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1999 Toyota Tacoma Question: p0300,p0303,p0304 trouble codes come on after engine warms up.

 

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jody4599, Sahuarita, AZ, March 16, 2012, 13:00
 Rookie

In the mornings when I first get going, no codes, everything works great. then the codes kick in when engine is good and warm and accelerating. If it is a very cool morning, it wont happen. I have changed everything under the hood and had a very good import shop look at it. They think maybe a small coolant leak starts after warmup. But I have a v6 and and cyc 3 and 4 on different sides. Any thoughts???

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  • Answer #1

    Greg's Orange Auto (13428 Answers) , Orange, CA - (714) 361-9386
    globalhelper March 16, 2012, 13:27
     Master

    YOU MAY HAVE A CRACKS IN YOUR CYL HEADS THAT DO OPEN AFTER WARM. IS YOUR OIL MILKY IF NOT CK YOUR COOLING SYSTEM FOR EXH GASES

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    jody4599, March 18, 2012, 15:33
     Rookie

    Thats what I was thinking, but cyl 3 and 4 are on different sides and the misfires happen at the same time when it warms up. I could be wrong, but seems I would get one then the other, not simutanously. I could be wrong though. No milky oil. I will check cooling system for exh gases. How do you do that? Is a special tester needed? Thanks for your advise, greatly appreciated.

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  • Answer #2

    patrick mannion from Greg Solow's Engine Room, March 16, 2012, 17:47
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     Master

    Have a simple chemical test known as a block test done see if you have a blown head gasket. Perhaps change the spark plugs, check compression is even, your engine has SHIM adjusted valves seen the clearance get tight on higher mileage engine and set misfire code like you say. Check for vacuum leaks, maybe a fuel injector issue.

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    jody4599, March 18, 2012, 15:36
     Rookie

    Ok, thanks for advise. spark plugs and fuel injectors have all been changed. I also did all the coils and wires. The shop that fixed some other issues checked for vacuum leaks and cylinder pressure. All were good. So will have the block test done...Thanks..advise is greatly appreciated...

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