'99 Yukon engine shaking & losing power

[laxman21]

Clean your MAF sensor.

 

[cstaebell]

I did not think it would be the fuel pump either, but a couple people have said it could be that. It does not shake will sitting in my drive way. I ran it up to 2500, and I felt a very, very faint vibration.

I will clean off the MAF sensor and see what happens.

There is one important thing I completely forgot to mention. A while back I had an issue with it idling rough. I checked the engine and a spark plug wire came loose. I put it back on and it ran great. Now I have this issue. I assume it is somehow related?

 

[chevyboy831]

I did not think it would be the fuel pump either, but a couple people have said it could be that. It does not shake will sitting in my drive way. I ran it up to 2500, and I felt a very, very faint vibration.

I will clean off the MAF sensor and see what happens.

There is one important thing I completely forgot to mention. A while back I had an issue with it idling rough. I checked the engine and a spark plug wire came loose. I put it back on and it ran great. Now I have this issue. I assume it is somehow related?

I dont believe it is. otherwise it would do it all the time.

 

[cstaebell]

I am contemplating changing out the distributor, rotor and cps. I have read about a lot of people with this problem doing that and it fixed it. Other than starting to change out every other friggin' sensor on this thing, I am not sure what else to do.

 

[chevyboy831]

I was about to go in that direction. But it would cause other issues too. Have u cleaned the egr passages? Egr workin ok?

 

[cstaebell]

Clean your MAF sensor.

Cleaned the MAF sensor. It definitely needed it, but did not solve my problem.

 

[chevyboy831]

any update?

 

[cstaebell]

any update?

Not yet. I got really busy with work and the holiday coming up and have not had time to work on it more. I talked with someone that said they had the same problem, and they said it was their ignition coil. I am going to try and run an ignition test today to verify that. Hopefully it is not too hard to change.

 

[knoslf]

I have a '99 Yukon SLT 4X4 with about 121,775 miles on it. The engine has started to shake rather noticeably around 50 - 60 mph. It is worse when going uphill and loses a lot of power. I then started getting the P0300 code for random/multiple misfires. I changed the spark plugs and wires, it did not help. I am hoping someone can help me pinpoint this before I have to replace a bunch of stuff. I know it could be injectors, vacuum line, egr valve, cat, etc. Any advice would be great. I feel it may be the cat or egr valve, but not sure.

I was having the same problem! I changed the fuel filter and pump, didnt help, changed the plugs/wires as well as the cap and rotor and POW!...runs like new now, I suggest changing your cap/rotor too since u already did the plugs/wires, my cap and rotor looked terrible...good luck!

 

[cstaebell]

I was having the same problem! I changed the fuel filter and pump, didnt help, changed the plugs/wires as well as the cap and rotor and POW!...runs like new now, I suggest changing your cap/rotor too since u already did the plugs/wires, my cap and rotor looked terrible...good luck!

I am going to try and get the cap and rotor changed out this weekend. So far i have changed plugs, wires, fuel filter, ICM and did not help. I did an ignition test, and everything seemed to be firing. After changing the ICM, it seemed to run slightly better, but that could have just been my imagination hoping it was running better. But I did notice something when I just test drove it. Shortly after I started driving it, it seemed to be hesitating slightly. It only did it briefly and I could not tell if it was due to loss of power or lack of fuel. I will probably change the ignition coil as well since I did the ICM.