Running lean and backfiring
07-01-2008, 04:32 PM
#1
5th Gear Member
Thread Starter
Join Date: Aug 2006
Location: Rotterdam, NY
Posts: 3,333
Running lean and backfiring
So I dont need a new motor. I got some help doing some tests and some tuning on my '92 5.0 but it still doesnt run right. The compression and leak down tests are normal.
The issue is a lack of power and intermittent backfiring. We checked the fuel pressure and it was at 32 psi so we bumped it to 40 and then to 44. The car ran awesome and had plenty of power.
Then when I got on the highway to go home the car started backfiring again. It will go up to 3500 rpm, stumble, the tach drops and then it backfires and carries on like normal until the next time I rev it or stomp on it up to 3500. It seems to have no power when its running like that.
Other times after shutting it off and starting it again it wont backfire at all but still feels like it lacks power.
When we had the plugs out for the leakdown test they looked really clean. They have about 500-1000 miles on them but they looked like new plugs.
The fuel pump is new (Walbro 255 l/ph), its got 24# injectors and the pressure is set at 44 psi.
Other mods are listed here:
http://www.cardomain.com/ride/2442696
Whats causing this issue?
The issue is a lack of power and intermittent backfiring. We checked the fuel pressure and it was at 32 psi so we bumped it to 40 and then to 44. The car ran awesome and had plenty of power.
Then when I got on the highway to go home the car started backfiring again. It will go up to 3500 rpm, stumble, the tach drops and then it backfires and carries on like normal until the next time I rev it or stomp on it up to 3500. It seems to have no power when its running like that.
Other times after shutting it off and starting it again it wont backfire at all but still feels like it lacks power.
When we had the plugs out for the leakdown test they looked really clean. They have about 500-1000 miles on them but they looked like new plugs.
The fuel pump is new (Walbro 255 l/ph), its got 24# injectors and the pressure is set at 44 psi.
Other mods are listed here:
http://www.cardomain.com/ride/2442696
Whats causing this issue?
07-01-2008, 11:23 PM
#7
D.R. THE PATHETIC DORK
Join Date: Jun 2007
Location: West Virginia
Posts: 30,863
RE: Running lean and backfiring
13 to 15 is optimal but I suppose 1 degree won't kill you......with misfires I usually use a portable lab scope but I know you won't have that so run a koer test and use the ecm ability to run a cylinder power balance test
07-02-2008, 06:20 AM
#9
5th Gear Member
Thread Starter
Join Date: Aug 2006
Location: Rotterdam, NY
Posts: 3,333
RE: Running lean and backfiring
Whats stock timing on these cars? I forget.
Im running premium (93) gas in the car to compensate for bumped timing.
I did a cylinder balance test and it checked out fine.
Im running premium (93) gas in the car to compensate for bumped timing.
I did a cylinder balance test and it checked out fine.