Frustrated: Idle Nightmare

[acalvo]

I've been working almost 12hrs a day for about 2 weeks on engine tune and I
still can't idle. A task that's supposedly takes a day or less to acheive.

What I've done so far:

Sealed air leaks I had, including 2 air ports on the top of the cylinder head, and sealed the IAC valve port completely.
I'm pretty sure I've sealed all significant leaks.

Re-calculated and droped Req_Fuel value from 6.0 to 5.0, due to problems with
resolution with the Fuel VE Table.

Made sure the Over Run Fuel Cut setting was turned to 'Off'.

Re-worked spark advance for cranking and for spark advance table. I started with
about 20degrees of advance and lowered 1 degree at a time, till I got the best
RPM increases during cranking. Engine has good combustion and it's RPM's rise up
to about 1000+ RPM's everytime during cranking.

Finally was able to set PW to about 2.2ms for cranking PW, and about 2.5ms from
900-1400 RPM's in the Fuel VE Table. I've been using MegaLog Viewer to track
the PW more carefully (the peaks and falls of PW based on RPM's). Also, I made
sure to have my 900-1200 RPM range richer than the 1200-1400 range so I could
force the engine into maintaining idle, but hasn't worked so far. I'm only using ASE Percentage
Table and Fuel VE Table 1 for tuning for now. All other enrichment tables are turned off.

Engine fires up and immediately dies. Idle tuning is becoming a living
nightmare. Currently, I'm trying to achieve idle with a 15% throttle position
opening. Also, I note that I can hardly produce vacuum; lowest pressure I've
seen is about 94kPa. PLEASE HELP!!!!!

Here I have the latest msq files just in case. I appreciate your help. If I
could just get a stable idle, I know I'll have a good starting point.

Any suggestions are welcome.

Thanks,

-A. Calvo

Fusion Motors
Turabo Formula SAE
Turabo University
2003 Honda CBR600RR block, 4-stroke, N/A with 20mm intake restrictor, stock coils
MS II Extra v.3.0 (wasted spark set-up)
164cc/min stock injectors

[LT401Vette]

Also, I note that I can hardly produce vacuum; lowest pressure I've
seen is about 94kPa.

That definitely sounds like a problem.
Are you sure it is firing on all cylinders?

[acalvo]

Well, I know all spark plugs are firing, since I always do a pre-check of spark before starting to tune, one spark plug at a time. However, I'm not sure if all cylinders are firing, since that would depend on the mixture entering each cylinder, which could vary. About the vacuum, I was told that the lowest achievable in my engine is about 80kPa, due to the cams. Either way, I still can't achieve idle.

I'm thinking it's due to ignition advance not being properly set. My question is, does timing has to be absolutely perfect in order to achieve idle, or is there usually a range of degrees in which it will idle properly?

[LT401Vette]

There usually is a 20-30 degree range where it will idle.

[turbo355]

You should get lower than 94pka at idle, you should be more around 65-75kpa at idle .

You didnt say if you are running a single throttle body or ITB's, if you have the throttle plate cracked a little too far with the ITB's to get it to idle then this will cause low vacuum signal, also if running ITB's you need one vacuum line from each port teed and going to the map sensor.

[acalvo]

I'm running single throttle body. I found out by another formula sae team running MSII Extra with nearly the same type of engine (600cc Honda), and they indicated that about the vacuum, the lowest it reaches is about 80kPa, due to cam timing in that engine. Anyhow, I'll proceed today first by checking timing with the timing light and fixing the offset.

[wes kiser]

Your sig leads me to believe you are using MAP for primary load, on a sportbike engine. This rarely works satisfactorily, and in a motorsports application is simply wrong. Switch primary load (at least fuel anyway) to alpha n.

If you don't want to use alpha n, you at least need to use ITB mode. I always use alpha-n for primary load sensing on any aggressively cammed/sporty application.