Help with building your Speeduino, installing it, getting it to run etc.
PSIG wrote: Fri Mar 17, 2023 10:41 pm I don't recall or missed the bank vacuum differential thing. Is the engine hurt or something? I wouldn't worry about '85 Honda being too sophisticated based on when we used other Honda pre-OBD stuff. ;) It's amazing how crappy simple but proprietary some OE stuff was back then. :lol:
You'll have to search back for the pics:
A couple of other issues I have had over the years and never to be resolved is balancing the two cylinder banks, cannot balance the cylinder on one side. I have never had better than 9" of HG (in the red zone) regardless of what I did:
Cylinder Bank Balance.jpg
Cylinder Bank Balance.jpg (84.9 KiB) Viewed 574 times
The vacuum gauge indicates that when the reading is in the red zone, it is "late valve timing, or leak at intake manifold or next riser". More than 15" of vacuum and it indicates late timing. Vacuum should be in the 10" to 14" of HG range.
I only have experience of Densos back to around 1987 but they have better resolution, separate idle tables, more corrections and they are coded much more efficiently so there probably isn't a speed advantage either. I'm not saying that they are too sophisticated just not as crude as a Speeduino.
That is certainly not going to help to get the idle down. :shock:

Without knowing the mechanism, it obviously suggests an issue with bank to bank adjustment. (unless a cam is out a tooth!)

It would be intersting to know how the manual says to approach balancing.
Been through all troubleshooting and setting ideas from Honda. Have also read in the Supplement manual regarding timing in that you time for #1/2 (wasted spark - viewing hole s on the left cylinder bank side - #2/4) and the flywheel mark is what is used - knew this. Read further because never time with any cylinder but #1/2. Since timing is confirmed using #1/2, further confirmation can be done using #3/4 cylinders. there is a second mark on the flywheel for this confirmation. Lastly, was reading the Squirt manual for information sake and found a section that referred to the dual cam sensor arrangement on these early FI systems. Mentions that this is to enable wasted spark on these engines. Brings to mind that the cam sensors are for wasted spark and the crank trigger wheel is for cylinder orientation. Which ever way this is more information than I had before. The other bit of info gleaned from my reading/browsing is that Hall Effect sensors work well with single tooth and half moon single tooth trigger wheels.
Cylinder Timing.jpeg
Cylinder Timing.jpeg (130.01 KiB) Viewed 1043 times
I am thinking Speedy, but there are some issues that are interconnected. Setup of vacuum hose(s), igniters and the OEM coils - it was mentioned that electronic components such as spark igniters can have a best before date. Will continue with the 36-1 wheel for the present.

The cylinder bank balance with the cylinder bank balance screw has been mistaken for the idle adjustment screw. Many make the mistake and confuse the idle screw with the cylinder bank balance screw. The cylinder bank balance screw adjusts the throttle plate opening. Will check as I mentioned.
Progressing the project from a read standpoint. Lots of good info that I am reading that clarifies what you good people have been saying. Always makes more sense after a few times.

Checked the throttle plates yesterday. Took off numbers 3/4 injector holders and checked the throttle plates for movement. Idle adjusting screw unscrewed to full in is about a mm of movement. Not a huge difference in throttle plate opening. The IAC system opening provide the majority of air for idle and coasting while riding. Having seen this, it makes sense why the engine is operating a bit rich on start with the OEM system (no adjustment for fuel/air mixture). Don't require a great amount of fuel for idle or coasting:
IAC Opening .JPG
IAC Opening .JPG (105.75 KiB) Viewed 904 times
The new VE table I'll be working with has better numbers in the 40 percent range. Adjusting the idle for too high a percentage will not achieve the aim. New VE table values:
VE Table - New.jpg
VE Table - New.jpg (79.43 KiB) Viewed 904 times
Setting up the coils today. Good riding weather today, ride on the Spyder is in order.

Have mentioned the vacuum system and what can be done. Thinking I'll start by using #1 cylinder vacuum for the MAP sensor, plug all the other vacuum ports related to the MAP system - can change to a different cylinder if necessary to find which one is optimal for the tuning. Thinking that the use of the four cylinders for MAP vacuum was keeping the MAP reading higher than it should be - has been reading in the 60/80 percent range instead of in the 30/40 percent range. Difference in tuning I'd suspect.

For my acronym list - VAG coils. Does VAG mean Volkswagen-Audi-Golf ? Just wondering.
Yes, correct regarding VAG :)

Just taking the MAP from one TB, is not so good as from Four. Four, with a smothing chamber in the middle, is better still.

Using 1 TB means you will get wild differences in MAP pressure as the engine goes from stroke to stroke. With the shared system, there is always one cylinder on the inlet stroke.

Regarding the 1mm of throttle plate opening. that is a vast amount of air difference. The first part of the throttle plate opening, is larger than any other. As the plate opens further and further, the difference per mm gets smaller and smaller per volume of air. It's because of the arc of the plate.

No one TB MAP should be any different from another. If it is, you need to resolve that.

Your first goal should be all cylinders having the same MAP reading at idle. when that is achieved, tuning will be easier.
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