Cobra Intake

speedytang · 05-13-2001, 06:27 PM

Installed my Cobra intake today and have a small problem. When the car idles which it does just fine it starts backfiring with a lean pop. When it warms up it sounds like a 9mm firing every 10-15 seconds. Checked the water no oil and checked the oil no water. Is this just a vacuum leak or am I missing something when I put everything back together. I also installed a new MAC 70mm throttle body which does have a to big of a hole drilled in the throttle blades because you can not get this thing to idle under 1200 rpm. Will call MAC tomorrow and see what kind of pain they are going to be about sending me a new throttle blade and I will ship the old blade back.

Old Guy with 87 GT · 05-14-2001, 05:29 AM

check your timing and check wire seqeunce. sounds like timing problem..i'm not an expert ...but sounds like wires are crossed in sequence....well hope i helped

speedytang · 05-15-2001, 07:18 AM

I checked the wires and the timing and everything seems to be fine until the car warms up. When I replaced the sensors from the old lower to the cobra lower could something be wrong with one of those sensors that would cause a problem when the car warms up. I also have no check engine light.

speedytang · 05-15-2001, 12:59 PM

New Update: Seems to idle ok I am going to take it for a test drive. I have been notified of something by my neighbors, the car is now twice as loud then before the intake and has a lot more lope. Ok guys and gals figure this one out. New cobra intake new throttle body and now twice the exhaust sound from tailpipe. HHHHMMMMMMMMM

JD93GT · 05-19-2001, 11:48 AM

I dont know how to fix your problem, but i can offer some advice about your exhaust being louder... If you put more air in, you are gonna get more air out. Now im sure it wont be twice as much, and im sure normally you wouldnt have twice the sound. But i think you should run with that. Meaning, check your o2 sensors, have you run the computer codes yet? If not you should, it will tell alot.

oldman · 05-19-2001, 01:15 PM

It really does sound like you leaned it out a bit. Were bigger injectors a part of the swap? You might be overloading the injectors. . .but then again, you mentioned there is no check engine light. Good luck

speedytang · 05-20-2001, 07:05 AM

Thanks Stangers, Found the problem and everything is running great. What happens is the EGR hole in the cheap paper thin gasket that came with the intake didn't seal. The exhaust gas entered two of the intake runners and I had my own cheap supercharger effect. Replaced the plenum gasket and runs great. Also had to replace a few spark plugs because they fouled big time.

05-13-2001, 06:27 PM	#1
speedytang Registered Member Join Date: Oct 1999 Location: Marengo, Ohio.USA Posts: 135	Cobra Intake Installed my Cobra intake today and have a small problem. When the car idles which it does just fine it starts backfiring with a lean pop. When it warms up it sounds like a 9mm firing every 10-15 seconds. Checked the water no oil and checked the oil no water. Is this just a vacuum leak or am I missing something when I put everything back together. I also installed a new MAC 70mm throttle body which does have a to big of a hole drilled in the throttle blades because you can not get this thing to idle under 1200 rpm. Will call MAC tomorrow and see what kind of pain they are going to be about sending me a new throttle blade and I will ship the old blade back.

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05-14-2001, 05:29 AM	#2
Old Guy with 87 GT Registered Member Join Date: May 2001 Location: Harrisburg, Pennsylvania Posts: 379	check your timing and check wire seqeunce. sounds like timing problem..i'm not an expert ...but sounds like wires are crossed in sequence....well hope i helped

05-15-2001, 07:18 AM	#3
speedytang Registered Member Join Date: Oct 1999 Location: Marengo, Ohio.USA Posts: 135	I checked the wires and the timing and everything seems to be fine until the car warms up. When I replaced the sensors from the old lower to the cobra lower could something be wrong with one of those sensors that would cause a problem when the car warms up. I also have no check engine light.

05-15-2001, 12:59 PM	#4
speedytang Registered Member Join Date: Oct 1999 Location: Marengo, Ohio.USA Posts: 135	New Update: Seems to idle ok I am going to take it for a test drive. I have been notified of something by my neighbors, the car is now twice as loud then before the intake and has a lot more lope. Ok guys and gals figure this one out. New cobra intake new throttle body and now twice the exhaust sound from tailpipe. HHHHMMMMMMMMM

05-19-2001, 11:48 AM	#5
JD93GT Registered Member Join Date: Feb 2001 Location: San Diego, Ca USA Posts: 52	I dont know how to fix your problem, but i can offer some advice about your exhaust being louder... If you put more air in, you are gonna get more air out. Now im sure it wont be twice as much, and im sure normally you wouldnt have twice the sound. But i think you should run with that. Meaning, check your o2 sensors, have you run the computer codes yet? If not you should, it will tell alot.

05-19-2001, 01:15 PM	#6
oldman Registered Member Join Date: May 2001 Location: Amarillo, Texas, 79107 Posts: 78	It really does sound like you leaned it out a bit. Were bigger injectors a part of the swap? You might be overloading the injectors. . .but then again, you mentioned there is no check engine light. Good luck

05-20-2001, 07:05 AM	#7
speedytang Registered Member Join Date: Oct 1999 Location: Marengo, Ohio.USA Posts: 135	Thanks Stangers, Found the problem and everything is running great. What happens is the EGR hole in the cheap paper thin gasket that came with the intake didn't seal. The exhaust gas entered two of the intake runners and I had my own cheap supercharger effect. Replaced the plenum gasket and runs great. Also had to replace a few spark plugs because they fouled big time.