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.
'99 Yukon engine shaking & losing power
- Thread starter cstaebell
- Start date
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I have only owned this Yukon for two years. I have not changed it in that time, and am not sure it was changed anytime before then. When I did the tune-up, the plugs and wires looked original, so I assume the fuel filter is as well. I thought about changing that, as I figured it could lead to loss of power if the engine is starved of fuel, but I wasn't sure if that would cause the engine shaking.
Well, I finally had a chance to change my fuel filter. Unfortunately, while it does run a bit better, the vibration is still there. I am wondering if it is an injector. Is that hard to change, or should I have a mechanic do that?
retorq
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Go back and check the wires over, use a water bottle to see if there is one not firing by hitting the header tube or the exhaust manifold with a stream of water while it's running
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Maybe time to start with a compression test to see if mechanical parts are ok. Injectors are of the stupid @&$#ing design that is inside the intake manifold and can't be accessed withouth removing the upper intake.
shyco:
shyco:Do I have to take off the fuel spider? I had someone tell me that the fuel system on these things was pretty crappy. They said that if I am lucky it is just the fuel pump. Not sure if it is worth spending that kind of money on this.
chevyboy831
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I dont think its the fuel pump. check compression to make sure the engine is mechanically sound, then check fuel pressure and how long it holds the pressure. and does it not doing while in your driveway and u hold the engine at say 2000-2500 rpm?
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 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
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I dont believe it is. otherwise it would do it all the time.
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
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I was about to go in that direction. But it would cause other issues too. Have u cleaned the egr passages? Egr workin ok?
Cleaned the MAF sensor. It definitely needed it, but did not solve my problem.
chevyboy831
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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
Full Access Member
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.
