Took the truck in to the Chevy dealer to diagnose & fix the "won't go over 15 mph, running on 4 cylinders, lots of codes" problem. They said "well, it needs injectors, and often those will cause this problem". So, OK, had them swap the injectors ($400 apiece, plus 13+ hours of labor -- ouch) as well as do a couple other things it needed (glow plugs and some steering linkage thingeys that are apparently a real PITA to DIY). It took them over a week, got it back on Friday, runs great. Well, it ran great on Friday and Saturday, I started it up this morning and the 4 cylinder + codes thing is back. ARGH.

--Ian

I was thinking "ouch, $1600 injectors" instinctively. Then I remember to double that.

That....sucks

Yeah. V8 diesels are great when they're working. :)

It went back to the Chevy dealer this morning.

--Ian

Is it throwing injector codes for one bank? probably bad harness. If both banks FICM is probably bad. All common problems on a early duramax.

It's throwing codes for 4 injectors, but they aren't on the same side. Dealer looked at the under-valve-cover harnesses when they replaced the injectors last week, said the under valve cover ones were fine and did not replace them. I really really hope they were right about that, I do not want to have to open up the valve covers again.

Codes from a couple weeks ago were:

P0202
P0203
P0205
P0208
P0380
P1262

P0380 is the glow plugs -- the dealer replaced those along with the injectors last week. P0202/3/5/8 are for injector 2/3/5/8 shorted to ground. P1262 is a general injector problem. Presumably it's 2/3/5/8 because that's one cylinder on each crank throw with 2 in each bank.

--Ian

Which year is this again? My father-in-law had a problem on his 2002 Duramax, ended up being the fuel filter or something similar. IIRC, there is no fuel pump separate from the injector pump. The injector pump does all the work, pulling from the tank, and any fuel flow issues can present as several different problems.

It's a 2002, and yeah, they lack a lift pump. The fuel filter has been swapped, dealer did it as part of the injector service, and the old one only had 12K miles on it anyway.

The dealer says it's the FICM -- that's basically a box with the big-ass transistors you need as injector drivers for a diesel. It's actually cooled by pumping fuel through it! The FICM is the thing most people on the net point to, it's probably a DIYable fix, but I'm told it can be tricky to get the right one (supposedly lots of little revs on non-year boundaries) and I don't really have the time to get it done myself before Laguna.

--Ian

All duramax don't have a lift pump. Makes life fun when someone fills the tank with gas instead of diesel. FICM aren't that bad to replace pretty sure it can be done in a hour or 2.

So it has a new FICM in it now. Did that fix it? We'll see when I go to start it tomorrow.

--Ian

So, Miatas@MRLS was fun. I ran in A as usual, so I managed to avoid the nasty traffic issues that everyone else was reporting.

About a month ago, I noticed that the Autometer EGT sender had stopped working properly. Investigation showed that the insulation on the thermocouple wires was made of plastic, and the heat from the exhaust manifold was melting it out through the stainless braid. Oops. I guess it shorted the two thermocouple wires somewhere above the manifold.

A replacement Autometer probe is $140, and is unlikely to fare any better than the previous one (having lasted about 18 months and maybe 4 or 5 track days), so I embarked on a process of looking for a decent replacement. I ordered one from Edge Motorworks, but it turns out to be intended for use with their gauge system and included an amplifier and a multi-pin connector with no documentation on what was what. I could have just whacked the probe off of it and tossed the electronics away, but it was too expensive for that, so back it went. Then I bought a series of $10-15 probes, none of which worked for various reasons (wrong size for the available fittings, too long, too fragile). I got one that looked like it would work the Wednesday before MRLS and put it in. Alas, it was very slow to respond, the wires must touch quite high up in the sender. Still, it was what I had, so I ran it.

3 laps in on the first session on Saturday and the motor got louder and boost got sluggish. Oops. I pulled it into the paddock, the sender was lying on turbo, having been blown out. Fortunately all the bits were still there, so once it cooled down I put it back in and cranked it down as hard as I could. Of course, without a proper cool down lap I boiled the brakes, so out came the quickjacks and off came the wheels so I could re-bleed them. Many thanks to Mike Hagerla for letting me borrow his foot. :)

After that the car ran fine the rest of the day, a couple sessions at 200 kpa, the others at 230. On the 4th session of the day it started starving for fuel in 5 and 6 again -- now I know the limits. I came in and put 9.5 gallons into it, so it's starving once it drops below about 3 gallons remaining. This meant I needed to refill it every 2 sessions, which is doable. While investigating this, TK and I checked the data logs. Oops, no logs on the DL1. Apparently it's not getting a good GPS lock and won't log anything without that. I hit the log button the remaining sessions of the weekend but I'm pretty sure there's nothing there, still need to investigate why. The MS3 logs were there, we investigated those and found that it was consistently knocking at 6500 RPM and 200 kpa. The MS3 was yanking timing and fixing it, so I turned that cell down.

Sunday ran fine until after the 3rd session when I noticed that the front rotors had cracked. I wasn't going back out with them like that, and while I had the street rotors with me as emergency spares, the repair time would have taken up the 4th session, leaving me with just the last session of the day. That didn't really seem worth the effort, so I loaded it onto the trailer and towed it home.

I spent most of last weekend doing family things, but did spend a few hours swapping the car back to the street brakes & tires. Some pictures of the carnage:

These DTC-60s were brand-new when I put them on Friday, they have a total of about 7.5 sessions on them:

http://www.codrus.com/miata/fm2r/brake-mrls-2016-1.jpg?

Both rotors have 3/8-1/2 inch cracks at all of the hat "ears", pointing in opposite directions:

http://www.codrus.com/miata/fm2r/brake-mrls-2016-2.jpg?
http://www.codrus.com/miata/fm2r/brake-mrls-2016-3.jpg?

So what have I learned from this? Well, as always Laguna is hard on brakes. DTC-60s and 11.75s lasted admirably at 200 kpa (getting 4-5 track days per set), but at 230 kpa they're getting eaten alive. Three options:

1) BRAKE LESS. Yes, I really need to do this.
2) Better cooling. I have the original 2" TSE ducts, but there are larger options on the market now
3) More better cooling, use the directional vane rotors instead of the straight ones.

Iniitally I'm going with option 2 (well, options 1 and 2). I picked up a 3" kit from Andrew last week -- haven't put it in yet. The directional vane rotors are an option, but they cost 3x as much as the straight ones, and it's unclear if they'll last 3x as long.

Oh, and not a peep of trouble out of the truck all weekend. Expensive fix, but so far so good.

--Ian

Jeez. You demolished your pads. :eek5: Hopefully mine last longer than that...

One thing that is often overlooked with the directional vane rotors (and, by extension, the APRacing j-hook rotors) is that not only is rotor life increased, but pad life is increased as well. That alone is well worth the extra cost if the pads last, say, 50% longer and the rotors last 50% longer (even if the rotors are 3X the cost).

Sure, I'm not debating that directional vanes are better. I'm just going to try the one-off cost solution first, rather than jumping straight to the increased consumable cost one.

BTW, chatting with TK last night, I realized the reason that the cracks are directional. This isn't just differential thermal expansion, the pads are actually tearing the rotor off the hat (when rotor is softer due to high heat).

--Ian

Hm. Poking at the MS3 logs that I finally got around to downloading, I noticed the peak oil temps were 270F. That's coming out of the cooler, yikes.

--Ian

Yikes indeed. Is it possible that isn't accurate? What are you running for a cooler?

Also, NCR South Bay is what, 26th this month? (if it happens)

I have no reason to think the reading is inaccurate. We put in the sensor the week before Miatas@MRLS, calibrated it beforehand with boiling water/etc, and it has given plausible numbers in all of the testing beforehand. It's a 13-row, 235 series Mocal cooler with -10 fittings, mounted in front of the crank pulley using the FM brackets. It probably doesn't get a huge amount of airflow in that location, but..

NCR South Bay is nominally the 4th Wednesday of every month, except when the Sharks are playing that night. So yeah, that'll be the 26th this month, and the NHL schedule looks clear.

--Ian

Bigger cooler time :)

Perhaps. I really need a sump temperature as well. I'm reading that 270F isn't a huge deal with a high-quality synthetic (I'm using RedLine 10w40), but I don't know what the *input* temperatures to the cooler are.

I changed the oil last weekend and kept a sample to send to Blackstone, we'll see what it says.

--Ian

Yeah, that's bad. I hate to think what the sump temps look like if that's the coldest the oil will ever be, after the oil cooler. Most German cars reduce engine power and rev limiters around 270*F sump temps to force the load down so the temps can recover.