Odd AFR lean spike at idle... tune and log attached

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kccampro
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Posts: 42
Joined: Sat Jan 08, 2011 4:06 pm

Odd AFR lean spike at idle... tune and log attached

Post by kccampro »

I'm getting close with my tune but there are still a few issues. My RPM at idle still hops around a little and I'm getting a odd super-lean spike in my AFR with no corresponding change in my MAP. Take a look at the log around 78 seconds... not sure whats causing it. Also, this is my first time posting a tune or a log so if you see something that looks odd please let me know.
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Porsche 928 track car - Chevy 350 TPI, 24 lbs injectors, mild cam, 7-pin HEI, MSIIv3.0 2.905
First time MS'er...
WASyL
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Location: Warszawa - Poland

Re: Odd AFR lean spike at idle... tune and log attached

Post by WASyL »

After opening your MSQ i got this message:

1 Warnings:
Warning: MSQ Units Mismatch for fRate! cc/min found in current configuration, g/s found in MSQ, values were not converted to new units.

Are You sure that this one is set correctly :?:

For TPI IAC in Idle menu 100 steps is quite low value, usualy You use 140-160 steps as starting point in Start Value.
In Injection Control i found injectors 30's rather then 24's as your signature states.
You set Trigger Offset at 0? is that also on engine(distributor) :?:
IAT Steps at Other Tuning are way off dorm IAC settings of 100 mentioned earlier :!:

best regards
Pontiac Firebird 305 LT1 intake, L82 cam
MegaSquirt II with mod's + TPI adaptor board, MSExtra 3.3
kccampro
Helpful Squirter
Posts: 42
Joined: Sat Jan 08, 2011 4:06 pm

Re: Odd AFR lean spike at idle... tune and log attached

Post by kccampro »

WASyL wrote:After opening your MSQ i got this message:

1 Warnings:
Warning: MSQ Units Mismatch for fRate! cc/min found in current configuration, g/s found in MSQ, values were not converted to new units.

Are You sure that this one is set correctly :?:

For TPI IAC in Idle menu 100 steps is quite low value, usualy You use 140-160 steps as starting point in Start Value.
In Injection Control i found injectors 30's rather then 24's as your signature states.
You set Trigger Offset at 0? is that also on engine(distributor) :?:
IAT Steps at Other Tuning are way off dorm IAC settings of 100 mentioned earlier :!:

best regards
Thanks for the feedback, it's always nice to have someone else look through the tune to catch what I have missed. Starting from the top:

The unit mismatch, is that jus a difference between your settings and how I have my tune configured? I don't recall having cc/min in my tune.

IAC setting is at 100 because those motor (and cam) seems to like a fair amount of air at start up. I have tried higher step values but it starts better with the value set to 100.

I didn't see anything under injection control that stated 30 lbs injectors so I will have to take a look again. You are correct, I am running 24 lbs injectors as my signature states.

Trigger offset set to 0 because I was (before this weekend) running a mechanical distributor with vacuum advance. I have just recently converted to the HEI and my trigger offse is 10 degrees.
Porsche 928 track car - Chevy 350 TPI, 24 lbs injectors, mild cam, 7-pin HEI, MSIIv3.0 2.905
First time MS'er...
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