Post header install ????
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,604
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From: Phoenix, Arizona
Post header install ????
Just got my car car back from EM - longtubes installed & no cats w/ .02 sims. Car feels/sounds awesome BUT the 1st thing I noticed was the popping/backfiring. Nothing severe but it feels like the car is all of a sudden running rich. I do plan to talk to Trevor @ EM about this but I thought I'd get some other input. Prior to the header install but after the Hotcam install, I had the PCM retuned. It almost seems to me that the tune is wrong now that I have the headers. Is that a possibility? Not throwin' any codes at this time and if it weren't for the popping/backfiring I'd be in heaven cuz the car sounds & feels awesome BUT......
I guess my question really is, would the addition of longtube headers require a re-tune?
Any thoughts?
Jeff
I guess my question really is, would the addition of longtube headers require a re-tune?
Any thoughts?
Jeff
Last edited by JEFNLSA; Jan 4, 2006 at 12:21 PM.
Melting Slicks
Joined: Mar 2005
Posts: 2,351
Likes: 230
From: Northeast FL
I recently put EM long tubes, RT cats, and a Borla cat back on my 94. Had a bit of popping at first but it went away after I checked all the plug wires to be sure they were on securely. Number 8 is the worst one to get to IMHO.
Or you could also check the routing of the plug wires to be sure they went back on the right cylinders too. Another guy in our club had two switched and it caused a problem. As you might expect.
Or you could also check the routing of the plug wires to be sure they went back on the right cylinders too. Another guy in our club had two switched and it caused a problem. As you might expect.
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,604
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From: Phoenix, Arizona
Originally Posted by jwt1603
I recently put EM long tubes, RT cats, and a Borla cat back on my 94. Had a bit of popping at first but it went away after I checked all the plug wires to be sure they were on securely. Number 8 is the worst one to get to IMHO.
Or you could also check the routing of the plug wires to be sure they went back on the right cylinders too. Another guy in our club had two switched and it caused a problem. As you might expect.
Or you could also check the routing of the plug wires to be sure they went back on the right cylinders too. Another guy in our club had two switched and it caused a problem. As you might expect.
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,604
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From: Phoenix, Arizona
Originally Posted by cuisinartvette
LTs and no cats can give you a slight popping sound when you let off the throttle
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,604
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From: Phoenix, Arizona
Originally Posted by Lichen
I saw your car down at EM - she's a beauty! After my Hotcam install, they had to burn 3 chips before she finally ran right. Go give Trevor some crap.
Yeah, I left him a message to call me. He's probably talkin' to someone else, so it may be awhile.
Race Director
Joined: May 2001
Posts: 14,165
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A free flowing exhaust such as long tubes, especially eliminating the cats will tend to create more of a popping / cracking noise when you let off the throttle. This is made worse if you have any leaks in the exhaust system. What you're describing is perfectly normal.
HOWEVER, if you've added headers you should have the car re-tuned, on a dyno if at all possible. Headers will change the amount of exhaust in the cylinder, thus the A/F ratio, and thus the tune.
HOWEVER, if you've added headers you should have the car re-tuned, on a dyno if at all possible. Headers will change the amount of exhaust in the cylinder, thus the A/F ratio, and thus the tune.
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Advanced
Joined: Jun 2003
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From: Annandale NJ
Same exact thing happened to my car after installing LT's and no cats. The popping went away though after driving for couple days. Now it ony pops when engine is still cold and letting off throttle.
Race Director
Joined: Aug 2003
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From: San Jose Pat Tillman - American Hero
I've got EM longtube and RT cats, and my car pops quite a bit if I let off the gas above 4k RPM... It can be embarassing, but if I'm on a mountain run by myself with the hatchvent in, I actually like it! Different strokes for different folks.
I definitely feel like my car runs on the rich side now, though. I really should get a tune....
I definitely feel like my car runs on the rich side now, though. I really should get a tune....
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by JEFNLSA
Thx...
Yeah, I left him a message to call me. He's probably talkin' to someone else, so it may be awhile.
Yeah, I left him a message to call me. He's probably talkin' to someone else, so it may be awhile.
Aren't you bringing the car by Bills place sometime soon? If you are let me know and I'll come over and listen to it, plus we can use Bills Auto-XRay scanner to look at your fuel trims to see what they're doing.
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by Perfusion
I've got EM longtube and RT cats, and my car pops quite a bit if I let off the gas above 4k RPM... It can be embarassing, but if I'm on a mountain run by myself with the hatchvent in, I actually like it! Different strokes for different folks.
I definitely feel like my car runs on the rich side now, though. I really should get a tune....
I definitely feel like my car runs on the rich side now, though. I really should get a tune....
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Originally Posted by Zix
Mine pops like CRAZY if I let off at over 4K...and yes I love it!! Sometimes it's loud enough to scare the other people around me...and well, that just makes me smile.
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,604
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From: Phoenix, Arizona
Originally Posted by Zix
Sorry bud...just got off the phone...
Aren't you bringing the car by Bills place sometime soon? If you are let me know and I'll come over and listen to it, plus we can use Bills Auto-XRay scanner to look at your fuel trims to see what they're doing.
Aren't you bringing the car by Bills place sometime soon? If you are let me know and I'll come over and listen to it, plus we can use Bills Auto-XRay scanner to look at your fuel trims to see what they're doing.
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by Nathan Plemons
And here I thought I always matched revs and downshifted into 3rd at 70 MPH because it assisted the brakes. Oh wait, no I didn't, that's just what I tell the police officer.
Le Mans Master
Joined: Jul 1999
Posts: 8,683
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From: Phoenix AZ
Originally Posted by JEFNLSA
I'll be there tonight. STOP BY.
Thread Starter
Melting Slicks
Joined: Jan 2005
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From: Phoenix, Arizona
Originally Posted by Zix
I just got off the phone with Trevor and Bill (he's down at EM now)...they said you'd be stopping by at around 5-5:30? Lucky for you I have nothing better to do!! Heh, I'll be by between 5:30 and 6.
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,604
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From: Phoenix, Arizona
Update:
Update:
Figured out the problem w/ the excessive popping/backfiring after the header install. I'm no expert mechanic so bear w/ me on the explanation. Trevor @ EM made a custom air tube that runs between the two headers. There is a fitting/hose that comes off the tube and runs to the air pump. Somehow the hose wasn't attached and as soon as we re-attached it...
BINGO 100% better. Although there still is some mild popping if you let off @ high rpms, the difference is like night & day. Not to mention the car runs 10x better. Trevor & Zix (Jay) explained to me how this could have a big effect on the PCM & fuel mxtures etc... Moral of the story, problem solved. It's like a completely different car. I knew that what I was hearing/feeling was more than what was being described by others w/ headers. Thx for the help...
Jeff
Figured out the problem w/ the excessive popping/backfiring after the header install. I'm no expert mechanic so bear w/ me on the explanation. Trevor @ EM made a custom air tube that runs between the two headers. There is a fitting/hose that comes off the tube and runs to the air pump. Somehow the hose wasn't attached and as soon as we re-attached it...
BINGO 100% better. Although there still is some mild popping if you let off @ high rpms, the difference is like night & day. Not to mention the car runs 10x better. Trevor & Zix (Jay) explained to me how this could have a big effect on the PCM & fuel mxtures etc... Moral of the story, problem solved. It's like a completely different car. I knew that what I was hearing/feeling was more than what was being described by others w/ headers. Thx for the help...Jeff
Last edited by JEFNLSA; Jan 5, 2006 at 09:53 AM.
