what is causing this pop/backfire?
Thread Starter
Registered User
Joined: Aug 2006
Posts: 3,705
From: Kansas
what is causing this pop/backfire?
alright guys, since ive done my headers/exhaust, i'll have a slight stumble and then if i get into the throttle during that stumble, it'll POP
It happens around 2000-2500 mainly, and will do it even if i floor it from a roll and it has to downshift
I have new plug wires (did it with old plug wires too)
new msd cap/rotor (did it with the old setup too)
what do u guys think it is?
ICM starting to go out?
coil?
plugs?
what?
It happens around 2000-2500 mainly, and will do it even if i floor it from a roll and it has to downshift
I have new plug wires (did it with old plug wires too)
new msd cap/rotor (did it with the old setup too)
what do u guys think it is?
ICM starting to go out?
coil?
plugs?
what?
Last edited by reamo04; May 8, 2007 at 04:12 PM.
Banned
Joined: Mar 2004
Posts: 3,577
From: Sandy VJJville
Misfire? I just did my longtubes/exhaust and I have the same symptoms you describe. The car stumbles in throttle and then occasionally there's a pop. I never got into it hard because I knew it was misfiring. Anyway, I got an SES light blinking in my face and the P0300 code. Are you getting any lights?
Thread Starter
Registered User
Joined: Aug 2006
Posts: 3,705
From: Kansas
Misfire? I just did my longtubes/exhaust and I have the same symptoms you describe. The car stumbles in throttle and then occasionally there's a pop. I never got into it hard because I knew it was misfiring. Anyway, I got an SES light blinking in my face and the P0300 code. Are you getting any lights?
and i had one burned plug wire, but i replaced it, and it did it with the old plug wires too
and now its staring to do it at higher RPMS too, right about the time it shifts
Registered User
Joined: Oct 2002
Posts: 2,277
From: Orange Kounty, Kalifornia
Make sure your BLMs are at 128. I've got tons of mods and if I part throttle then stop I had the "pop" too on a Manual Trans. If you get your car tuned properly, not just spark & fuel, they can adjust your injectors to slightly fatten or trim your fuel so your BLMs are balanced at 128. A split BLM is a different story....
BLM is Block Learn Multiplier.
Have you had your car tuned since the install? What other mods?
It's kind of tough to diagnose over the web but if you are increasing the flow of air you will likely affect your programming. It depends what else may have been done to the car and you may be flowing slight amounts of fuel into the exhaust causing the "pop".
Under normal driving it doesn't sound like the pop is occuring, just that slight part throttle stumble.
BLM is Block Learn Multiplier.
Have you had your car tuned since the install? What other mods?
It's kind of tough to diagnose over the web but if you are increasing the flow of air you will likely affect your programming. It depends what else may have been done to the car and you may be flowing slight amounts of fuel into the exhaust causing the "pop".
Under normal driving it doesn't sound like the pop is occuring, just that slight part throttle stumble.
Thread Starter
Registered User
Joined: Aug 2006
Posts: 3,705
From: Kansas
Make sure your BLMs are at 128. I've got tons of mods and if I part throttle then stop I had the "pop" too on a Manual Trans. If you get your car tuned properly, not just spark & fuel, they can adjust your injectors to slightly fatten or trim your fuel so your BLMs are balanced at 128. A split BLM is a different story....
BLM is Block Learn Multiplier.
Have you had your car tuned since the install? What other mods?
It's kind of tough to diagnose over the web but if you are increasing the flow of air you will likely affect your programming. It depends what else may have been done to the car and you may be flowing slight amounts of fuel into the exhaust causing the "pop".
Under normal driving it doesn't sound like the pop is occuring, just that slight part throttle stumble.
BLM is Block Learn Multiplier.
Have you had your car tuned since the install? What other mods?
It's kind of tough to diagnose over the web but if you are increasing the flow of air you will likely affect your programming. It depends what else may have been done to the car and you may be flowing slight amounts of fuel into the exhaust causing the "pop".
Under normal driving it doesn't sound like the pop is occuring, just that slight part throttle stumble.
i have not had the car tuned, i have been meaning to and just got the money to do it, but dont want tog et it tuned if its my opti since thatd be where i need the $$. I can scan it while i drive it and monitor it i guess and see what the BLMs are, but today it started doing it at higher RPMS too, starting to wonder if i have an injector going out, or if i fouled a plug or something cause it did run rich for a while
Thread Starter
Registered User
Joined: Aug 2006
Posts: 3,705
From: Kansas
also, when we did headers, we did not hook up any emissions, but the EGR is still plugged in
AIR hoses are not hooked up except for the one that goes to the CAI
could those be part of the problem?
AIR hoses are not hooked up except for the one that goes to the CAI
could those be part of the problem?
Registered User
Joined: Feb 2005
Posts: 346
From: ohio
Are they Race headers or emission headers with the fittings open? If so yeah, that could cause it, considering it is creating a false Exhaust leak bringing in unmetered air before the O2's.
Also did you get new coated headers? The coating could have burned off and ruined your 02's, not an uncommon occurance.
Also did you get new coated headers? The coating could have burned off and ruined your 02's, not an uncommon occurance.
Thread Starter
Registered User
Joined: Aug 2006
Posts: 3,705
From: Kansas
Are they Race headers or emission headers with the fittings open? If so yeah, that could cause it, considering it is creating a false Exhaust leak bringing in unmetered air before the O2's.
Also did you get new coated headers? The coating could have burned off and ruined your 02's, not an uncommon occurance.
Also did you get new coated headers? The coating could have burned off and ruined your 02's, not an uncommon occurance.
They are emissions headers, and the fittings are capped off, but if i remember right, the air pump has multiple tubes, and then there is one that goes to the intake tube, could air be comming in through there and into the intake tube?
What do u guys recommend?
Get the tune? Hold out and replace opti? Check plugs?
Last edited by reamo04; May 8, 2007 at 10:11 PM.
Thread Starter
Registered User
Joined: Aug 2006
Posts: 3,705
From: Kansas
is there a way to test the ICM?
also, whats a way to check the IAT?
mine only started doing this after headers/exhaust mine u, it may be a coincidence though and something could be going out
Registered User
Joined: Oct 2002
Posts: 2,277
From: Orange Kounty, Kalifornia
Shoebox @ www.shbox.com has some pics of the ICM and a cooling mod. It doesn't discuss how to test it though.
Thread Starter
Registered User
Joined: Aug 2006
Posts: 3,705
From: Kansas
ALRIGHTY
scanned the car today and drove around with it
BLMs = 128 in open loop, no surprise there
Closed loop - anywhere from 113-127, so a little low, and they were not both the same, but always within +/- 2 of eachother, right bank was always a little higher than left.
They are low when it pops, then when im at idle, they are around 127
so, do u guys think i just need a tune to get this fixed?
scanned the car today and drove around with it
BLMs = 128 in open loop, no surprise there
Closed loop - anywhere from 113-127, so a little low, and they were not both the same, but always within +/- 2 of eachother, right bank was always a little higher than left.
They are low when it pops, then when im at idle, they are around 127
so, do u guys think i just need a tune to get this fixed?