fabrication question

[Belgian1979]

Cruise is within limits (<5% difference overall in VE, in a lot of places it's around 1%). At idle and transition areas I have up to 20% difference in VE, with the cylinders close to the iac supply running at 15-20% VE difference. The result is uneven running and an engine that tries to hunt.

And that VE difference is measured with what? You still use closed-loop and believe blindly what lambda tells?

Have you balanced you itb setup with manometer? With itb it's always first thing to do.

It's balanced every year or ca. 700 miles with the tool that is designed for this.
I'm sure that lambda is not 100% accurate, but I'm sure it's close. The difference is too large to be attributed to the O2's.

[Belgian1979]

Throttles and runners are never perfect so some degree of variation is understandable. Plugging iac improved the imbalances.

More parts means more variables, there is no way around that.

With the iac system, the bigger the lines and the less they flow, the more likely they'll be matched......which is why you probably want to set the throttles open as much as possible before opening the iac. So set hot idle with iac off, then iac will add for load and cold only. I think that's your best shot.

As soon as I have the intake together I'm going to play with this some more.

[Newold1]

I know Mike is great with camshafts and far better than me with a lot of experience but I have never had good idle quality experience on an electronic EFI engine with an idle under 1000rpms with an LSA's below 110 degrees on cams with durations similar to yours.

Some racers run this way but they have to settle for 1000-1200rpm idles with cams specs. like yours. Just my experience.

[Belgian1979]

I know Mike is great with camshafts and far better than me with a lot of experience but I have never had good idle quality experience on an electronic EFI engine with an idle under 1000rpms with an LSA's below 110 degrees on cams with durations similar to yours.

Some racers run this way but they have to settle for 1000-1200rpm idles with cams specs. like yours. Just my experience.

My idle was +-1050-1100 rpm. I intend to set it to 1200 after the manifold goes back on.

[Heinz1]

Newold 1
Maybe it helps, look at the Motec Webinar - Helpful Hints on Idle Control
https://www.youtube.com/watch?v=H-zHSvZ7PSg&hd=1

[modok]

Wait....aren't you the guy with the oil burning v-8 with the strange intake?
What is this thing?

Correct, you may not have followed other threads but the problem was the vacuum chamber of which the plate bent towards the lifter valley letting oil in which then got sucked in the runners.

I saw a picture of it once, but I thought it had two throttles.
it has 8??

[Belgian1979]

Wait....aren't you the guy with the oil burning v-8 with the strange intake?
What is this thing?

Correct, you may not have followed other threads but the problem was the vacuum chamber of which the plate bent towards the lifter valley letting oil in which then got sucked in the runners.

I saw a picture of it once, but I thought it had two throttles.
it has 8??

yes

[Kevin Johnson]

Apart from all the other issues and considerations, this will definitely confound the purity of the signal to the ECU. Flow through the IAC will cause a proportional rise in indicated MAP. Visualize a vacuum gauge connected via a small diameter hose to a steady vacuum source, lets say 30 kPa. Now start drilling holes in the line. Every one raises the gauge reading as the leakage increases. Suppose you drill 5 holes. The gauge MAP reading is now lets say 60 kPa. Finally, start blocking off various holes with you fingers, like playing a flute. The MAP reading now fluctuates erratically between 30 and 60 kPa even though the source signal is unchanged.

Reaching back in my memory. Yves, wasn't there an earlier issue with your gas tank acting as a cooling-radiator/heat-sink due to radiant heat from your exhaust heating the returning petrol? I am guessing this will also cyclically heat up your booster and thus would be a reason not to have it included in the system.

Fuel gets heated up by the engine while it passes in the fuel rails and gets returned to the tank. Not exhaust related.

Here is a picture of your brake booster next to your exhaust:

[Belgian1979]

Maybe it's me but I don't see the connection

[Kevin Johnson]

Maybe it's me but I don't see the connection

When the booster chamber is heated (raising the pressure of the partial atmosphere present relative to manifold vacuum, say) and/or you apply the brakes there will be a migration of heated gases into the hose (despite the one-way valve). The interconnected hoses act as a small plenum and some of this heated air could diffuse and influence sensors or bleeds. The hypothetical action appears to address the symptoms.

I may be wrong but I think MadBill worked in this general area while at GM (?). I would pay close heed to his thoughts/cautions.

Good luck.

[Rick Finsta]

I know Mike is great with camshafts and far better than me with a lot of experience but I have never had good idle quality experience on an electronic EFI engine with an idle under 1000rpms with an LSA's below 110 degrees on cams with durations similar to yours.

Some racers run this way but they have to settle for 1000-1200rpm idles with cams specs. like yours. Just my experience.

I've got a Jones cam on EFI and one of my stipulations was idle speed and vacuum. My engine idles just fine at 14.7:1 AFR, 800-850rpm, 65kPa, and the cam is 288/292 (244/248 @0.050") 0.550/0.565" lift on a 108. I had a similar UD Harold grind in there before with about 10 degrees less duration at 0.050" and it idles the same as it did.

[Belgian1979]

I asked on the MS forum if I could use 8 map sensor signals, do averaging and use the average value in the fueling calculation. If this would work from a practical point of view, it would let me do away with a common vacuum log for the map and I could then employ one way valves for the iac and other air sources. This would reduce cross talk between cylinders and effectively separate them.

[mk e]

I asked on the MS forum if I could use 8 map sensor signals, do averaging and use the average value in the fueling calculation. If this would work from a practical point of view, it would let me do away with a common vacuum log for the map and I could then employ one way valves for the iac and other air sources. This would reduce cross talk between cylinders and effectively separate them.

I had a board designed, based on a circuit sketch I found on the MS forum, that reads upvto 12 sensors and sends the strongest signal out to the ecu so it works with any ecu. It was like $20 for the bare board, maybe $150 with all the parts including the MAP sensors, it will hold 12 MAP + 1baro, but can be literally just cut to the number of Maps you need or leave it long and don't install the parts. It can also accept 12v or 5v as power depending how you assemble it. It could also be build as a bread-board, but much neater on a pcb.

I can give you the design, is open, or put you in touch with the gut who designed it, just let me know if your interested....it works GREAT on my engine, much better than I even hoped.

[Belgian1979]

I asked on the MS forum if I could use 8 map sensor signals, do averaging and use the average value in the fueling calculation. If this would work from a practical point of view, it would let me do away with a common vacuum log for the map and I could then employ one way valves for the iac and other air sources. This would reduce cross talk between cylinders and effectively separate them.

I had a board designed, based on a circuit sketch I found on the MS forum, that reads upvto 12 sensors and sends the strongest signal out to the ecu so it works with any ecu. It was like $20 for the bare board, maybe $150 with all the parts including the MAP sensors, it will hold 12 MAP + 1baro, but can be literally just cut to the number of Maps you need or leave it long and don't install the parts. It can also accept 12v or 5v as power depending how you assemble it. It could also be build as a bread-board, but much neater on a pcb.

I can give you the design, is open, or put you in touch with the gut who designed it, just let me know if your interested....it works GREAT on my engine, much better than I even hoped.

I might need that. I have an add on board that lets me hook up 8 maps already. I just need to figure out how to average all of them and then output the signal for MS to be used as map input.

[mk e]

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