Wtf!!! Backfire!!

MadHandle8169 · May 16, 2005

So I recently installed my Intake Manifold and I'm pretty sure it doesn't leak as I did everything right and tightened everything down according to specs. But this could be unrelated to the install because everytime I race my car and shift to 3rd I get a loud backfire. I installed an X-pipe a long time ago and used a C Clamp to connect it to the header because one of the bolts broke and maybe that is starting to leak, I should get around to getting new headers. What causes a backfire though any suggestions what to check. I don't really get performance lose just the backfire than everything is normal. Timing is at 14* and I run 92-93 octane. Thanks.

MadHandle8169 · May 16, 2005

Any suggestions???

I used the search and have read that if it comes from the intake it is a lean condition and if it comes from the exhaust it is a rich condition. I am almost positive it came from the exhaust. When I took apart my car my throttle body had carbon on it as well does this mean I'm running rich and how can I fix this?

IM_FASTER_THAN_ · May 16, 2005

I would check your intake and make sure that it is bolted down really good. And i would also check and see what your fuel pressure is at. I would almost bet that you are running a little lean if you put a aftermarket intake on, and never changed your fuel pressure that means your have to be running lean. Let me know what you find out

95conv5.0 · May 16, 2005

its running rich!

MadHandle8169 · May 16, 2005

This is a probably a newb question but how do you check your fuel pressure? I'll double check all the bolts but I'm pretty sure the intake is bolted down. How would I adjust the car if it is running lean or rich?

TheDamned · May 16, 2005

i have backfires since a long time, i think its really badass.. i put it in 2nd on decell at 30mph , it pops like HELL its so badass ppl are like WTF hahahha

MadHandle8169 · May 16, 2005

Well are the backfires harmful to my car. That is my main concern. If it is not harmful then that's fine I don't care.

CBZGT50 · May 16, 2005

A back fire means there is fuel in the exhaust. Hence, you are running rich. Get an afpr (adjustable fuel pressure regulator) and a fuel pressure gauge for your rail. Then you can tell us what fuel pressure you are running at. With the afpr, you can tune the pressure and tune the engine better. Might want to bump that timing down while your getting the other parts.

How does the car idle? If the idle sucks, you are losing vacuum and you would have a leak prolly at the intake. If it idles fine always, your prolly ok on the seal. I just went through that crap last weekend (sealing the intake) and it ended up being a pcv valve (GT 40 intake) that kept poping out.

MadHandle8169 · May 16, 2005

My car idles better than before the intake swap because I got all new vacuum lines however I think the thermostat is leaking a little antifreeze I'll try to tighten those bolts again but other than that I think the install went without a hitch.

I can't see the intake leaking because I ran my friend with an 02 GT and he won but only by a half car I hung right with him all the way through 3rd. I'm positive he has exhaust and I think cold air intake too. So if it was leaking I would have power loss, correct.

Also if my car is running rich and I advance the timing rather than retard it like suggested wouldn't that lean it out or am I talking crazy? My car doesn't ping or anything.

I was reading about the Fuel Pressure Gauge and it goes where the schrader valve goes but how does the AFPR work and where does it go?

CBZGT50 · May 16, 2005

MadHandle8169 said:
My car idles better than before the intake swap because I got all new vacuum lines however I think the thermostat is leaking a little antifreeze I'll try to tighten those bolts again but other than that I think the install went without a hitch.

I can't see the intake leaking because I ran my friend with an 02 GT and he won but only by a half car I hung right with him all the way through 3rd. I'm positive he has exhaust and I think cold air intake too. So if it was leaking I would have power loss, correct.

Also if my car is running rich and I advance the timing rather than retard it like suggested wouldn't that lean it out or am I talking crazy? My car doesn't ping or anything.

I was reading about the Fuel Pressure Gauge and it goes where the schrader valve goes but how does the AFPR work and where does it go?

You are correct about the retarded timing. Though, that has to do with valve timing and if you decrease your valve timing, just by a hair, you may not get the back fire. I would worry about burning a valve if you get too many backfires, then it will always back fire. But that is minimal at this point, the aFPR sits at the back of the schrader valve on the same rail. There will be a vacuum line coming off of your upper intake to it. you will have to take the upper intake back off and there will be 3 allen screws under the fpr. I think you can do it without having to take off the rail. It is a difficult job but best in the end if you plan on more modifications like injectors or heads. You WILL need it then. You shouldn't have to replace your upper gasket either since it is a dry gasket. Infact I swapped my Cobra intake bolts to threaded rod to make studs just so it is easier to put the intake on.

I have a set of Cobra Valve covers if you are interested. You could change them out when you take the top off. I bought a used set of 94 95 cobra covers and had them chromed.

Let me know if you need any more help.

MadHandle8169 · May 16, 2005

CBZGT50 said:
You are correct about the retarded timing. Though, that has to do with valve timing and if you decrease your valve timing, just by a hair, you may not get the back fire. I would worry about burning a valve if you get too many backfires, then it will always back fire. But that is minimal at this point, the aFPR sits at the back of the schrader valve on the same rail. There will be a vacuum line coming off of your upper intake to it. you will have to take the upper intake back off and there will be 3 allen screws under the fpr. I think you can do it without having to take off the rail. It is a difficult job but best in the end if you plan on more modifications like injectors or heads. You WILL need it then. You shouldn't have to replace your upper gasket either since it is a dry gasket. Infact I swapped my Cobra intake bolts to threaded rod to make studs just so it is easier to put the intake on.

I have a set of Cobra Valve covers if you are interested. You could change them out when you take the top off. I bought a used set of 94 95 cobra covers and had them chromed.

Let me know if you need any more help.

Wait I'm confused I said advance and you said retard. So can I advance my timing to say 15* or 16* and see if it still backfires. Then if not go with the AFPR.

CBZGT50 · May 16, 2005

Yes you are confused.

You said advanced would lean not me. Don't worry about that. Worry about VALVE TIMING! Just retard a little like to 12 deg. Don't worry about the afpr for this reason. But you will need one if you are running rich. There are two subjects there. Don't make this a 3rd grade conversation. The afpr and fuel pressure gauge will allow you to TUNE your car while the retard/advace will set valve timing.

Now remember if there is gas in the exhaust, then that usually indicates that fuel or combustion is getting into the exhaust. If you retard the timing, you will change the cam timing and the exhaust valve will close sooner. If you bump down to 10deg and it is still backfiring then that means that not ALL of the fuel is getting burned and you are rich in your mix. Does that make more sense. I'm old skool and sometimes the fuel injection is a PIA! It takes tuning to get it right. Distributor, vacuum, fuel, cam degree. All of those can effect the TUNING of your car.

MadHandle8169 · May 17, 2005

Alright I'm going to see if my car backfires again today and if it still does I will decrease the timing. If still no luck I'll try to get the money for the AFPR because I have no money due to college.

Wtf!!! Backfire!!

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