Need some ideas from the guru’s in here. I have a rattle from my engine. I think it is pinging.
It happens on regular unleaded, it doesn’t happen on premium.
It happens under load.
Car is m100 sirion, 3cyl.
I run it on premium mostly. recently had engine mounts and cracked alternator brackets replaced, thought the rattle might have been one of those things so I switched to regular unleaded. It started to ping right away.
I bought some octane boost/injector cleaner and the ping stopped almost as soon as the fuel in the tank made its way to the engine.
My parents bought the car new. It mostly did short runs with long periods sitting around. I thought the injectors might have some deposits clogging the spray pattern. I have run a lot of injector cleaner through over a period of time with little change.
I have read a while ago sometimes carbon buildup can increase compression if its bad enough. The exhaust disintegrated a while ago, i don’t know how long it had been slowly failing for but i heard many years ago that the increased backpressure can eliminate the factory scavenging and lead to carbon buildup.
Just after some thoughts on things i can try. I’d rather not go to the length of opening up the engine as I don’t have the time these days. If needs be i’ll just keep filling it with premium.
How long since the fuel filter was replaced? It could be clogged enough to do this. Also injector cleaners only have limited results if the injectors have crap in them, might pay to have them professionally cleaned. Only other thing i can think of apart from said carbon buildup is maybe timing belt has stretched a fraction?
Yes, would be good if you can verify it has adequate fuel pressure. I’ve had lean out due to blocked the in tank filter screen, but was so bad the car also stalled under hard acceleration.
I had initially discounted fuel supply issues as it doesn’t have an issue with premium. I thought it would do it with premium as well if it wasn’t getting enough fuel.
I’m not sure when the fuel filter was last replaced, It’s due for a oil change so I’ll check on replacing the fuel filter too.
I’m taking it for a couple of long runs this week, maybe that will clean some things out.
Thanks for taking the time to reply.
Do you have a key hole usb camera? Look down a plug hole to check that carbon possiblity. Have you checked oil blow by? If there is a lot of oil coming out of the crankcase and ending up in the manifold that can mix wit fuel and reduce octane levels. Keen to hear it you figure it out.
Ignition timing, well no not really. Cam timing well you can with mod’s to the timing gear or with a vernier cam wheel. Mine is retarded with a vernier gear about eight deg which shifts the power/torque a bit higher. I have other mods that had further increased the low down torque but not much was happening higher up. The retarding moved the curve up the rev range and it was a taller curve anyway.
stay away from anything with ethanol in it