My Grand Marquis runs on 91 RON/87 AKI, with the recommended dose of MMO at each fill up. My average fill up is 65 liters/16.3 gallons, and I add a 200 ml (just under half a pint) of MMO each time.
Ever so often, I would hear that rattling/marbles in a can noise (detonation) coming from the engine under partial load. I’m not sure why, but if I mix TC-W3 with the MMO, or just use TC-W3, the detonation becomes much more frequent, even under light load. Anyhow, I am either extremely light on the throttle or would depress it a bit further to avoid detonation. Switching to 95 RON/91 AKI would make a slight bit of a difference, but not much. Using 98 RON/94 AKI would eliminate the detonation completely.
My driving is extremely easy on the car; pick ups are rather nice and gentle and I barely exceed 100 km/h (63 MPH) with cruise control on most of the time. Every so often I would get up to 120-140 km/h (75-88 MPH), but very briefly before I drop speed. Then again, I average about 12-12.5 L/100 km with my 3.08 axle ratio.
When I was merging on a highway this afternoon, I floored the gas all the way to pick up speed, something I haven’t done for a long while. Looking in the rearview mirror, I could see HUGE clouds of brownish-black smoke. I floored it a couple of times, and the smoke was still there. So when I got home, I went somewhere isolated to rev the engine a bit.
If I constantly keep my foot on the gas, there is no smoke. But if I suddenly tap the gas ¾ of the way, release it and keep doing it, there’s huge clouds of brownish-black smoke coming out. I could see loads of it coming from the left tailpipe looking out the open door, although it seemed a bit more on the right from what I have seen in the mirror.
I did this for a good 3 minutes, and although a bit less, the smoke was still there. So I believe the combustion chambers are literally caked in carbon deposits, which I find a bit surprising, because MMO is supposed to soak up and break loose carbon deposits. The exhaust is considerably cleaner than it was when I bought the car though, so the MMO must be doing something.
Anyhow, it’s kind of worrying that there’s so much of this built up inside the engine. I don’t want to keep driving it like I stole it either, but is there anything else that might cause this other than my grandpa driving style? Thanks!
Ever so often, I would hear that rattling/marbles in a can noise (detonation) coming from the engine under partial load. I’m not sure why, but if I mix TC-W3 with the MMO, or just use TC-W3, the detonation becomes much more frequent, even under light load. Anyhow, I am either extremely light on the throttle or would depress it a bit further to avoid detonation. Switching to 95 RON/91 AKI would make a slight bit of a difference, but not much. Using 98 RON/94 AKI would eliminate the detonation completely.
My driving is extremely easy on the car; pick ups are rather nice and gentle and I barely exceed 100 km/h (63 MPH) with cruise control on most of the time. Every so often I would get up to 120-140 km/h (75-88 MPH), but very briefly before I drop speed. Then again, I average about 12-12.5 L/100 km with my 3.08 axle ratio.
When I was merging on a highway this afternoon, I floored the gas all the way to pick up speed, something I haven’t done for a long while. Looking in the rearview mirror, I could see HUGE clouds of brownish-black smoke. I floored it a couple of times, and the smoke was still there. So when I got home, I went somewhere isolated to rev the engine a bit.
If I constantly keep my foot on the gas, there is no smoke. But if I suddenly tap the gas ¾ of the way, release it and keep doing it, there’s huge clouds of brownish-black smoke coming out. I could see loads of it coming from the left tailpipe looking out the open door, although it seemed a bit more on the right from what I have seen in the mirror.
I did this for a good 3 minutes, and although a bit less, the smoke was still there. So I believe the combustion chambers are literally caked in carbon deposits, which I find a bit surprising, because MMO is supposed to soak up and break loose carbon deposits. The exhaust is considerably cleaner than it was when I bought the car though, so the MMO must be doing something.
Anyhow, it’s kind of worrying that there’s so much of this built up inside the engine. I don’t want to keep driving it like I stole it either, but is there anything else that might cause this other than my grandpa driving style? Thanks!
