Guys, I wanted to post this here because I figured I could use some smart guys opinions. Here is the deal...

On the way home from Houston the other day I was just driving along, EGT's at about 1350 or so, everything good, then all of a sudden my car felt like it lost half of its power. I noticed my EGT's dropped to about 900, my exhaust got louder and sounded like a honda. I drove it for a while and it still accelerated just really slowly and it was like driving a honda. I checked my A/F gauge while this was going on and it seemed fine, it was cycling like normal. So after a few minutes it stopped, it felt like my car "kicked" back on, EGT's returned to normal and everything felt fine. It did it twice on the way home.

So I get home and just let my car sit overnight. Last night I hook up the datalogger and pull the codes. I have the usual... Map, Coil A, Coil B, EGR, but I also had P0300 Multiple random misfires. In my datalogger software there is an upper box of codes and a lower box. The lower box had the codes Rich, Misfire Cylinder 2, Misfire Cylinder 3, and the same P0300 Multiple Misfires.

I was just wondering what happens when the ECU sees multiple misfires, also what do you think is going on? I am confused. I drove it to work today and it seemed fine. Any suggestions?

Brynden

how old are your plugs, how old are those wires and did you check to make sure the wires didn't pop off. also check your injector wires to make sure they are all on tight... then once all is done pull the neg off the batt. and let it sit for ten min and then hook it back up and run the dataloger

2006 WW IX MR
2003 BBY EVO VIII (sold)
256.9WHP & 277.9torque
http://s90395832.onlinehome.us/forum//index.php?sid=a70942a7f65043e6c873e12dcd300692

1998 Eclipse RS --show car--

I've had similar symptoms when my car ran overly rich as well.

My car's done the same when I first tuned her, or sometimes really early in a cold Illinois morning, when the temps from my intake or coolant temperature sensor hasn't yet warmed up, hence preventing my car from going into closed loop. Then, if I briefly go into boost, kicking in my secondary injectors, this can cause the car to run very rich and even misfire (or stall), which cause similar symptoms that you described above.

That's obviously what it sounds like to me. The misfire sounds are probably occurring because your spark plugs were becoming overwhelmed and couldn't fire enough to keep up with all of the gas your injectors were supplying.

You might want to take your car to a wideband and get her tuned, according to a/f ratio. You may also have an issue with a failing temperature sensor, or maybe a bad O2, even though your codes haven't shown that. However, I've had O2 sensors that have failed without a code being indicated. Perhaps one of your sensors (As listed above) just briefly failed, or you just need some more tuning?

_____________________________________
Jason ESi-T

04' BMW 325Ci
91' Nissan 240SX
98' Eagle Talon ESi (sold)

I agree with these guys, sounds very much like it could be an extreme rich problem, I've have similar when playing with fuel and the cams.

The other possibility I see would be the ECU dropping into safe mode, but I doubt this because usually it doesn't just come out of this without turning the car off.



15.9 @ 86.7mph
97 Eclipse RS

Injen CAI, 55mm TB, P&P Intake, Crower Stage 2 Cams, Hooker Header, GS-T Muffler, AFX UDP, Crane Ign Amp, S-AFC

Brynden,

What's you AFC settings at Low Throttle? Also, check the plugs. They may be fouled up enough from before that they are giving up on you now. From what I've seen of your hi throttle afc settings they looked to be ok with your setup.

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft

In addition to all the comments in the previous posts, I'd like to add that multiple cylinder misfires could also caused from a bad coil pack or fouled plugs. When I checked my coil pack, the resistance was just above spec. Also, if your timing is off, for instance, from too much timing retard, will cause the misfiring. Yet another thing is if the MAP is "seeing" boost. That will sometimes cause the misfiring. Most of these I've personally experienced, especially when I got rid of Missing Link. I still don't have the ML, but I have reinstalled HRC's FCD and that misfiring has ceased (so far).

___________
Kon C

"Sometimes, a man has to do what a man has to do."