Originally Posted By: Spykem4e
Alright, since I work on the road all day with my car, I have lenty of km's and time for testing it. Yesterday, I let the gas tank at almost empty. I fuel it with Shell-V power 91 octane + AC Delco fuel system cleaner. I let the car sits overnight.
Started the car this morning: it runs great. Give it some throttle, respond very good.
No more small shudder during a stop light.
But I could hear the pinging under very light throttle between 25 km/h and 50 km/h. (approx 20-30mph). The difference this time is that the pinging is not very loud at all. You have to mute the radio to hear it versus without the premium gas that you can hear it with the radio "on" at normal volume.
I disable the air conditioning and the vent and the pinging was gone at same throttle.
I can hear the car pings only since I switched to PP, thats strange. Maybe its just the timing switching from M1 to PP but who knows...
My car calls for 87 octane, does putting 91 will have any bad effects on my engine?
Could it be a timing chain issue that is maybe stretched? Would it be throwing a check engine light? I'm trying to figue out the car since I'm almost living in it.
OK, now were are getting even deeper. Some may not beleive this, but I can assure you it is true that if you run premium fuel (like you are with the 91) in a car that calls for 87 you will create deposits of carbon in your engine. This may be far off - but if you've got carbon and you first start the car - the fuel will soak into the carbon instead of being burned and that would create a lean condition = rough engine. Then when the fuel is fullu soaked in the carbon and the engine gets it's fuel = smooth engine. The fact that you have knocking/pinging points me to this theory. I've seen this on a GM pickup once. We cleaned the injectors on the rail (not the in the tank stuff) with BWD fuel and intake cleaner and immediately afterwards the engine was running lean for a good 5 miles until the computer relearned the fuel trims! He had that much carbon in the engine! He told me he ran nothing but 93 in his truck - a 4.8L that called for just 87. True - could it could have been cheap gas and not the octane that caused his particular issues - but still running 91+ gas when not called for is a waste and the car is not programmed to run on it.
What now? I'd seafoam the heck out it! That would clean off the carbon and go from there! (I'm referring to the dumping of Seafoam into the intake via a vacuum line or thru the intake throttle body itself w/engine running. Do a YouTube search and you'll see how it's done.
Well -it's another cheap try. Wish I was nearby and could come to see you personally - we could hammer that problem done!
Alright, since I work on the road all day with my car, I have lenty of km's and time for testing it. Yesterday, I let the gas tank at almost empty. I fuel it with Shell-V power 91 octane + AC Delco fuel system cleaner. I let the car sits overnight.
Started the car this morning: it runs great. Give it some throttle, respond very good.
No more small shudder during a stop light.
But I could hear the pinging under very light throttle between 25 km/h and 50 km/h. (approx 20-30mph). The difference this time is that the pinging is not very loud at all. You have to mute the radio to hear it versus without the premium gas that you can hear it with the radio "on" at normal volume.
I disable the air conditioning and the vent and the pinging was gone at same throttle.
I can hear the car pings only since I switched to PP, thats strange. Maybe its just the timing switching from M1 to PP but who knows...
My car calls for 87 octane, does putting 91 will have any bad effects on my engine?
Could it be a timing chain issue that is maybe stretched? Would it be throwing a check engine light? I'm trying to figue out the car since I'm almost living in it.
OK, now were are getting even deeper. Some may not beleive this, but I can assure you it is true that if you run premium fuel (like you are with the 91) in a car that calls for 87 you will create deposits of carbon in your engine. This may be far off - but if you've got carbon and you first start the car - the fuel will soak into the carbon instead of being burned and that would create a lean condition = rough engine. Then when the fuel is fullu soaked in the carbon and the engine gets it's fuel = smooth engine. The fact that you have knocking/pinging points me to this theory. I've seen this on a GM pickup once. We cleaned the injectors on the rail (not the in the tank stuff) with BWD fuel and intake cleaner and immediately afterwards the engine was running lean for a good 5 miles until the computer relearned the fuel trims! He had that much carbon in the engine! He told me he ran nothing but 93 in his truck - a 4.8L that called for just 87. True - could it could have been cheap gas and not the octane that caused his particular issues - but still running 91+ gas when not called for is a waste and the car is not programmed to run on it.
What now? I'd seafoam the heck out it! That would clean off the carbon and go from there! (I'm referring to the dumping of Seafoam into the intake via a vacuum line or thru the intake throttle body itself w/engine running. Do a YouTube search and you'll see how it's done.
Well -it's another cheap try. Wish I was nearby and could come to see you personally - we could hammer that problem done!
