Rough idle, Cyl 3 miss fire on 1996 Toyota Tacoma

Symptom: 1996 Tacoma 250,000 mi. Rough Idle- P0303 Cyl 3 miss fire. Adjusted valves- #3 was a zero lash- brought to spec. Cleared codes- Good drivibility several hundred miles, now P0303 is back along w/ Cat eff. below threshold. Vehicle runs ok in open loop, but when sensors come on line data is such: AFR- 20:1 at idle + 19% long term FT O2/1 .34-.55V O2/2 .34-.55 Injector resistance measured out at 15.4 Ohms- spec is 14.2 max- Cyl 1 inj. measured out at 15.2. AFR is very lean, ECU is Calling for lots of fuel. Maybe fuel press is low?

by in Phoenix, AZ on December 28, 2010
1 answer 1 comment
ANSWER by on December 28, 2010
the miss has put unburnt fuel into the cat and did it in. the cat is a result of the miss. start at basics. do a compression test first. do a second cylinder to compare pressures. yes, do afuel pressure check as well. adding 19% indicates either a vaccuum leak or a mass air flow. the injector resistance looks good but does not indicate spary pattern. just some ideas to follow up. Roy
COMMENT by on December 29, 2010
Thanks Roy, I'm going to do just that this weekend. Did the brake clean trick looking for leaking manifold...nothing. Now that I thinking about It I did have a few hot start issues this summer. Fuel again? (Arizona)- crank / no start. Wait 5 min fires right up.

Related Content