Why's my beetle defying physics?

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
bazibbo
Posts: 63
Joined: Sun Nov 06, 2011 1:04 pm
ECU Model: S40 Pro
Location: East Yorkshire

Re: Why's my beetle defying physics?

Post by bazibbo »

Yep sorry meant closed loop... Brain / hand / typing issue Stevie! (Get more of those recently)

I'll borrow a gauge and get the compression test sorted Drew. Cam timing shouldn't be out, think its a line up the dots job on a beetle.

Did a bit of work on the engine breathing tonight, not helping the issue at hand but should stop some of the oil leaks. Oil change tomorrow.
bazibbo
Posts: 63
Joined: Sun Nov 06, 2011 1:04 pm
ECU Model: S40 Pro
Location: East Yorkshire

Re: Why's my beetle defying physics?

Post by bazibbo »

A quick interim report.

Well things are looking quite a bit better than they did at the last rolling road session last year. We think, or I'd like to think that the work I did on the fuel supply had sorted the issue. Most, though not all things got checked due to time constraints, but ignition and fuel pressure were spot on.

There's a little more work to do on the rollers, we didn't get up past 4000k and I think there's a few light throttle glitches to sort, but things are looking up.

Image


Image

The fuel compensations aren't a million miles off, or at least a big improvement over the previous ones.

Image

The retard shows a big improvement too... I've not shown you the ignition advance map (!) but we're certainly not retarding it by up to 50% as before.

I need a bit more work on it, then I'll probably lift the boost to 1 bar and try to get to my 150 at the wheels target. No power run as things weren't finalised, but I should have one at the next session.

Oh and yes, I was totally wrong with the intake temperatures Stevie... never rose above 28 degrees.
stevieturbo
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Re: Why's my beetle defying physics?

Post by stevieturbo »

Now obviously there are many ways to achieve an end result, and I guess the numbers up there...well, if the end result is ok, then it shouldnt matter.

But there is still a right and wrong way to do things.

The engine should have been tuned normally aspirated, using the TPS vs RPM table, with compensations set to standard. ie 100kpa SHOULD be 0%
80kpa -20%, 60kpa -40% and so on etc
Certainly as far as 100kpa, ie atmospheric goes, I can see no logical or sensible reason that this is not 0%
It would suggest to me that the main TPS vs RPM map has not been tuned correctly, which may then have a knock on effect elsewhere.
Of course, varying compensations in the other map could then try and correct that...not the ideal way to do things though. 2 wrongs dont make a right.

Now looking at the table above, it is fairly clear that has not been done. That isnt to say the end result isnt ok though, but for someone who looks at that map, it will still look wrong.
Again the problem using TPS and compensations...is one map only tells a fraction of the story. Both maps need to be looked at to get a picture of what might be happening.

As for timing...IMO that map is rather strange unless you havent actually went over 0.5 bar boost yet. Hence all the numbers above are the same ?

Those compensations will just be applied to the 100% TPS column on the main map. So it would be unusual for 150-180 all being the same, and even stranger for the 200kpa row to retard the timing by a smaller amount.

At 100% throttle or 150kpa for example....how much timing do you actually have ? on and off boost

It's a pity the S40 doesnt datalog, as it would yield very useful information to see what is actually happening at the engine.
Rob Stevens
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Re: Why's my beetle defying physics?

Post by Rob Stevens »

Fully agree with Steve here, 2 wrongs don't make a right, this is a crazy map and will be a nightmare for anyone else to try and fix.
Please, please just set fuel compensations to standard. I'd also keep away from the twin pressure compensation maps. what if all of a sudden your engine comes on boost at 1500rpm, the fuel map is wrong. Also the correction should be 0% at 100kpa and 100% at 200kpa, this isn't a black art but basic physics.
bazibbo
Posts: 63
Joined: Sun Nov 06, 2011 1:04 pm
ECU Model: S40 Pro
Location: East Yorkshire

Re: Why's my beetle defying physics?

Post by bazibbo »

They did tune the TPS vs RPM N/A map first and then the compensation maps.

Literally removing the turbo inlet, restricting it and pointing it elsewhere and only then did they start on the 2 boosted correctors - advance and fuel.

I do totally agree... its odd that the basic physics isn't coming up as I'd expect it to and when everyone else is telling me the aircooled turbos run as per anything else.

I think this goes back to my original question.. why? Is it simply a case of incorrect mapping or could the problem not be a problem, just very odd engine charactoristics caused by a leak under boost or something else. I think the answer I'm getting off the opperator is that despite the physics of it.. the engine is demanding it.

Again the problem is that I don't have the knowledge... I have to rely on the rolling road opperators to sort it. And believe me, I'm as frustrated as you all most probably are :cry:

Bear with me...
Rob Stevens
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Re: Why's my beetle defying physics?

Post by Rob Stevens »

It's just an engine, nothing special about beetle engines, just why make it so complicated with those compensation maps, at 1.3bar the corrections range from +40% +70% and back to 50% I don't believe you can accurately map it like that, I don't think the compensation would change 20% in just 250rpm unless the fuel map is wrong in its self.
Also I wouldn't recommend running with the turbo air pipe disconnected, this can lead to turbo over-speeding with disastrous results.
bazibbo
Posts: 63
Joined: Sun Nov 06, 2011 1:04 pm
ECU Model: S40 Pro
Location: East Yorkshire

Re: Why's my beetle defying physics?

Post by bazibbo »

They fitted a restrictor, something along the lines of a 'big' socket to stop the turbo spinning up.

They are big jumps aren't they! I'm back these for some work in 3 weeks, though I'm gonna call as I drive past and pose some questions.

ta guys
stevieturbo
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Re: Why's my beetle defying physics?

Post by stevieturbo »

I would seriously consider finding a tuner that is competent.

As I said earlier, I have huge concerns about what they were doing the last time. Now after reading more...I have even bigger concerns. Given how things have "progressed" so far, I would NOT be going back near that place again.

Have they ever tuned any engines before, on any brand of ecu ?

And as for tuning n/a, simply unbolting the wastegate flap so it's lying open should be safe enough. But really, tuning MAP vs RPM would have the job done in no time, and be far far far easier to do. Even for the person who is trying to tune the car at present.
stevieturbo
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Re: Why's my beetle defying physics?

Post by stevieturbo »

Sent a PM about a guy sort of in your area who is familiar with DTA and can tune cars.

I really cant see any reason to go back near the last place, unless it's to get a refund !

Out of interest. How much dyno time has there already been and paid for ?
Rob Stevens
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Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Why's my beetle defying physics?

Post by Rob Stevens »

DTA recommends if using RPM/TPS with compensations (set to standard) that the main fuel map represents the on boost situation, so no need to map as a NA engine.
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