|
|
|
|
| Author |
|
|
Registered
Join Date: Aug 2005
Location: Michigan
Posts: 3,381
|
O2 Sensor Issue, Popping/Backfiring
I installed a GHL CAT bypass pipe along with a new O2 sensor on my '85 911. Actually it was a O2 sensor that was Bosch 13913 from a Ford that they said was compatible. I've been running with a Borla 1in and 4out for some time now. The GHL is new.
Cat by pass-disconnected 02 sensor question Ok, so with the O2 sensor hooked up I get LOTS of very noticeable popping and a couple times a VERY loud pop that actually shoots flames. You can see them after dark. That was actually kinda cool. Anyways, if I disconnect the O2 sensor everything smooths out and there is very little popping sounds. I would assume a little bit of popping while decelerating or downshifting would be normal but not that much. The car almost feels out of time. Should I try another one or get the OEM part or disconnect it all together? Any thought's or ideas would be greatly appreciated.....
__________________
Bill 997.2 |
||
11-10-2006, 04:21 PM
|
|
|
Registered
Join Date: Jan 2002
Location: Long Beach CA, the sewer by the sea.
Posts: 37,787
|
Double check your gaskets for proper sealing. These aftermarket units need some massaging to fit well. I just installed a DEC and had to do a little tweaking on the flanges to get them to sit flat on the header pipe flanges. I cinched those pretty good before negotiating the cat onto the muffler. If those gaskets are leaking, you will get popping. Since the car ran fine before, it has to be this or the O2 sensor. I used the same ford sensor and it's fine. I'd wager on the gaskets leaking. If you take the cat back off, you will see where it leaked. Best to correct this and then install another new set if that is, in fact, the problem.
Listen to me, I've had a 3.2 for 40 days and I'm giving advice. 
|
||
|
11-10-2006, 05:54 PM
|
|
|
Registered
Join Date: Dec 2004
Location: Novato, CA
Posts: 3,064
|
Yes, exhaust leaks near the O2 sensor can increase the oxygen content of the exhaust and fool the DME into leaning out the mixture, hence the pops. Check it carefully. You can do this while running (to begin with) by carefully passing your hand over the flanges to feel for gases escaping. Good luck,
ianc Edit: I would say to check for leaks both hot and cold...
__________________
BMW 135i. Nice. Fast. But no 911... "I will tell you there is a big difference between driving money and driving blood, sweat and tears." - PorscheGuy79 Last edited by ianc; 11-10-2006 at 10:02 PM.. |
||
|
11-10-2006, 06:42 PM
|
|
|
Registered
Join Date: Aug 2005
Location: Michigan
Posts: 3,381
|
Ok, tomorrow I'll check for leaks and report back.... Thanks guys!
__________________
Bill 997.2 |
||
|
11-10-2006, 07:03 PM
|
|
|
Registered
|
Decel Valve
I have an '83 w/CIS so this may not apply but...
I installed a cat bypass pipe and a home modified dual out muffler. I had some high idle issues and found that my Decel Valve was sticking. I have disconnected the vacuum line to the valve which has fixed the high idle problem but have found that my car pops on deceleration (while in gear). For consideration, Good luck, Gordo
__________________
Don "Gordo" Gordon '83 911SC Targa Last edited by Gordo2; 11-10-2006 at 08:31 PM.. |
||
|
11-10-2006, 08:29 PM
|
|
|
Registered
Join Date: Dec 2004
Location: Novato, CA
Posts: 3,064
|
Quote:
ianc
__________________
BMW 135i. Nice. Fast. But no 911... "I will tell you there is a big difference between driving money and driving blood, sweat and tears." - PorscheGuy79 |
||
|
11-10-2006, 09:38 PM
|
|
|
|
Registered
Join Date: Aug 2005
Location: Michigan
Posts: 3,381
|
Well I started the car and felt for leaking but didn't feel anything. So I just tightened down all the flange bolts just in case. Believe it or not it made a difference. Not completely fixed but it doesn't pop hardly at all now. Only when I downshift with lots of RPMs, but I would think that's normal for my set up. Correct?
__________________
Bill 997.2 |
||
|
11-13-2006, 04:02 AM
|
|
