Simtek ECU advice please
 

Hi All,

I live in Kenya and i have just had a Simtek ecu installed today complete with antilag and launch control.

It has been mapped to my car by a local mapper here who does a lot of rally car mapping and has installed a few simteks here in Kenya and has thus mapped the car to the parameters and conditions of where i live - like ambient temps, fuel quality, altitude etc).

The car is a version 3 type R STI. The boost has been set to 1.4 bar. The launch control has been set at 5000 rpm. The antilag has been set at stage one. Unfortunately we do not have the advantage of a rolling road or dyno so we had to map it on the road so i dont have a print out or anything to put up but according to the mapper the car is running at max power with max safety (no det, charge temp is ok, fueling has been set right as it was running quite rich etc, etc). The air flow meter has been deleted and he put an air intake temp sensor on the manifold where the brake booster vacuum pipe was plumbed. So now i have very hard brakes (no spongy feeling) which i guess i can get used to. So far does everything sound right to you guys???

Now after mapping, the car has very rough/erratic idle (like a rally car) at around 1200-2000 rpm. I've been told this is because the throttle (butterfly flap) is left slightly open due to the antilag. However when i switch the antilag on, the idling settles down to a steady 1500rpm. Is this normal? I have been told by the mapper that my rev counter is reading higher by 500rpm according to his computer so its lower than than that in actual effect - probably 1000 rpm.

Also, with this erratic idle setting the car is undriveable around town or at low speeds (under 3000 rpm). I have seen videos of guys with simteks on youtube and they dont seem to have these characteristics on their cars. So is there something not right with my mapping? Will i have to compromise the antilag setting to something milder in order to get a more driveable car?

All this said however, the car pulls so well throughout the rev range in all gears - except 5th - which is the longer UK 5th and i get a lot of flutter. Can anything be done about this?

Also, i had a quick peek under the bonnet after a short run with the anti lag on and the turbo housing was burning red hot.... is this normal???

Any advice will be greatly appreciated fellas.

Cheers,

Hello matey,

Had the same thing with mine. I had the "hunting" on idle and then when driving the car at 2,900 rpm would stutter before coming back to life again under or over that rev range.

I spoke with JollyGreenMonster here in the UK and met him and problem has gone.

It would seem a pretty common thing on the Simtek to be honest. Maybe worth speaking to the rep who fitted and mapped the Simtek.

As for the Antilag. I don't use mine all the time due to the heat temps etc. As about if I left the ALS on and drove it when I got to 2,900rpm it was pretty bad and mad the car lerch violently. Again as above JGM resolved this.

Steve

The problems that you are suffering are all part of running with a jacked open throttle. The idle hunts up and down due to the fuel and ignition cuts keeping the idle speed from going mad. They stop when you turn the antilag on as the cuts are removed from the idle portion of the antilag map. The only way to sort it properly is to talk to your mapper about having an electronic throttle kicker installed, this will allow the car to idle perfectly normally when off, but still give you the air required for decent antilag when switched on.

As Martyn said and driving around with antilag on is never smooth.

The ALS effect is mostly dependent on the quantity of air allowed into the engine, the more air supplied the more the ALS effect will be noticeable. Consequently ALS systems can be more or less aggressive. A mild ALS will maintain a 0 to 0.3 bar pressure in the inlet manifold when activated whereas, when inactive, the pressure in the inlet manifold with the throttle closed would be in the region of -1 bar (absolute vacuum). :freak3:

Your main problem is the car has been mapped as if it is a rally car. I think you need to go back and be more specific about what you want. The jacked open throttle and no servo vacuum pipe is not a good idea on a road car.

Thank you all for your input. I have another mapping session set up for this coming friday so hopefully the mapper will be able to address all my problems.

@ stevesbluwrx - do you know what exactly JGM altered in order to get rid of this and make the car more driveable at the bottom end?

@ MartinJ - should the ecu not be able to control the idling to what you want it at? I'm basically looking for it to idle smoothly when ALS is off and i dont mind the 'hunting' or high steady idle as mine is when the ALS is on. Would closing the throttle slightly more when ALS is off make it better do you think?

@ dynamix - that's what i thought too but mine seems to be the opposite scenario. Steady but high idle when ALS is on and rough idle when ALS is off and the car lurches below 3000 rpm. I dont mind the lurching when ALS is on as i would not be sitting in traffic with my ALS on. Its the lurching when the ALS is off that gets to me.

@Yoohoo - while idling with ALS on or off my boost gauge shows nearly 0 bar pressure - i.e. no vacuum?? I suppose that is due to the partly open throttle setting...

@ zen performance - yes maybe the fault is mine as i did tell him i want the car as rally like as possible but i meant that only while the ALS is on. Hopefully i can have the issues sorted on Friday. You say the jacked open throttle and no brake servo vacuum is not a good idea - what do you suggest i do as an alternative?? The guy used the brake servo vacuum on the inlet to attach the inlet temp sensor. The alternative was to drill a hole somewhere in the manifold but i'm afraid of filings falling inside?? Is there anywhere else on a phase 1.5 manifold one could connect the air temp sensor??

Further issues i noticed today is that the car smokes quite a lot on cold start up. This car used to throw water from the exhaust every morning but not anymore. I believe it is still running very rich. I have always had my FPR set at 4 bar - is that ok?

Again thank you all for the advice and forgive me if i have asked silly questions. I'm not new to Subarus but my technical knowledge is not as sharp as some of you on here!!

Cheers,
Imran

Not when you are using a jacked open throttle, and having to use cuts to keep the idle speed down.


It is of course easy to have a perfect idle, but you will have to ditch the jacked open throttle and either settle for milder antilag, or use the electronic kicker I mentioned above.

Martyn

Thanks Martyn.

Where have you guys mounted the ACT sensor. As i said mine has been mounted on the inlet manifold where the brake servo vacuum pipe is plumbed and thus i've got hard brakes. is there another place this can be mounted so i can retain my normal brakes??

When the ALS is on, my car smokes with the pops and bangs - is that due to rich fuelling?

How can i get rid of the compressor surge/flutter (not sure what the correct term is) in 5th gear?

Why is it that the rally cars here seem to have the opposite idle effect as to what is happening to my car? The rally cars seem to idle wildly when the ALS is on and seem to settle down to a steady idle when ALS is switched off at the end of a stage?? Mine idles wildly when ALS is off and steady but rough and loud when ALS is switched on??

Is my fuel pressure too high at 4 bar?

Cheers
Imran

hi,
You can mount temp sensor in intercooler or pipework close to throttle body,
but when running 'jacked open throttle' you will have no vacuum for brake servo anyway.

A possible easy fix is to use a manual choke cable with a switch output to select map 2 and connect cable to the throttle next to accel cable (spare), then rig up a electric vacuum pump to supply your servo when on map 2 as well.
Map 2 being only for rally mode:)
Map 1 for going to the shops etc.

Simon is the guy to talk to mate. Everyone i know has had issues with Simtec including me. Maybe you should ask Simon to fly down to you :D

A more sensible and considerably less expensive solution would be to return to the original installer and implement the solutions that I have already suggested via e-mail to the mapper....

You should be able to achieve a max idle variation of around 150 rpm with the throttle jacked open to the extent you have by adjusting fuel cuts and the rpm cut axis.I am assuming that the idle is around 1800RPM which would be normal with this set up.

The kicker or additional cable options are however the best if you reqire OEM idle characteristics and still wish to have positive boost ALS as opposed to "pops and bangs".Be aware however that turbo life will be seriously reduced with this strategy.

Steve.

@ Alladin - LOL thanks for the suggestion. Funnily enough my mapper and good mate back here is called Simon too (Simon Sharpe) and as Steve says that would be the best for me cost wise and logistically!

@ Steve - many thanks for the email mate - Simon forwarded it to me this morning. I am going back to him on Friday to get all the issues sorted.

The idle varies between 1200rpm and 2000rpm when warm. And its steady at 1500rpm when ALS is on. When you say i should get a variation of around 150rpm with my current throttle position, at around what rpm value should that be roughly?? That sounds good compared to what i have right now!! LOL!

I dont mind not getting OEM idle characteristics but i need some sort of driveabilty below 3k revs in traffic situations.

Also, is there ANYTHING i can do about the turbo flutter in 5th gear?? its really annoying? Would i be better off changing it back to the normal JDM fifth rather than the current UK longer 5th?

Otherwise many thanks once again Steve.

Imran

PS - forgot to mention that today the car is just refusing to start. Heavy smell of fuel so i guess the plugs are fouled due to the rich fueling. So will need to get those out tomorrow and give them a good clean and put them back and try again.

With a jacked open throttle I would normally aim the idle to be 1500 -1800 RPM.You can have really whatever you wish - it just depends where the fuel cuts are set to start in the ALS OFF Fuel cut map.If you tell Simon (Kenya) what you would like he can set it up to this.

You will however always experience a slight "jerkiness" at very light throttles as the fuel cut is reduced progressively down to zero as the throttle opens.The technique with jacked open throttle set ups is to really be on or off the throttle.You can't have a set up where you have 98% cut at zero throttle - to ensure the engine does not rev away - and then go instantly to 0% cut otherwise the throttle would feel like an "on-off" switch!

If the turbo flutter you describe is compressor surge then this can be mapped out also by reducing the waste gate base duty in the gear related waste gate table.

Hi Steve,

So are you telling me that if i want my car to idle (hunt) only between 1000-1200rpm when the ALS is OFF and retain the steady idle at 1500rpm when ALS is ON with the current JOT position i can have it and not compromise the effectiveness of the ALS when it is switched on??
And will this setting make it more driveable below 3k rpm i.e reduce the jerkiness? I understand that it will never be absolutely jerk free as per your last post but it will at least be manageable in traffic or low speed situations??

Yes i believe the term i have been told by others in the know on this forum re my turbo noise in 5th is compressor surge. Glad to know it can be sorted.

Thanks again for your time and expertise.

Imran

Hi Steve,

Simon managed to get the idle steadier now. Its steady (for the most part) at 1300rpm now when the engine is warm. Car still cuts out at cold start. The main thing is that i can now drive the car around town which is the most important thing. He had to close the butterfly a little and fully open the idle control valve. So i believe the antilag has been toned down a bit.
Still getting the flutter in 5th at high boost though. Car is running at 1.3/1.4 bar and about 1.5bar in 5th. Is that safe on standard sti internals. Engine was rebuilt about 10k back.
Taking it back on monday to get the cold start sorted.

Just wanted to say thanks for your help!

Imran