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Old 05-08-2012, 06:34 PM   #1
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Hey guys, got an issue that bugs me a bit, just curious if anyone has any input
specs
93 NA with a SNC 1.6l
MS1 3.0
stock coils
mitsu 16g
dsm 340cc
blah blah

problem im getting is, occasionally, more random, nothing specific causes it, it can do it under load, or not
i get a buck. like a cylinder cuts out, then comes back, like i said it will just randomly do it when driving, very rarely it will do it in boost.

other question is, which im leaning towards either the turbo seals or valve stem seals
if i completely let off the throttle, engine brake, then start giving it gas again, it smokes, but thats the only time.
now, its not the PCV or breather, as i can unhook both, and it still does it at the same situation.
im replacing the turbo tomorrow, so that will eliminate the possibility of that, assuming it still smokes
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Old 05-08-2012, 06:36 PM   #2
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Deceleration smoke is usually valve seals.
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Old 05-08-2012, 06:41 PM   #3
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thats what i was thinking, as long as i press the clutch in when i let off its fine, i just have a habit of engine braking
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Old 05-08-2012, 06:49 PM   #4
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I had the same issue as you with the bucking. in my case the cas was missing an event on the very rare occasion and thus spark would not fire.
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Old 05-08-2012, 06:51 PM   #5
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like a failing cas? or incorrect settings in wheel decoder settings?
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Old 05-08-2012, 08:38 PM   #6
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I don't know if this applies to MS1 but...


I had the same issues on MS2. It was getting sync loss on the CAS signal. Just log when it happens (easier said than done). If it's a sync issue, you will see "Sync Loss Count" count go up, and "Sync Loss Reason" will go to 38 or 39.

Building an opto isolator circuit fixed it for me.
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Old 05-08-2012, 09:34 PM   #7
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Quote:
Originally Posted by soviet View Post
I don't know if this applies to MS1 but...


I had the same issues on MS2. It was getting sync loss on the CAS signal. Just log when it happens (easier said than done). If it's a sync issue, you will see "Sync Loss Count" count go up, and "Sync Loss Reason" will go to 38 or 39.

Building an opto isolator circuit fixed it for me.
i havent found anything in terms sync in tuner or megaview
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Old 05-08-2012, 10:17 PM   #8
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i had a similar issue but mine is during cruise. At the event my afr's would drop into the 12's then pop up to 15:1-16:1 and be fine again. it seemed to me like it was getting a false acceleration signal cause my injector PW would jump up just before each event. so i opened acceleration wizard on tunerstudioMS to check my settings and everything looked good so i drove with it open to see if the green ball was jumping around but it stopped doing it. at first i was mad cause it wouldnt fail while i was watching so just saved my settings and closed the window. that was 2 weeks ago and it has yet to act up yet and i drive the car daily. not sure what fixed it but it stopped.
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Old 05-08-2012, 10:25 PM   #9
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Yeah, I have no idea what fixed mine either, but the cas is still the same one.
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Old 05-08-2012, 10:52 PM   #10
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my afr is staying almost exact at 14.7-15.2 cruising, it doesnt change when it bucks though
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Old 05-08-2012, 10:59 PM   #11
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if its a misfire your afrs should change alot... do your injector PW's change during the buck? can you get a data log of the event?
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Old 05-08-2012, 11:10 PM   #12
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i have a datalog i left running for a while, but i dont see anything that shows any sign of it happening
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File Type: msl 2012-04-16_13.01.15.msl (1.79 MB, 53 views)
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Old 05-08-2012, 11:53 PM   #13
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do you not have a TPS or an intake air temp sensor?
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Old 05-09-2012, 12:00 AM   #14
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This is exactly what is happening to me. In for details. I'm gonna throw a CAS at it and see if it stops. Mostly happens on the freeway.
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Old 05-09-2012, 12:02 AM   #15
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Quote:
Originally Posted by fastivab6tg25mr View Post
do you not have a TPS or an intake air temp sensor?
1.6 throttle body still
i have a IAT sensor, but i still need to tune it in, it completely leans out the car when i plug it in
Quote:
Originally Posted by MartinezA92 View Post
This is exactly what is happening to me. In for details. I'm gonna throw a CAS at it and see if it stops. Mostly happens on the freeway.
i had a CAS fail on me shortly after getting the car, so this one was my spare
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Old 05-11-2012, 04:42 PM   #16
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new turbo etc is on, still has the smoke, so must be valve seals, never felt any bucks, putting DP on this evening, car sounds like a cummins (no joke)
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Old 05-14-2012, 03:25 AM   #17
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car is running better now, still running e85. running 10psi on the 57/73mm, 12 makes clutch slip.
found myself running short of fuel saturday night, out messing around, after 4000rpm my afrs started dropping to 13.2
pulled the 305cc's today, threw in some low imp 660cc's, after rewiring the injector harness, i retuned the fuel, however, im having an issue at idle, its popping and idle searching
any ideas?
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Old 05-21-2012, 12:11 AM   #18
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the video is sideways for some reason, but it started bucking again
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Old 05-24-2012, 01:31 AM   #19
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so with gas or e85
340cc or 660cc
more advance or retarded timing
too rich to lean

i still get the buck, i completely redid my settings in TS, even disabled accel/decel, still have the buck. its almost like im loosing power when it bucks, since the tach and oil pressure gauge drops as seen in the video.
wet or dry out doesnt make a difference, however im wondering if i have a failing coil, or if by the off chance i have a spark plug partly fouled. although even if it was a miss from a plug, the tach wouldnt drop 800rpm then bounce back
the IAT is hooked up now as well, and still no change
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Old 05-27-2012, 02:31 AM   #20
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so it turns out in my case, i had killed the plug wires in less than 7k miles (ngk's) and fouled 1 plug. replaced those, double checked base timing with light, was 3d advance, changed that, and its running alot smoother now, still a random pop every now and then, but no where near as bad as before
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