Low speed pinging engine noise?

[svx_commuter]

Hi,
I get a pinging noise from the SVX engine sometimes. Let me explain. It happens from a standing start at very low throttle opening when I am going up a hill. It continues until the throttle opens up some and the speed is faster. (I notice it more when there is a wall next tot eh road on the driver side and I roll down the window.) Does any one know if this is something I should worry about? Anybody know what causes this?
I am still getting around 25 mpg in my commuting. So I think everything is working okay and there hasn’t been a CEL for a long time.

Thanks

[oab_au]

Originally Posted by svx_commuter

Hi,
I get a pinging noise from the SVX engine sometimes. Let me explain. It happens from a standing start at very low throttle opening when I am going up a hill. It continues until the throttle opens up some and the speed is faster. (I notice it more when there is a wall next tot eh road on the driver side and I roll down the window.) Does any one know if this is something I should worry about? Anybody know what causes this?
I am still getting around 25 mpg in my commuting. So I think everything is working okay and there hasn’t been a CEL for a long time.

Thanks

Gidáy John, Pinging and low throttle openings, don't go together. So I doubt it is this. Could it be a heat shield or some other rattle?

Harvey.

[svx_commuter]

Originally Posted by oab_au

Gidáy John, Pinging and low throttle openings, don't go together. So I doubt it is this. Could it be a heat shield or some other rattle?

Harvey.

Greetings Harvey,
Oh yes it is pinging and not heat shields rattleing around. It has that nice rapid high frequency to it with distinct pings. Not at all a sheet metal noise.

I am thinking the the EGR valve is sticking open. Is that a possiblity?

Take care,

John

[NikFu S.]

Salutations.
I have no idea, but is the ping in sync with rpms or no?

[Beav]

It would be the EGR sticking closed John, not open - if that is indeed the problem. Knock sensors don't turn on the check engine light, even though they set a code. You need to pull codes and see if they are faulty.

[svx_commuter]

Originally Posted by NikFu S.

Salutations.
I have no idea, but is the ping in sync with rpms or no?

It is a random sound. I think it is the knock from a bad flame front.

[svx_commuter]

Originally Posted by Beav

It would be the EGR sticking closed John, not open - if that is indeed the problem. Knock sensors don't turn on the check engine light, even though they set a code. You need to pull codes and see if they are faulty.

The knock sensors are just fine. I installed new ones about 6 months ago. I do not have any engine codes so I am thinking it is something mechanical.

I thought that Exhaust Gas was not recycled at idle/low throttle setting. That is why I thought the EGR was sticking open. The EG was making the engine run too lean. So set me straight on this please.

So if the EGR is closed the engine is running to rich?

Any way. How do I fix this problem?

[Beav]

Primarily the EGR is in place to reduce NOx which occur at high combustion temperatures. A spin-off result is the reduction of detonation. Being that the exhaust gas is normally only about 2% O2 it is inert. This allows the compression to remain high but reduces temperature and slows propagation. If you experience detonation it could be from lack of flow, i.e. the EGR would be closed. An open EGR @ idle normally causes very poor idling or stalling. Typically the engine has to be at normal operating temperature and above idle for it to open. Some cars also need to be in a forward gear.

When the ECU commands the SVX EGR to open it also watches for a temperature increase at the EGR sensor, just above the valve. If it doesn't register increased temp after the valve is commanded open it will set a low/no flow code. However, if the ports are plugged/restricted beyond the sensor it wouldn't necessarily detect that issue.

As Harvey stated, it is more normal for pinging to become more pronounced with heavier throttle. Some pinging at light throttle with increased engine load (hills, etc.) can occur but will always increase with additional throttle, at least until the transmission shifts down a gear or two and reduces load. Overheating, poor gas, incorrect timing, wrong spark plugs, carbon build-up, etc. can all contribute or cause the situation.

[vg30dett1990]

My car does the same thing i cant figure it out

[svx_commuter]

My SVX does this at a very light throttle opening. When I get the pinging I only have to increase the throttle and the ping goes away and after the engine rpm’s go up it does not ping at all. Well it didn’t last year. This year I think it is getting worse as it seems to be happening at slightly higher engine revs but still goes away when the rev increase enough. It definitely does this only when the engine is hot. When the engine is cold it does not do it.

So what makes the engine combustion chamber run too hot at low speeds? The A/F is too lean?

I don’t have any engine codes so the ECU thinks the EGR is working fine.

I am thinking it is not because of dirty EGR passages since the manifold pressure is pulled down real low at light throttle openings. What do you think?

[immortal_suby]

The thing that makes me leary of the EGR system is that on 3 separate svx motors I have pulled the intake from the EGR pipes have been all but completely plugged with mung. I can't imagine much of anything flows through them well.

On the other hand I haven't ever heard any pinging.

[mbtoloczko]

From what I've been reading, the low throttle pinging that you are describing is a lack of exhaust gas recirc. Here are a couple good articles:

http://www.asashop.org/autoinc/nov97/gas.htm

http://www.fordscorpio.co.uk/egr.htm