I put in my timing adj last night in my '02 GT; set it at 13 degrees and took it for a spin, felt nice and luckily the car didn't surge and jump like 've been told some of the '99 and newer cars do when the timing gets advanced.. When i got back in the car later to drive it, the Service Engine Soon light came on about a 1/4 mile down the road? There seems to be no change to the way the engine is running. Is this a "red-herring"? I'm running 93 octane and didn't hear any pinging (plus it was really cool here yesterday)... Does my 4.6 have a knock sensor that will trigger a code or am I burning too lean and the O2 sensors tripped a code? How do I clear the code and try again?

 

you dont have a nock sensor, go down to your local autozone or pepboys or advanced discount they will read the code to tell you whats going on, then come back here and tell us what it is.

 

Is it flashing, or just on?

Hey Spike, I thought these things had knock sensors. R U sure about that.

The light could have come on for any reason. Let us know what you find, but get that code read.

 

we do not have nock sensors. if i remember correctly that is

 

Seems the garage ran the ses code and got back a "low RPM Misfire" code. He said they had another customer with a similar problem. I guesss with the timing advanced and the cold weather setting in, the plugs have a ahrd time lighting the mixture. His recomendation, if I wanted to keep my timing at 13, was to run a lower grade octane when it was cold outside. or I could pull the timing back a degree...... Does this make sense to anyone? I couldn't feel a misfire at idle but he said it probably wouldn't be noticeable..... I would think the coil packs would provide a plenty hot spark.. ?

 

leave the timing and clear the codes and run around with the tank full of 93 it have just been a fluk.

 

What you were told sounds logical. But, I wonder with the lower grade of fuel if you will get pre-ignition under load.

The higher the octane, the longer the fuel takes to burn. Pre-ignition (or knock or pinging) is when you get ignition before spark. This is not a good thing. Higher octane fuel will resist knock better than low octane fuel.

Things like load, compression, and heat will increase the tendency of pre-ignition and therefore require higher octane. The opposite can also be true.

If you have colder plugs, plus advanced timing and the weather is cold, you might need to either decrease timing OR decrease octane to prevent a miss-fire.

My car has a miss during cold weather with the one step colder plugs. But it quickly goes away when the car wamrs up (in less than a minute).

 

or just might have been a fluke it happens sometimes when the comp is learning whats up.

 

Any update on whether you got it fixed or not?

 

I'm picking it up tonight, I had them take a look at the "first thing in the morning, second gear grind" that the 3650 has gained a reputation with. They cleared the code and I guess I'm just going to leave the timing as it is and keep running 93 octane and see if it happens again. I can live with a undetectable low RPM miss, but I don't want to do head gaskets. If it repeats itself, then I'll just pull the timing back a degree or two (especially during winter since the rain/snow will prevent any aggresive driving) and put it back when the weather warms up. Thanks for all the advice, I'll get the ang of this.

 

I had the same problem when I put mine on. I read the codes and said same thing. It has to do with the harmonic balancer, sometimes if you re-torque the bolts it clears up. That's what I did and it worked for me.

 

Re-torque what bolts? the one big one in the balancer or the 3 holding the sprocket to the hub?

I bumped the timing back to 12.5 and no light yet? could be because I re-torqued the bolts I guess?