1996 toyota t100 2.7 l - 5 speed

Ok i got a hell of a delima. My truck broke down 2weeks ago. It was popping and all kinds of shit. So I changed the plugs wires cap and button didn’t fix it. Then got a code reader it was saying o2 sensor. So I changed the front one. It started running great. Then 2 days ago all the sudden it started backfireing. Engine light flashed then stayed on. Hooked up the code reader it said 2 codes p0304 and another one lean mixture. But now the lean mixture one went off on its own but its still backfireing I smell fuel it’s saying cylinder 4 misfireing. Any ideas peeps. If anyone has any hit me up. Phone number 845-467-1250. If I don’t answer shoot me a text. Please help anyone its my work truck looseing money.

 

Welcome to TW
Maybe @Beretta4x4 can help

 

Have you checked engine timing with a timing light?

 

Welcome to TacomaWorld!

 

Welcome to TW!!

 

Thank you everyone. I don’t know how to do that. Im not that macanically inclined. But im hopeing its not that. Because when the truck first started messing up it was a popping and backfireing really bad. So I changed the plugs wires then the cap and button. It still did it. So I went and bought a code reader and plugged it in. It said o2 sensor bank 1 and bank 2. So i took the cat off punched it out. Changed the o2 sensor before the cat then put the cat back on. But the back o2 sensor i left the same one on it but blugged it in. Then I started the truck it ran great better than ever. Then a week later. The check engine light came on. I plugged the code reader in it said o2 sensor again. Then the following day the truck started popping like a missing spark plug. Check it on the code reader again it said missfireing cylinder #4. Then the next day the o2 code went off. But the engine light flashes then stays on. Sometimes I smell fresh unburnt fuel. Now ive done everything my knowledge knows about. Really stumped need my work truck back going right. I do plan on bypassing the o2 sensors. So that I can run my exaust I ordered for the truck flowmasters single to a dual exaust to make it nice and loud.

 

Welcome to TW!

 

Hi and welcome