What happens if you max grams per cylinder?
06-25-2003, 11:27 PM
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What happens if you max grams per cylinder? I've been fighting a pretty nasty miss problem lately. Right around 5000 or 5200 RPM's my car seems to studder a little - at the track it even nosed down once. I have been pulling my hair out trying to figure out the problem. I checked plugs and gap, wires, etc, and I even ran ATAP and logged misfires but even when it happenned, the PCM didn't detect any misfires.
I made a few pulls tonight, and it was of course, still missing. But when I ran the calculation for grams /cylinder on my data, I came up with one frame of 1.21 g/cyl at 5200 RPM. This is right where my miss is. The PCM table at this point only goes up to 1.20. Could exceeding this cause the computer to skip out for a second or go to some other table that I don't have dialed in? I am getting no knock, and the A/F is right at 11.5:1 tuned on a wideband. The MAF doesn't seem to be maxed either, I am at about 42
Thanks for the help guys.
-Geoff
I made a few pulls tonight, and it was of course, still missing. But when I ran the calculation for grams /cylinder on my data, I came up with one frame of 1.21 g/cyl at 5200 RPM. This is right where my miss is. The PCM table at this point only goes up to 1.20. Could exceeding this cause the computer to skip out for a second or go to some other table that I don't have dialed in? I am getting no knock, and the A/F is right at 11.5:1 tuned on a wideband. The MAF doesn't seem to be maxed either, I am at about 42
Thanks for the help guys.
-Geoff
06-26-2003, 01:50 AM
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Re: What happens if you max grams per cylinder? I'm pretty sure it just reads the last cell for the rpm it's at. Mine stops at 1.0 g/cyl (lucky 98's 
), but I've made it up to 1.29 g/cyl. Haven't had a stutter from it. Do you have a sharp drop in the timing table?
), but I've made it up to 1.29 g/cyl. Haven't had a stutter from it. Do you have a sharp drop in the timing table?
06-26-2003, 09:23 AM
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Re: What happens if you max grams per cylinder? I don't have any big jumps. All the cells are sequentially one degree apart or the same. Maybe when it goes off the table at peak torque (4500 rpm and low timing like thirteen) it locks the timing at the last cell it was at, then comes back on the table and reads at 5500 or so and is at seventeen or eighteen - resulting in a timing jump like +4 or +5 degrees. Would a sudden timing change cause a hesitation? Maybe I could thrown a Maf Translator or rescale the MAF table a few percent to see if it goes away.
Also, I have been using ATAP on the road so I never get a lot of frames to work with. I am going to get a couple hours on the dyno in a couple weeks and this looks like a good thing to try.
-Geoff
Also, I have been using ATAP on the road so I never get a lot of frames to work with. I am going to get a couple hours on the dyno in a couple weeks and this looks like a good thing to try.
-Geoff
06-26-2003, 04:11 PM
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Re: What happens if you max grams per cylinder? Sure you need to pull the timing back to 13 degrees? When I first put more blower on I dropped the timing back like that and richened it up, and it made it sputter at wide open. Brought the timing up and leaned it out some and everything cleared up. Might be something to try? fwiw, I ran about 26-27* max timing on 5lb.
