Yukon Shaking

[99_YUKON]

I have a 99 Yukon SLT it has check engine light i went to check it out and have 3 O2 sensors bad and a 4 cyclinder misfire it also shakes when in driving and stopped and when i let my foot off the brake it shakes till i step on the gas. It also runs kind of sluggish. I check for vaccum leaks , changed the spark plugs , spark plug wires , fuel filter , mass air flow sensor , air filter , 3 O2 sensors and got the fuel injection cleaned. Its running better still not like it should and it still shakes and still has check engine light with 4 cyclinder misfire. Any ideas?

[omegafiler]

Sounds like you've got some pretty bad misfires going on if it's shaking like that. How many miles do you have on it? Have you tried a top engine clean, like seafoam? If you do a search for seafoam, you'll find lots of good info on it. It's highly recommended for high mileage and dirty engines. I used the Amsoil equivalent, but it did wonders on my old 400 series Tahoe, like what you have.

 

You'll have to change the oil again and if the engine is dirty enough, it can foul out a plug or 2. But it's worth it.

[99_YUKON]

Sounds like you've got some pretty bad misfires going on if it's shaking like that. How many miles do you have on it? Have you tried a top engine clean, like seafoam? If you do a search for seafoam, you'll find lots of good info on it. It's highly recommended for high mileage and dirty engines. I used the Amsoil equivalent, but it did wonders on my old 400 series Tahoe, like what you have.

 

You'll have to change the oil again and if the engine is dirty enough, it can foul out a plug or 2. But it's worth it.

 

 

I have 135,000 miles on it. i havent tried anything like that. Iam going to give a try.

thanks