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91 383 - bucks during wot- tune looks good

 
Old 02-15-2017, 09:36 AM
  #21  
JimLentz
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Originally Posted by madmatster View Post
my gut is telling me this is where my problem is. that sensor should read high voltage the entire time i have my foot on the pedal, regardless of anything else going on. right?
Yes, the voltage should stay high while you are at WOT.
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Old 02-15-2017, 01:20 PM
  #22  
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Originally Posted by madmatster View Post
On the last pull on the log, record 6580 has me at 100% wot, then at records 6582-6585 i'm at 0%, then by record 6586, i'm at 100% again. (sensing i went from 0-100% in one record) like i lifted, but i def did not lift.
this happened on the 3rd pull too.. at record 5327
Sorry dude, but I will have to disagree with you here. These are the records you are referring to:



You are just doing some serious acceleration with gear changes there. You can see from the log, that MAP value drops at the same time your throttle blades closes, when you change gear. I still can't find any evidence from the log that you TPS-sensor is failing.

Originally Posted by madmatster View Post
I am going to do some more logging this weekend, and try to get a sense exactly where in the rpm range i'm getting my bucking.
I'd happy to see those logs too!
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Old 02-15-2017, 02:02 PM
  #23  
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Originally Posted by Paccanini View Post
Madmatster sent me one of his Datamaster log file and here is a screenshot of one the WOT pulls (red line = TPS-%). I assume it's done with 3rd gear:



As you can see, knock counts (blue line) increase from 171 to 182 between 2400 and 3400 rpm (black line). Mat, is this the rpm range where you sense bucking? Although ecm sees knocking, timing isn't pulled down. I wonder if the tuner has zeroed out the knock retard table in Power Enrichment mode. This can be done, if you suspect a false knock. Too much timing can cause knocking, but while knock count increases in the log, total spark advance is only 20 degree (pink line). Timing shoudn't be the problem? As many have said before, tuning is difficult without WB. Anyway, narrow band is showing 898 mV, when knocking begins. I would richen up the tune at that point and see if it helps any.

Another thing I didn't see any of this from the log file you sent me:



If you have another log where this occurs, can you send that file to me too? If you are able to do more WOT runs with logging, do it with 3rd gear from 2000 rpm till the end. That way we can see is the knocking always there. Remember to avoid the cops.
Looking at the datalog screen shot I'm wondering why you are not "all in" timing wise at around 2,500rpm and by what I see, the timing is not being pulled, but the knock counts go up. You should shoot for about 12.6 A/F at WOT. 14.7 at idle is ok. Back to the NB O2, you "really" need a WB O2 to tune this motor.
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Old 02-15-2017, 02:22 PM
  #24  
madmatster
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Originally Posted by Paccanini View Post
Sorry dude, but I will have to disagree with you here. These are the records you are referring to:



You are just doing some serious acceleration with gear changes there. You can see from the log, that MAP value drops at the same time your throttle blades closes, when you change gear. I still can't find any evidence from the log that you TPS-sensor is failing.



I'd happy to see those logs too!
your graph is much more clear than mine when i view it in datamaster. that def paints a nicer picture and is more telling when i'm shifting.

i'm going to do some 3rd gear pulls from 2k like you suggested, and see how that looks.

thanks again!!

Originally Posted by Buccaneer View Post
Looking at the datalog screen shot I'm wondering why you are not "all in" timing wise at around 2,500rpm and by what I see, the timing is not being pulled, but the knock counts go up. You should shoot for about 12.6 A/F at WOT. 14.7 at idle is ok. Back to the NB O2, you "really" need a WB O2 to tune this motor.
that's what it sounds like. i need to learn a lot more about this before i know what to do with a wideband o2.... and since all of the experts here are no where near me in NJ... my learning curve isn't going to be very impressive.
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Old 02-23-2017, 10:02 AM
  #25  
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little update on my progress...

with the help from paccanini, who's been walking me through a bunch of things, i've eliminated a few things from the table.

TPS- i had some issues with my cable bracket and my tb. Its not squared up. I managed to bend that bracket a bit and i get full 100% wot during my pulls now. I've tested the sensor, and it looks like its working well.

Distributor- visual inspection of the cap and rotor look fine. i ohm'd out the primary and secondary coil. all within spec.

I swapped the injectors from one side to the other, in hopes of something turning up on the datalog as it bucks. I will have that log looked at soon. Next up is to swap the ignition wires from one side to the other. in hopes of the data log showing something.

Plugs were changed a few weeks ago to ngk6's.. gapped to .50.
(had the same issue with ngk55's gapped to .35)

here's a quick video of the bucking. it only seems to occur in wot, from 4k-5k.. then it clears up to red line.
its a bit blurry, and you can hear it more than see it. it's pretty pronounced.

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Old 02-11-2019, 07:42 PM
  #26  
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Ancient bump, I know. But I have taken ownership and since this car has a sort of, "Chain of custody" on the forums I figured I'd keep that going.

The car still had this issue when I purchased it and also had a Holley ECU installed which unfortunately didn't help solve the issue. During a compression test, It was found that cylinder 2 had no compression. The intake valve was too tight and not sealing to the head. In addition to this, cylinder 8 exhaust valve rocker was not aligned properly with the guide plate and was half off. These have since been fixed, the car has been properly tuned and it now runs like a bat out of hell. It will easily hang with cars worth 5-10x what I have into it. The car made 353 whp and 363 tq on a very stingy mustang dyno.

I don't post often, but if I ever go to sell the car I want the next owner to know that I cared for it just like the previous two owners did so I wanted to post this update.

Last edited by Excaliburvette; 02-11-2019 at 07:50 PM.
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