Hit a slight snag the other day.
I had the car out on Wednesday doing some more logging and when I had it in some low level boost trying to get some map cells populated, I noticed a, well, engine "burp" is about the best way to describe it. Never had that before, so it did kind of unnerve me a bit. I thought, "NOW what?" But the car got me back home OK. I actually did another tune and took the car out again, but didn't go into boost, and the car drove OK, but seemed rather rough at idle. And the timing looks a bit squirrelly too. Backing up a little bit, when I loaded that tune (#0027) I was pulling off of the garage apron and noticed that the oil pressure gauge was reading ZERO. Yeah, THAT caught my attention! But then I noticed that all of the gauges were dead. So I pulled back onto the apron and found out that I couldn't get the EFILive box to talk to my PCM. Sheesh.... So I just shut everything down, disconnected the V2 cable and rebooted the PC, and luckily I could then talk to the PCM again. But odd thing is that the gauges wouldn't come back until I reloaded that same tune again.
But the car seemed to run OK after I took it out again, but I didn't run it up into boost at all, which is probably a good thing.
Later on in the evening, I was looking over the log for that run where I had the hiccup, and I noticed something odd right where the hiccup should have been in the log.
Looked like timing advance just gave up and dropped to zero. This appeared to correspond ALMOST with a bump in the engine rpm trace, but not exactly. It seems to lead it a bit. The drop in advance seemed to line up with a slight rise in RPM, and then it dropped down. Then I noticed that the boost reading from the MAP sensor dropped like a rock right after that dip in spark advance. The more I thought about it the more it seemed likely that I had a boost pressure leak suddenly show up. But it is kind of a puzzle why the timing advance drop seemed to precede the boost drop out.
So today (Thursday) I popped the hood and started poking around. First thing I noticed was that it appeared that the airbridge had been rubbing on the underside of the hood again. Then I noticed something was different about the airbridge plumbing.
Here's a pic of the airbridge plumbing right after I got it put together.
And here we have what I noticed today.
That gap showing the aluminum tube between the two clamps was completely gone. And the bottom of the airbridge had come loose completely of the MAF sensor housing.
Sigh......
So I've got the airbridge and MAF sensor pulled out of there now. One thing I did find out is that the reducing coupler between the throttle body and the aluminum tube going to the air bridge is really not rated for boost. Summit's website didn't indicate that and I only found out by going to other sites trying to figure out what the thickness and number of plies are in that coupler. Apparently there are NO plies and it is just simply a single ply of rather flexible silicon. I thought it seemed rather soft when I installed it, and my guess is that it is way TOO soft and it was possibly ballooning out under pressure, pulling on the airbridge. But how that aluminum tube got sucked further into that coupler kind of has me baffled.
And this might even explain why I wasn't able to get over 8 lbs of boost out of those 10 lb wastegate springs.
In any event, I've got a new coupler on order that is supposed to be designed for boost conditions, so I guess the car is dead in the water for a bit waiting for that part to show up. In the meantime I'm going to cut away that part of the MAF housing that is supposed to fit into a notch on a coupler or airbridge so that the airbridge fits more snuggly on that end. I was actually looking for an aluminum MAF body, but couldn't find anything that looked like it would be an easy replacement. I'm not sure if that plastic MAF housing is getting too pliable when it gets hot, and therefore allowing the lower part of the airbridge to slip off of it. Anyway, all of the aftermarket stuff I looked at was either too long, or too wide, or both, which would mean too much fabrication to get it all back in place. So I'll just have to see if what I monkey around with when the new coupler comes in holds up well enough or not.