Originally posted by mjweimer
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I checked what's the recommended timing for Catcams cams with similar profile. It seems to be intake open 0,6mm at TDC and Exhaust 1,15 mm. I actually had them almost the opposite with intake at 1,25 mm and exhaust at 0,95 mm. I decided to test the Catcams timing specs. I ended up with 0,55 mm and 1,2 mm. Getting them exactly to Catcams specs would have required another round of adjusting but I figured the difference doesn't really matter. Timing cams is kinda tedious because to get a reliable result you first need to set the engine to TDC, measure and adjust the cam and then turn the engine two full rotations to get back to TDC with the timing chains properly tensioned to verify the adjustment. At least for me, adjusting one camshaft takes at least two iterations to get it close to correct timing and after adjusting the second cam you still need to doublecheck the first one because both adjustments are behind the same bolts. In an E30 the job is further complicated by the narrow space between the engine and the radiator but there's just enough space to turn the engine and with a mirror and a light you can see the timing marks.
We have been working with Pasi for a new tune for the engine. The MAF reads very high values which puts the tune at the very edge of the map. We figured it's because of my bigger MAF and how it's been scaled in the tune. Pasi used the MAF scaling from Alpina which also uses the bigger MAF but he suspected that Alpina also had some hardware change in the ECU to go along with it. So my MAF is actually showing too much air flow. It's not a problem as such because it still shows a logically changing value. But the fuel and ignition maps had to be rescaled for the higher MAF readings. After adjusting the cams I flashed in new maps that Pasi made and I have to say that the changes made a huge difference. The car is now much more civilized and nicer to drive. It's funny how much better it is now even though I didn't have much to complain about even before. I'd say you no longer notice the ITBs in a negative sense. The car is surprisingly smooth to drive. Although there is some extra play in the drive line. I suspect the dual mass flywheel and the CV joints at the half shafts. Previously I had some misfires at idle and have been planning to tackle that issue but adjusting the cams got rid of those. It kinda feels like I lost a little bit grunt at the bottom end but after driving it for a while I think it's just that the torque curve is just more even now so I've just gotten rid of some peaks and valleys. It was difficult to say if I got any more high end power since lately it's been rainy in Finland and on wet pavement it's hard to assess because of traction issues.
After the changes we did some more logging and work on the fuel map and then it was time to take the car to the dyno again to get objective data. The plan was to make a duno pull with the intake cam fully advanced and another one with the cam constantly at basic setting (retarded) to see when the vanos needs to change it's position. The green lines are vanos advanced and the pink lines are vanos retarded. The red lines are the previous run before adjusting the cams and ignition advance. The colors are not great for making distinction between the lines.
The optimal switch point for vanos seems to be at 4500. I programmed the vanos to start turning at 4300 to give it time to change. For some reason the mixture was very rich despite Pasi actually pulling some fuel from it before. It may have something to do with how the fuel map was rescaled or with previous adaptations messing up the logging. Anyway I tried pulling some fuel from the WOT enrichment table be we were not able to test that because the car started to run very badly like it was only running with five cylinders. I thought I had made some mistake with modifying the maps and tried reverting the changes but to no success. I checked if there was any obvious issue like oil in the spark plug well or something like that but couldn't find anything. I suspected a faulty coil and we wrapped up the dyno session. However, when driving home the car worked perfectly normally even with full throttle and high revs. The issue may have been as simple as a wet spark plug because of excess fuel. The fuel map needs to be checked.
The dyno pulls that we managed to make give me an idea of how the engine works. If you combine the green curves before vanos switch point with the pink curves after it you can see that until 5500 the engine works a lot better than before. The curves are pretty smooth and we got rid of the massive dip at 4900. After 5500 the operation is pretty much identical to before. The engine produces the max torque really low at 2400 and the RPM of the max power is also pretty low. The max power leaves much to be desired. With these cams and this displacement I should be looking at max power of 230 - 250 hp at around 6000 - 6500. So the power band should be moved higher up. I'll probably try retarding the intake cam even more. Maybe even to the point that the intake valves are fully closed at TDC without the vanos engaged. Shortening the intake channels would also be worth trying. Currently the length from the plenum to the intake valve is around 415 mm which is pretty long. Shortening the distance will require some work because I actually need to fabricate shorter intake runners (trumpets) for the plenum. Probably I should first do some kind of test setup using cheap standard velocity stacks and then fabricate or maybe 3D print something more refined. But the weather is starting to look pretty bad so for now we just try to get the fuel map right and then the car goes away for the winter. I wish I had a shop but haven't found anything suitable.
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