reedsrx300

OK, so I told my Daughter that this 99 RX300 was a great buy. Brief history in case it helps. It was a long time owner, well maintained etc.125,000mi drove great when we bought it.. Started running bad not long after(500 miles +-). This may not matter but... I found mice EVERYWHERE. Air cleaner completely clogged, cabin filter full of mice. Cleaned everything, new PCV.,Used carb cleaner on throttle body and IAC. Cleaned MAF and all AF sensors. I used carb cledaner and looked closely for vacuume leaks, chewed wires etc but didn't find any. Also searched threads after I registered but didn't find much.
Initially the car idles good after codes are cleared, but starts missing as soon as I put it in gear. Got it down to 3 codes misc. misfire 0300, 0302, 0303 (misfire #2 and #3). Switched the coils between 2 and 4 but cylinder misfires stayed on same cylinders. Both plugs were clean white and no different between 2 cylinders. I think it's gotta be fuel. But Fuel filters don't seem to cause this problem on this car, and 2 main cylinder misfires are on different fuel rails. I let the gas run down and dumped extra fuel injector cleaner in and ran 100 miles. not much change. problem starts as soon as i put it in Gear. Best advice is start replacing injectors, but the cost!$$$ I want to be sure that is the issue. I can replace the #2 injector to see if it eliminates the code for that misfire, but it just seems like I'm missing something. Been working on it all day to save face (and$$$). Any Ideas?

Z07

I would start with the fuel filter. Then measure fuel pressure. Then I would send the injectors off for service before I bought new ones. Jon at Fuel Injector Connection is a great resource.

salimshah

Welcome to CL.

Have you checked the vacuum with a gauge? Sorry I dont know what the gauge should show.

Also trace the wires to the injector.

There are few things yu can do, but it might be worth the money to take it to dealership.

Salim

Bobster999

Most likely you will find an Ignition disruption somewhere in the system. If not a coil pack, its probably somewhere in the wiring or possibly even in one of the spark plugs.

reedsrx300

Thanks for the help! I will check on the Fuel filter today, The PCV valve was really bad and I did see gunk in the Vacuum lines. Where would be a good place to check the vacuum. I checked for Vacuum leaks, but didn't look to see if the lines were clogged. Had a nightmare experience with sludge in an otherwise beautiful Toyota Avalon and home there is no serious problem here.
I looked for electrical issues again last night (in the dark) but couldn't find any shorts.
Also, I initially discounted the OCV valves because the misfires were on opposite sides, but could they both be acting up?
I'll let you know what I find.

Z07

Checking in the dark is good. You can also mist water over the area too. If the car runs at idle fine then acts up under load then returns to normal with the load removed I would move ignition down on my list of suspects. Does it rev freely in park?

reedsrx300

Yes, and it Idles pretty well until I put in Drive or reverse. I even backed it up to a tree and looked for shorts with it in reverse, found nothing. Also Just got a fuel pressure gauge and pressure is fine at Idle(at banjo fitting on fuel rail after presure regulater). This is driving me crazy! Do I need to check fuel pressure when it is in gear? Or is the problem somewhere else. Also, Fuel pressure test says to disconnect the #2 Vacuum line. Don't know which it is, but will that affect the accuracy of the reading? (around 45-47 psi). I can't believe I have multiple injectors going out at once, also that doesn't account for the misc misfire 0300 which I think means other cylinders are misfiring also
Other Ideas?.

reedsrx300

Thought I'd re post my problem with more details. Recap; Car recently purchased. Ran great appeared well maintained, just not driven much. Week or 2 after purchase it started running rough not sure if it happened suddenly or over short period. Found mice and big nest in air cleaner (and cabin filter) Completely clogged thought I had found the problem. Not so. Idles fine revs fine, but starts missing as soon as I put it in gear. Cleaned MAF, Iac(think thats what its called-on throttle body), cleaned AFsensors, new PCV. Sprayed carb cleaner around vac lines and can't find a leak. Still shows codes for misfire on #2, #3, and misc (0300). I have also looked for shorts or sparks at night. nothing. Got fuel pressure gauge this morning and pressure is fine(47-49psi), both in park and when in gear. I also switched coils on #2 with #4 and codes didn't change, still included 0300 also. Both plugs looked the same nice and dry-normal.
So I'm thinking about the mice again. I haven't found any visible damage in engine compartment but it's hard to see behind intake and back side. I'm going to try to look for shorts and vacuum leaks with car in drive (going to be a little tricky by myself). What changes when a car is put in gear?

Z07

That vacuum line is for the fuel pressure regulator. disconnecting it simulates no vacuum in the intake like in wide open throttle when fuel pressure should be highest.

Note: a dirty fuel filter won't reduce pressure but rather flow until it is really dirty.

Bobster999

I still don't think it will be fuel related. Most likely either somewhere in the ignition system, or even a grounding problem possibly in the ignition system. Even a worn spark plug can cause those symptoms. Unfortunately, troubleshooting drivability issues are time consuming even for professional techs with the knowledge and tools.

sktn77a

iTrader: (2)

Did you clear the codes after you switched the coils over? Which code reader are you using?

reedsrx300

Yes I cleared them and the same three came back up the cylinder didn't change so I assume the coil isn't the issue. I also replaced the front bank spark plugs to see if it would eliminate the front misfire code for cylinder 2. It didn't show as many misses as the #3 but was still missing, and still got the misc misfire code. I have used both a fancy Solaris reader I borrowed, and the one at Auto Zone.
I also checked fuel pressure, but didn't remove the vacuum line. it was about 48 at Idle and didn't change when I put it in gear.
I want to stress again that it Idles fine before I put it in gear, and it doesn't throw any codes even after Idling and revving the engine, the engine revs fine in park. Im looking for things that adjust in the engine/transmission as soon as you put it in gear. It just seems like that would narrow the problem.

pilot2

You have a lot of patience...sounds like it is time for a professional analysis. :-/

carguy07

This matters! Start taking things apart and inspect every wire you can see.

alpinearea

I am having the exact same problem with my 2000 rx300. It idles fine but starts to misfires with a load on it. Putting it in gear. Did you ever find out what the problem was?