure to be smaller i.e nearer 80mbar or 200 mbar for boost response to be better?

Many Thanks in advance,

S10EAT

 

[Dan FR]

Closer to 200 will yield better low down response.

 

[S10EAT]

Thanks for that Dan!

 

[Dan FR]

No problem, have you had it mapped since? Have you done a full throttle log?

 

[S10EAT]

I'm in the first stages of mapping but even after using a few versions of the new map file I still have crap response until 3000-3500 rpm, I mean like feels 100 bhp until that level! makes pulling away from junctions and traffic lights a nightmare!

I've done many 011 logs since first starting the mapping, can't work out what the problem is, also tried various lengths of the actuator, currently set up for just under 70% duty cycle @ 4000 rpm (needs tweaking slightly shorter. But I have had it more like 80-85% (abit shorter) and it made not alot of difference to boost response low rpm and had boost spikes.

 

[S10EAT]

Here's one example of a 011 log I've literally just done.

1386 1380 1104 21.5
1365 1716 1176 21.5
1386 1752 1248 25.1
1428 1800 1320 23.9
1491 1884 1380 23.9
1533 1932 1428 24.7
1575 1980 1476 24.7
1617 2040 1500 24.7
1680 2112 1536 25.9
1743 2172 1572 27.5
1785 2232 1620 26.3
1848 2292 1656 27.9
1911 2340 1704 26.3
1974 2364 1752 24.7
2016 2388 1800 25.9
2100 2412 1836 25.5
2142 2424 1872 24.7
2205 2448 1920 25.5
2268 2472 1956 27.1
2331 2472 2016 29.5
2394 2484 2124 35.5
2478 2496 2208 38.6
2562 2496 2280 42.2
2646 2496 2352 47.4
2709 2496 2388 49.4
2793 2496 2460 54.6
2856 2496 2496 56.2
2919 2496 2544 60.6
2982 2496 2580 64.1
3066 2496 2616 67.7
3129 2496 2652 71.3
3192 2496 2688 76.1
3255 2496 2724 80.1
3339 2496 2736 82.5
3402 2496 2664 80.5
3486 2496 2508 77.7
3570 2496 2364 73.7
3633 2496 2268 69.3
3717 2496 2208 66.1
3801 2484 2184 65.7
3864 2472 2196 65.7
3927 2460 2220 66.1
3990 2448 2244 66.5
4053 2436 2268 66.9
4137 2400 2280 68.1
4200 2376 2280 67.7
4263 2352 2280 67.3

 

[Dan FR]

Are you mapping this yourself? Have you logged fuelling (008)? and if still running the smoke limiter, the MAF readings (003)? If it's not getting enough fuel you will struggle to build boost.

That log looks awful, turbo just does not want to spool, i bet it's even slower than standard with that much lag. Boost control isnt great either but that can be tidied later, scope for more boost aswell.

 

[S10EAT]

Dan,

Did a log of the IQ a while back, you are right it doesn't look like I'm getting enough fuel between 1400-2700 RPM.

Engine speed IQ driver's req IQ via rpm(Torq) IQ via MAF
2850-3150 65-70 52-54 52-60
/min mg/R mg/R mg/R
1470 0 46.9 25.5
1428 69.7 43.4 37.6
1554 69.7 48.9 36.2
1617 69.7 50.5 37.1
1680 69.7 51.6 36.2
1743 69.7 53.3 36.8
1827 69.7 54.9 39
1890 69.7 56.5 39
1932 69.7 57.1 38.7
2016 69.7 56.3 40.9
2079 69.7 56 41.5
2142 69.7 55.7 40.9
2205 69.7 55.5 42.3
2289 69.7 55.2 42.3
2352 69.7 54.9 48.6
2415 69.7 54.6 50.8
2478 69.7 54.4 52.4
2541 69.7 54.4 52.4
2625 69.7 54.1 52.7
2709 69.7 53.8 54.4
2772 69.7 53.8 54.9
2835 69.7 53.8 54.4
2919 69.7 53.8 55.5
2982 69.7 53.8 53.8
3045 69.7 53.8 55.2
3129 69.7 53.8 53.8
3192 69.7 53.8 56.3
3255 69.7 53.8 56.3
3318 69.7 53.8 56.3
3423 69.7 53.8 56.3
3486 69.7 53.8 56.3
3570 69.7 53.8 55.5
3654 69.7 53.8 52.4
3717 69.7 53.8 51.1
3801 69.7 53.8 50.8
3885 69.7 53.8 50
3948 69.7 53.8 50
4011 69.7 53.8 50.2
4074 69.7 53 50
4137 69.5 51.3 49.7
4200 69.2 50 49.1
4263 68.9 48.6 49.4
4305 68.6 48 48.9

What do I start to look at? Injector seals were replaced in April. Could this be tandem pump related?

IQ balance is within spec +1.67 on injector 4 being the highest.

Thanks,

Dominic

 

[Badger]

Nothing to do with seals, that looks like a mapping issue with fueling.

 

[S10EAT]

Thanks Badger!

 

[Dan FR]

Sorry mate, missed your reply. Have you checked MAF readings?

Difficult to say for sure, fuelling will likely be due to low MAF reading due to lack of boost. Have you adjusted the stopscrew any further? Stil 150mbar difference in the group 11 test? Have you checked the actuator is moving the VNT mech correctly? one swift smooth motion, with the actuator help open/closed without any creep during the group 11 test? Is there anotable change to the engine/exhaust sound during this test?

It could well be a mapping issue though, how much have you changed from the standard map? happy to have a look if you want to send me a copy

 

[S10EAT]

Dan,

No worries, thanks for the reply.

I'll do a fresh MAF log at lunch and post it.

From looking at the IQ log would you say my tandem pump is ok? I know it's leaking at the head/pump gasket at the moment, would the gasket leak cause loss of vacuum?

Can't seem to find an answer to that question anywhere!

Thanks,

S10EAT

 

[Dan FR]

Impossible to say regarding fuel, the fuelling logs only indicate what the ECU thinks it is injecting based on the map and how long the injectors are active. If it's only a minor leak then this is unlikely to be a problem (aside from the obvious leaking of fuel!)

As for loss of vacuum, i have no idea. If you check the actuator is fully opening/closing (and holding) during a group 11 test you can rule this out as an issue until you get it fixed.

 

[Badger]

You had any more luck with this?

 

[bilko]

i have the same issue on my caddy van with a pd170 hybrid.

had it mapped but the tuner never adjusted the stop screw.

lag and plooms of diesel reek upto 3k and then it starts to go well.

made 190bhp but terrible to drive and often underboosts going up hills and hits limp mode.

 

[daytona246]

i have the same issue on my caddy van with a pd170 hybrid.

had it mapped but the tuner never adjusted the stop screw.

lag and plooms of diesel reek upto 3k and then it starts to go well.

made 190bhp but terrible to drive and often underboosts going up hills and hits limp mode.

Who mapped your car mate? I seem to have the same issue on my ibiza. did it ever get resolved?

 

[S10EAT]

UPDATE: Sorry for the late reply, thanks for your posts.

I ordered a vacuum gauge to check the vacuum output of my tandem pump, tested today at the tee piece off the main pipe and was getting 27-28Hg of vacuum which from what I've read is plenty.

Next step is to get the car on some ramps and remove the snapped stop screw (don't ask!) and replace and then adjust to be shorter and get it nearer 200 mbar (currently 144)

I've had a few more map revisions sent by my tuner but boost is still not meeting requested, which leads me to believe the only thing I have left to check is the stop screw.

I really do wish these turbos are set them up with the proper vane gap before they are sent out to customers.

Any one else had any progress with theirs?

Thanks,

S10EAT

 

[Dan FR]

Ive never seen a re-con turbo set up correctly, doesnt suprise me at all

Are the map revisions any good? i.e. tuner knows what hes doing yeah?

 

[S10EAT]

Dan,

Yes, I believe him to be a tuner of experience and a good reputation.

Below is the latest map boost log:



What do you think of the boost?

Thanks,

S10EAT

 

[Dan FR]

Looks absolutely terrible to me, specified looks about right, actual is terrible, huge underboost then overboost with no control. Why haven't you plotted the N75 DC? Need that to see what the ECU is actually trying to do