I drove my other daughter to school in the Cobra this morning, and am picking up my son from school at the end of the day for the last day. I think driving the kids to school will be a good thing to do with this car. I hooked up the MegaSquirt's autotune, which is pretty good overall it seems but at least enough to work on getting the tune closer in the ballpark. I've had some spots that are both significantly rich and significantly lean, and the throttle tip-in enrichment settings I played with some to get where I want them. I also messed around with the coasting fuel cut-off, something that I normally prefer not having, but the decel popping was annoying and I'm sure annoys other people more than it annoys me. After getting home I sat outside for a bit and looked at the car, where I noticed that the front brake rotors are smaller diameter than the rear - something I'd missed before. On the rear I went with the 95 Mustang Cobra brakes, which are the same caliper as standard but a larger diameter. Functionally the brakes are fine, but it looks wrong. So that may be something I look into to update eventually, but I've got other fish to fry first. There will be continued tuning for a while, but MegaSquirt does make this pretty simple to do.
All three kids have gotten their drive to/from school in the Cobra. The school year is over, I've (finally) achieved the milestone I set out. And they all agreed that it was a big deal to them, lots of fun, and they want me to do this more when the next school year starts. This morning I did some tuning, and then I did some additional tuning both before driving to pick up my son and then while waiting for him to get let out. The computer interface makes this really easy: The big thing that I was immediately noticing as problematic was the lack of throttle tip-in enrichment (accelerator pump in carb terms). The software makes this really easy. I was able to play around some with me moving my right foot and seeing where the delta throttle position would be, which helped to make me pick my x and y points on throttle enrichment. Huge and immediately noticeable response on the drive back. It still could use some more, but this is a big improvement. The first issue I seem to be coming across is that at some combination of throttle and RPM it feels as though there's a cut-out occuring. I was observing it at full throttle at 4500 RPM and part throttle around 5500. It could just be that area needs more fuel tuning, which I'm going to work on first and wouldn't surprise me at all. I have the Microsquirt set in ITB mode (which is a combination of MAP/speed density and Alpha-N/TPS-based) and I definitely do not have that set properly yet. It might also benefit from some better plugs, and it might have too much of a spark plug gap. Edelbrock (cylinder head manufacturer) had a recommendation and I went with those, but they could also have gotten worn some with how the engine's been treated the past couple of years (poorly, bad mixture, sitting, etc.). I'll keep working on fueling for a bit first, though. What's most amazing to me is how all of the little imperfections that were bugging me looking at the car in the shop now just don't matter driving it. It drives really, really well. There are lots of details to work on, and I'll do those, but now I can focus on some minor things while I get the RX-7 improved for the next track night and get the RV ready for our summer travels, making notes and minor changes here or there.
I put some EBC bluestuff pads on the GTI this weekend in preparation for next week's Track Night, along with a set of Centric high carbon rotors. I was a little concerned about how well they would operate when cold, and the pedal did need a little more pressure at first, but they've bedded in nicely and the difference from stock is no longer noticeable. I'll report back with a pirep next week. I'm hoping the GTI will be fairly gentle on the brakes, the front rotors are 340 mm, same as the Golf R, but with the GTI single piston caliper. That's a big rotor for a 3000 lb car with 220 hp.
Did you get #5 cylinder figured out, and if not, does that affect the fuel ratio read-out or the learning negatively at all?
That's a good question. No, I haven't figured out why the #5 cylinder won't pull vacuum from my hand while the other 7 will just yet. The O2 sensor is in the left bank exhaust (which is where the #5 cylinder is) so any richness or leanness on any cylinder there would impact the reading there. One thing that I'd noted was that after my first drive, the readings were very rich. I reseated the MAP sensor and it got back to normal. I didn't have the computer hooked up in that time period, but my guess is that there was vacuum leak around the MAP sensor that was impacting the reading of the MAP sensor and thus impacting AFR. That may prove to be a problem point in which case I'll have to figure out another solution. I need to check for vacuum leaks around that #5 cylinder as that seems the most likely. I also may need to richen up the mixture in the few areas where I have it running leaner, as I have 14.7 as my target in the low throttle/low RPM areas. I think I may have heard a bit of pinging there and I'll probably richen that up, just do something around a 12.5ish baseline. I'm running premium fuel and compression is only around 9.5:1 with aluminum heads, but 14.7 might prove a bit lean at the moment if there's a lean cylinder that is actually seeing something even a bit leaner than that. The ignition timing I'm running is basically a canned curve, starting with around 10-15 degrees at idle (that would be at a normal idle of say 700 RPM), around 25ish by 1500, and then maxes out at 35-38 degrees. There's very little vacuum advance in there, only a few degrees, which I think could be improved upon. I haven't driven it enough to mess with ignition timing yet. I will need to do some more alignment work. The left front wheel needs to be raised a little bit (other 3 I seem to have about perfect), and then I'll need to do a bit of toe in. Too much toe out now, and the steering wheel isn't 100% straight. I'll get those things taken care of at some point, probably when the front Yellow Stuff pads. The rear yellows showed up, so depending on how things go this week and next week I'll find a time to put those in and make adjustments. Yesterday after getting home from bringing my son back from school for the last day I'd crossed over 100 miles on the odometer. That's not fully accurate as the initial drive was registering something on the order of 2-3x the actual speed I was going since the speedometer wasn't calibrated yet, but let's call it just around 100 miles on the car thus far. The thing just keeps driving better with expected minor tweaks, and few issues. The car's exceeded all of my expectations.
Sounds like you are almost out of projects. RV is basically done, Cobra same same, and RX-7 on its way. Whats next? Cant have you getting too bored...
Not even close. I still have a good number of tickets on the RV to do, the Cobra will need paint and body work as will as continued tweaks along the way to get to where it's a car I just drive and enjoy. There's not a shortage of work there. I ordered another carb rebuild kit for the RX-7 and I'm going to see if there's some more fueling/power to be had out of that engine. But at some point I do also expect that there will be an engine swap involved. That car is definitely far from done, and I expect to continue to be the primary track weapon. Don't forget about the diesel swap in the Land Rover, that's been on the back burner for some time, and I've also got some projects on the R1150GS (which remains my primary dirt ride) that will need to be done. Nope, not even close to out of projects...
Yeah, I’ve mostly accepted that with other plans nothing is happening with that this year. And I’m leaning towards just reducing the fleet.
Actually it’s very intentional to have only a single passenger. It forces one on one time rather than kids fighting in the car time.
