1992 5.0L mustang MS2 PnP, heads, cam, intake. Idle with AC on?

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a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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#42
Got a chance to data log tonight, I notice as I go into boost range of about 5-6lbs and about 3700-4000 RPM it feels as though the engine surges as though Im losing spark(did this before, decreased plug gap and it went away.) Im using all stock ignition, plugs gapped to .038 wondering if I need a stronger coil, re-gap plugs tighter, or if I'm way off in what I'm thinking is the issue. Attached current tune and data log.
Dude you are lean when that starts to happen... look at the log at 5-6 psi you are 13.5ish AFR thats no bueno in boost my friend. In the upper RPM/boost areas you are right on target but you lack fuel where your 'blowout' is occuring. My math says you need to add 8-10% fuel in this area to compensate.
 

AUBURN1111

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Oct 17, 2000
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#43
I still see spots where I'm leaning out and feeling an RPM drop, not sure whats cause it or if theres still some adjusting needed on the VE table. It seems most pronounced around 4-4500 5-7lbs of boost. Ive attached data logs.
 

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AUBURN1111

Founding Member
Oct 17, 2000
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#44
@a91what latest data log from last night, same tune as above. Car feels strong all the way through second gear, usually spins the tires about 3000rpm, shift to 3rd and around 4000RPM under boost I got a drop in RPM and similar in 4th, almost feels like it did when the plugs weren't gapped incorrectly. Im not sure if its a fuel or spark issue, not sure if what Im using is not up to speed with the addition of the S-trim
 

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AUBURN1111

Founding Member
Oct 17, 2000
539
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49
Mobile, AL
home.earthlink.net
#45
Trying to work through some minor drivability issues, cold start the car oscillates for a few seconds before stabilizing at a nice idle, also noticing a slight stumble when blipping the throttle, sometimes having to feather the clutch a little to get going. Adjusted some of the Accel/Enrichment settings without much difference so reset them back to what they were.
 

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a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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Hillsborough county
#47
Its the little things that make a tune great, the changes i made were mostly fuel related it seems like. anytime the car is under load the AFR needs to go rich, beyond this the next issue would be timing in that area... but the timing issue can be harder to pin down so its best to get fuel spot on then tune the IGN table...

as an example if the timing is to far advanced in the low load area during low speed cruise [barely on the throttle] the engine can experience bucking, this is because the engine is making [or trying to make because of high advance] more torque than is needed to maintain speed... = the short version..
 
Jul 7, 2005
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#48
Sounds like your almost there...time for :burnout: videos