bleSId

when I bring the RPMs up quickly, my engine makes sounds like its going to stall but never does....anybody got any ideas?

this usaully happens when im passing or revving up the engine
although the sound isn't particular to any rev range,

my civic Si did the same thing and later that week the clutch and driveshaft decided to leave the vehicle at 70ish miles per hour, so somebody must understand my concern

rooney2006

mine does that when it first starts up, but i just thought it was because the transmission was cold.

bleSId

thats what i thought but, it does it even when im driving at any speed.

it sounds like a gear slipping on its teeth which is what scares me

shdoug

I'm lost. How does a grinding gear sound like it's going to stall? And how does an engine sound like a grinding gear? It's probably not major, but can you describe it in more words?

bleSId

forget the grinding gear thing, i listened to it whel my dad sat in the driver's seat. if you remember in the movies when cars ran out of gas there was a knocking sound.......thats what it sounds like when you press on the gas

shdoug

That's called "pinging" or "spark knock". Also sometimes called detonation, it is usally caused by a small protion of the fuel igniting prematurely before the piston reaches top dead center. The usual causes are over-advanced ignition timing, low octane fuel, overheating, carbon build-up in the combustion chamber (a techron treatment should help this) or sometimes a lean fuel mixture. Are you using premium unleaded fuel with no ethanol? The octane rating should be 91 or 92. Any higher than that may indicate ethanol or methanol being added but I think that has to do with the part of the country where you live. Also, many gas stations in cold climates add alcohol to their fuel in the winter. If the problem goes away in the summer this could be the cause. Try switching brands. BP is usually a great brand with good consistency. Try the BP ultimate for a couple of tankfuls and see what happens. Ignition timing is not adjustable on my M104 engine. I'm not sure about yours.

bleSId

To address the premature ignition problem, is there any way this can be fixed without burning up my wallet?

The problem with testing if it is the changing climate(winter vs. summer), If it is going to do what my Civic did, the results are going to be catastrophic!!!! the Civic's repairs ran about $2000, for the clutch and the havoc the clutch reeked while I was trying to stop.

As far as the fuel thing goes I take it to BP almost all the time. When Im in town I get gas from the guys that work on my 4E, they say its specially made and I really have no reason to not believe them.

I don't want to risk losing my car, if I have to I'll drive the Civic in the meantime but, I can't stand it when my cars just sit there

mgw_300e

I run 93 octane gas with ethanol (15%?) and I've never had any detonation or any other problems.

shdoug

The fact that your octane is so high should compensate for the lower flash point of the ethanol. That fuel is not available at most places around here. I only know of 1 station in Omaha putting ethanol in premium fuel, even in the corn state if you can believe it!

Also, I'm concerned about the higher combustion temp of ethanol doing something bad to the valves. As you know, I don't have an owner's manual so I have no idea what MB recommends. My BMW manual specifically says no ethanol is to be used.

Just a thought as to what could be causing that problem.

mgw_300e

93 octane must burn cool enough that even with ethanol it doesn't burn too hot.
I'd bet that cheap gas + ethanol = hot engine.