Scott.T

iTrader: (2)

Layout on Page 11 updated with latest info.....

Hanslow

Scott, thanks for the offer. Not ready to build it yet, I have to work up to these things

Will drop you a line nearer the time about the bits.

Cheers

Steve

MY02

I have been following this thread with great interest.

I have a MY02, which I would like to increase the boost slightly (about a 2 PSI increase would keep me happy).

I have seen earlier in this thread that one person found that fitting the fuel cut lifter increased their boost by 0.1 bar, I have also seen a post on I-club:

http://www.i-club.com/forums/showthr...hreadid=178352

I tried changing this coupling for a bigger one, which increased the boost by about 1 PSI for a fraction of a second then the boost went down to around 13 PSI and slowly, increased to standard 14.5 PSI.

I understand that this is the ECU seeing the boost is to high and compensating.

Do you think that if I used one of the circuits on this thread and the new coupling that I would get a reasonable increase in boost without having to start changing the restrictor or adjusting the actuator ?

If so which is the best (easiest) circuit, I have some knowledge of electronics along with a decent power supply and oscilloscope to test the circuit.

Thanks for any help / advice.

MY02

Chris.Palmer

John,

I honestly thought this would work http://www.analog.com/productSelecti..._296_496_c.pdf

Any comments please?

Regards,

Chris

john banks

I would say yes, the momentary peak you have will hold if you remap the MAP sensor. I am using the easiest circuit on here - a zener diode, LMC7111 and a variable resistor. You need an op amp that will take rail to rail inputs. If you want more you will have to change the restrictor, use a valve (restriction or bleed setup) or adjust the actuator. If you can build the circuit it is not hard to do the other stuff. But please be conservative with your settings - with a fuel cut lifter if you go too high you could get into untold levels of trouble!

john banks

Chris, I could not find a dual rail to rail op amp in a single package that had separate power supplies for each op amp. This is what you need because you are powering one op amp off the other - looking at the datasheet this is one I considered. You could use TWO of these to do the two op amp circuit, but not a dual op amp in one package unless I have missed some detail somewhere in the datasheet - but looking at the pinouts there is only on V+ and V- for each package.

Chris.Palmer

DOH - You're right - I' missed the blatantly obvious - Apologies John.

I'll get my coat!

David_Wallis

Scott any luck with the other?

David

Scott.T

iTrader: (2)

It's Starting to do my head in... YHM

Scott.T

iTrader: (2)

David,

Just waved the 'Adaptor' circuit under the nose of one of our design engineers, and he seems to think that it will work. We just need to get the data in the correct format.

I wasn't able to use the facilities lunch time, as some bugger was using it for work purposes. So I'll have another go later.

David_Wallis

no probs..

David

Scott.T

iTrader: (2)

Anybody want the parts for the circuit, as I can place an order but there is a minimum £10 order quantity.

I'll then post them on to U.

John, have you got the full list inc. suitable box and wire ? I can't be arsed to search through all the options.

[Edited by Scott.T - 4/5/2002 8:11:14 AM]

john banks

CC - I would love to put an EGT probe on, but I don't have a clue where to put it. I know you said the turbo, but that would be like me taking a hammer to a danish pastry. Can I pay you a visit? Some put it at the outlet of cyl #3? After the turbo seems easiest - do I just use the K- thermocouple we use for intake through a tiny hole with sealant, or do I need to have something brazed onto the pipe?

On MY99/00 ECU, just adjusting the actuator is similar to what Scott says, except it just results in peaks and each time the ECU reduces the duty cycle, but it doesn't show any evidence of learning. So yes you need the fuel cut lifter as well.

Scott, I think it would be nice to see if we can get James' design working before we make a parts list - I think is will be much better. If you still want it just say.

[Edited by john banks - 4/5/2002 9:15:18 AM]

Cosie Convert

John

The probe we use for charge temp will be no good for EGT, It's not rated high enough.

There is a probe (I posted details months ago and now forget part No) in RS. 'K' type high temp up to 1000 deg C it has a 100 or 150 mm stainless steel sheath and it's 1.5 mm diameter. Cost approx 14 pounds

I measure EGT at the turbo inlet via a pinhole drilled through the turbo. I can do this for you no problem.
If you measure in the downpipe you will see a lower temp as the turbo has done some work and reduced the heat content of the gas. You also have radient and convection losses. I believe the difference is in the region of 150 deg C but will vary depending on what the wastegate is doing !

If you get a probe I can fit it for you, it's a push tight fit althought I add some exhaust sealer to be sure to be sure.

Edited to say - John, If you can drill 1mm holes up the middle of 5mm bolts you can do this !! I'll just point you at the right bit of the turbo

[Edited by Cosie Convert - 4/5/2002 11:49:22 AM]

Cosie Convert

Just so nobody gets the wrong idea, It's not big and it's not clever to run 2 bar on a standard 95 WRX.

There is serious risk of

and a distinct possibility of

finally, depending how many bikes you out-gun, beware of








[Edited by Cosie Convert - 4/5/2002 11:47:04 PM]

Paul_H

I've found that adjusting the actuator on my car (MY99) yields good results initially, but then you're into diminishing returns i.e. I get the same boost with the actuator rod tightened by 3 turns as I do with it tightened by 2 turns, at least I wasn't able to discern any difference. So I'm going to leave it at 2 turns and reduce the preloading on the diaphragm.

If you want more boost than this then a reduction in the restrictor size is required. I think we should have a WARNING here - small changes in restrictor size have a massive effect on the held boost.

The standard restrictor on my car is about 1.1 to 1.25 mm - difficult to be more accurate at the moment. A 1mm drill passes through it with a little clearance, a 1.5mm drill is way too big to pass through.

I made up a brass restrictor with a 1mm orifice and went for a run. After warming up, I opened the throttle going onto the motorway, looked at the boost gauge and got a fuel cut before I could even get the swear words out. 1.5 Bar!! Way, way, way too much. I'm not nearly brave enough to emulate CC's Give-a-Toss meter

At least it proves that the new fuel cut works. So I've got some work to do. Those Maplin drills sound like the business, John.

Edited to add - car did not feel any faster at this silly boost level - shows that you can have a serious overboost situation and not realise it - fuel cut protection here is essential.

[Edited by Paul_H - 4/6/2002 12:17:12 PM]

john banks

It should be 1.2 as standard.

Try 1.1 and then give it a "jiggle" to make it 1.15. Then fine tune with your actuator.

I find 0.1mm == 3 PSI whereas about three complete turns of the actuator are similar.

Edit to say I just remembered there isn't a 1.1 in the Maplin kit I have. Oh well, just jiggle the 1mm drill a bit more!

[Edited by john banks - 4/6/2002 12:42:55 PM]

john banks

Not if you are careful (yes I have snapped one)

Just been out with a new setup:



The resistance ended up at 0.95K and 4.38K to be able to run 18.5 PSI on a PPP. At this level and a little higher there was no effect on today's atmospheric pressure reading of 2.33V.

If you went lower it would allow your boost level to be held for about 3 seconds and then it would pull the duty cycle back a bit.

Certainly you could not control boost with the potentiometer.

I did try to test whether it still had a fuel cut by disconnecting the wastegate, but I chickened out of holding too much boost for too long. I then put it back to standard PPP and again I did not want to hold it and wait for fuel cut. I am confident from the way it sees high boost and adjusts that it would also fuel cut if necessary, and also from bench testing.

I am going to go back to my original circuit as the one shown does work, but I am concerned about how much the fuel cut might be raised - to get a 0.3V cut at 4V you end up with 0.4-0.5V cut at 4.3V.

With the original circuit I was using the fuel cut was at 20.3 PSI by choice - only 1 PSI above the original PPP fuel cut and 1.3 PSI over maximum held boost, whereas with PPP on the circuit above you end up with a 23-24 PSI fuel cut - AND it has to be sustained for over 3 seconds. Seems too high to me.

[Edited by john banks - 4/6/2002 4:16:59 PM]

john banks

Yeah, but it don't have a 1.1! Even if it did you still might need to jiggle. Alternative is an adjustable valve.

[Edited by john banks - 4/7/2002 8:28:48 PM]

john banks

Good one Harry, sold in multiples of 5 - ideal if you bust them! Or one for a friend

[Edited by john banks - 4/9/2002 12:46:14 PM]

john banks

It uses the same op amp, is easier to build - you would just need a 470R pot or similar and a zener. Depends on what boost control method you use - if it is the factory setup I would suggest the later easier circuit. If you are using a bleed/restrictor/Dawes valve all you need to do is change fuel cut and not otherwise so the earlier circuit might be better.

The key weakness for me with this thread's general setup seems to be that you lose performance compared with a Dawes/EBC unless you lift the boost at least 2-3 PSI over standard. So on the track my top end boost will come down when I turn down the midrange. This might not be a bad thing - will think about it, but you can still slap a Dawes back on easily.

[Edited by john banks - 4/10/2002 9:13:25 AM]

Chris.Palmer

Scott,

Workshop Manual Diagnostics

Section 2-7b - Page 61 - MAP Sensor Diagnostics.

2.1v = -26.7 KPa
2.6v = 0 KPa
3.1v = +26.7 KPa

& is linear - no min & max given though

I converted these figues to PSI & extrapolated.

They should be correct, but, it would nice if someone checked, even I make mistakes (regularly)

Chris

PS - I love quoting the Workshop Manual

[Edited by Chris.Palmer - 4/10/2002 10:23:55 AM]

James_PowerMad

John,

I've not been on the Scoobynet for a while!!!

Your original problem, and some of the later observations are probably down to the diode reverse leakage current...

When the voltage across the Zener is less than Vz, you can still expect a few microamps to leak through it, especially for more powerfull ones like you are using.

With those early high resistances (20k), I calculated that approx 4.6 microamps would have been enough to cause the 0.02 v offset at atmospheric voltage (not unusual for a zener).

On another note, the business about how much current the ECU draws from the sensor... A/D converters usually draw a short sharp 'snap' of current each time they sample the input. The ECU probably does has an op-amp at the input (and some form of filter an input protection if they have any sense), but bear it in mind.

I have also been working on my boost setup recently...

I have expanded my EBC so that it re-synthesises the MAP voltage to send to the ECU, rather than simply T'ing into the MAP line. It can be commanded by its RS232 MMI interface to set a particular MAP offset pressure (the system is linear up to 3 psi, and then flatlines at 3 for the programmed offset, then continues linearly up, hence increasing the set-point, and fuel cut by the same amount).

Results:
I set the MAP offset to 3 psi, and set the boost target to 18 psi. On testing, 18 psi was what I got (without any fuel cuts), but I can't say that I really noticed an increase in acceleration, but just an increase in whining noise (like the turbo was labouring more).

*EDITED: This is compared to the approx 14.5 psi that my MY98 ECU gives me as standard.

I guess I should benchmark the acceleration properly (rather than just how it feels).

When I set a MAP offset, but let the ECU control the boost (by putting my EBC in bypass mode) the ECU does NOT seem to adapt by increasing the boost - John, you were right about that.

[Edited by James_PowerMad - 4/10/2002 6:02:26 PM]

john banks

Sounds a good circuit James - can you post details for interest?

I will probably go Ecutek custom mapping in the near future, but until then the circuit you inspired is the business and it is **MUCH** quicker at 19 PSI than 14.5 (MY00) or 16.5 (PPP).

[Edited by john banks - 4/10/2002 6:12:33 PM]

James_PowerMad

So, do you really *NOTICE* the difference when you increase the boost by 3 or 4 psi? - I mean from a g-force perspective.

I certainly don't!

Could it be that your PPP ECU is making better use of the extra boost (fueling / timing etc)?

None of the other supposed 'noticable power increase' mods (Magnex BB, and ITG filter) have made any difference IMO. Perhaps I'm just insensitive!

Well, I now have a ScoobySport DP on order, and I hope all you de-cat ravers are not exagerating when you mention your massive power increases, 'cos I'll be mildly annoyed if it doesn't kick a*se! ;-)

As far as my EBC is concerned John...

It is a PIC 16F877 microcontroller programmed in C. It has a command line interface via RS-232 (I keep my old Psion 3a in the glove box!) It can do:

Active boost control / 'soft' bypass of ECU signal through to solenoid

Logging of Timestamp, RPM, TPS, MAP, Lambda, ECU duty ratio, EBC duty ratio (down the RS-232 to a laptop, then to Excel).

Modifications to all boost control parameters (spool-up compensation stuff / held target pressure) via command line.

Store all user parameters / learned stuff to FLASH memory.

Binary RS-232 command mode for 'live' electronic gauges - I have programmed a live boost gauge on the Psion 3a, which I occasionally hook to the dash!

And finally, this last weekend I added the MAP signal re-mapping functionality.

EDIT: Whoops, grammar!

[Edited by James_PowerMad - 4/10/2002 7:45:13 PM]

john banks

Yes I find 1 PSI across the range noticeable. 4 PSI makes it a completely different car.

How does your active boost control work? Can you go into more detail?

David - a bit of both might be required to get the right results - actuator is more precise if your heatshield is easy enough to get off. The restrictor is in the pipe from the turbo outlet to the T-piece.

[Edited by john banks - 4/10/2002 8:33:41 PM]

David_Wallis

I also found the following site which may interest john http://www2.arnes.si/~uljfer3/elect/e_search.htm found this whilst looking to see if there were any equivalent op amps that maplin sold..

The op amps order code from farnell is 641443 if anybody needs it.

David

Edited to say that I have ordered samples from national semiconductors...


[Edited by David_Wallis - 4/11/2002 10:42:41 AM]