Sunday, December 23, 2007

It's Christmas

I've not been very active recently on this blog. That's mainly due to it now being winter and the car being officially kept off the road since they've started salting the roads.

I was actually surprised how long the good weather held out for though, since I kept driving the car into late November. Durig this time, I almost got the installation of the PLX Devices data logger installed. The only things still to be hooked up are the speedometer and knock sensor, which will then enable me to get some on road dyno testing done, since I installed the optional G-meter.

I have got some results from the data logger already though. There's definitely something odd going on with the inlet pressure. At first I thought the pressure sensor in the engine bay was not calibrated correctly, since according to this the inlet pressure was going off the scale. However, I'm now starting to think that the boost controller may not be reading the correct pressure and that there's a leak in the vacuum hose to the controller.

I've been slowly reducing the inlet pressure using the boost controller and indeed, if I keep it low then I seem to be able to work out the hesitation that I'm getting around 4000 rpm. So I definitely think the stuttering problems are inlet pressure related.

I've been logging the inlet temperature also. This has been quite insightful, since it is typically running at around 50 degrees C and only when hard pushed does it get up to 70 odd degrees. So it's much less than I anticipated, which means I can stop worrying about changing out the intercoolers and save some money there.

The strange and slightly worrying thing is the engine speed signal. It routinely drops and runs lower than the actual speed. This is worrying since I've tapped into the signal from the engine speed sensor, so if I'm getting an unreliable reading then it's likely that the ECU is also, which may mean that the ECU is not operating the engine as well as it should be.

I've also been monitoring exhaust gas temperature and been pretty surprised here also. The normal operating temperature is around 200-300 degrees C and you have to push very hard to get it up to around 700 degrees C. I've not had it anywhere near 900 degrees C, which is when I start to worry a bit.

I also hooked up the wideband lambda probe to the ECU via the data logger and have been keeping an eye on the mixture. I think that the wideband actually responds too quickly for the ECU since at idle the engine revs have been swinging up and down a bit. Also, the mixture may be a little too lean at idle, since the car seems to stall a bit easier. But that could be to do with the colder weather also?

I still need to tidy up in the cockpit, since there's wires running everywhere in the passenger foot well. I've left it messy until I complete the installation of the data logger. I also need to figure out where to mount the device. It's pretty ugly and the screen is pretty crap too since it's almost impossible to read it on strong daylight. I wouldn't recommend anyone buying this data logger... I'm not particularly impressed with it to be honest.

In the long term, I'm planning on changing out the ECU. Jarle in Norway is currently updating the one on his bi-turbo with a Haltech ECU and if it all goes to plan then I think I'm going to go the same way. May be a job for 2008.

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