Hey everybody, I've got an issue with my truck that I'm hoping that someone out there may have an insight...

When I'm on the highway, cruising in 4th, everything feels great. When I come up on a hill,and start into the incline, the truck starts shuddering progressively worse, and then shifts down third gear, than all is well.

(Having had this same problem in previous American trucks, it usually wound up being the transmission that was on the way out.)

But that's not all,

The check engine light came on, P0304 - 4th cylinder misfire. I checked it, it's looks to be sparking fine (arc). Had an autoparts store diagnose and clear the code.

It's been starting pretty rough off the line at lights, unless I floor it - that seems to smooth it out mostly. The previous owner had some 35" tires on it for about 8 months, i was figuring that this might have warped the brake rotors, but there again, I don't know.

BTW, this is a 5VZ-FE, with an A340 tranny.

Cheers!

 

just clearing the code will not make the problem go away. You need to look into what is causing that P0304 code.

 

yeah, the code translated to the 4th cylinder having a misfire, which after checking, doesn't seem to be a problem.

I'm aware that clearing the code does not fix the problem, I just thought that the information might help.

Essentially I'm trying to see if my gut feeling of this being a transmission problem is wrong (read: I'm hoping I'm wrong. and that I don't need a trans. rebuild).

I've read in other threads dealing with this code on a 5VZ-FE engine, that the valves or injectors or ? had similar symptoms to what I'm experiencing.

Also, the engine/trans has 121,000 miles on it - hopefully lost of life left, right?

This is my first 'Yota ever, just hoping I didn't get a lemon...

 

check out that #4 cylinder. just because it is sparking doen't mean that the cylinder is firing right, especially under load. missfires can often be misconstruded and transmission problems. usually you don't notice them as much when the RPMS are higher. not a bad idea to check or maybe change your trani fluid. haven't usually seen tranis go out but anything can happen. defietly make sure it is running right before thinking about trani issues.

 

finally went for professional help - it actually looks to be an ignition problem! That's both a relief, and a problem - as we haven't figured it out, but are getting closer...

Thanks for the ideas!

 

Change your plugs and wires. I had the same problem, truck ran fine most of the time, only under load did it miss fire.

Do it.

 

Same thing happened to me when I just bought my 96 T100. It misfired around 3.5k-4k. Changed the plugs and wires, and it runs smooth as anything now. 185k miles strong!