Problem: BOOST Spike + Fuel Cut.
Oct 31, 2006, 10:40 PM
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Problem: BOOST Spike + Fuel Cut.
Wassup,
I just got done installing my 4-puck clutch last weekend and took it out for a test drive the past few days here... and i have a couple problems to bring up to you guys and see what you think about this..
When i start off and floor my car, my boost spikes up to 20-21 psi then goes down to 15 psi. when i reach 4500rpm-5000rpm my car starts to have a fuel cut.
i really dont know whats wrong with my car, but if you guys have any experience with this issue... let me know if this is a common problem to all evos? or can this be resolved by doing something to it?
I am running stock fuel pump, pump gas, FMIC, intercooler pipings, intake, and 3" TBE.
and my car is a 2003 evo 8
I just got done installing my 4-puck clutch last weekend and took it out for a test drive the past few days here... and i have a couple problems to bring up to you guys and see what you think about this..
When i start off and floor my car, my boost spikes up to 20-21 psi then goes down to 15 psi. when i reach 4500rpm-5000rpm my car starts to have a fuel cut.
i really dont know whats wrong with my car, but if you guys have any experience with this issue... let me know if this is a common problem to all evos? or can this be resolved by doing something to it?
I am running stock fuel pump, pump gas, FMIC, intercooler pipings, intake, and 3" TBE.
and my car is a 2003 evo 8
Nov 1, 2006, 09:55 AM
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Originally Posted by Warrtalon
Yes, fuel cut is normal if you aren't tuned and have more airflow from raised boost, IC pipes, intake, exhaust, etc. Do you have an FMIC, IC pipes, intake, and TBE with a stock fuel pump and stock tune? Please say no!
Nov 1, 2006, 09:58 AM
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hmm 15 psi at 4500 rpm i dont believe that is normal either.. but you do need a tune..or your engine is going to go bye bye... I cant believe you would get all that and get no tune..
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Nov 1, 2006, 10:44 AM
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Umm, does not sound like fuel cut... are you getting an overboost code set? Sounds more like a bad boost leak than fuel cut.
A walbro is a good idea, but will not prevent fuel cut due to overboost by any means.
To start, you should get a tactrix cable and a copy of Malibu Jacks mut logger from aktive matrix then do some logging, that will tell you if you need a walbro and if you are infact hitting the boost limiter.
A walbro is a good idea, but will not prevent fuel cut due to overboost by any means.
To start, you should get a tactrix cable and a copy of Malibu Jacks mut logger from aktive matrix then do some logging, that will tell you if you need a walbro and if you are infact hitting the boost limiter.
Last edited by Mad_SB; Nov 1, 2006 at 10:47 AM.
Nov 1, 2006, 10:56 AM
#9
Fuel cut is likely, because he has all those free-flowing mods but no tune. It happens all the time on Evos in cold weather with exhausts and no tune, because the lessened backpressure causes a raise in boost, and the increased airflow at higher rpm causes fuel cut - the ECU is set to cut boost if the MAF HZ (airflow) exceeds a preset level.
He doesn't need to log anything to see if he needs a fuel pump - that is not the reason for fuel cut. We are just saying it's not smart nor does it make any sense to have those expensive mods without having the most important mods for power and safety: fuel pump and a tune.
He doesn't need to log anything to see if he needs a fuel pump - that is not the reason for fuel cut. We are just saying it's not smart nor does it make any sense to have those expensive mods without having the most important mods for power and safety: fuel pump and a tune.
Nov 1, 2006, 02:50 PM
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The reason I was giving the thumbs down on fuel cut is the 15 psi at 4500 rpm comment.
I suppose if he is hitting fuel cut due to the boost spike and subsequent load overrunning the boost limit of the stock ecu, that would pull down the boost and cause the lower boost.
I had a utec on the car before ecuflash, so i never actually experienced fuel cut, jut the overboost cel code.
I suppose if he is hitting fuel cut due to the boost spike and subsequent load overrunning the boost limit of the stock ecu, that would pull down the boost and cause the lower boost.
I had a utec on the car before ecuflash, so i never actually experienced fuel cut, jut the overboost cel code.
Nov 2, 2006, 05:07 AM
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I agree War, 15 psi is a long way from fuel cut, so the op's description is very vauge.
Shocker, we need a better description of what is going on here. Are you saying that when you do not get fuel cut your boost curve spikes to 21psi gauge, then falls off to 15 psi gauge by 4500-5000 rpm? Or it falls off to 15psi when you do hit fuel cut?
What rpm are you getting what feels like fuel cut?
one thing you might try is going wot latter in the rpm range.. may sound silly, but again most of the time I have seen fuel cut due to "over boost" it occurs lower in the rpm range, very close to peak torque, since you hit peak load at that point and "over boost" fuel cut is driven by the load value.
Shocker, we need a better description of what is going on here. Are you saying that when you do not get fuel cut your boost curve spikes to 21psi gauge, then falls off to 15 psi gauge by 4500-5000 rpm? Or it falls off to 15psi when you do hit fuel cut?
What rpm are you getting what feels like fuel cut?
one thing you might try is going wot latter in the rpm range.. may sound silly, but again most of the time I have seen fuel cut due to "over boost" it occurs lower in the rpm range, very close to peak torque, since you hit peak load at that point and "over boost" fuel cut is driven by the load value.
Nov 2, 2006, 08:15 AM
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Originally Posted by mad_VIII
I agree War, 15 psi is a long way from fuel cut, so the op's description is very vauge.
Shocker, we need a better description of what is going on here. Are you saying that when you do not get fuel cut your boost curve spikes to 21psi gauge, then falls off to 15 psi gauge by 4500-5000 rpm? Or it falls off to 15psi when you do hit fuel cut?
What rpm are you getting what feels like fuel cut?
one thing you might try is going wot latter in the rpm range.. may sound silly, but again most of the time I have seen fuel cut due to "over boost" it occurs lower in the rpm range, very close to peak torque, since you hit peak load at that point and "over boost" fuel cut is driven by the load value.
Shocker, we need a better description of what is going on here. Are you saying that when you do not get fuel cut your boost curve spikes to 21psi gauge, then falls off to 15 psi gauge by 4500-5000 rpm? Or it falls off to 15psi when you do hit fuel cut?
What rpm are you getting what feels like fuel cut?
one thing you might try is going wot latter in the rpm range.. may sound silly, but again most of the time I have seen fuel cut due to "over boost" it occurs lower in the rpm range, very close to peak torque, since you hit peak load at that point and "over boost" fuel cut is driven by the load value.
the fuel cut happens when i apply the gas and revving at 4500-5000 rpm boost spiking at 21 psi. after the fuel cut the boost level tapers down to 15 psi. it happens when i start off from a dig and on a roll.
forgot to mention too that i have a SES light on. I will get the codes to you guys in a few..
Last edited by projekt_shocker; Nov 2, 2006 at 08:31 AM.
Nov 2, 2006, 08:37 AM
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Originally Posted by nigletsyz
a bit off-topic, but don't beat on your new clutch.. you need to break it in properly. Otherwise, you'll end up spending more $$$ replacing it in a month or so....
