Backfiring???

**paratrooper** · 10-09-2009, 10:12 AM

Installed pacesetter longtubes hi flow cats DMH cutout at the y pipe and a k and n intake and now my 02 z is backfiring like a mfer. How can I alleviate this? Check engine light I also on I've been told it's the rear o2 sensors. Do I need to have the engine tuned? Obviously I'm new at this. any help will be much appreciated. Thanks!
Eric

BadBlueBird* · 10-09-2009, 11:19 AM

Originally Posted by paratrooper

Installed pacesetter longtubes hi flow cats DMV cutout at the y pipe and a k and n intake and now my 02 z is backfiring like a mfer. How can I alleviate this? Check engine light I also on I've been told it's the rear o2 sensors. Do I need to have the engine tuned? Obviously I'm new at this. any help will be much appreciated. Thanks!
Eric

rear o2s as well as spark plugs.

**paratrooper** · 10-09-2009, 12:49 PM

What do you reccomend I replace them with?

**2K2SLPSS** · 10-10-2009, 08:22 AM

i used NGK TR-55 when i did new plugs and wires.

**GatorSS** · 10-12-2009, 08:58 AM

Originally Posted by paratrooper

Installed pacesetter longtubes hi flow cats DMH cutout at the y pipe and a k and n intake and now my 02 z is backfiring like a mfer. How can I alleviate this? Check engine light I also on I've been told it's the rear o2 sensors. Do I need to have the engine tuned? Obviously I'm new at this. any help will be much appreciated. Thanks!
Eric

How well do you understand, and how comfortable are you with computers & software? If very well, I suggest you purchase some good software and custom tune it yourself. With the right software, you have almost limitless tuning capabilities. You will not regret it. On the other hand, if computers intimidate you, or you are only at a beginner/basic level of comfort & understanding with them, then seek the advice of a professional tuner.

**davydman** · 10-12-2009, 05:16 PM

gator, what software would you recommend he buy?

**35th-ANV-SS** · 10-12-2009, 05:20 PM

I think people on here use HP Tuners and a wideband. Could be wrong though.

***SMWS6TA*** · 10-13-2009, 10:05 AM

You are getting backfires because you need a tune. You are now running rich at idol/low speeds and lean at WOT. Check Frost out (One of our site sponsors). He has a really great deal and he will tune out the Rear O2's and about 10 -15 other things. I think shipping and tune is around $165. Far cheaper than buying the tuner and software.

**wheeliE-maxx** · 10-13-2009, 01:50 PM

Originally Posted by SMWS6TA

You are getting backfires because you need a tune. You are now running rich at idol/low speeds and lean at WOT. Check Frost out (One of our site sponsors). He has a really great deal and he will tune out the Rear O2's and about 10 -15 other things. I think shipping and tune is around $165. Far cheaper than buying the tuner and software.

If it's popping on decel wouldn't it be too lean? Like on my dirtbike when it pops you richen the low throttle fuel screw. I don't know if he means on decel though, i'm just asking the question for myself.

**Too Fast** · 10-13-2009, 02:20 PM

Originally Posted by paratrooper

Installed pacesetter longtubes hi flow cats DMH cutout at the y pipe and a k and n intake and now my 02 z is backfiring like a mfer. How can I alleviate this? Check engine light I also on I've been told it's the rear o2 sensors. Do I need to have the engine tuned? Obviously I'm new at this. any help will be much appreciated. Thanks!
Eric

Most likely it is backfiring because the plug wire(s) aren't connected correctly, or something else is loosely connected. We've seen this happen a lot, and later the OP comes back to say, "yeah, you guys were right, I didn't have number -x- plug wire on completely.

You need a tune to turn off the check engine light, if you deleted your AIR injection. Otherwise your light is on most likely from the backfire/misfire.

Originally Posted by SMWS6TA

You are getting backfires because you need a tune. You are now running rich at idol/low speeds and lean at WOT. Check Frost out (One of our site sponsors). He has a really great deal and he will tune out the Rear O2's and about 10 -15 other things. I think shipping and tune is around $165. Far cheaper than buying the tuner and software.

The car won't backfire just because he needs a tune, and just because of his recent new pieces. Frost will do a good job on a tune, from a lot of happy people who've posted on this forum. I've had my Hookers and ORY for almost 3 years now, the only issue I've had is my check engine light on, gas mileage is up, track times are quicker. I'd love to have it tuned, but haven't gotten to it yet. Oh yeah, sounds a lot meaner now too!

**paratrooper** · 10-14-2009, 06:28 AM

Don't mean to sound completely ignorant but what exactly would
getting a tune from frost entail ie what exactly
is the tune and how is it applied?

**tep98ws6** · 10-14-2009, 08:44 AM

mine is backfiring as well, but only immediately after i let off the throttle in 3rd gear ... do you have a cut-out by chance? i'm tuning it tonight and i'll let you know if a tune helps any.

**Too Fast** · 10-15-2009, 02:31 PM

Originally Posted by paratrooper

Don't mean to sound completely ignorant but what exactly would
getting a tune from frost entail ie what exactly
is the tune and how is it applied?

A "tune" is optimizing your PCM for the modifications you've done. Since you've installed LT headers, you've altered the efficiency of your engine, for the better! A tune will give you more aggessive spark advance usually, and will alter your fuel/air ratios for the improvements you've made. Our cars are self tuning to an extent because they use a Mass Airflow Sensor, but Frost has helped many people here, even better than the stock tune can self-compensate for modifications. However, a tune will not fix any backfiring problem, unless the tune is so out of whack that it would have run that way before you put on the headers. That's why I think the backfiring is something caused from the header installation, not the headers themselves. Especially if there was no backfiring before headers. Now go find that loose plug wire/cracked spark plug.

**Badass WS6** · 10-15-2009, 03:52 PM

Originally Posted by paratrooper

Installed pacesetter longtubes hi flow cats DMH cutout at the y pipe and a k and n intake and now my 02 z is backfiring like a mfer. How can I alleviate this? Check engine light I also on I've been told it's the rear o2 sensors. Do I need to have the engine tuned? Obviously I'm new at this. any help will be much appreciated. Thanks!
Eric

My '99 z was backfiring alot on startup and sometimes wouldn't start on the first try. Turns out, my cam sensor was the culprit. Replaced that and have had no more embarrasing backfiring issues since.

**lt1stocker** · 10-15-2009, 08:36 PM

go to the last thing you did!!! You installed headers. A backfire or pop in the exhaust during coast is caused by a leaking exhaust system close to the heads, it's air being pulled back into the exhaust system. check around the header flanges for signs of exhaust gas leakage, a better or thicker gasket may be required.(percy's gasket on e-bay) On my racecar, i always use red silicone on the header gaskets, usually just in the middle of the flange plate cause the bolts will bow them.
This is why i posted on another thread about the cheap headers from ebay, I'm an LT1 guy but a friend wants me to street/strip his 99 z28, and I'm worried that I still have yet to see/hear any problems from those cheap header setups.