2001 24 valve "skip" at idle
08-04-2016, 02:23 PM
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2001 24 valve "skip" at idle
Hey everyone new to the forum but have been reading threads for awhile. I have a question hoping someone could point me in the right direction. My 01 five speed is stock 128k except a 4" straight pipe but after driving for roughly 20 minutes when it comes down to an idle it'll act like its missing or has a "skip" if I turn the truck off then on again it goes away. Fuel pressure is about 13 psi cruising and 18 psi at idle. I can't find any info at all, any help would be appreciated!
08-04-2016, 08:50 PM
#2
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Welcome to DTR! 
Only one system can cause a skip or miss, and it's fuel. Two possibilities come to mind, a failing injector or the VP44 is starting to have issues. Your lift pump seems healthy.
Is the check engine light lit at all? Even if it is not, you can still check for codes since you have an 01. Cycle the key three time between the off and on positions, ending in on. Don't start the truck. Again the key sequence is ON - off - ON - off - ON. Then watch the odometer display and write down any codes that may pop up. It will show codes from both computers, the ECM and PCM. In the odometer display they will show as PCU and ECU, no way to make an M with our odometers. If there are no codes for that module, it will simply show a row of dashes (---------). Also, after each module is displayed, it will read P DONE. The test is not over until it checks both modules, you will see P DONE twice, and then it will go back to showing mileage.
Another way to help pinpoint it is to use a mechanics stethoscope when it is missing and see if you can locate the miss to a particular cylinder. If the miss happens across all cylinders and not just one, then I would suspect the VP44.
Post back and let us know if you found any codes.
Only one system can cause a skip or miss, and it's fuel. Two possibilities come to mind, a failing injector or the VP44 is starting to have issues. Your lift pump seems healthy.
Is the check engine light lit at all? Even if it is not, you can still check for codes since you have an 01. Cycle the key three time between the off and on positions, ending in on. Don't start the truck. Again the key sequence is ON - off - ON - off - ON. Then watch the odometer display and write down any codes that may pop up. It will show codes from both computers, the ECM and PCM. In the odometer display they will show as PCU and ECU, no way to make an M with our odometers. If there are no codes for that module, it will simply show a row of dashes (---------). Also, after each module is displayed, it will read P DONE. The test is not over until it checks both modules, you will see P DONE twice, and then it will go back to showing mileage.
Another way to help pinpoint it is to use a mechanics stethoscope when it is missing and see if you can locate the miss to a particular cylinder. If the miss happens across all cylinders and not just one, then I would suspect the VP44.
Post back and let us know if you found any codes.
08-07-2016, 08:54 PM
#3
Registered User
My 99 truck shown in my signature had a very similar issue years ago, right around 190,000 miles. At that time mine was all stock except for 4" exhaust.
My truck ran fine, no power loss or any drivability issues. But when i would stop at a red light, I would get what can best be called a miss. There would be a quick shudder as if one of the cylinders did not fire . It happened almost all the time once the engine was warmed up.
When it would do this, there wasn't really a pattern to how the "miss" would hit. Sometimes just once while waiting a whole red light, other times 2-4 of them in a row. As soon as I stepped on the throttle it went away.
I had no codes either.
Mine ended up being injectors. I opted for a set of Bosch RV275 since they are "factory" for this engine but still about a 50-hp upgrade.
Changing them was actually quite easy. And it's a good time to check valve lash while you have the cover off. If your the kind of person that does your own regular maintenance and consider yourself halfway decent with a wrench, this is a job you can handle (many injector manufactures include instructions too)
Good luck!
My truck ran fine, no power loss or any drivability issues. But when i would stop at a red light, I would get what can best be called a miss. There would be a quick shudder as if one of the cylinders did not fire . It happened almost all the time once the engine was warmed up.
When it would do this, there wasn't really a pattern to how the "miss" would hit. Sometimes just once while waiting a whole red light, other times 2-4 of them in a row. As soon as I stepped on the throttle it went away.
I had no codes either.
Mine ended up being injectors. I opted for a set of Bosch RV275 since they are "factory" for this engine but still about a 50-hp upgrade.
Changing them was actually quite easy. And it's a good time to check valve lash while you have the cover off. If your the kind of person that does your own regular maintenance and consider yourself halfway decent with a wrench, this is a job you can handle (many injector manufactures include instructions too)
Good luck!
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