Fantom

ok guys, I've jsut got back from having a power engineering diagnosis test which has identified that my HKS mushroom filter was a bit worse for wear. The foam had got all bent somehow and just had a hole letting in all the crap. This had clogged up the air flow meter and in turn the ecu was getting false readings. After this was cleaned and put back my cars power went from 245bhp to 261bhp! a nice gain. However, to get to the 285-290 figure im looking for, it looks like I have to spend a lot more money. I'm looking for an alternative basically. The ecu is standard. The mods are, HKS fuel cut denfencer, HKS EVC boost controller, HKS Mushroom filter, HKS full decat Super Drager exhaust. Thats about it. To achieve the bhp results I was running the evc on the high setting of 1 bar that the previous owner had set it up like.
It appears that I can achieve at least 280bhp without having to uprate the injectors and fuel pump, although I know a lot of you would suggest doing this.
The limiting factor is det. I was using 97 ron fuel with no booster. There is some knock but the ecu is doing what its supposed to do and retarding the ignition so my engine is safe. However this is restricting my power figure. The way I understand it is that the hks bodge up the boost things are fooling the ecu so that more boost can be run, but the petrol and air mix is determined by the ecu and is for only 0.8bar set up? thats right aint it? hence causing the detonation.
The remedy according to Power Engineering is to use a z4 plug in chip which will use the fuel and air settings from an sti setup, preventing the det and allowing my power to increase to the 280ish I want. However the cost of this is substantial at over £700.
So guys, I'm looking for a suggestion on how to get that extra 20 bhp and run my car safely at 1 bar with no det and not bankrupt myself at the same time. Is it possible???
Any help would be appreciated.
Regards
Steve

mark@wrx

You would be best talking to someone like AndyF regarding an Apexi ecu. They are about £700 IIRC.

Delboy2

Or a cheaper alternative would be to locate a Scoobyecu if you are on a budget

Cheers

mark@wrx

Rocking horse poo anyone?

Fantom

had a scooby ecu on my last car, and it didnt work so im not going down that route. Apexi power fc would be good but its still gonna cost me over £700 and i have to drive to scotland?
There must be some dodgy sti chip thing i can use??

Scott.T

iTrader: (2)

??

Fantom

followed the instructions given, was one of davids chips. car turned over but wouldnt start. reconnected j1 resistor and back to normal. wasnt able to resolve the matter......................

sparkywrx94

ecu uses the MAF to calculate fuelling requirements, if you are using fuel cut defenser the you are just modifying the MAP signal which although may slightly affect the fuelling I think? I may be wrong, It wont give you any problems. You could run 1.1 bar and get around 300 bhp without any problems if you use optimax and some octane booster to be on the safe side.

more boost means more air being taken in past the MAF so fuelling isn't a problem unless you injector duty cycle is maxing out. I would suggest you check the injector duty cycles and try and get the air fuel checked using a wide band lambda and use optimax and some octain booster.

Anything over 1.1 bar I would advise on a new fuel pump and regulator. With the regulator you could slightly increase the fuel pressure to gain some extra fuel.

From my own experience with a 94 wrx and the same setup as you, I managed 315 bhp and 265 lbft torque running 1.15 bar with uprated pump and regulator.

But in heinsight I would not go down that route again because I always got some amount of det in cold weather when the inlet temps are lower because the earlier cars didn't have a inlet temp sensor so the ecu couldn't modify the fuelling according to the temp. This is why I think that these earlier cars run quite rich as standard to cater for any deviation in induction temps. To fix this you have to run a richer setup but in doing so the MPG will increase and some power will be lost.

If you are going to spend that amount of money then you may as well get an Apexi Power FC which will transform you car completely and keep everything running sweet.

feel free to correct me if im wrong

Mark

Fantom

The trouble is, the ecu is using the most degrees of knock correction that it can to prevent det. Therefore its massively reducing my power. So how do I stop the det? using octimax and booster isnt going to make that much difference is it?

Jay m A

iTrader: (2)

Firstly, optimax and booster will make a difference - IMO NF booster works the best. Try it and see how the knock correction goes - remember to do an ECU reset too.

Try and find a Z4 ECU, you can get them for £150 from breakers. You should be able to up your EVC to 1.1 bar to get your 280BHP

Fantom

any more suggestions??
if i just swapped my ecu to a z4 one, would it be that simple? or would i have loads of other porblems to sort out? surely it cant be that easy to just use another cars ecu??

Delboy2

The Z4 ECU has a slightly higher boost target but with a less aggressive ignition map (map is very similar to the PPP map) so would be less likely to DET and is just a case of unplugging your ECU and fitting it in its place As far as the scoobyecu is concerned you must have just been unlucky as they are a quick/cheap route to more horses

Cheers

Fantom

do you know this for a fact? if thats the case then I gotta get myself one of those! much better than £625 + VAT for a chip to go in my original ecu!!!
I better get searching
Only problem is i dont have a knocklink anymore so I cant check if there are any problems once fitting the new ecu.
Has anyone out there put a z4 ecu in their wrx? what results did you get??

Cheers
Steve

Delboy2

The ignition maps are the same and the fuel maps are nigh on identical. The main differences are the correction maps and the boost maps. The boost target on the Z4 is 12.71 psig whereas the PPP is 13.64 psig - the only problem you may encounter is that the Z4 has a speed limiter

Cheers

Tone Loc

iTrader: (1)

The MAF sensor effectively measures/compensates for the density of air. Therefore any changes in temp are catered for as the density changes as a result. So cooler dense air = higher load, therefore more fueling (if this is the case in the standard map). Could be that due to the cool weather you were seeing slightly more boost and as such going into a higher load area of the map you don't normally see where the ignition was slightly too far advanced, so more KL noise.

Apexi PFc is the same here as the OEM ecu, no AIT.

Tony.

Scott.T

iTrader: (2)

I 2nd that and can confirm the Z4 is 112mph and the PPP 175mph.
but if you fit it to an import it'll probably have the speed limiter removed by other means anyway.

Fantom

yes my car already has the limit removed by some blitz speed thing wired up to the ecu.

so basilcally, with my set up, if i stick in a z4 i should see around 280-290bhp running 1 bar of boost and 97 ron????

Scott.T

iTrader: (2)

A Z4 is from a 1995WRX (260ps). So with additional mods you would see what you are after.

TomRa

Does fitting a Z4 ecu remove the need to run OB with Optimax on an import? Along with less chance of det?

Jay m A

iTrader: (2)

No. Its a jap import ECU so expects to see jap fuel.

vulnax999

iTrader: (7)

Which means Optimax and Octane Booster.

Roojai

Z4 would be a big improvement, but I reckon best bet would be to give david from API a call. He can hook you on to someone that can put a scoobyecu type chip in your car and map it the way you want it, ie. for uk fuel, and for what boost level you want.
This will give you a boost target of anywhere up to 17psi, no fuel cut, no speed limiter and a safe map that pulls hard low down in the rev range too. Just under 500 quid (before VAT) but that includes time mapping the car and getting DET cans on it etc!!


If that's too rich then go fo the Z4 and use octane boost and/or upgrade you IC to a non-slanty type

Fantom

ok guys........I cant get optimax that easily, so its bp ultimate 97 ron for me. And I cant be bothered to buy octane booster all the time, so im just going to have to deal with a bit of knock correction. What i'd like to confirm is, if i switch to a z4 ecu will i see an improvement even though im staying on 97ron fuel???? I'd say from your opinions that it would be better, however I want to make sure before I go and buy one.
I wish I could afford a proper ecu and remap but I just cant justify that kind of expense. I've been wasting money on cars since I was 18 and I just cant keep doing it.....need to start getting some savings together. However, if I can get the desired 280bhp for small money, then I will be very happy
so..........whats the answer???????? Can i get another 20bhp by switching to the z4?

Roojai

Z4 is definately an improvement on what you've got, might give you 20. I think the Z4 is slightly better on 97ron fuel than your ecu too. So, two reasons to get one

Fantom

thankyou, thats what I wanted to know

Steve

Delboy2

As above, the boost target on the PPP is 13.64psig with nigh on the same IGN/FUEL maps as the Z4 so with a slight increase in boost may yield the desired 280hp but may be a good idea to raise the boost either with the use of a wideband or on the rollers to ensure the AFR is safe

Cheers

Scott.T

iTrader: (2)

Z4 ECU would be fine on 97RON. It runs the same fuel and Ignition maps as the Prodrive MY96 PPP plus the Z4 runs less boost.

Prodrive recommended 97RON for all Pre96 PPP cars.

The earlier ECU's such as U8 and 2C WRX ECU's are the ones that may prefer OB. But to be honest if their running stock boost then they should be pretty safe on 97RON too. Alot of it is a miff and an excuse often used for a blown engine.

Roojai

Scott T et al,
while we are on the topic, and to hijack:

I think scoobyEcu and Vos chips use Z4 code, but with different boost targets/timing.

Why does my car feel SO much more responsive off-boost with these chips in place than on the straight Z4?

Scott.T

iTrader: (2)

Boost Control / Duty cycle probably has alot to do with it. Running much higher duty cycle in lower revs in order to try and achieve better low down grunt/boost.

Most of my remaps were base on a Z4 base map, but I thought the VOS ones were based on a Legacy.

StiX

iTrader: (4)

I have a MY95 with a Z4.

I am guessing that I am running about 280bhp with a full-decat and green panel filter.

Slightly off topic, would I be able to up the boost to give a bit more power using a Blitz Dual SBC Spec S Electronic Boost Controller that is advertised for sale on here? Would I need an FCD as well or could I just up the boost to 1 bar say with the Z4 on its own without fuel cut?

Also, I used to put OB and Optimax in. After fitting a knocklink, I tried not putting in OB and there was no difference, so I now I just put in Optimax. On the motorway at between 80-90 the first green light flickers on and off and thats it. Up to the redline in 3rd I get the same - first green light - so I guess I don't need the OB.