Bucking / hesitation issue - a lot worse when cold but warm too
Sep 8, 2013, 09:09 AM
#1
Bucking / hesitation issue - a lot worse when cold but warm too
The car is a stock Evo 9 2006 (has an exhaust but the issue was there without the exhaust as well so don't consider that)
The issue:
The car when cold starts normally, has a few hiccups with idle but generally works fine.
If you try to give it a bit of gas it starts to "stall" at 1800-2000 rpm - sounds like a soft revlimit going brrrrrrr but not increasing RPM.
If you drive off - it does the same - not always but it's not operating smoothly.
The symptom however over time goes "away" when the car warms up. It still bucks a bit but A LOT less when it's warmed up. Also the car feels quite laggy for a stock 9 with a 3" exhaust.
CEL goes on but only for EGR errors, which I've already corrected.
What could be the cause of this? Map related changes don't affect it much, we've replaced the sparkplugs and coils.
Also - to note - above 3500 RPM when on boost, the car pulls and drives normally so I'm really stomped... I was thinking MIVEC but that wouldn't cause the actual bucking and breaking up at low RPM, probably just lag - or am I mistaken?
If anyone has had a similar issue I'd really like to hear an idea.
The issue:
The car when cold starts normally, has a few hiccups with idle but generally works fine.
If you try to give it a bit of gas it starts to "stall" at 1800-2000 rpm - sounds like a soft revlimit going brrrrrrr but not increasing RPM.
If you drive off - it does the same - not always but it's not operating smoothly.
The symptom however over time goes "away" when the car warms up. It still bucks a bit but A LOT less when it's warmed up. Also the car feels quite laggy for a stock 9 with a 3" exhaust.
CEL goes on but only for EGR errors, which I've already corrected.
What could be the cause of this? Map related changes don't affect it much, we've replaced the sparkplugs and coils.
Also - to note - above 3500 RPM when on boost, the car pulls and drives normally so I'm really stomped... I was thinking MIVEC but that wouldn't cause the actual bucking and breaking up at low RPM, probably just lag - or am I mistaken?
If anyone has had a similar issue I'd really like to hear an idea.
Sep 8, 2013, 11:43 AM
#2
Evolving Member
I am having the exact same issue. Checked the plugs and they seem fine.
When I put it in first and lightly press the gas pedal, it goes all the way rich and it bucks like crazy.
At cruise, AFRs are jumping from 10.0 to 15.
When I floor it, it pulls just fine.
I will log tomorrow and see if something is off.
When I put it in first and lightly press the gas pedal, it goes all the way rich and it bucks like crazy.
At cruise, AFRs are jumping from 10.0 to 15.
When I floor it, it pulls just fine.
I will log tomorrow and see if something is off.
Sep 8, 2013, 02:13 PM
#4
OP, have you done a boost leak test?
Its fine when running wot probably because you're in open loop.
I am having the exact same issue. Checked the plugs and they seem fine.
When I put it in first and lightly press the gas pedal, it goes all the way rich and it bucks like crazy.
At cruise, AFRs are jumping from 10.0 to 15.
When I floor it, it pulls just fine.
I will log tomorrow and see if something is off.
When I put it in first and lightly press the gas pedal, it goes all the way rich and it bucks like crazy.
At cruise, AFRs are jumping from 10.0 to 15.
When I floor it, it pulls just fine.
I will log tomorrow and see if something is off.
Sep 9, 2013, 01:36 AM
#5
I am having the exact same issue. Checked the plugs and they seem fine.
When I put it in first and lightly press the gas pedal, it goes all the way rich and it bucks like crazy.
At cruise, AFRs are jumping from 10.0 to 15.
When I floor it, it pulls just fine.
I will log tomorrow and see if something is off.
When I put it in first and lightly press the gas pedal, it goes all the way rich and it bucks like crazy.
At cruise, AFRs are jumping from 10.0 to 15.
When I floor it, it pulls just fine.
I will log tomorrow and see if something is off.
Sep 9, 2013, 08:31 AM
#7
Evolving Member
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