Backfire and flames shooting out of my tailpipes....something wrong??

**Hurley711** · 04-15-2007, 03:56 PM

Here is the deal. My car is a cam/header/ORY DD. 78k miles on it, cam and headers went on within last 15k miles. Recently while driving I have gotten some backfire, it happens when I am crusing and decide to get on it real good. For instance if I am driving a consistent 70 MPH for 8-10 miles than I downshift into 3rd and ride it up to about 85-90, when I let off it backfires usually everytime. Friends of mine have been behind me twice and said flames shot out the back. WTF is going on here?

**Mr. Luos** · 04-15-2007, 04:23 PM

You need a tune.

**Hurley711** · 04-15-2007, 04:26 PM

Originally Posted by Mr. Luos

You need a tune.

Is this usually a rich or lean situation?

**Hurley711** · 04-15-2007, 04:29 PM

Last tune was 12k-14k miles ago last year during cam install....tuned with LS1edit

**Rivi** · 04-15-2007, 04:29 PM

rich,the unburnt fuel gets mixed with enough ox in the exhaust and bang

**Hurley711** · 04-15-2007, 04:29 PM

Any tuners near Philly?

**BlackLT1Z28** · 04-15-2007, 04:31 PM

Could be rich, but might be timing. Either the timing is off (retarted) and the A/F mixture isn't completely done burning by the time the exhaust valve sucks it all out and it finishes the combustion out in the exhaust, therefore the backfires and possible flames. Or it could be rich and not all the fuel is ignited in the cylinder and when the exhaust valve opens, the rest of the gas is sucked out and ignited later...but running that rich would usually cause running problems and I don't think you are running too rich.

**Hurley711** · 04-15-2007, 04:40 PM

just left a message with harris speed outside of philly here, i'll get them to tune it.

**02Hawk** · 04-15-2007, 05:28 PM

harris is a great place heard nothing but good. and they have a dyno day comin up on the 29th i believe

**Hurley711** · 04-15-2007, 06:07 PM

Originally Posted by 02Hawk

harris is a great place heard nothing but good. and they have a dyno day comin up on the 29th i believe

what do they charge for the dyno day? How many pulls at what price?

**02Hawk** · 04-15-2007, 06:15 PM

its 40 dollars for 3 pulls

if you look in the eastern member section theres a thread on it with details

**Hurley711** · 04-15-2007, 06:26 PM

Originally Posted by 02Hawk

its 40 dollars for 3 pulls

if you look in the eastern member section theres a thread on it with details

They get a solid crowd over there? I gotta get in for a tune, I am asssuming you get your dyno #'s with a full tune

**02Hawk** · 04-15-2007, 07:00 PM

ya you should if its dyno tuned lol

**Anthracis** · 04-15-2007, 10:52 PM

Definite Dyno tune needed. It should be fine after.

**Hurley711** · 04-16-2007, 03:23 AM

Could it be part of an exhaust leak?

**PFM** · 04-16-2007, 11:33 AM

Could be you have a spark plug wire melting into your headers causing misfires.

**Hurley711** · 04-16-2007, 12:00 PM

setting up an appt to get plugs changed and full dyno tune, chalking it up to good maintenance 14k miles after cam install

**Rich L** · 04-17-2007, 04:19 PM

Originally Posted by Hurley711

Is this usually a rich or lean situation?

Your running rich. Thats better than running lean.

One question...

Did you remove your cats? If so... you will have much more backfire.

**Vexzer** · 04-17-2007, 06:19 PM

Rich, lean, plug wires? All wrong IMO. Ever see the fire from a racer under deceleration? Basically -you don't care how it burns once it's outta the chamber. If your valves are ok, you're ok. If you don't have an exhaust leak under idle or acceleration its no concern. Tune for power.

**PFM** · 04-18-2007, 05:38 AM

Originally Posted by Vexzer

Rich, lean, plug wires? All wrong IMO. Ever see the fire from a racer under deceleration? Basically -you don't care how it burns once it's outta the chamber. If your valves are ok, you're ok. If you don't have an exhaust leak under idle or acceleration its no concern. Tune for power.

I don't know about that dude. I had a set of MSD 8.5s put on my car the other day and about 2 days later I started getting bacefires and I found on the #6 cylinder the plug wire had started melting into my header pipes. I moved it out of the way and I haven't had the trouble since. That #6 is always giving people trouble.