Highway run

Two nights ago, I got it up on the highway for the first time.  First was a trip up Hwy 99, which let me get up to about 50 or 55.  Truck ran great, and although I was gentle with the clutch, the first couple gears were pretty good.  No engine hiccups or anything.  I was pretty nervous, since I still don’t have current tabs, and the thing isn’t exactly innocuous.

Then I got it over to interstate 5.  This was about 7:30 or 8 at night, and the interstate was busier than I expected.  Still, I was able to run it up to the rev limit in 1st and 2nd gears, and the computer limited me much earlier than I expected.  I asked for a redline of 6300 or so, I don’t remember exactly, and I think I was halted at about 5000.  That might be a problem with my tachometer, or with the redline setting (PCM variable), OR it might be a problem with the ignition system.  The limiter was pretty abrupt, and it did shake the truck more than I thought it would, so I didn’t push it more than those two times.  WOW, did it pull hard up to that limit though!  I didn’t have much time to watch, and there was traffic so I couldn’t watch too closely, but I think 2nd gear redline was about 50 or 55.  Once on the highway, I worked my way over to the fast lane and got it up to about 65mph, which let me get into 6th gear.  Running at 65 in 5th got me about 1800 or 2000 RPM, while 6th dropped it all the way down to 1300.  Remember, idle in the LT1 is 900 RPM, and I was running OVER the speed limit at 65 at 1300 RPM.  BARELY off idle.  The engine was almost silent, and it was doing hardly any work at all.  True, it wouldn’t accelerate worth anything, but it cruised along (with cruise control!) without a problem.  I was also able to run in 3rd and 4th without an issue at those speeds, although in 6th if I let speed drop to 60 or below, it started to bog pretty bad. Most of the time around town was done in 2nd, sometimes maybe 3rd.

Problems:  I think the synchro in first is pretty much gone, since I have to be almost <5mph to get it in without any grinding.  Not a big deal, since I don’t expect to be engine braking in first gear all that often, even at the track.  Reverse is still a problem, which I think may be related to the clutch system not being fully bled.  There’s some slight feeling to dropping the truck into 1st from a standstill even without letting the clutch out, so maybe the 1st & reverse are related.  I’ve heard that getting the clutch bled completely is much harder than I expected.

Oil pressure still isn’t reliable, and that may be due to a wiring problem, or to the oil pressure sensor not being calibrated for a high volume pump (although that may or may not affect pressure, depends on the rest of the system).  I’m going to talk to the harness guys and double check the wiring, then I’ll probably end up with an Autometer oil pressure gauge.

I also received two OBD codes:  P1661 and P1642.  1642 is either the Vehicle Speed Output circuit or the Fan Control Circuit, depending on who you ask.  I think it’s the latter, which would make sense, I think.  If so, it’s a non issue–both fans work well, and are operating as I want them.  1642, however, is the maintenance indicator light problem code, which MIGHT prevent me from passing emissions testing.  I’m not exactly sure what causes this fault, so I’ve got to do some research.

Also, as I got back to the house after the test drive, I started having power steering issues.  It might be a kinked and bound hose, or it might be a lack of bleeding of the system.  I’ve seen both recently on this truck.

I’m still looking for a tuning shop in the Seattle area that will do LTx engines; I have a lead on one that hasn’t gotten back to me.  If you know any, let me know!

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