speed wrote:Pm a mod and they should be able to help you when they get the time
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Cool thanks Steve. I will do that.
No photos today but just wanted to report a very brief drive experience. Since more or less finishing the guts of the new turbo conversion a week ago I have had an infuriating problem which meant that I couldn't build much boost (about 0.3 bar), and my car ran with less power than when supercharged. "Boost leak" I thought, but couldn't hear anything or find anything loose. "Wastegate actuator spring too soft", was the next thought, but a much bigger spring had almost no discernible affect. "Not enough preload on the wastegate" a mate suggested and this time, glancing at my gauge as I tried to load the engine up I did get a little extra boost - now to about 0.4 bar. Now thoroughly confused and wondering if perhaps I had left something in a pipe which was now blocking up the intercooler, I decided to take the wastegate actuator pressure line off to rule out an issue with the wastegate. Back on the street, I did notice slightly more boost again, with 0.5 bar for sure and I thought I might have seen the gauge flicker to 0.6 bar for a split second. Car was starting to misfire under load too. It was only when I went to my datalog to see exactly how much more boost I had attained that I noticed that the recorded MAP did not go up as high as the gauge reading I saw. The ECU map sensor and gauge are on the same line split using a 'y' piece so this seemed odd. Under the dashboard again and I checked the hose which seemed OK, but I replaced it with new silicone anyway. I got my air pump with gauge and tried pumping into the line and watching the ECU MAP value. It went up, then dipped down immediately and no matter what I did, I could not 'pump up' the line suggesting the sensor was leaking. It was a $30 part I bought new off eBay. I had an electrically similar sensor on a Stack boost pressure gauge in my shed, so cut this off and spliced into my car loom appropriately and repeated the test. ECU was now displaying exactly the air pressure showing on my air pump gauge and with no leak in the system, I could pump it up to the limit of the sensor, about 3 bar absolute. I thought it was a bit strange that this issue was occurring on top of my boost issue, but regardless went out to see if the accurate MAP sensor would at least make the car run properly on the limited boost I was getting. Turning onto the road I shifted into second, noting that small throttle inputs resulted in pretty jerky forward motion. I put some revs on to smooth everything out then put my foot down to 90% TP with about 4500rpm on the dial and stuff happened so fast I didn't fully comprehend what was happening until the engine cut out. My little car squatted way back like it was trying to catapult me down the street, then it all got too much for the rear tyres which stepped out in wheel spin. It was a new experience for me in this car. Conscious of the fact that my wastegate was effectively stuck shut I tried it again, to make sure it wasn't a fluke, and it went just the same, a lot of force then an abrupt halt as I hit the boost limit set in my ecu. What a blast....I'm sitting here smiling just thinking about it and certainly you could not wipe the smile off my face for the rest of the day after it happened.
Just goes to show that simple things going wrong with control systems can have unpredictable effects. My MAP sensor has probably been no good since I put it in, but my tune had compensated for it during the brief time I used this ECU with my supercharged setup. My low throttle transients etc are now all wrong so I face the task of road tuning that stuff again. But you just need that one shove in the back when you put your foot down and everything comes together to make the work seem worthwhile. I am looking forward to getting back into the car over the weekend and running up a bit of a tune to get general drive-ability back into the ball park, and maybe putting my foot down once in a while, just for scientific purposes.
Sorry about the long post. The way my memory is going I wanted to record what happened for my own benefit! Have a great weekend all, I certainly intend to.
Omar
