A Whole Lot Of Extra Timing?

[bubba]

Been having some problems with pinging once the car is at normal operating temperatute. Plugged the laptop in the other day and saw some crazy timing numbers.. at about 3500rpm it's hitting 40deg BTDC..

So is it possible for an ecu to shit itself and throw in a bunch of extra timing?

Car is pretty stock engine wise, has an exhaust/pod/boost controller and a stock ecu. Didn't ping when I bought the car but after a few months it started to.

[blind_elk]

From what I've read, 40 on a low load (ie cruise) at 3500 would not be out of the ordinary. 40 at 3500 on boost ... now that's another question.

[Kinks]

You would be surprised how much timing a car will run especially under part throttle cruise.

The only RELEVANT measurement you can make is your base timing at idle. You measure this with a timing gun and the bottom plug disconnected from the throttle position sensor. It should be 15 degrees BTDC.

[bubba]

Yeah base timing is at 15BTDC. I mentioned 40degrees to my mechanic and he was like that's pretty high.. he said take some base timing out of it which will be pretty gay off boost.

I'm moving through trying to eliminate things, so far done the plugs, fuel filter and changed AFM's. Next on my list is fuel pump and CAS aswell as try another ECU.

Cheers guys, keep the ideas coming

Can the timing belt stretch when it get old and result in this sort of pinging? it pings pretty bad if I give it more than say 10% throttle when at normal operating temperature.

Also, a tiny misfire has developed over the last few weeks. Not consistant and not repeatable, just does it randomly and usually at low revs getting on the throttle a bit, doesn't miss under load (happens maybe once a week).

[blind_elk]

Stretching the timing belt will ordinarily only change cam timing. I doubt it would change it so much as to induce pinging.

What plugs did you use? A dying fuel pump could induce pinging by leaning the mixtures out (not capable of delivering enough fuel).

[bubba]

Not sure what plugs, they're just what my mechanic gave me as listed in some book - it was playing up before the plug change though. Fuel pump is on the cards for next payday

So 40BTD isn't anything to be worried about?

[ssshonky]

as some quick form of insurance.. If I were you I would run out and stick BP Ultimate 98 in it ( if you dont already)

either that or stick some octane booster in there.. that should help reduce the pinging a bit.

Pinging can get pretty serious so dont wait too long before you get it fixed!

also .. does it ping more on really hot days?

Make sure your mechanic goes thru the correct Proceedure for setting the base timing

( some engines you need to disconnect the tps .. rev past 3 grand .. etc etc )

Not sure what plugs, they're just what my mechanic gave me as listed in some book - it was playing up before the plug change though. Fuel pump is on the cards for next payday

So 40BTD isn't anything to be worried about?

[ssshonky]

hey bubba your in perth hey? why not take it to a reputable workshop and get em to test it all out ASAP

some motors can survive pinging pretty well .. but not others.

don't want to be up for a rebuild.. give the octane booster a go

[bubba]

Always run it on U98 and I've tried octane booster to no avail Doesn't matter what the ambient temperature is, it just has to be at normal operating temperature for a few minutes and it starts to ping. The thing that really gets me is it didn't do it when I first got the car, it wasn't until a few months later that it started to ping. It has also gotten worse lately. It seems like something is/has deteriorated..

As for the timing.. what exactly is the correct procedure? sitting there at idle it reads 15BTDC on the laptop and with the timing light the mark is on 15BTDC.

I'm not really fussed about a rebuild.. it's only an RB20 which wouldn't get a rebuild.. if it blows then it's time to put an RB25 in or my mates RB30DETT

If I cruise it it's fine, it's only when it comes on boost with maybe 1/4 throttle that it pings, does it at 13psi and at 10psi (no noticeable difference).

I would rather not take it to one of the big workshops as I have a good mechanic that works for mates rates (when he gets time) and he knows RB engines reasonably well (he built the aforementioned RB30DETT). I'm trying to source a Bosch fuel pump so we'll see how that goes.