I have a 2002 f150 5.4l. 135000 mi. It runs and drives good except for when you start up a slight grade and the torque converter locks up to maintain speed it starts to spark knock or detonate. If you gas it a little more and down shift to 3<SUP>rd</SUP> the spark knock stops. I looked in the owners manual and it said that some detonation is ok. Is this what ford is talking about? I didn’t think any detonation was ok.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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Your not clear enough with the information.
What speeds are you at when this happens?
The reason for asking is the system operation is complex because a number of areas are active at the same time.
Normally the road speed has to be close to 45 mph to upshift from third to OD under very light throttle.......then to lockup as the last event..
We need to know what's happening in this interval , first.
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. Since the trans is electrically controlled by the computer, shifting, OD and lockup are under computer control by logic assembling this information from the engine RPM, the road speed and the TPS position for upshifting.
The same system is in effect for downshifting.
If there is an issue with the trans control, there should be a code set.
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Later as the road speed gets upward above about 55 mph the EGR system is called to operate.
If this system opens at the 'wrong time' the motor can detonate because another series of events take place that can cause it.
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This is why you need to be more clear about when, what speed, throttle application etc.
As you can see the TC does not normally lock up until the rest of the upshift has completed.
After analysis, then some pointing to a cause might be possible.
It could involve the TPS, VSS, TC converter fault and/or an EGR system fault your not being awhere of until all this is broght to attention..
Good luck.




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Lets say im traveling at 60 mph and i have the cruse set. When I start up a light grade and the cruse tries to maintain 60 mph the first thing you notice is that the torque converter unlocks. At that point the engine starts to detonate. If the cruse still cant hold the speed the transmission will down shift to third gear at witch point the detonation will stop. No trouble codes.

 

Ok that is the info needed.
Here is what happens 'normally'.
The EGR was open at the time the TC unlocked and should close after the speed increases, the load increases as sensed by the TPS position and RPM increases from the gearing change.
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With the EGR open, the fuel is cut back, exhaust gas is allowed to enter the intake and ignition timing is advanced.
This causes very lean air to fuel ratios not because of excess air but the mixture is polluted with exhaust gas that does not burn the second time and just enough fuel to fire the cylinders in a normal manner to be transparent to the driver..
The advance in timing is because the resulting mixture needs to be fired well ahead of normal timing by as much as 38 degrees depending on throttle opening and speed.
If this system hangs open when it is supposed to close you can get some serious ping and detonation under load.
Here is what I would do.
1. The vacuum regulator that controls vacuum to the EGR could have it's air filter plugged. It is under the round cap on the EVR.
If this filter is plugged enough it causes slow shutoff of the EGR.
Reason is the EVR is actually a 3 port device. When it releases under control of the computer, it's output port goes to 'air' so the EGR will release from the vacuum shut down letting air back into the EGR so it closes once it has been opened.
2. Remove the EVR, remove the cap, clean the filter, spray clean the EVR and reassemble.
To see if this is the case, remove the EGR hose connection so the EGR cannot open, and take a drive. If the detonation/ping goes way that's the trouble.
If yes, it has nothing to do directly with the transmission.

Good luck.
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Thanks for the feed back. I'll have to do some checking.