Celica Forums General Discussion Engine and Performance burbling noise from engine area that happens on acceleration

Hey wondering if anyone could point me in the right direction here. I'm getting this weird pulsating or burbling noise whenever I accelerate (goes away when foot is off accelerator). It's intensity changes with revs. Sound definitely is coming from front end. I'm backfiring a little bit soemtimes also out the rear end. Could it be a misfire and gases igniting in the exhaust system? I changed my spark plugs with new densos the other day and while I was doing that I noticed 2 out of the 4 ignition coils were browned whereas the other two were pure black. Could they be bad? I have no CEL or anything.. I did pull the wires from each plug while car was idling and each time it did sound like the car wanted to stall but maybe they are failing only on higher loads?

I know it's not an exhaust leak as I've had it in to the garage to check already.

Which Celica, which year, how many thousands miles?

Did you do any recent maintenance or repairs?

Are there any check engine codes?

Are there traces of oil in coolant reservoir or coolant in oil which could indicate leaks in head gasket or cracks in engine?

What are cylinders' compression?

These are my guess: The 2 black plugs mean oil is burned in the cylinders. The oil could cause ignition problems and misfirings, making burbling noise.

Oil in the cylinder could come from a number of causes but most likely due to worn or stuck oil ring on piston.

Try the cheapest fix first, clean and unstuck oil ring by cleaning the engine valves, pistons and cylinders, and get rid of any oil sludge, by adding 1 Q Motor Medic GUNK into engine oil, idle engine 5 minutes, put in new oil and filter. Clean again after 1,000 miles to see if compression improves and engine smoother.