Yesterday I finally I had a real crack at tuning the new truck engine. Now, up to this point, I was never 100% sure that all this stuff would work, so it was time to finally find out.
As you may remember from my last post, I had replaced the stock ECU with this contraption:
Now, this replacement ECU is an ebay-bought / junkyard ECU from a similar 80's GM vehicle, so I had to just assume it was ok. Plus, me and Dr Frank had fiddled with it as necessary to get this tuning business to work.
First we had to desolder the original EEPROM chip holder, and solder in a replacement that a normal ribbon cable could be plugged into. Which meant pulling the ECU completely to bits, and going from this:
to this ...
to this:
Those pics are from the
www.moates.net site, who sell a lot of the hardware needed to do this tuning lark, but you still have to 're-engineer' the ECU yourself. So it was me and Dr Frank who did very similar steps to those above. Actually we converted the spare ECU months and months ago, but it's only now that it was time to put it to use.
Now, neither my or Dr Frank's soldering skills are exactly world class, and you can see how much soldering and desoldering of intricate bits on a TWENTY year old fragile circuit board is necessary, so again, I just hoped for the best.
The black box taped to the ECU in the first pic is an 'emulator', which pretends to be the chip that was originally in the ECU, allowing me to change parameters using a laptop and TunerRT software.
You can see in the first pic that a ribbon cable snakes inside the ECU from the emulator box, it is plugged into the new hole in the ECu:
The other end of the black box has a USB cable that leads to my laptop.
Ok, now last time I fired up the truck with the new engine, I still had the original stock pre-build ECU sitting under the dash where it lives and connected. The truck ran like a dog as expected, as the new engine has much bigger fuel injectors than the original, as so was running wasy too rich, as the stock ECU doesn't know about the bigger injectors.
So, yesterday, I finally unglugged the old ECU, and connected the new cobbled together affair in its place. Now as I'm sure you all know, if the new ECU wasn't fully functioning, the truck wouldn't run at all, we all know that a burnt out 'brain' means an engine won't run at all.
I connected up my laptop using TunerPro RT software, and changed the FUEL CONSTANT from the stock 134 down to a much lower 92 to compensate for the bigger injectors, and 'uploaded' this to the black box of tricks.
Then, finally, we fired up the engine.
WOOHOOO!!! It fired up and ran MUCH better immediately, it was working.
Now for the really fun part.
With the engine running, I changed the Fuel constant on my laptop to a slightly different number. AS SOON AS I pressed 'ENTER' on my laptop keyboard, the engine idle note of the truck changed IMMEDIATELY to a slightly different sound.
REAL TIME engine manipulation by laptop folks!!!
Unforunately we ran out of petrol (and daylight) soon after, so we had to call it a day. I was also trying to get feedback data from the truck with an ALDL to USB cable at the same time, but couldn't get it working. I've realised today that I hadn't configured the right COM port, so hopefully I'll get it working next time. What THAT allows me to have, is a 'dash' on my laptop showing the current RPM, Vehicle speed, Throttle Position etc at the same time as being able to alter fuel and spark.
Also, I haven't fully wired up the WideBandCommander yet, which has another USB cable allowing me to monitor Air Fuel ratio exactly on the laptop too. I'll get that wired in this week, and next weekend we'll finish a few minor mechanical jobs like some vacuum pipes and dipstick, put in some more fuel, and we'll have a really good crack at getting this engine tuned to the point I can drive it to the MOT station (at which point after the tuning REALLY starts)
