I have a 90's corolla - silver-top 20 valve 4a-ge auto that pings badly when going up hill in low-ish revs. 200,000k's. I don't think its a bearing as it doesn't have that same distinctive sound, and doesn't have the consistent "clunk" sound. So i think it's maybe detonating, i run 95 octane in it. Would retarding or advancing the dizzy fix this! or would it be better to run an octane booster additive!Thanks for any help humans
ema1,
May 24, 10:59am
Have the ignition timing checked over, possible it could have an EFI/ ECU related problem. Being an EFI set up it will have a diagnostics terminal, haveit's fault codes checked out , that should point you to any likely sensor or other ECU/EFI related problems! Has it had any cambelt history recently at all!
ceebee2,
May 24, 11:02am
Ignition timing needs retarding, but you will need a timing light and someone to use it correctly.
nufix72,
May 24, 11:04am
Try ultimate (BP fuel) or get it tuned. If you into DIY maybe start with new spark plugs, make sure you take them out when engine is cold. Usually a good task for the weekend. From memory you will need a 15mm socket from repco or similar store, has to be a deep 3/8 drive socket. Do not do it yourself if you havent got some mechanical skills.
-roadkill-,
May 24, 11:06am
Thanks. Not too sure on cam belt history. Could the stretch in the belt be enough to change how the ecu system is reacting with the timing!
nufix72,
May 24, 11:08am
Yes it could, and if it has hit the limiter do notdo it again. If the belt snaps you have a large bill to pay or a near worthless car.
-roadkill-,
May 28, 5:55am
Cam belt has been done. will check date again but it seemed alright. I checked the ignition timing today with timing light, 10' btdc. I couldn't find the diagnostic plug to short E1 and TE1. But i gave it a go anyway, and noticed when doing the timing, the crank pully indicator lined up good with cover. However, the mark on the crank moved around slowly as i revved it higher.is this okay!I now using 98 octane as a temporary fix, it reduces the pinging.
m16d,
May 28, 6:31am
Are you sure its pinging, and not a death rattle.!
nufix72,
May 28, 6:39am
If you did not bridge TE1 to E1 it should read about 15 btdc. The marks will move when increasing RPMs this is normal. Look for a small plastic box with diagnostics written on top to get correct ignition timing. It has a diagram inside the lid with TE1,E1 etc. on it.
-roadkill-,
May 28, 6:42am
hahah, pretty sure it aint one of those.
-roadkill-,
May 28, 6:45am
ok, thanks for that. Can please explain to me why/how it would move with increasing revs, then goes back to original place as revs decrease!
r15,
May 28, 6:49am
as the timing advances and retards with vaccuum / ecu assistance.its all good. its meant to :)
intrade,
May 28, 11:26am
you want to remove the sump and check bigend play as when they get play the pinking will get worse and worse untill finally the rod pokes thru the side of the block. once the timing cant retard no more.
snoopy221,
May 28, 11:29am
Kin aye intrade for sure. [While ya got da sump off remove da spark plugs]
Actually i'd be more looking at tired spring weights in ya distributor. or a broken spring. Spark HAS to be advanced to burn petrol at higher RPM's asthe RATE of combustion doesn't increase so spark is advanced for higher rpms.
ema1,
May 29, 7:38am
Hands on diagnoses by a Toyotaor other reputable technician would be a sensible decision as there could be more than one thing here causing what you describe, could be even totally unrelated to some of the answers on here. Let us folks here know what you find as being the cause and remedy action taken to sort it.Mmmmmm before it goes bang preferably.
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