another detonation question

[fireguy12117]

i searched through the threads under pinging and detonation and got some ideas, but i have a couple questions. i do have a pinging issue on a remaned motor thats got maybe 7-800 miles on the block. my detonation only seems to occur when i am at highway speeds, like accelerating onto and once i am on the highway, its horrible. i can rag the bejeezus out of the throttle around the surface streets and nothing, not a peep, the motor just climbs through the rev's without a sound. when i am on the highway, its almost constant and pretty prenounced.

how can the same rpm's on the motor at 40-45 and 60-65 have two completely different things happening as far as detonation, like is there, or not there?

and what scenario does this point too: timing, lean fuels, or carboned over cylinders?

its a reman thats got a shit ton of idling time and driving without getting up to temp as i was dealing with a whole bunch of other issues (2 bad pcm's) so i suppose its not impossible to have carboning issues...and as for the RPM's, the only thing in my mind is what gear i am, as far as the motor the rev's are rev's, or am i missing something there as well?

 

[Beanmachine7000]

As to why it doesn't so it in lower gears is because the cylinder walls don't get hot enough to pre-ignite the gas/air mixture... When you are at lower rpm's in a higher gear the cylinder pressure is incresed (increased load on the pistons) which creates more heat, therefore pre-igniting the fuel... Switching to a lower gear usually clears up detonation for this reason... I would say timing is incorrect more than likely... 1000 miles isn't enough to build up enough carbon to increase your CR...

 

[GreenMachine]

I have been doing some research on spark plugs sound like your plugs could be to hot here is a good link to look at
http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp3.asp?nav=31000&country=US

 

[fireguy12117]

boy that was a bad typo in the title huh?

well that gives insight for why it doesnt do it at lower loads if you will. i am totally open to ideas here. i did see some stuff on replacing the coil pack, but to me it seems thats a go/no go componant where some feel it can get weak over time. im undecided. but that also led me to wonder about the plugs- ill have to read up on that linky, thanks.

last i knew the timing was where it should have been as best i could tell. i used a timing light on the crank timing marks and they were on, pulled the SPOUT connector and got 10 degrees out, so beyond that i have to assume ive checked what i can and its good. this motor does not have the cam synchro on the back of the block.

anyhow, thanks guys, ill keep researching.

 

[RangerSVT]

To correctly time an engine (ford EFI), pull the PIP (spout ), set timing to 0, then install PIP...Ford ECU's change timing as much as 30*, if it is not set to 0, then when the computer changes the timing, it will be off...
Did you check into running mid grade fuel?? Also, are you running platinums?? If your engine calls for platinums, or double platinums (like my 96), then you need to have them. I tried to run reg platinums, and got 5000 miles on it then started missing like crazy, relpaced plugs, ran great. I used to get pinging running regular fuel, which also killed my DP plugs in about 10-15K miles. I now run mid grade fuel and DP plugs, no prob since
SVT

 

[Ozwynn]

I am going with timing. I could explain why it does it at WOT and not at cruising but that would be irrelevant. your timing is off...... to far advanced. anyways that is an easy check. use a get a timing light and find the specs for your engine/ECU combo to find out where your engine should be timed ...... on a happier note ...... sounds like your EGR is working perfectly......... as far as retiming it ...... I got no idea on a 4.0L

 

[shadetree]

If the engine you are talking about is either of the ones in your signature, the ignition timing is controlled by the computer and cannot be changed.shady

 

[fireguy12117]

it is. there is no way to adjust the timing AFAIK. i didnt assemble the long block so i cant speak to the particulars, but i understand that the cam and the crank are nearly impossible to get mistimed when assembling the motor. something about there being keying to keep you from botching it.

pulling the SPOUT put the timing at 10degrees and the normal idle advance was past that so i more or less left the timing research at that point since i couldnt see where else to look to confirm things.

i cant remember what plugs i put in, i just know i asked for whatever the computer recomended, so that needs to be looked at. probably my next best place to be looking it sounds like.