Timing issue on 302 Explorer
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Timing issue on 302 Explorer
I've had a detonation problem lately on my truck that seems to occur in low rpm's when the truck is under load, especially in overdrive.
I was able to purchase an OBD-2 scantool from www.Autoenginuity.com which I am very happy with. Now I'm not the best troubleshooter yet, but I did notice that in one of my datalogs from a short trip to the store and back that my timing advance is way too high(or at least i think it is). It fluctuates from around 18 degress at idle to 40 degrees at higher speeds. I've attached an excel datalog sheet that hopefully some of you guys can look at along with some of the other readings so I can get this fixed!
http://img.photobucket.com/albums/v97/south59/academyhome.jpg
http://img.photobucket.com/albums/v97/south59/academyhome2.jpg
The truck is a 96 v8 with 142,000 miles. new plugs(gapped properly) along with wires. the maf is clean, and the truck isnt throwing any codes.
I was able to purchase an OBD-2 scantool from www.Autoenginuity.com which I am very happy with. Now I'm not the best troubleshooter yet, but I did notice that in one of my datalogs from a short trip to the store and back that my timing advance is way too high(or at least i think it is). It fluctuates from around 18 degress at idle to 40 degrees at higher speeds. I've attached an excel datalog sheet that hopefully some of you guys can look at along with some of the other readings so I can get this fixed!
http://img.photobucket.com/albums/v97/south59/academyhome.jpg
http://img.photobucket.com/albums/v97/south59/academyhome2.jpg
The truck is a 96 v8 with 142,000 miles. new plugs(gapped properly) along with wires. the maf is clean, and the truck isnt throwing any codes.
Lead Driver
Joined: Nov 2002
Posts: 9,555
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From: Concord, NC
10 degrees is the base timing. Actual timing will be 10 degrees plus whatever advance the computer commands. It still has a distributor, but I think it might have a crank angle sensor like joners said. I think checking the base timing is a good idea for the first thing to try. I'm a little concerned at the short term fuel trims, though. It looks like the computer is having to correct quite a bit to get the air/fuel ratio where it wants it. Can you correlate the high fuel trims to the rpms and speeds where it is pinging?
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I wish I could set the timing myself, but unfortunately the only way I can do that is through a tuner. This truck is distributorless uses a coil pack...I was thinking that those might be going out.
Others have told me that I could in fact have a bad PCM....which is advancing the timing alot farther than it should. Any ideas?
The truck is definitely pinging the most noticeably when the timing is at its highest, but i dont see any correlation to the times that it pings(40+ mph / low to moderate acceleration) to an abnormal Fuel trim value.
Heres the full excel datalog sheet, watch the timing rise all the way to 42....
https://webspace.utexas.edu/jm3474/academy%20home.xml
Others have told me that I could in fact have a bad PCM....which is advancing the timing alot farther than it should. Any ideas?
The truck is definitely pinging the most noticeably when the timing is at its highest, but i dont see any correlation to the times that it pings(40+ mph / low to moderate acceleration) to an abnormal Fuel trim value.
Heres the full excel datalog sheet, watch the timing rise all the way to 42....
https://webspace.utexas.edu/jm3474/academy%20home.xml
Last edited by south59; Oct 23, 2005 at 07:21 PM.
Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
From: Concord, NC
I think that even with coil packs, you should be able to set the base timing. Do you have a timing light? If you do, I would check for timing marks and test the actual timing. Take what you get from the timing light and compare it to what the computer is saying the advance is. If it is different, then the base timing has moved and needs to be reset. The 42° sounds right, though. The mustang 5.0's ran that much advance, at least in '89-'93. I don't know a lot about explorers, so I'm not sure how to do that. Maybe a Haynes manual would have that included somewhere. I couldn't get the link to the excel sheet to work for some reason, even when I copied and pasted. I am interested in looking over that file, so if you want to email it to me, just send me a PM and I'll give you my email address.
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From: Delta B.C.
Well... here are a few thoughts for you...
1) what kind of plugs did you put in there??? I had pinging in my 4.2L F150 with anything other than OE...
2) what do your PCV hose and breather hose look like... I have been seeing a lot of fords recently with callapsed hoses causing a lean enough condition not to trigger the SES light, but enough to give driveability
3) vacuum leaks along the intake to cylinder heads....
1) what kind of plugs did you put in there??? I had pinging in my 4.2L F150 with anything other than OE...
2) what do your PCV hose and breather hose look like... I have been seeing a lot of fords recently with callapsed hoses causing a lean enough condition not to trigger the SES light, but enough to give driveability
3) vacuum leaks along the intake to cylinder heads....
More Turbo
Joined: Jun 2004
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From: Sweden
Timing chain slack can cause problems in this area. I remember it was impossible to time because the cam was jerking back and forth at low rpm. At higher rpm it could ping easily- not only does the distributor have timing problems but the valve timing is also off.
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From: Delta B.C.
Good call Dannym... I have seen that on a 3.8L now that I think of it... with that millage it a really good thought!!!
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Originally Posted by Mr. Bob
Well... here are a few thoughts for you...
1) what kind of plugs did you put in there??? I had pinging in my 4.2L F150 with anything other than OE...
2) what do your PCV hose and breather hose look like... I have been seeing a lot of fords recently with callapsed hoses causing a lean enough condition not to trigger the SES light, but enough to give driveability
3) vacuum leaks along the intake to cylinder heads....
1) what kind of plugs did you put in there??? I had pinging in my 4.2L F150 with anything other than OE...
2) what do your PCV hose and breather hose look like... I have been seeing a lot of fords recently with callapsed hoses causing a lean enough condition not to trigger the SES light, but enough to give driveability
3) vacuum leaks along the intake to cylinder heads....
2-went out and looked- they look good
3-whats the best way to check for vacuum leaks?
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Originally Posted by Dannym
Timing chain slack can cause problems in this area. I remember it was impossible to time because the cam was jerking back and forth at low rpm. At higher rpm it could ping easily- not only does the distributor have timing problems but the valve timing is also off.
Interesting, Is this easy to check? I'm debating to take this thing down to a mechanic i know in San Antonio, but maybe you guys will be able to get me through it
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