Hey guys, I just bought this 1997 SC300 a couple of weeks ago, then yesterday, a check engine light appeared. Failed smog horribly, gross polluter. The check engine light came on a day after I did smog. Then I got the codes retrieved today as shown:

P0300 Random Misfire Detected

P0303 Misfire Detected, Cylinder 3

P0304 Misfire Detected, Cylinder 4

P0171 System Too Lean (Fuel Trim)

Has anyone had these codes shown all at once? And does anyone have any answers on what should be replaced on my car? Smog showed 3 to 4 times the max allowable measure, and its 10 BTDC.

If anyone has any input, go ahead and reply, would love to hear ANY answers!! Thanks!!!

 

MOVED TO PROPER SECTION.

Wow all that on a 97?? When was the last time your spark plugs were changed out? How are you cap and rotor? Are the wires a little old? Timing should be at 10 degrees.

 

Thanks JspecSC3 for moving the thread in the right area, LOL sorry!! The person I bought it from said all that has already been changed, but I think I should change them anyways... So good, my timing is good, I guess i'll check the wires, and cap and rotor, any other ideas possibly? And im trying to search, but is there a write up for tune up for the sc300's out there?...

Thanks.

 

What I thought it may be is the o2 sensors, but those codes would pop up wouldn't they? Maybe spark plugs? Spark plug wires?

 

Anyone with any input at all?...

 

today i just deleted the codes, just to see if the same ones appear again, which most likely will happen, how long does it usually take for the CEL to pop up again?...

 

Are you using premium fuel? Because my parents used 89 octane on their 00 gs300 and the check engine light came on. The car was barely drivable. The codes were misfire on 3 cylinders.

 

I had a coil wire go bad recently and it was only 10k old.

 

at the time, i was trying out 89 octane for like 4 gallons only, possibility maybe? when they put premium did the code go away?...

 

sorry but the coil wire your talking about is the spark plug wires right?

 

I used a code reader and cleared the codes first. It actually had 5 codes. I don't remember the exact number but it did say misfire detected twice and misfire in cylinder 2, 3, and 6.

My dad put in a bottle of octane booster and filled it back up with 93 octane. After that it never came back on and drove perfect. This was about 2 weeks ago.

 

hmm... very interesting.. i'll see if that helps..

 

Okay, deleted the codes to see if they pop up again, put fresh chevron 91 octane, light hasn't came back on for about 150 miles so far, anyone with any input?...

 

Since you have a p0300 code, something is likely affecting all the cyls despite having 303 and 304 as well. Things like fuel, bad sensor readings, timing, spark (possible plugs but don't forget the coil, dist, ect).

A p0171 code, 99 times out of a hundred indicates a bad mass air flow sensor. Pull it out and see how much crap is on it. If it's a hot wire maf you could attempt to clean it. I have seen bad gas (water in the tank) cause misfire and too lean codes at the same time.

A vacuum leak will also cause a too lean code and could cause misfire codes if it's a bad enough leak.

KC

 

mines is a 97 2jz maf, i've heard mixed responses on cleaning this on a 97, should i just leave it alone if i dont see any dirt or whatnot, but if there is dirt or anything on there, is there a safe way to clean it on the 97 maf's?..