Stutter/misfire under load/boost
07-26-2012, 02:09 AM
#1
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Stutter/misfire under load/boost
MY miata is turbo'd and built up.
I'm running a megasquirt PNP ecu with what seems to be a fairly decent tune.
I don't run lean or excessively rich.
I AM running a VTPS on the car, because i was told it would fix this issue but it hasn't.
At about 4k RPM and higher, when i MAT the throttle (push it all the way to the floor) under acceleration, it will get like a stutter, and jump the rpm back about 300 for a second on the gauge, its very fast but it will occur lots.
Like ill punch it and it will go good then . .. . ... . . . sort of pattern of stuttering.
If i just give it about 75-80% it will still haul and i won't have this issue, but it would be nice to have a full range of throttle motion..
Any suggestions?
I have gapped the spark plugs smaller and it didn't fix it. I was thinking spark might be getting blown out, but I'm only running 7/8 psi.
I'm running a megasquirt PNP ecu with what seems to be a fairly decent tune.
I don't run lean or excessively rich.
I AM running a VTPS on the car, because i was told it would fix this issue but it hasn't.
At about 4k RPM and higher, when i MAT the throttle (push it all the way to the floor) under acceleration, it will get like a stutter, and jump the rpm back about 300 for a second on the gauge, its very fast but it will occur lots.
Like ill punch it and it will go good then . .. . ... . . . sort of pattern of stuttering.
If i just give it about 75-80% it will still haul and i won't have this issue, but it would be nice to have a full range of throttle motion..
Any suggestions?
I have gapped the spark plugs smaller and it didn't fix it. I was thinking spark might be getting blown out, but I'm only running 7/8 psi.
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07-26-2012, 10:05 AM
#2
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That's almost ALWAYS spark blowing out. Do you have a WBO2? If so, does the AFR stay solid before the stutter and then go very lean all the sudden during stutter? That's the excess unburned air.
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07-26-2012, 05:57 PM
#5
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It doesn't have the boost cut set and the plugs are NGK something.. a 7 heat range gapped to .25"
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08-03-2012, 07:03 AM
#9
So i m kinda having the same problem as OP did.
My car is a 2001 eu spec 1.6 with built motor, rev ms2 ecu, toyota cops.
Plugs are NGK BKR7, 0.32 gap.
When i floor it(wot) the car sometimes will jump 300-400 rpm back,usually around 6K Rpm and under load,like in 4th gear lets say.Tach jumps back also!
I have logs ,i will post them afterwards.
Any ideas?
My car is a 2001 eu spec 1.6 with built motor, rev ms2 ecu, toyota cops.
Plugs are NGK BKR7, 0.32 gap.
When i floor it(wot) the car sometimes will jump 300-400 rpm back,usually around 6K Rpm and under load,like in 4th gear lets say.Tach jumps back also!
I have logs ,i will post them afterwards.
Any ideas?
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08-04-2012, 04:31 AM
#11
Overboost protection is set at 17 psi, i use wastegate's spring boost atm, roughly 10 psi.
Here's the log
Download 2012-07-18_02.45.56.msl for free on uploading.com
Check what happens when i 'm at 100%tps, when the rpms start clmbing.
Btw i am in 4th gear.
Here's the log
Download 2012-07-18_02.45.56.msl for free on uploading.com
Check what happens when i 'm at 100%tps, when the rpms start clmbing.
Btw i am in 4th gear.
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08-04-2012, 05:08 AM
#12
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Which firmware are you on? If you are on 3.1.6, then there is a known bug that causes a random misfire. I can help with the upgrade once I am back from vacation on the 10th.
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12-12-2012, 11:59 PM
#15
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Just thought i'd help out anyone else who had this issue.
I had forgotten it and It was recently brought to my attention.
But the issue was:
In megatune there is an overboost protection, mine was set to just below 8.
After i re loaded the base map, i went through each and every setting and found out that it turned off the overboost protection which is why i wasnt experiencing the problem after the re-load.
Once i got it tuned, i had to overboost set to somewhere around 15 i believe, and havent had the problem since!
So FYI to all those who experience this, CHECK YOUR OVERBOOST PROTECTION!
I had forgotten it and It was recently brought to my attention.
But the issue was:
In megatune there is an overboost protection, mine was set to just below 8.
After i re loaded the base map, i went through each and every setting and found out that it turned off the overboost protection which is why i wasnt experiencing the problem after the re-load.
Once i got it tuned, i had to overboost set to somewhere around 15 i believe, and havent had the problem since!
So FYI to all those who experience this, CHECK YOUR OVERBOOST PROTECTION!
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01-23-2013, 03:11 PM
#16
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My log suggests I'm hitting overboost protection at 150kpa but I have a standard t25 actuator and the dashboard mounted boost gauge showed just under 10ps which was Tee'd off the same line.
I have the map line tee'd off the FPR then through the firewall then to the ecu with a T in that line to the boost gauge.
At or close to WOT it does it just a fraction under 4k rpm but if I use less throttle it will go above that.
Is this a bad map signal or a genuine reading? Can someone have a look at my log and see?
I have the map line tee'd off the FPR then through the firewall then to the ecu with a T in that line to the boost gauge.
At or close to WOT it does it just a fraction under 4k rpm but if I use less throttle it will go above that.
Is this a bad map signal or a genuine reading? Can someone have a look at my log and see?
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