99 K1500 rough idle

[Browning151]

I've got a 99 K1500 (OBS, its the pic in my sig) w/the 5.7 that kept throwing a P0305 code (Number 5 cylinder misfire), usually only happened at high speeds on the expressway. Replaced the plugs, wires, rotor button and dist. cap today and so far the P0305 code is gone but at idle the truck still feels like it is skipping some. It runs great no problems at speed but its a little irritating with all that replaced and still having a little skip. Anyone have any suggestions to get it to idle out smooth? Thanks for any suggestions.

[Browning151]

Ok, so after all that work this weekend on the tune-up I got on the expressway today and the dreaded SES light came on again. Took it to a buddy at the dealership, said that now its a P0300B general misfire, he checked ALLData and said that I should replace the ignition coil so off to the parts store I went, put in the new coil and I still have the skip at idle and its still throwning the code on the expressway, usually around 75mph and in the 2500-3000 RPM range....anyone have any clues where to go from here? Im stumped

[2000CAYukon]

Has the cam retard been set using a scan tool?

The drive gear on the dist can wear and cause a rough idle and a miss at higher rpms.

If the dist is removed, the cam retard must be set using a scan tool.

A leaking fuel pressure regulator can also cause a miss. Test the fuel pressure and see if it drops when the engine is turned off.

//2000CAYukon

[Browning151]

Originally Posted by 2000CAYukon

Has the cam retard been set using a scan tool?

The drive gear on the dist can wear and cause a rough idle and a miss at higher rpms.

If the dist is removed, the cam retard must be set using a scan tool.

A leaking fuel pressure regulator can also cause a miss. Test the fuel pressure and see if it drops when the engine is turned off.

//2000CAYukon

I bought the truck in august with 113k on it and it now has 121k on it and since I have had it I havent messed with the cam retard or removed the dist, Im really hoping its not the gear on the dist. Whats the best way for me to check the fuel pressure? Is it normal for it to sound like the fuel pump primes when I turn the truck on and when I turn it off?

thanks for the help //2000CAYukon

[2000CAYukon]

Best way to check the fuel pressure is with a fuel pressure gauge. Normal is 60-65 so you need one that goes to 100 PSI.

Take the dist cap off and try to rotate the dist. If the gear is worn, it will feel really loose. The drive gear can be replaced by removing the dist.

Good Luck,
//2000CAYukon

[Browning151]

Originally Posted by 2000CAYukon

Best way to check the fuel pressure is with a fuel pressure gauge. Normal is 60-65 so you need one that goes to 100 PSI.

Take the dist cap off and try to rotate the dist. If the gear is worn, it will feel really loose. The drive gear can be replaced by removing the dist.

Good Luck,
//2000CAYukon

I did notice there was some play when I was putting the rotor button on, do you know about how much would seem acceptable? It also looked like it wasn't sparking directly from the center of the tab that sticks off the button, it looked like just the corner looked burnt. Seems like to me that it should spark from the center of that little tab instead of from one corner. Would that seem to indicate the gear is worn to you? I can try and get a picture of the old button if my description isnt too clear. Thanks again for the tips, Im going to try to get the fuel pressure checked tomorrow.

[2000CAYukon]

It might make sense to have it scanned and make sure the cam retard is within spec. The misfire counts can also be looked at to see if it one cylinder or many. Usually with a worn dist gear, the misfires will be random.

I looked for the post that had the picture of the worn dist gear, but I can find it.

//2000CAYukon