Misfiring problem

[phatal1320]

I got a bad misfiring issue on my 94 Tahoe it's tbi injection 227k miles did a tune up a few months ago it only misfires going up hill which is odd I hope it's not my camshaft and I reset my timing on my motor to stock settings and still runs like its misfiring if anyone has any ideas I would greatly appreciate it thanks.

 

[phatal1320]

Hmm

 

[BattelWagun]

I would check the fuel pressure.

 

[gpracer1]

Did the misfire start after the tune up or has it been doing it before?
Misfire one cylinder or many?......feeling a miss or totally running like crap.
What did you do for a tune up?

 

[99Yukon4x4]

When I bought my 99 Yukon, I did the tune up myself. I found after 3 months, I was getting a misfire, then got to the point it started throwing a code. Had Advanced run the code, and found my #4 cylinder was misfiring. I pulled the plug, and found that it was fouled big time. I cleaned it off, and the check engine light went off. All other plugs and wires were/are in proper working order. Just realizing that my piston rings on the #4 cylinder are bad, since I have already replaced that plug after 6 months.

 

[SunlitComet]

guess the OP gave up?

 

[gpracer1]

guess the OP gave up?

 

[phatal1320]

Yeah ever since I had the truck it has this misfire I bought a fuel filter changed it out and it ran way better but still misfiring the. Changed the plugs wires and cap n rotor... But realized my buddy had gotten me platinum plugs maybe that might be part of the problem? I dunno so here soon I wanna change them out with auto lite copper cores... Truck does have 227k miles aswell and someone gave me the idea of one of my lobes on my camshaft is flat? I dunno hopefully I can get this resolved and thanks for your guys input.

---------- Post added at 12:51 AM ---------- Previous post was at 12:49 AM ----------

And it's always misfired since I've owned it

 

[chevy_338]

Yeah ever since I had the truck it has this misfire I bought a uel filter changed it out and it ran way better but still misfiring the. Changed the plugs wires and cap n rotor... But realized my buddy had gotten me platinum plugs maybe that might be part of the problem? I dunno so here soon I wanna change them out with auto lite copper cores... Truck does have 227k miles aswell and someone gave me the idea of one of my lobes on my camshaft is flat? I dunno hopefully I can get this resolved and thanks for your guys input.

---------- Post added at 12:51 AM ---------- Previous post was at 12:49 AM ----------

And it's always misfired since I've owned it

as thus is a 94 with a tbi no auto light please. AC Delco is the way to go. Just get regular plugs you have to ask for them. Or they will give you platinum ones. Only vortec motors should should run any thing that should run platinum plugs as it has a higher burn and higher coil out put. So here is my input put in ac Delco and see what it does and there a lot cheeper.

 

[gpracer1]

Sounds like you need to start from scratch.
First thing is a compression test.....need to know if all the cylinders are even able to fire.
A bad cam lobe might not show up on a compression test though since the cranking speed is low (unless its got no lift at all on the intake side).

Then you could pull the valve covers to look at the rocker arm movement of each while cranking. Then carefully look at the valve springs for broken spring.