98 F150 with 5.4L engine miss - stumble
#16
02-16-2009, 10:40 AM
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I Think I must have read every post on every forum that there is on the internet about this problem and similar ones for the 5.4L Misfire with no DTC.
I am an ASE master Tech and have been for more years then I care to think about.
I have a customer who has a 98 with a problem of misfires with no stored codes which is making me think about retiring very soon. Although I am not one to replace parts without a very good diagnostic that in my mind warrants it. I don’t have the luxury that dealers do, of being able to throw parts and hope it works and the customer pays either way. If I don't fix it The customer doesn't pay. I'm ready to through the kitchen sink on this one.
I grew up servicing cars that had points and plugs and darn little else, I helped to resolve the Cadillac V8-6-4 relocation of the MAP issue when computers in cars were just babies in 1979 and early 80 and by all measure have kept up with emerging technology. So don't sell your ability short in not being able to come up with a positive solution for this one. If I find a solution beyond dynamite that actually does I will post it
I am an ASE master Tech and have been for more years then I care to think about.
I have a customer who has a 98 with a problem of misfires with no stored codes which is making me think about retiring very soon. Although I am not one to replace parts without a very good diagnostic that in my mind warrants it. I don’t have the luxury that dealers do, of being able to throw parts and hope it works and the customer pays either way. If I don't fix it The customer doesn't pay. I'm ready to through the kitchen sink on this one.
I grew up servicing cars that had points and plugs and darn little else, I helped to resolve the Cadillac V8-6-4 relocation of the MAP issue when computers in cars were just babies in 1979 and early 80 and by all measure have kept up with emerging technology. So don't sell your ability short in not being able to come up with a positive solution for this one. If I find a solution beyond dynamite that actually does I will post it
With todays cars factory scanner are the way to go. Expensive yes but if you make your living they are must have items.
#17
02-16-2009, 01:49 PM
The first to be tested/ruled out is primary @ 0.55 ohms and secondary @ 5,500 ohms.
Most coils don't fail this way, they fail under load = low grade misfire. With low grade misfires, primary and secondary can pass all day long with no success revealing low grade problems.
Techs find those low grades thru stress testing using the Rotunda WDS, the follow procedure - Go to the Oscilloscope Tool and select Channel 3, then select Auto, then select COP_STRESS_TEST_RED. That will find the low grade problem thru pre-configured settings. I never whitenessed this being done, just read the instructions - Dial 800-ROTUNDA lol. I stress test the unconventional way - Monitoring thru a pulse reader that sort of acts like a noid light, but constructed for coil pulse and wired thru the firewall for drivecycle monitoring. It's hardly worth the time.
If you take it in, they can pinpoint and replace, but for the price of coils @ $70 a set. It's easier just replacing them all. Just helped my dads buddy with a F250 5four. He purchased a set of Motorcrafts from the dealer 3 months ago
- Still had problems. Installed a set of Globals, fixed her right up. He's trying to return the Motorcrafts - Haven't heard if that was successful lol.
A few Pulse Readers, I use a different type, but these could work if you want to go thru the trouble -
Most coils don't fail this way, they fail under load = low grade misfire. With low grade misfires, primary and secondary can pass all day long with no success revealing low grade problems.
Techs find those low grades thru stress testing using the Rotunda WDS, the follow procedure - Go to the Oscilloscope Tool and select Channel 3, then select Auto, then select COP_STRESS_TEST_RED. That will find the low grade problem thru pre-configured settings. I never whitenessed this being done, just read the instructions - Dial 800-ROTUNDA lol. I stress test the unconventional way - Monitoring thru a pulse reader that sort of acts like a noid light, but constructed for coil pulse and wired thru the firewall for drivecycle monitoring. It's hardly worth the time.
If you take it in, they can pinpoint and replace, but for the price of coils @ $70 a set. It's easier just replacing them all. Just helped my dads buddy with a F250 5four. He purchased a set of Motorcrafts from the dealer 3 months ago
- Still had problems. Installed a set of Globals, fixed her right up. He's trying to return the Motorcrafts - Haven't heard if that was successful lol.A few Pulse Readers, I use a different type, but these could work if you want to go thru the trouble -
Last edited by jbrew; 02-16-2009 at 02:11 PM.