Misfire

[richyr]

I got a Chevy 2007 Tahoe few days ago and first it showed multiple misfires. I cleared the DTC codes and now it's showing the 4th cylinder misfire. Motor even outs at higher rpm but runs rough and shakes at idle.any idea or common problem known to be with this year. Was told a crankshaft sensor could cause it but my experience says do a complete tune up . wires plugs and possibly coil packets.Any ideas or past experience?

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[Doubeleive]

swap the coil packs and see if the misfire follows the coil, that's going to be the easiest place to start

 

[Kraig]

If you just got it and don’t know the maintenance history, change plugs and wires while you’re swapping a coil.

 

[richyr]

I tested the plug wires with my timing light and all the wires are showing that they are firing but going to look at plugs today. Someone said something about a crankshaft sensor causeing the problem but don't think it could be

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[avalonandl]

Well without reading the codes your flying blind.

 

[richyr]

I've been reading codes whole time lol keeps throwing p0304. Switched out coil packs and still throwing same code on misfire on cylinder 4 .checked spark plug looked almost new and smelled like gas.still doing same thing.first it was multiple fire but now it's only throwing that code

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[Doubeleive]

I've been reading codes whole time lol keeps throwing p0304. Switched out coil packs and still throwing same code on misfire on cylinder 4 .checked spark plug looked almost new and smelled like gas.still doing same thing.first it was multiple fire but now it's only throwing that code

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if you are SURE that the coil packs, plugs & wires are good, then check for a intake vacuum leak -spray some starting fluid around the edges of the intake gasket and listen for a change in idle

 

[kbuskill]

Cylinder 4 is an AFM cylinder. Not good news.

 

[RET423]

I am betting you need a cam and lifter replacement.

 

[Kraig]

Swap the #4 injector with another—if it’s sparking and smelling like fuel something is definitely amiss. If it’s not that i’d Start looking at AFM issues.

 

[richyr]

Switched plugs between cylinder 2 and. Cylinder 4 and now I have p0300 multiple misfire instead of the p0304 cylinder 4 .and showing fault on both fuel banks

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[Kraig]

Swapped spark plug?

 

[Doubeleive]

Switched plugs between cylinder 2 and. Cylinder 4 and now I have p0300 multiple misfire instead of the p0304 cylinder 4 .and showing fault on both fuel banks

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I thought you said they all tested good?, I ran into this issue before had to shot-gun it, new plugs, new wires, new coils, intake gasket, (did knock sensors while in there), new maf. problem solved.

 

[richyr]

I thought you said they all tested good?, I ran into this issue before had to shot-gun it, new plugs, new wires, new coils, intake gasket, (did knock sensors while in there), new maf. problem solved.

When you put timing light on each spark plug wire shows all of them firing

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[Doubeleive]

When you put timing light on each spark plug wire shows all of them firing

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Perhaps but that doesn't mean they are "good" they could be just plain worn out, I can put a screw driver near a plug and get a spark, doesn't even have to touch it

 

[07Tahoe76]

07 Tahoe LTZ just had a misfire on cylinder 7, got that fixed now engine is shaking again at idle, no check engine light yet like the first time. What could it be? Also traction control and brake light are on simultaneously. Please help

 

[07Tahoe76]

 

[kbuskill]

07 Tahoe LTZ just had a misfire on cylinder 7, got that fixed now engine is shaking again at idle, no check engine light yet like the first time. What could it be? Also traction control and brake light are on simultaneously. Please help

When you say "got that fixed"... what exactly got fixed???... plug, wire, coil pack, fuel injector, AFM lifter???

The TC and ST lights will come on any time you have a misfire.

A scan tool like the Tech2 or even a bluetooth OBD2 scanner with the Torque Pro app would be very helpful as you can look at real time data to determine the cause of the misfire.

 

[Fischer]

I got a Chevy 2007 Tahoe few days ago and first it showed multiple misfires. I cleared the DTC codes and now it's showing the 4th cylinder misfire. Motor even outs at higher rpm but runs rough and shakes at idle.any idea or common problem known to be with this year. Was told a crankshaft sensor could cause it but my experience says do a complete tune up . wires plugs and possibly coil packets.Any ideas or past experience?

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Man I had a misfire check engine light came on cleaned up my mass air flow sensor drove around for awhile light went out everything's been great since

 

[07Tahoe76]

When you say "got that fixed"... what exactly got fixed???... plug, wire, coil pack, fuel injector, AFM lifter???

The TC and ST lights will come on any time you have a misfire.

A scan tool like the Tech2 or even a bluetooth OBD2 scanner with the Torque Pro app would be very helpful as you can look at real time data to determine the cause of the misfire.

Only the Spark plugs and wires were replaced....where do I get the tech 2 and or scanner?