Got a low rpm ping
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Joined: Jul 2002
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From: Bend,OR
Got a low rpm ping
I have adjusted the timing starting at 10*btc and have gone up to 13* and it has not improved. does this mean I need to back it down farther or advance it? the motor is a 95 roller cam 351w .
thanks
later
thanks
later
New User
Joined: Sep 2003
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I would start out with........
setting the timing to factory specs at idle. Then I would check your total timing. If you have too much total timing it copuld cause you to have a "ping". If the total timing is okay, I would suggest using better gasoline- a higher octane or switch brands.
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Joined: Jul 2002
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From: Bend,OR
I dont know what the factory timing is for this motor. does anyone know of hand? I do notice when I fire everything back up after i connect the spout the timing light shows it in the 20 -30 range for total timing, if that helps at all.
Lead Driver
Joined: Sep 2002
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From: Gateway to the West
Kem,
I assume its a truck engine. Most were 10-12* BTDC but the real answer lies on an underhood decal from that model year truck with that particular engine. I have run my own down as low as 7-8* BTDC as a base timing setting. Knock and ping are usually a sign of too much advance resulting in late firing and the exhaust valves opening before the combustion cycle is finished. Too much retard results in bogging down and sluggish acceleration due to premature firing and loss of compression from intake valves not fully seated yet.
20-30 BTDC or ATDC? Have you cleared any codes that may have been generated during the time you were setting the base timing? One other silly question but I'll ask it anyway... was the engine at op. temp. when the base timing was set?
I assume its a truck engine. Most were 10-12* BTDC but the real answer lies on an underhood decal from that model year truck with that particular engine. I have run my own down as low as 7-8* BTDC as a base timing setting. Knock and ping are usually a sign of too much advance resulting in late firing and the exhaust valves opening before the combustion cycle is finished. Too much retard results in bogging down and sluggish acceleration due to premature firing and loss of compression from intake valves not fully seated yet.
20-30 BTDC or ATDC? Have you cleared any codes that may have been generated during the time you were setting the base timing? One other silly question but I'll ask it anyway... was the engine at op. temp. when the base timing was set?
Last edited by greystreak92; Nov 24, 2003 at 05:27 PM.
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Joined: Jul 2002
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From: Bend,OR
truck was at operating temp, the motor was out of a 95 f250. the 20-30* was when i had the spout connected and was just seeing what it was at while running. because you set your timing with spout out then after its reconnected the ecu adjusts timing to. Now when i run this motor down the hwy or for long periods of time the check engine light comes on. could this be from a bad o2 sensor, i never changed it out from when i had the 302. also when i had the upper intake off this motor before install i noticed the 2 inner most runners looked lighter in color then the rest like they were running lean? lean would cause ping correct?
thanks late
thanks late
Elder User
Joined: Oct 2002
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From: Medina, Tn.
O2 sensor will cause the Check Engine light to come on but there are other causes as well. I normally replace mine about every 50,000 miles though. My timing is at about 11 and I get a slight ping but any less, I seem to loose noticible power. Also, check plugs, wires, cap and rotor and even the coil can cause it to ping.
Good luck,
Good luck,
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From: Bend,OR
im wondering if it could be my plugs, they are way to long for some reason so there are places that cross . Ive never been a fan of the tailor plugs because they can be a pain some times. What are a good set of plug wires that are a nice fit to the 351 efi. I also know my egr tube is busted could this also help cause such pinging. I notice now that im running around 8-10* i still have ping but the performance is gone to big time. I put 89 octane in but it was from ampm gas yuck.
im rambling sorry
late
im rambling sorry
late
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Elder User
Joined: Dec 2002
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From: Monterey bay area
A non working EGR will cause pinging.....
I may have another EGR stovepipe laying around in the garage....if you need it.
Best thing to do is to fix that first, then pull the codes.....
I had my engine at 10*BTDC and got it up to 8* BTDC with no pinging....
(alum heads help suppress pinging) The only factor I have with pinging is the quality of the fuel....some companies refine their fuel better than others...
giving you a truer octane rating. Others get you in the neighborhood.
THe intake runners will only tell you if there has been oil seeping into the runners via the oil filler tube vent....getting sucked into the TB assy and into the intake...
Too hot of a spark plug will also cause pinging, hotter plugs help the engine burn cleaner, at the cost of that hotspot and pinging....cooler plugs allow you to run a better timing setting....(by dissapating heat better thus reducing or eliminating the ping)
Do check the initial timing......and set it to stock spec....advance it until you hear pinging.....and back it off a bit.
DO try some 104+ and tell us what it does, if no fix, get cooler plugs.
I may have another EGR stovepipe laying around in the garage....if you need it.
Best thing to do is to fix that first, then pull the codes.....
I had my engine at 10*BTDC and got it up to 8* BTDC with no pinging....
(alum heads help suppress pinging) The only factor I have with pinging is the quality of the fuel....some companies refine their fuel better than others...
giving you a truer octane rating. Others get you in the neighborhood.
THe intake runners will only tell you if there has been oil seeping into the runners via the oil filler tube vent....getting sucked into the TB assy and into the intake...
Too hot of a spark plug will also cause pinging, hotter plugs help the engine burn cleaner, at the cost of that hotspot and pinging....cooler plugs allow you to run a better timing setting....(by dissapating heat better thus reducing or eliminating the ping)
Do check the initial timing......and set it to stock spec....advance it until you hear pinging.....and back it off a bit.
DO try some 104+ and tell us what it does, if no fix, get cooler plugs.
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Elder User
Joined: Oct 2002
Posts: 573
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From: Medina, Tn.
As a last thought, the # 7 and #8 plug wires can cause a slight ping if they are crossed improperly. Mine was doing that a few years ago and then ai read a TSB from ford and that is what they say. Never know.
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