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MS II - 4.6 Rover Spark


drfranky

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Totally wrong, never seen anything like it!

As above, have alooksie on here for a 3.9/4.0 map, they are much the same being the same bore/stroke!

I take it is still a 4.0, and you haven't done anything with the crank? I only ask as a 4.0 rebuilt with 4.6 rods and pistons.... doesn't that make them poke out the top of the engine?

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Ok, so I reduced the advance at tickover to about 10.. but the truck had no problem with 25 degree..

I have a max advance of 29 at WOT and 100 % tps.

Milder accelerations tps 65 - 80 have a bit less advance

I don't think that map is THAT off.. :blush:

As for the 4.0 pistons, wouldn't a higher compression engine aggravate the liner slipping issue on 4.6? I cheaped on the t-top liners.. :wacko:

post-67886-0-01633600-1415147120_thumb.jpg

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Totally agree on that FridgeFreezer. That's why I switch the 4.2 plenum that has the round TPS [these are absolutely totally unreliable] to a 4.0 plenum that has a bosch TPS and the new GM style flat connector idle valve.

I just feel that the truck is more responsive on TPS rather than manifold vacuum..

As for the idle valve, I would say that PWM is probably the way to go... the stepper is nerver quite right.. some idle is at 900 sometime at 1000.. all in all, I think you guys are right, if I had to do it again, I'd go MS1 extra...

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Ok, so I reduced the advance at tickover to about 10.. but the truck had no problem with 25 degree..

I have a max advance of 29 at WOT and 100 % tps.

Milder accelerations tps 65 - 80 have a bit less advance

I don't think that map is THAT off.. :blush:

As for the 4.0 pistons, wouldn't a higher compression engine aggravate the liner slipping issue on 4.6? I cheaped on the t-top liners.. :wacko:

Er "Nope"

your 10 is a 0 KPA - thats falling off a cliff engine braking....

10 at 40-50 KPS is where tickover is

TOO much spark generates heat / damage as much as too lean.

That spark table has nowhere enough definition, look on the A-Z thread on tuining MS and take a look at those tables and then make yours up, MS1 has less cells as MS2 so its just streych everything a bit

I would post up stuff, but getting ready for 5 day event to france 100 rivers !!

Nige

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I just feel that the truck is more responsive on TPS rather than manifold vacuum..

That is likely just a matter of tuning it properly - MS still uses the TPS in speed-density for accel-enrichment but you can also use MAP-Dot either instead of or as-well-as TPS-Dot, "Dot" standing for rate-of-change in these cases, so how fast you push the pedal down / how fast MAP changes rather than the absolute position of the pedal / amount of load.

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Er "Nope"

your 10 is a 0 KPA - thats falling off a cliff engine braking....

10 at 40-50 KPS is where tickover is

TOO much spark generates heat / damage as much as too lean.

That spark table has nowhere enough definition, look on the A-Z thread on tuining MS and take a look at those tables and then make yours up, MS1 has less cells as MS2 so its just streych everything a bit

I would post up stuff, but getting ready for 5 day event to france 100 rivers !!

Nige

Hey Nige, these are %TPS value not KPA!! sorry I should have mentioned that! Have a good trip!

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As for the 4.0 pistons, wouldn't a higher compression engine aggravate the liner slipping issue on 4.6? I cheaped on the t-top liners.. :wacko:

Slipped liners are not compression ratio related - heat related. Using low compression 4.0 pistons in a 4.6 gives you a compression ratio of about 9.2:1 - about halfway between a low comp 4.6 and a hi comp 4.6 - a good compromise between increased compression ratio (power) and the need to use higher octane fuel.

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Slipped liners are not compression ratio related - heat related. Using low compression 4.0 pistons in a 4.6 gives you a compression ratio of about 9.2:1 - about halfway between a low comp 4.6 and a hi comp 4.6 - a good compromise between increased compression ratio (power) and the need to use higher octane fuel.

What do you use for the head gasket? The old steel gasket or the telflon coated one? Do you have issue with blown gasket?

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