The latest MSQ is on the way via email, Charlie. The engine does run beter with the spark lead you added in the lower bins. I drove about 60 miles and wrung it out pretty good - spent some time in each gear + OD OFF with some brake pedal. It's a good day for tuning... a light rain and wet roads to keep the brakes cool.

The truck holds a light highway grade at 70mph without boost, but I'm getting into boost in 2nd gear at 25mph under moderate acceleration..... around that area appears to be the weak spot.

I'm still suspicious that I'm not getting enough power from the cams.... I've heard no knocking yet. This afternoon I may play with the detonation sensor sensitivity and see if it picks up anything.

I did find the missing 2 psi of boost when I let the transmission kick down and wind the engine a bit..... so with the restricted exhaust, the boost pressure reduction at lower rpms may be due partly to my head intake port work, but it's probably due more to the cams.

Brendan, the soft knocking sound that we heard from the cabin is still there...... I've about concluded that it's coming from the fuel pressure regulator hammering when it pulses.... the knock rate is the same as the pulse felt in the return lines.

Frank

Have I mentioned I like factory FPRs. I have yet to see an aftermarket FPR that is stable.

Nothing looks wrong with the fuel map.

I would try adding some timing where the engine feels week. Go up 2* over a test area and drive it. When you feel you are near a limit, either push a test say a small area up 3* to force knock but then start backing off 1* to make it safer. If knock was not detected in a test area raise the surrounding bins and test again. Sooner or later you will get into the knock circuit, or detect it yourself.
Knock will probably be around 17-1800 Rpm and 3-3300.

When you get around to an exhaust the Aussies have headers for these but if staying with iron then use the original Y pipe but go to 2 1/2 back from the original joint where the two sides meet.

Also on the timing map you can go up into the 50s for the vacuum advance. I gave you a very conservative amount of timing, I can make a more aggressive one if you want. All this timing increase has been off power in the cruise range.

How much boost have you seen with it so far, 130 KPA or up to 150?

It could be because I still have the 5/16" hard lines and have incorporated 3/8" fuel injection hose for the rail returns to the regulator and from the regulator to the 5/16" hard return line. I wanted an adjustable regulator because the injectors may be marginal up top, depending on how much power the engine makes..... they're 325cc/32lb @ 3Bar. The regulator is now set at 43 psi.



Thanks very much. I think I'll enable auto-tune in the next lower bin row and let it have a go at tuning the areas just off-idle.



I'm off in a few minutes to try it - this time I've set the knock detector with just enough to keep it unlit at idle and will see what it does.



I've seen those headers, but I think I'm happy with my ported factory manifolds and Y-pipe arrangement.... a little restrictive at the junction, but who knows - it might work like a venturi/merge collector and accelerate exhaust gas through the narrow area to the larger pipe. Yesterday I made a Tuesday appointment with a shop to bend and install a 2 1/2" exhaust to join the Y-pipe with a transition. I'd prefer mandrel bends, but for $250 including a Dynomax muffler and bolted flanges, it'll be good enough to use for a while - then maybe the bends can be used to copy for a mandrel-bend set later.



I've seen the boost gauge go to 7 psi for very short durations under kickdown conditions around 30 to 60 mph..... haven't looked at the laptop under boost, but 7 psi would be right at 150Kpa.

Frank

When I build onto a factoy Y, I whittle back till the new pipe is a clean weld to the factory pipe. I do this by squeezing the new pipe to an oval and trimming the factory part back till they mate.

I might let them do that on mine, but it does require a new Y-pipe if I ever put it back in stock trim..... probably won't, though.

After driving another 50 miles, I've decided to wait until I can get on a dyno to tune the ignition further. I tried advancing the spark in 2* jumps at 2000rpm/100Kpa and never heard a knock or saw the indicator light after increasing as much as 10* over the 21.4 you wrote to the ignition map. That's a lot of change without any indication and maybe it's what it wants - but it concerns me when there's so much extraneous noise that can cover up a death rattle.

I reset the lockout parameters in the config file to let auto-tune work in the low Kpa bins - then did some driving in low and 2nd gears as well as 4-Lo at crawl speeds. The VE map keeps changing - I have it set for small changes with 5% lumpiness, so I guess it'll take a while to get it right.

Overall, I'd say the tune is slowly improving.... the blower sounds nice at redline. <img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/ignore.gif" alt="" />

Frank

Cool.
I hope some day to get down that way to visit some of you guys and your projects.
I tought I would be down in Cheraw next month but nothing is firm yet.

Cheraw isn't far from Columbia, so let me know if you make the trip.

Frank

I pulled the plugs to try the set that's 2 heat ranges colder...... didn't work - even when gapped to .034". They just won't light the mixture with the OE coil, so I guess I'll order a set 1 heat range colder and see if they work.

Here are the OE heat range plugs - they look great and suggest I'm making some progress on the tune:



Frank

Why do you want a colder plug? That is old school chevy tuning stuff. Put a set of ND Iridiums in and leave it. The VR4 runs the same plug as the NA engines.
Your combustion chamber is the same as the late 2.6 engine and using a Starion for example they do not need cold plugs.
I can not see that you should need a cold plug if Mitsu did not see the need to in the production engines.