messed around with MBC, now misfiring???
May 15, 2011, 07:13 AM
#1
messed around with MBC, now misfiring???
Really in need of some help guys, Ive been using the search for a while and coming up with a lot of different possibilities, although I think my situation is a little different.
I just got my car a few weeks ago with no boost guage other than the 15psi max built in. Car is tuned to 21 and has full bolt-ons. I turned the boost down a little bit just because I didnt want to hit any spike without being able to see it.
car was running fine until I decided to replace the greddy rs it came with for a stock 9 dv. I threw the greddy back on immediately after realizing the tune was built around the BOV venting to atmosphere. ugh.
so after fiddling with the whole bov thing and returning it to its "original" state, it starts missing on WOT.
I turn the mbc down some more, and realize its boosting to only 13-14max. woops. Changed the plugs, tried dialing the boost again, and things worked 'well' for a few minutes. NO missing.
then, it starts missing again on hard pulls.
Steps ive already gathered taking:
Replace battery (mine is fairly weak)
replace coils
replace wires
replace cam angle sensor
replace map sensor
I dont think its any of these, but then again, I am ignorant. Anyone else have any ideas?
I just got my car a few weeks ago with no boost guage other than the 15psi max built in. Car is tuned to 21 and has full bolt-ons. I turned the boost down a little bit just because I didnt want to hit any spike without being able to see it.
car was running fine until I decided to replace the greddy rs it came with for a stock 9 dv. I threw the greddy back on immediately after realizing the tune was built around the BOV venting to atmosphere. ugh.
so after fiddling with the whole bov thing and returning it to its "original" state, it starts missing on WOT.
I turn the mbc down some more, and realize its boosting to only 13-14max. woops. Changed the plugs, tried dialing the boost again, and things worked 'well' for a few minutes. NO missing.
then, it starts missing again on hard pulls.
Steps ive already gathered taking:
Replace battery (mine is fairly weak)
replace coils
replace wires
replace cam angle sensor
replace map sensor
I dont think its any of these, but then again, I am ignorant. Anyone else have any ideas?
Last edited by prowakeskater; May 15, 2011 at 08:05 AM.
May 15, 2011, 07:29 AM
#3
i have a stri laying around... guess I can try to install it at work today (verizon) lol
also need to install my wideband, too. Theres already a bung in the test pipe just waiting for it..
should I log a couple pulls and send them to anyone who wants to take a peek?
also need to install my wideband, too. Theres already a bung in the test pipe just waiting for it..
should I log a couple pulls and send them to anyone who wants to take a peek?
May 15, 2011, 07:38 AM
#4
May 15, 2011, 08:03 AM
#7
During shifts, when the air would normally vent to atmosphere with the greddy, my RPM would jump because the air got recirculated. I guess I could try setting the stock 9 dv to VTA...
Last edited by prowakeskater; May 15, 2011 at 08:12 AM.
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May 15, 2011, 08:19 AM
#9
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You mentioned that you a very new to the car. It sounds like you do not know the exact history of the car or what is going on with it. Before you edited your original post, you said you were working on your car WHILE at work at Verizon. That is not a situation you want to be stuck in. You live in Cincinnati - Buschur is right up the road.
In my mind, it would be worthwhile to have them look the car over. They have far more experience diagnosing and tuning Evo's than it sounds like you do. Instead of possibly stranding yourself or causing future damage to your car, turn the boost DOWN, drive the car conservatively and have Buschur or whoever else with experience look at it. Doesn't have to be Buschur - I just mentioned them since they are relatively close to you.
In my mind, it would be worthwhile to have them look the car over. They have far more experience diagnosing and tuning Evo's than it sounds like you do. Instead of possibly stranding yourself or causing future damage to your car, turn the boost DOWN, drive the car conservatively and have Buschur or whoever else with experience look at it. Doesn't have to be Buschur - I just mentioned them since they are relatively close to you.
May 15, 2011, 08:26 AM
#10
youre right, I bought the car from a guy who got it from an auction. The oil pan has a leak, the entire AC has been yanked, an incorrect serpentine belt was installed when I got it, but the car ran perfectly when I received it. It just started hiccuping after the BOV incident and messing with the mbc
May 15, 2011, 08:32 AM
#11
Evolved Member
what it sounds like is ur running more lean now, before when you were VTA your bov ( big no no), your car is already preset from the factory to run recirc, and it accounts for the air thats recircing, since you were vta, youll run a bit rich between shifts due to less air with same fuel being injected. Now since you did the right thing and recircd your 9 valve, your car is seeing more air but tuned for less, so in essence your running more lean which is causing the misfire issue, your best bet, get retuned for recirc, on either bov. Theres my 0.02, besides transient response between gears is much better recirc then vta.
May 15, 2011, 08:52 AM
#12
what it sounds like is ur running more lean now, before when you were VTA your bov ( big no no), your car is already preset from the factory to run recirc, and it accounts for the air thats recircing, since you were vta, youll run a bit rich between shifts due to less air with same fuel being injected. Now since you did the right thing and recircd your 9 valve, your car is seeing more air but tuned for less, so in essence your running more lean which is causing the misfire issue, your best bet, get retuned for recirc, on either bov. Theres my 0.02, besides transient response between gears is much better recirc then vta.
the car is tuned for the air VTA, so im not running rich or lean between shifts, and its not missing between shifts. Its only missing during pedal-shoved-to-the-floor.
i know it doesnt really make sense. But the car is in the exact same condition right now that it was when I got it. maybe I shouldnt relate the whole bov experiment to this problem...
May 15, 2011, 09:36 AM
#13
I put the car back to the same state it was in prior to me messing around with the BOV, and thats when the missing started.
the car is tuned for the air VTA, so im not running rich or lean between shifts, and its not missing between shifts. Its only missing during pedal-shoved-to-the-floor.
i know it doesnt really make sense. But the car is in the exact same condition right now that it was when I got it. maybe I shouldnt relate the whole bov experiment to this problem...
the car is tuned for the air VTA, so im not running rich or lean between shifts, and its not missing between shifts. Its only missing during pedal-shoved-to-the-floor.
i know it doesnt really make sense. But the car is in the exact same condition right now that it was when I got it. maybe I shouldnt relate the whole bov experiment to this problem...
I'd suggest you install the wideband and the boost gauge pronto. If you are unsure about how to do it, take it to someone who is certain that they can do it right. While you're experimenting, you don't want to assume wrong, and get to buy a motor for your mistake...
May 15, 2011, 09:52 AM
#14
How do you know what the car was "tuned" for when you got it from a guy who got it from an auction, you don't have your wideband installed, and don't have a boost gauge? Not dissing you, just pointing out that you really don't have the information necessary to know what's happening with your car or your tune.
I'd suggest you install the wideband and the boost gauge pronto. If you are unsure about how to do it, take it to someone who is certain that they can do it right. While you're experimenting, you don't want to assume wrong, and get to buy a motor for your mistake...
I'd suggest you install the wideband and the boost gauge pronto. If you are unsure about how to do it, take it to someone who is certain that they can do it right. While you're experimenting, you don't want to assume wrong, and get to buy a motor for your mistake...
but, youre definitely right. I need to get my wideband and boost guage in tomorrow and drive extra conservatively until I get this figured out. Theres a shop about 40 minutes from me that deals with evos, im think gonna take it there.
wish me luck