Tim's WRX Powered Truck!
I own a modified 1992 Subaru Brat pickup that’s been featured in Retro Cars Magazine (6 page feature Oct 2010) and in Banzai Magazine (5 page feature Jan 2011). It has been converted to look like a Tamiya R/C model that was made some years ago but with the added punch of running gear from a 1996 Subaru Impreza WRX STI.
After fitting all of the running gear I looked into stand alone engine management and opted for M-Tech’s V4 ECU as it ticked all the boxes for my requirements and the company was local to me too. Once I had it running and mapped by M-Tech I was at first happy with how it ran and performed but then things went downhill fast. I had 2 ECUs die for no reason and it ate 3 crank sensors in this time rendering the truck useless.
Also, I was having cold start issues and there was an excessive smell of unburnt fuel on over-run which concerned me greatly but didn’t seem a big issue to the tuner at M-Tech. It was there whilst I was working as M-Tech’s master technician/fabricator that I met Will for the first time as he had brought a vehicle down with a faulty V4 ECU and we got chatting about my problems to which Will replied he could sort them out for me.
The truck was now becoming so unreliable I needed to get it sorted as every time I got in it to start it I didn’t know whether it would start or break down once I started driving it. Please remember, this is my daily driver!
Anyway after a few long conversations over the phone with Will he gave me a list of things to sort out on the truck before he would proceed with remapping it for me.
I emailed the map over from my truck over to him so he could get an idea what it was like and where improvements could be made.
First problem was the wiring which had been done at M-Tech and this was shockingly bad. So much so that I had to employ the services of an auto electrician to sort it out and he was amazed that my truck ran and hadn’t had an electrical fire either! Coilpack fed directly, unfused, from the battery anyone?!
Will also advised an upgrade to the cooling system to ensure that air charge temperatures were safe. I fabricated a chargecooler system which did the job nicely and sent Will a message to let him know. By the end of the day a date had been arranged for mapping!
Will arranged to make the 250 mile trip down to me on the Friday evening so that we could get started on the Saturday morning first thing. First job on the list was to wire in the throttle position sensor as up to now the map was using manifold pressure against rpm to run which Will said was a bad way to map an engine.
Half an hour later it was all wired in and calibrated – now to start mapping!
Will had prepared a new base map and once loaded in straight away the truck sounded smoother on idle and didn’t struggle to tick over at all. Apparently the old spark map was actually retarded at idle!
With all his tuning gear plugged into my ECU and a wide band lambda in my tailpipe we set off for a drive. The first run up the road was an eye opener for us both as the fuel was at a lambda value of 0.67 (not lambda 1.00 as it should be) which in Will’s words “way too rich and risking the engine with fuel bore wash” to which he promptly altered the fuel map so on cruise it runs at lambda 1.00.
Whilst I drove around Will made adjustments until he was confident we could start some full throttle runs on our designated test road that had a nice long hill to climb which would load the motor up nicely!
After 8 runs up the same hill with Will adjusting the fuelling the difference was astonishing….. On the first run we hit 65 mph on full throttle and on the last run I was flat out in 5th gear doing well in excess of the legal limit….put it this way we were well into 3 figures on the speedo & pinned into our seats!
Will had noticed there was an issue with the spark break points which had been written wrong in the original map and only allowed one reference point between 5000rpm and 7000rpm! He corrected this instantly along with activating the fuel shut off on over run which wasn’t switched on either. With this function enabled there was no more stink of fuel in the cabin when no throttle was applied downhill or slowing down.
I thought my truck was fast before he got his hands on it and I couldn’t believe the hidden power Will had found just with tinkering with the map! The man is a legend in my book and certainly knows what he is doing when it comes to setting a motor up correctly!
To say I was happy was an understatement as my face hurt from grinning at the new found power I had at my disposal! Next morning I went outside to try and start the truck from cold as normally it’s a pig to start from cold but as soon as I turned the key it burst into life and ran from cold a whole lot better!
It’s been just over a month since Will mapped it and it’s started every time reliably since. I’ve done a track day with it at my usual track (Castle Coombe) and I can also confirm on track it’s a whole lot faster! I’m pulling over 20 mph more on the straight than before and I’ve seen my lap times come down considerably and happily, I’m using a LOT less fuel than before!
Will Pedley is a guy that knows without a shadow of a doubt how to map an engine to achieve optimum performance safely and fault find a map in areas that need improving. I would recommend him 100% to anyone who needs a motor mapped correctly and he is only a phone call away with answers whatever time of day you ring!
Thanks again Will, I can’t wait for the next power increase…
Tim Starling