Made it to the dyno:
https://youtu.be/unU9RJR6VcYThis was the best pull we got out of the car, but I will get back to that. Been a very busy couple of weeks since them. To pick up where we left off, I was trying to tackle a fuel pressure problem related to old lines, and the new Walbro 450 pump. Research said that I needed to add a second return line to get around a known pinch point in the tank return line. The weekend before the dyno day, I got to talking with the owner of SCR Performance, who told me straight up that the factory regulator would not handle the flow from that pump, and would need to be replaced. The tricky part is the factory regulator is not in line, it is bolted to the fuel rail, and has an O-ring fitting to connect it. Fortunately, it meant I had an excuse to get into the machine shop and actually make something functional for my car! So I took off the FPR, brought it into the shop at work, and between breaks, lunch, and a long afternoon, I made a simple FPR-delete piece:
Attachment:
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It works very well, fit nicely, and no leaks at all! I also went to the dyno shop a few days early, and they sold me an Aeromotive adjustable FPR. Only had to drill one different hole in the mounting bracket, and then it fit really nicely onto some already existing studs on the firewall:
Attachment:
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After the dyno checkup on that Friday, I started working on the return line. I was very pressed for time since there was an autocross the next day. Thanks to some very helpful people on the E30 Facebook groups, I found that the best place to run the return line is into the filler neck, and drop some submersible hose down into the tank to stop aeration. So I marked a point, pulled the filler neck, and drilled a hole. I could not get any acceptable bulkhead fittings or anything that would fit my application, so I set up a highly specialized custom jig *cough* a bench vise and a zip-tie *cough* and used JB weld to assemble the fittings:
Attachment:
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As you can see here, I really didn't use very much JB Weld... So I left it to sit overnight, and it held! The submersible hose fit right where I wanted, so I went ahead and reinstalled the filler neck. A quick aside here, submersible hose is REALLY expensive! Like $33 a foot! And I had to order it in. Anyways, I reinstalled the filler neck, test fit it with my return line, and it worked great! But I wanted more JB Weld on it, so I went to pull the return line off and it snapped off in my hand
. After considerable fiddling, and only a small amount of panic, I managed to reattach the brass fitting with a TON of JB Weld. I should mention at this point that it is now 10:00 at night, the night before the dyno. So I went to bed, hoping that the JB Weld would set overnight and be strong enough. So two hours before needing to be at the dyno my car looked like this:
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Luckily, the JB Weld set, I attached the hose, and I applied another thick layer of JB just to make it even stronger over time. And it held! We set fuel pressure at 50psi on the dyno and it is working perfectly.
Now to the elephant in the room, the crazy high-RPM breakup on the dyno. I should mention that we spent the entire morning and part of the afternoon tinkering with wiring before even getting on the dyno. They were beyond helpful in diagnosing and fixing my cam sensor problems (improper wiring), and getting the idle going as best as possible. We were immediately seeing some issues that wouldn't be fixable that day. The first was that as soon as we got the cam sensor working, my coolant temp signal got super wonky. Jumping all over the place randomly, which really messed with the tune. The next issue was that when the RPMs dropped too low, like 500 RPM, cylinder 6 would stop firing. We weren't (and still aren't) really sure why. Another problem is a very rough, and surging idle. The last problem of course is the breakup under load. Nonetheless, we pressed on, and even with the litany of problems, the car still made 100 rwhp, which was already higher than my lowest estimate. They guess once everything is fixed it will be making 130-140 rwhp on their Mainline Dyno, which they claim generally reads low. That means it would be making noticeably more than the stock 168 bhp, which I would be very happy with.
Rob, the guy who was tuning my car on the dyno, works in electronics, and agreed to help me diagnose the car under the table. The issue with the coolant sensor, and some of the idle problem was simply fixing the shielding on the crank and cam signals. So already the car is running much better. We got together again the other night with an oscilloscope, to try and adjust the VR trim pots, and determined that the incoming signal from the crank position sensor was actually inconsistent. So we are 95% sure that the problem is in the sensor itself, or its wiring. I think sensor, because they are a known weak point on these engines, and this one is almost 200k miles old. So I have a new one coming, but it won't be here until almost July.
Big shout out to the Boost Creep, who tuned the car, and DIYAutoTune, who I've been continuously exchanging emails with through this whole process. I have a little break until the new sensor arrives, so I'm going to take a little break from the car, except maybe mounting the front fender flares.
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