problem with spuddering - Miata Turbo Forum - Boost cars, acquire cats.

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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 04-27-2009, 02:30 PM   #1
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Default problem with spuddering

It seems that when I get to around 5k rpm and above, no matter the load, it starts to sputter. I lessened the gap on the spark plugs to no avail... I am going to log a run right now. Any ideas? AFR seems fine when it does it..
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Old 04-27-2009, 04:01 PM   #2
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A short in the CAS lines? We had a car with that problem - when it happened, it was very RPM Specific.
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Old 04-27-2009, 04:16 PM   #3
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are you running cops? i would look at that or wires... my FI thunderbird had what seemed like spark blowout at just high load, changed and gapped plugs at .40, no dice... changed everyhting BUT the wires... once i did.. well, i just kicked myself.
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Old 04-27-2009, 04:19 PM   #4
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I had the same thing happen to me, changing the plugs fixed it.
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Old 04-27-2009, 04:31 PM   #5
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cracks in the ceramic insulator could be an issue also.
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Old 04-27-2009, 05:08 PM   #6
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alright ill get new spark plugs, and I just ordered better plugs for the toyota COPS so I can eliminate my wiring as a issue.

Any way to check the CAS output? There seems to be no odd things on the datalogging. I need this fixed before sat for the dyno day haha.
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Old 04-27-2009, 08:33 PM   #7
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Put new plugs in, and same thing. What should I start lookin at next? It seems to do it at above 4000 rpm and 3 to 5 psi boost.
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Old 04-27-2009, 08:38 PM   #8
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This kind of spuddering?



Make some french fries.



Can we get a good datalog on it?
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Old 04-27-2009, 09:28 PM   #9
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Quote:
Originally Posted by cardriverx View Post
Put new plugs in, and same thing. What should I start lookin at next? It seems to do it at above 4000 rpm and 3 to 5 psi boost.

do you have any settings that might trigger then? never happened before?
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Old 04-27-2009, 10:15 PM   #10
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Quote:
Originally Posted by Braineack View Post
do you have any settings that might trigger then? never happened before?
Never happened before. no settings eaither, launch control, rev limit, boost cut is all ok.
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Old 04-28-2009, 01:10 AM   #11
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Ok here are two logs. I think I need to re calberate my LC-1, because its reading almost a full point higher than normal .The first log is my regular map for like a year, The seconded log is with 17 fuel points added above 100 kpa! .

Every time I was at full throttle, it was studdering. You should be able to tell by the bumpyness of the rpm graph.

Im not sure what to do guys. Vacuum at idle is perfectly normal, and driveing out of boost is fine. Maybe its a loose wire??

HERE IS THE FIRST LOG Free File Hosting Made Simple - MediaFire
Attached Files
File Type: xls better.xls (290.3 KB, 55 views)
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Old 04-28-2009, 02:20 PM   #12
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well it was a freaking loose contact on the coil plug. What the **** lol. Well dyno day here I come!!
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Old 04-28-2009, 06:25 PM   #13
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i was about to tell you to swap out the coil with someone to check it out. i just went thru an ordeal that turned out to be a coilpack "going" bad!
mine would run fine until i got into boost. couldn't figure it out, especially since it started happening immediatly after another completely unrelated fuel issue. finally the car started running bad at idle and i found it in seconds, AFTER i ordered a 150 dollar serial adapter to datalog with my link ecu. glad you found it quick.
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Old 04-28-2009, 06:31 PM   #14
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Glad you figured it out cdx!

Oh the things you could have beaten yourself up chasing down...
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