Had my car rolling roaded in the summer and was quite happy it made 251bhp.
Its a 93 wrx with an Apexi ik, decat and an apexi backbox using the standard ecu (W6 240ps) and an IHI turbo of unknown spec.
I've just had it rolling roaded today and made 244bhp i was not happy.
The car specs are 93wrx ,apexi ik ,decat ,full exhaust and a Z4 ecu (260ps) and IHI turbo of unknown spec.

The operator informed my that the boost wasn't being held and the pickup was poor (eg summer run gave me 140bhp@3000 revs todays run 140bhp@3300) and the fuelling was all over the place and leaning out at high end revs.

Why is this?
I didn't expect a huge gain but definately didn't expect a drop.

Thanks for any help
Paul

 

I wouldnt be concerned about the figures to be honest as 7bhp is not a huge difference in my opinion. was it the same rolling road and was it run in identical condition, gear, tyre pressures etc as before?
What is concerning is it leaning out higher up the range. Try cleaning the maf, I tend to clean mine at least once a month, it amazes me how much it gets soiled (dirt/dust) through my induction kit (dry induction kit), be gently with it though. Also check for any loose hoses. (my 93 every now and again I have to pull the intercooler back towards the throttle body as I need some new jubilee clips and not got round to it yet)

 

My car with loads of mods and a 20G only just broke the 300 barrier at Triton today so i wouldnt worry too much about figures its all about what it drives like on the road IMO

 

Thanks for the replies but my main concern is that i've replaced my ecu with a more powerful version yet ran less power and f**ked up the fuelling.
Yes jaytc2003 it was the same rolling road, same gear, air temp different (summer now autumn) but the tyre pressure was different (50 in summer 40 today).
How do you clean the MAF as i've been told not to spray anything onto the sensor (this does seem a contetious point with the people i've spoken to)
Nice car by the way scooby-tc

 

sorry if the pictures are too big.
The first 2 are of the run on sat 28th with the Z4.
The second 2 are of the run without the Z4 in the summer.

Any help/advice would be greatfully received
Thanks

 

paul....ive a z4 you can try if you want i never had any problems when it was fitted

 

Cheers i'll have a run with my old ecu and give you pm depending on the results
Thanks

 

BTTT anyone with any more ideas?

 

When I clean my maf, I either use compressed air (from a can so quite lowish pressure) or a lint free cloth to gently wipe the elements, be gentle though dont be hamfisted!!

 

Cheers i'll give that a go

 

If the 1st 2 plots above are the more recent run then the fuelling is rich, not lean. It's running approx 10.5AFR at 6800rpm which is quite rich and you WILL be loosing power.

from what I've seen of recent Triton RR days/plot. They run in 3rd not 4th, so you may not of achieved full boost. Also these other runs show a tendancy to also read rich.

As mentioned in one of the other posts above, I wouldn't worry about it too much.

 

Many thanks scott for the quick reply

 

so should i stick with the Z4 and how do i sort out the fuelling if i'm going to run the Z4.
I'm going for a power run this Friday should I ask then to run it in 4th
Thanks
Paul

 

Run in 4th if possible. This will help achieve target boost and should also cause it to run a little leaner. But there are many RR factors that can effect both boost and AFR, so you can but hope.

 

Once again thanks for the help Scott

 

IMHO, just changing the ECU for one from a more powerful model ( i.e. going to Z4 etc ) doesn't mean it will make your car faster / run better. If you haven't got the engine and ancillaries it expects - cams, turbo, air flow, exhaust, air filter, injector size etc. then it will be trying to run as best it can against what the ECU expects to be there, and will, within it's range, adjust to suit the currently fitted situation. Safety may go out ofthe window as the ECU thinks / sees a signal from say the MAF and puts fuel in to suit but if that is too little fuel as the induction system is not the same as it expects , them melt down!

But it's not a substitute for mapping the ecu to the exact engine system. A ScoobyECU or aftermarket ECU mapped will achieve so much more, and more safely! Then it will work with the engine poarts to get the best from them, and work within a safely set up range.

 

A Z4 should improve and early WRX.
The Z4 map is basically the same map that Prodrive fitted to the UK cars. That certainly had no ill effects and is quite different to the standard UK map found in a V7 or 7D ECU.
Much like changing from a W6, U8, 2C ECU (240ps WRX) to a Z4 (260ps) WRX.

If it feels better on the road compared to the 240ps ECU, then ignore the RR figures above.

 

The W6 & Z4 are for use with the MHI TD05 - if you have an IHI turbo fitted what are you using to control the boost? If you are using the standard boost control it is likely that it will not control properly as the ECU's duty cycle map will not be correct for the boost profile of the IHI turbo.

Cheers

 

Interesting Delboy2 .. I am sure my OEM ECU was a W6 ( JDM import MY94 wagon ) and it had a TD04 ?

Apexi PFC now, super!



Scott, I concur, you know these maps, I was going on general principles.

 

W6 is for TD05 - 11.47psig held to redline - Fuel-cut 14.57psig

Cheers

 

Having a r/r today with the W6 in instead of the z4 to see what is what.
It is cold today so may be hard to compare with the z4 run
Admittedley it does seem to 'feel' better with the W6 fitted.

Thanks for your input people.