Car backfiring
Thread Starter
Registered User
Joined: Sep 2002
Posts: 18,098
Likes: 1
From: Lake Stevens, WA
Car backfiring
Hi guys,
My 2000 S2000 with 39,000 miles has developed a small back firing habit. It only happens when the car has been sitting for a little while (1-3 hours since last being driven.) When letting off the gas to execute a gear change, the car will backfire. It pretty much always happens on the first gear change and sometimes on the second but never anytime afterwards. It's not a large "bang," nothing that will scare little kids or make perched birds take flight, but it's most certainly noticable. I do have an aftermarket exhuast. (HKS) From my understanding, backfiring is caused by unburned fuel that has made it's way in the exhuast system. Like I said, it only happens if the car has been sitting for an hour or two or three. If I drive the car after it has been sitting for just a few minutes it won't backfire, sitting overnight, it won't backfire. Any thoughts? Anybody else with similar experiences? Could fouled plugs or running rich cause this? Any help would be much appreciated, thanks in advance.
Jason
My 2000 S2000 with 39,000 miles has developed a small back firing habit. It only happens when the car has been sitting for a little while (1-3 hours since last being driven.) When letting off the gas to execute a gear change, the car will backfire. It pretty much always happens on the first gear change and sometimes on the second but never anytime afterwards. It's not a large "bang," nothing that will scare little kids or make perched birds take flight, but it's most certainly noticable. I do have an aftermarket exhuast. (HKS) From my understanding, backfiring is caused by unburned fuel that has made it's way in the exhuast system. Like I said, it only happens if the car has been sitting for an hour or two or three. If I drive the car after it has been sitting for just a few minutes it won't backfire, sitting overnight, it won't backfire. Any thoughts? Anybody else with similar experiences? Could fouled plugs or running rich cause this? Any help would be much appreciated, thanks in advance.
Jason
Registered User
Joined: Apr 2003
Posts: 22,888
Likes: 3
From: Covington WA, USA
Originally Posted by BBY2KS2K,Apr 17 2005, 03:26 PM
Could fouled plugs or running rich cause this?
The reason it happens when the engine is cold is most likely because the cold engine walls quench the flamefront, allowing unburned gas to go through. This could be a timing issue, a spark plug issue, an ECU issue, etc.
It can be bad for the cat and the muffler.
Trending Topics
Joined: Oct 2000
Posts: 14,269
Likes: 42
From: Redmond, WA
No, but the description you give, teamed w/ the fact you have an aftermarket exhaust, leads me to that particular "stab in the dark" based on my vast knowledge of how shit can not work right 
The jokes about the HKS are a rusting out, cracking welds and generally poor workmanship thing between me and Ben
The jokes about the HKS are a rusting out, cracking welds and generally poor workmanship thing between me and Ben