Don't know what Fuel Sys is, but ECT=Engine Coolant Temperature, STFT=Short Term Fuel Trim, LTFT = Long Term Fuel Trim, B1=Bank One (near the firewall), B2=Bank 2 (near the radiator)

 

Your ECT temp is pretty low. I would assume it would be upwards of 180, at least.

Ajkalian, you are quick. Beat me to it.

 

re: P0304

What do your spark plug electrodes look like? They should be a light brown color, if the cylinder combustion is normal.

According to the FSM, the P0304 trouble code could eventually cause damage to the emission system ... the catalytic converter or maybe the O2 sensors.

Time for new plugs, wires? Total long term fuel trim listed in FSM ... idling ... only about 1%. ... O2 sensor worn out?

 

Plugs (a couple months old), wires & coils are all new. Plugs look fine too.

http://www.toyotanation.com/forum/1...4th-generation-1992-1996-1997-2001/675553-cylider-numbering-id.html#post6333137

Car wasn't totally warmed up yet when it threw the code.

The miss is intermittent, comes & goes.

So the FSM lists all these parameters somewhere? Where should I be looking?

I'm trying to get this thing figured out before I do wreck the cat...

Thanks guys,

 

Congrats on the scanner. The P0304 code, is the freeze frame info always the same?
That is only during startup and openloop engine operation. You may have to reset the code stored in history to get another reading. If you can determine this it will help your trouble shooting.

 

Fuel Sys 1 OL
Your fuel system is in Open Loop, meaning the engine is not in fuel control.
Fuels Sys 2 OL
This is the same as Fuel Sys 1 except it is for Bank 2 being in Open Loop.

Calc Load 67.5%
Calculated Load - you were accelerating. This is determined by the amount of air passing through the Mass Air Flow Sensor.

ECT (F*) 152.6
Engine temp. Your freeze frame data doesn't show how long the engine has been running this trip. I'd like to see 180F to 220F You might have a bad thermostat if the engine was running more than 30 minutes. This has nothing to do with your P0304.

STFT B1 0%
LTFT B1 10.2%
STFT B2 0%
LTFT B2 7.8%

These are your Short Term and Long Term fuel trims. This is how much fuel the computer is adding or subtracting. I like to see STFT go from positive to negative rather than staying positive. Anything more than 10% when you total STFT and LTFT for each back means the engine is running lean (not enough fuel or too much air) You don't have a lean code yet because it has to get to about 20% before it pops the MIL. Long Term Fuel Trim is calculated over time depending on what the STFT is.

You said you have new coils and plugs. What brand parts did you use?

 

You will have to get the 2 day subscription ... download the factory service manual. A small fee is required for the subscription. l ...Lots of other useful information.in the FSM:
http://www.techinfo.toyota.com/

... Go to the Gen 3 V6 Mechanical section ...The diagnostic section starts at about page 400.

... fuel trim readings seem to be subject to interpretation ... previous page it says fuel trim is ok if within +/- 20%

P. 434 ... V6 Mechanical Section ... gives fuel trim recommended parameters.

... As I recall, there was a recommendation posted here recently ... that said to go ahead and replace the O2 sensors after 100,000 miles. ... Maybe it would be useful to monitor the fuel trim performance on both banks for a while ... idling ... driving. If there is significant variation, that could indicate a problem.

 

Wow that's all good info!

I use NAPA, they give me a discount. They were the upper end Eichlin brand and NGK plugs.

If I have the Toyota FSM do I still need that subscription?

The second time it set a code the freeze frame fuel trim was different. I forgot and reset before I wrote it down but I remember seeing - numbers. Checked connections, pinched wires etc and drove it again and it did fine but that's been its MO...

I even swapped the plug and coil from 4 with 6 to make sure I didn't get a bad new one.

 

No ... if you have the FSM for your engine/model/year ... you don't need anything else.
There is a Haynes Manual ... but I believe the Toyota FSM is the one that has more useful information.

 

No ... if you have the FSM for your engine/model/year ... you don't need anything else.
There is a Haynes Manual ... but I believe the Toyota FSM is the one that has more useful information.

What mean FSM ??

 

I lied. It does save the last freeze frame:

Fuel Sys 1 CL (so I guess that's Closed Loop? What's the difference?)
Fuel Sys 2 CL
Calc Load 60.8%
ECT (F*) 134.6
STFT B1 -0.8%
LTFT B1 10.2%
STFT B2 17.2%
LTFT B2 7.8%
Eng RPM 2039
Plus this when I scrolled down, didn't see that before:
mph 29
IAT (F*) 30.2 (Intake Air Temp?)

Guess I should go ahead and replace the 02 sensor as a maintenance item anyway.

 

Ref second time code was stored, was the engine in open loop? If so and you keep getting P0304 with having swapped plug/coil, you could try swapping injector.

 

ok, so you get code P0304 whether the engine is in open or closed loop. This can now be taken into account. Open loop the O2 sensores are not being utilized. Closed loop O2 sensors feed emission control info back to ECU. Since you have the scanner see if you can use it to pinpoint the problem before changing out more parts. This is of course easier said then done. There is a lot of info out there, its a learning curve. I'm sure someone with particular info on this engine could tell you which part or parts to change but then you wouldn't learn how to use your scanner Good luck.

By the way, the experts advise is to do an engine compression check first so that you don't end up changing at lot of parts to not avail. A 1996 engine could have internal problems causing misfires.