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Old 03-12-2008, 07:20 PM   #1
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Default strange bucking issue

I have some weird **** going on for the last couple weeks. My logs all look good, with no sign of anything fucked up but the tach drops down like its cracked out, and its driving me crazy. At roughly 2700-3500rpm at <75kpa it happens, and twice today the same thing between 5000-5500 at 100kpa. What else should I look at? AFRs are solid all the way through every cell according to my datalogs.




thanks for the help.

oh, I have a 9093pnp running no maf.

Last edited by hustler; 03-12-2008 at 07:33 PM.
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Old 03-12-2008, 07:30 PM   #2
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Maybe the 8-9* change in timing between 100 and 128kp?


Down low i have no idea....the only time i ever got bucking with my old ms'ed escort was either when it was too lean/advanced or when i had the accel enrichment dicked up.
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Old 03-12-2008, 07:31 PM   #3
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Where is the MAP line plumbed in? It could be interference.
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Old 03-12-2008, 07:33 PM   #4
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Where is the MAP line plumbed in? It could be interference.
I changed it from the t-body location to the rear, and it still does it.
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Old 03-12-2008, 07:37 PM   #5
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i have a feeling your issue is not MS related...
you may want to check your cars grounds, im not sure if the 1.6 cars are at the same location as 1.8 cars, but mine are kind of under the TB and one kind of under the heater hoses, check those and make sure they are kosher
if your grounds check out good, check your plugs and plug wires, your problem almost sounds like a slight missfire...
good luck, i really hope you get it all sorted before your track day



ps-fwiw, your maps look good, a change in 1 degree in timing will not cause these types of issues ( i would hope)
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Old 03-12-2008, 07:39 PM   #6
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Quote:
Originally Posted by whaaamx5 View Post
i have a feeling your issue is not MS related...
you may want to check your cars grounds, im not sure if the 1.6 cars are at the same location as 1.8 cars, but mine are kind of under the TB and one kind of under the heater hoses, check those and make sure they are kosher
if your grounds check out good, check your plugs and plug wires, your problem almost sounds like a slight missfire...
good luck, i really hope you get it all sorted before your track day
it will have a new motor in it by then, so this problem will probably go away and be replaced with 10 others.
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Old 03-12-2008, 07:47 PM   #7
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change the mapdot threshold to 255 to rule out accel enrichments.
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Old 03-12-2008, 10:20 PM   #8
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well, its not the enrichments. What's next?
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Old 03-13-2008, 12:15 AM   #9
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Looking at this part of the fuel map i see a couple things you could fix. If your idle is a little uneasy you should make all of the idle cells the same value instead of jumping around 33 35 37 35. It will idle better if they're all the same when you are using larger injectors.
Do a little hand smoothing as well to make these numbers closer. I don't really care what youre afrs but with that much jump in VE I can understand why there is a stumble around 2700. I could be completely wrong but make those numbers within 2 VE of each other.
Worth a try.
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Old 03-13-2008, 01:24 AM   #10
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thanks, I'll try this tomorrow.
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Old 03-13-2008, 04:40 AM   #11
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Hustler, feels like bigass misfires? My car did the same thing. Tach would swing all over the place (sometimes down to 0) and the car would fall on its face. You need spark plug wires.
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Old 03-13-2008, 08:59 AM   #12
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Hustler, feels like bigass misfires? My car did the same thing. Tach would swing all over the place (sometimes down to 0) and the car would fall on its face. You need spark plug wires.
they're 6 months old.
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