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Old 07-13-2008, 11:11 PM   #1 (permalink)
Doug
 
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Exclamation Engine stutter, need help interpreting data log

So I used ecuExplorer to capture these logs because recently I started having some stutter/bucking starting at around 3000 rpm (described here).

I'm using the latest Cobb stage 2 93 4EAT map w/Helix DP & Prodrive axleback. No CELs to date.

Here is a 5 second portion of a log that shows an example of what I'm talking about. This isn't at WOT, but under moderate acceleration. Notice the car gradually accelerating but the rpm falling off in the highlighted sections. I am NOT lifting off the throttle during these spikes; there is always constant, increasing pressure on the accelerator:



Here is another one. Again I've highlighted where the engine speed either trends downward or flattens out despite constant input on the accelerator from my foot:


If it would help I can upload the entire csv files for each of these pulls, but this is really my area of concern. I'm brand new to data logging, so if there are other parameters I should be looking at then let me know. I've been advised to look for cylinder roughness, but I can't do that on ecuExplorer and I've been unable to get my ECU to connect to RomRaider so far, but will keep trying.

I've been through several tanks of gas since I originally noticed this problem and suspected bad gas, including a bottle of Techron and a couple bottles of Heet w/isopropyl alcohol for good measure in case it was water that was the culprit. I think the symptoms have gotten better over the last two weeks, but the problem remains.

If anyone can venture a guess that might help me with my stuh stuh stutter, I'd appreciate it.

Doug

EDIT: .csv files now attached, if anyone's interested
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