TO PING OR NOT TO PING?

Sorry but I forgot to add the following....

Since I have upgraded from 28s to 31s, can that cause the engine to lug or ping? I generally keep the RPM's around 2200-2400 in 5th gear (I have a 6 speed). In the higher gears after the engine is warm and mainly while going uphill (little or big), I get this noise on the passenger side that sounds VERY similar to the soft top side window 'pinging' against the metal support bow when the wind blows. I can't quite distinguish if that's it, or if the engine is pinging because I am not 100% sure whether it's coming from the front or the back. It's a high-pitched noise. It is NOT rhythmic or steady, but rather comes and goes intermittently. This noise does NOT happen at city/town speeds of 50 mph or lower. I ran a tank of 89 through her, and it seemed to be drastically reduced after 1/4 of the tank was used and for the rest of the 3/4 of the tank. I have now refilled again with the 89 and the noise is back. I have not used 1/4 of the tank yet, so I don't know if it will be reduced again once I get to that point. I do have a tendecy to 'stuff' as much gas in the tank as I can get (even after the automatic shuf-off on the spout kicks on). Would this be causing the problem too?

I highly doubt you can make a 4.0 engine ping at 2500 rpm under almost any driving condition.

At that rpm, you are way up in the torque curve and should have tons of power to accelerate uphill fast even using regular gas.

My Jeeps have tons of power when fully loaded for camping at that rpm, they will 'hold' 2300 rpm at least on anything.

I would be suspecting something else is making the noise.

I can only start a ping if I am way down into the mid teens for rpm or have gas my CJ7's 258 doesn't like in it. (old carb engine, apples and oranges to a 4.0's systems)

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > >> Quick question...

Engine are more prone to ping at lower RPMs when rate of expansion is slower and load is high. You would know this if you had any realy knowledge of this.

All the more reason it can ping because when engine is making good torque it is near its VE peak (Volumetric Efficency) where effective pumping pressure are the highest for its mixtures being burned and these higher pressure need more octane

I take this with a grain of salt since you think 3.31 gears with 33's is a great combo, you really do not have a clue what good pulling power is. (you have very low standards)

Of course you would because you are clueless here

How much octane you need depends on engine temp, air temp, load, humidity, altitude and well as deposits in engine from age and minute oil usage too which lowers octane needs. Octane needs are not constant and the trick is to use a high enough octane to meet maximum needs. What people need themselves can vary and is not universal 87 does it all as clueless here suggests. BTW, I do not use 87 in anything made since early 80's.

----------------- TheSnoMan.com

Thanks for the quick responses.

SnoMan -- You're right, I really don't have much knowledge of what causes pinging. I really do appreciate the fact that you're not being rude about it. I was just a little confused though when you said engines are more likely to ping at lower RPMs, then in the next paragraph, you said that higher RPMs would be all the more reason an engine would ping. Those statements contradict themselves (unless I am missing something that I don't quite understand).

Any input regarding the 'rattlesnake noise'? It's just a soft 'purring' type noise. Not real loud at all, but does quit when I back off the accelerator just a touch.

You said highway or lower speeds it happens Tire noise? Did you see if it happens when you in neutral?

Did you get your gas at the same place both times? They shouldn't have done it quite yet, but if a station got a tank of winter blend gas, this could be causing your problem, if it is indeed pinging. By running in

5th gear, you shouldn't be experiencing ping. The reason I say this is that you would have heard it before with the stock tires in 6th gear, but if you weren't listening for it, you may not have heard it.

The way you describe it, it sure sounds like pinging, but in reality it could be someone totally unrelated. Without actually being there to hear it, the only suggestion I can offer is to try filling up again with 89 octane, but either go back to the original gas station, or if it was the same station, ask them if they changed to winter blend fuel already.

One other thing I just thought of is to see if you can find fuel with no ethanol added. Some vehicles just don't run decent on the mixed fuels. It usually says right on the pump if there is ethanol added.

Chris

On My 05TJ Rubicon Sometimes not always I can hear a slight ticking sound Kinda like the lifters.

One day when it was really cold outside (-28C) I started it without the block heater plugged in It made a very loud ticking noise but only for a few seconds Someone somewhere said that it wasn't the lifters but something else. I forget what he said it was. Something not to worry about though. (I think) It might have been in the "Rubicon owners forum"

Try searching there for it if ya want.

c wrote:

Tracie, have you considered a rattle from the exhaust hitting something? If the exhaust plumbing sits close enough, it will rattle when the engine rpm is just right to resonate. Same thing will cause the heat shield on the cat to buzz under specific conditions. Given the RPM range you describe, I'd be looking for mechanical noise as well as for ping.

The definitive answer about ping would be a full tank of high test gas under identical conditions. No noise, likely ping. Noise still there, rattle time.

I did get it at the same station, but I don't know if they have switched to winter blend yet. I will try going to a different station to see if the car still does this. I don't know if this makes any difference, but I did notice it since the day I drove it off the lot (bought it brand new with 74 miles on her).

Thanks for the link to the forum. I think I'll scout around in there and see what I can find. : D

If the exhaust is sitting close enough, is that something I can re- route, or do you just live with it? It isn't anything I can't live with. I was just curious as to what is causing the noise. But like I said in the earlier post, I DO remember hearing it even with the stock tires since the day I drove her off the lot brand new. It may even be characteristic of the type of engine that is in it (NSG 370?) or something like that. I'll check underneath to see if there is anything loose that may be rattling.

The only other noise that she makes that I can't figure out is the single pop she makes when turning corners (left ONLY), or once in a while when going straight. I have a feeling it has something to do with the steering colum. I distinctly hear it up front towards the center. She doesn't do it all the time, only when feels like it. Other than that (and the possible engine noise -- if not normal), she runs like a dream.

Sno,

I, for one, appreciate your knowledge and contribution to the group, but statements like "You would know this if you had any realy knowledge of this." and "Of course you would because you are clueless here" are irrelevant and worthless.

Carl

I will second the CAT's heat shield. That is located under the passenger footwell still isn't it?

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

Tracie, Mike was basically telling you what you are hearing was probably not engine pinging. Snoman was trying to contradict Mike because that's his mission in life when it comes to this newsgroup. Welcome to the club. :-)

Snoman has a real problem with Mike Romain, and he's only here because he has stalked Mike to here from another other group. Mike has forgotten more about real-world Jeeps than Sno will ever know, and is one of the most helpful folks here.

Sno will undoubtedly make an "I've had Jeeps for a million years and therefore Mike is wrong and I know everything" statement, but know that Sno has only come to this group relatively recently and more often than not enters a thread only when he's trying to make Mike look like an ass. So it's really his advice that should be taken with a grain of salt.

Could it be your new tires?

Funny, there isn't much difference between Hispanic newsgroups and Anglo newsgroups. I kept expecting to see "hijo de puta" in Snoball's message. I put him back in my kill file of course.

Saludos,

Earle

One some vehicles, you can hear a faint ticking sound from the injectors, but I've never been able to hear them at highway speeds. It is usually with the hood opened and your head in the engine compartment.

Chris

FrankW wrote:

If I was rude, it was not toward you. I have a running battle with Mike Romain and some of his very bad advise. The true octane of a engine as I stated is not a constant. In cooler damp weather you can get by on less octane than in hot dry weather. I think the confission you have about knock vs RPM is from I stated that engine are more prone to ping at lower RPM (lower meaning below 3500 to 4000 RPM) because of flame speed verse rate of expansion in cylinder from piston velocity which increases with RPM. Also as I stated engine operating at or near their torque peak have their highest pumping efficency and highest cylinder pressures. Higher octane fuel burn a bit slower and also resists self ignition better for tempatures and pressure in mixture before and durring a normal burn BTW, the mixture does burn not explode. When it exploded it creates the load knock that some hear at times. (this is why diesels rattle because they are in effect detonation engines)

The reason you are hearing it then is because the advance is still rather high for best economy and power at the throttle setting and octane of fuel is not high enough for that combo and current environment and you are on the edge of more serious knock. (a little light ping hear and there is okay you just to not want to sustain it) Also, ping is very hard on your valves in that it can cause them to vibrate in their seats and leak and in time cause them to burn. (this is one of the main causes of burned valves in a otherwise normally operating engine) Detriot today uses a lot of tricks to try to quell knock to keep consummers happy with cheap gas with EGR and spark retatrding being common means. EGR dilutes incoming mixture and reduces availble oxygen which slows combustion and lowers peak pressures too to limit NOx and a side benifit is it reduces octane need a bit but it does reduce efficency too. Retarding spark is used by basically all brands today as it is easy to do and keeps consumer happy but it does lower power and MPG. I would suggest you try some 90 ot 91 octane for a while and drop back to lower octane in cooler weather in fall/winter. (you can mix 87 and 93 together and get 90 for about same price (50/50 mix) as straight 89.

----------------- TheSnoMan.com

Well, it is an 06. Why not have the dealer deal with it. Or atleast see what their 'experts' have to say.

He's been in mine since he started his BS in alt.trucks.ford...

Wouldn't I get the same effect if I had the dealer retard the timing a bit?