Monday, July 17, 2006

Holy throttle body!

I've just spent the afternoon at Rica Engineering. The intention was to remap the fuel (since the car was running too rich) and to set up the boost controller.

Things we're looking a bit peculiar from the start. First we checked that the Lambda sensor was working OK by monitoring the exhaust O2 with another probe. The car seemed to be responding OK, adjusting to throttle responses by enriching and then making lean the mixture. However, we started to notice that the car was runnning very rich, with mixtures of Lambda 0.6!

Before even looking at the fuel map, we had a good look at the new intakes to see if they were working OK and to check that they weren't pulling in hot air from the engine bay. We concluded that everything seemed OK.

A couple of remaps were tried out, but something very strange started to happen. Suddenly the car was only producing about 230 hp (and continued to run rich). We then checked the boost pressure... about 0.2 bar! Something seriously wrong was going on since the fail safe pressure for the boost system is around 0.7 bar. This implied a big leak!

We both covered the inlets with our hands and straight away we saw and heard where the problem was... the connection between the throttle body and the Y-piece connecting to the two hoses from the intercoolers. We disconnected the Y-piece and found that the rubber gasket was damaged and worse still, there was a big hole in the throttle body in the grove that locates the fastening screws. You can see it in the center of the picture below (please excuse the poor quality... I took it with my phone):

It appears that someone's been a bit over enthusiastic when tightening one of the bolts. It also looks like the gasket may never have been in the right place, since it appears it may have been damaged during installation when tightening the bolt that caused the damage to the throttle body.

So, before I can proceed any further, I need to purchase and install a new throttle body! So that's items 23, 24 and 27 in the picture below:

And item 20 in the picture below (I'll probably get a couple of these):

Of course, this now delays me picking up the new wheels, since I don't want to drive the car with such a big leak in the inlet system.

The parts drawings are courtesy of EurospareS, from who I'm getting a quote for the required parts.

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