Gridlock Mikey

*NOT A RANT OR A DIG, JUST LOOKING FOR SOME POINTERS*

Had TEK3 done to my MY00 UK car, all is well and i'm lovin the extra shove, however after about 400 miles, I have identified an "issue" that I wondered if it could be resolved mechanically or do I have to go through the aggro of being availiable at the same time as the mapper!

SYMPTOMS

1st, 2nd, 3rd gears, excellent, car flies and I see 18PSI on the old boost gauge
4th and 5th, incredible on Wide Open Throttle (WOT) and ok if cruising. If however I am say doing 80mph on the motorway and want to pull out to overtake, I either gradually apply pressure to the accelerator or if circumstances dictate I apply WOT. The car leaps forwards, turbo starts spooling and speed increases.
If I then, once upto the required speed to overtake, hold the throttle at say half way, the boost "hunts" like a ba5tard. I will see 20 PSI, the ECU retards the boost to say 5 PSI then it builds back to say 15, back to 7 upto 16 down to 8 and then holds at about 10. This all happens with the throttle held in one position.
It also happened on a long sweeping left hander joining the motorway (A50 at Jct24 of M1 for those that know it) Fab bend, can be done at 80mph but you need to "feather" the throttle, couldnt do it today cos me boost was all over the shop.

The symptoms are the same as if you had too smaller restrictor in your boost plumbing except it's not at WOT that the boost is being retarded, it's when you are at half throttle.

I refitted my recirc OE dump valve as It was suggested that my Forge VTA could have been leaking, but alas it wasn't the problem.

Anything else it could be do you think? Or does it seem that the mapping just needs a little tweek?

Otherwise, mightily impressed

Gridlock Mikey

TTT

john banks

Mapping needs a tweak. Sounds like the maximum duty cycles in the part throttle areas are rather high for the boost targets. This is usually a problem on full rather than part throttle but it depends on the style of the mapper.

I used to use MY99 AE800/801 style non-progressive duty cycles and boost targets so effectively the boost is not closed loop on part throttle but this makes it very smooth and easy to modulate.

Gridlock Mikey

Cheers JB

Bob Rawle

Actualy more likely a need to adjust the boost dynamics not max duty, John the 800 code was non TPS progressive the 801 code is TPS progressive. You were meaning set flat boost map values I think so either code worked at max duty on part throttle ?

Two port solenoids can exhibit this problem, sometimes the only solution is to change to a three port.

bob

john banks

AE801 is not TPS progressive (for either duty or boost target) either http://www.ecutek.com/tuning/oemcompare/ or according to the AE801 image on my laptop. AE800 and 801 had the same values in the boost control maps, there may be differences in the code but I couldn't see any practical difference in behaviour.

If the maximum duty cycles were not too high then there wouldn't be a need for changes in boost dynamics, especially not still on the standard turbo.

An unstable oscillating closed loop boost control situation is being setup because the parameters or hardware are incorrect. 99/00 boost control is weak though depending on maximum duty cycle to control peaks, turbo dynamics set low to stop oscillation never seemed to be workable to me to still have good response.

Mikey would find better control with a Dawes with the right bleed hole IMHO.

Bob Rawle

John Stevey D confirmed specifically that it was, and thats how I find it as well to be honest. The 800 rom code has a bad bug that means the tps input does not influence the boost maps at all whilst both 801 and 802 are fine. It is a boost dynamics problem, max duty should not be used as a band aid. Dawes is a band aid as well imho, no reason at all for it not to be right. If things are too lively then the three port is the last resort and does deal with it again appropriately mapped. GM is talking about boost oscillation not over boost.

No disrespect intended John, I find the boost dynamic maps are extremely useful to specifically control spool rates and overshoot.

I've only ever had one car that I couldn't fix in this way, the three port cured it though however boost dynamics still needed sorting.

bob

john banks

If you look at the tables for AE800 and AE801 though Bob you will find that the duty cycles and boost targets are flat. So an AE800 and 801 will both give the smooth control I like, but it is all down to preference. Whether AE800 then doesn't run TPS control if you change the tables (because of a fault in the actual code) I don't know, as I always tried to use newer code as advised by Stephen. I used newer code with flat tables to get smoothest results.

No disrespect either, it is different approaches again Bob - I know for example you like a lot of boost on part throttle which I don't really like. I found turbo dynamics disappointing to control overshoot and run a nice closed loop system on 99/00 - if you don't use large values the duty cycle doesn't ramp up quickly, if you do then it oscillates if you rely on that to catch the overshoot. I always found that the Dawes was preferable to the 3 port as well. Band aids maybe, but my setups have always spooled up as well as they do with a disconnected actuator hose with good control and I like how they drive.

Here we have a classic example from the poster in the thread - he had better boost control on his Dawes than he does with his remap because the weather changed...

john banks

Just to add, that with the new age setups, from what I fiddled with, I found them far preferable for control because you could use initial and held duty cycles (amongst other nice compensations), rather than maximum and minimum. The held value from what I could see did not seem to limit it from going higher. You could then use aggressive gains and have a nice critically damped system with minimum effort. But again, it depends on the style that you map with. Horses for courses rather than a right or wrong way, unless you send a customer away with an oscillating car

Aztec Performance Ltd

iTrader: (234)

Mine uses a Dawes to control boost (tek3 map) and I must say it does it rather well (from a customer perspective). 3-port appartently is affected by seasonal changes.

Different mappers approaches I guess, but its not right to suggest that 'Dawes is a band aid...'

Bob

Gridlock Mikey

So are you suggesting that I stick my DAWES back on? I thought that having the Tek 3 was a way of having the ECU (802 by the way) do the work with all the other parameters adjusted to minimise engine problems. Am I wrong?

Turbotits

iTrader: (2)

I also have a boost issue which the techies may have an opinion on?Its a 2002 sti with full de-cat,Fuel pump,panel filter and tek3. I dont know if i have a map problem or if it mechanical?
The problem: If i'm cruising in 5th or 6th gear with just a slight bit of boost say 1 or 2psi and floor the car i only get half boost (10psi). If i let the car come into negative boost for just a split second and then go wot then i get full boost (20psi).

I can make the boost do this to order.Its fairly easy to drive around the problem as if i know i want full boost i just come of the throttle before i go to wot.

Any opinoins would be a great help.

T

john banks

Mikey, putting the Dawes back on would solve your problem, but so would the correct settings in the map, whichever mapping style is used to solve it there is no need to have it oscillating. There is a gear compensation ROM that is available that will also keep the kick in lower gears a la Dawes without having overboost in higher gears, don't know if your car is running this or not.

T, it could be the map or mechanical, actuator could be sticky or it could be the map, needs datalogging of wastegate duty and boost to find out, as well as looking at the wastegate actuator arm/seal/spring tension.

Bob Rawle

John the tables are only flat cos thats what someone put in them, change to progressive and you will see what I am talking about, you should have noticed the ae800 problem, generates v fast response and tries to do the same to all tps settings, and just sit and watch the x axis as you apply throttle, goes nowhere !!! I always map progressive boost, but I do like the throttle to be responsive and so do customers it seems.

Three port was std fit to an Impreza from MY92 to 96 so hardly a band aid, even Prodrive agree.

Mikey you are not wrong, however if it can't be resolved properly then its one option, be aware though that if you do the ecu will have its safety boost cuts all bypassed which is not good news, in my view at least.

John new age boost control is easy to sort without any need for anything else, especially these days with the better software thats been made available. In any case the new age ecu has boost learning built in.

cheers

bob

john banks

Exactly Bob, flat tables are in the AE800 and AE801 as they arrive from the factory, and I prefer how they drive that way to progressive (I didn't find the bug as I didn't use AE800 code very often, and certainly not with progressive control), it is not a case of right or wrong but opinion, and yours and mine differ here, as in other things. That's OK by me, would be boring otherwise

I still prefer a Dawes to a 3 port to drive as long as I can get the boost curve I want and trim the part throttle by careful bleed hole sizing. I'm not just referring to 3 ports mapped by me either. I think the AVC-R is also rather lacking with A-B bugs and 500 RPM Ne point intervals as well, plus the self learn is hardly smooth. I keep it because it is easy to adjust and convenient, but it isn't the last word in boost control. My old box running a 2 port was in many respects better in terms of achieving a critically damped response with the minimum of variables to adjust (which is a good sign that the algorithm is "better"), but user interface, packaging, R&D meant it wasn't worth taking further.

Andy.F

Just to clarify, it is only the ECU's ability to reduce boost that is compromised if you fit a manual boost control valve such as a Dawes.
The ECU still retains full control of the overboost cut, ignition retard and fuel enrichment as engine safety systems.

Andy

scoobyDAZZA

my scooby my00 is doing a similar thing after my tek3

when im driving at a steady 70(ish) in 5th
with just touching the throttle the boost gauge goes up and down
only happens in 5th
if i go to overtake by gradually pressing it firmer then the boost gauge may go up to say 5psi then without moving my foot it will drop to 0 then 5 then 0 etc

sounds like i need a3 port then
which is just as well,cuz im getting 1 saturday when bob re-re-re-re-re maps mine

ps,all the remaps cuz i keep adding bits ;-)

Andy.F

It's not 2 or 3 port that causes this, as previously mentioned, it's the boost/wastegate targets in the mapping.

Andy

Bob Rawle

When gradually increasing boost if you fix your foot the boost will fall back, to maintain light boost you need to progressively increase throttle gently.
bob

graham72

hi bob, just a quick question, i have a tek3'd ecu mapped by you that came off a friend of mines car, andy (micared) in southampton. all i know is that its still unlocked.
can you give me a rough idea how much to re-remap it to suit my car?
pm if neccesary (sp)
cheers
graham