1999 Avalon Random misfire Random Cylinder Misfire P300,P301, P305

[edge10]

1999 Toyota Avalon (Cali emissions) with 35 K miles Idle quality is off, but power is way down when driving and exhaust smells rich.

I swapped the coils and same DTCs came up. Freeze frame data shows higher short and long fuel trims on bank 1 (rear) and O2 (AF) sensor incomplete. What should I continue to check ? Is Bank 1 AF sensor going bad, even there is no DTC ? This sensor was replace with Denso (OEM) in 2008 with less than 10 K miles on it.

 

[Trav]

You may have sticking injectors. The 99 with CA emissions use the plastic body Denso injectors used on the 2000+ federal models, with only 35K on it they may be sticking due to the filters inside coming apart. Just one possibility but I see it often.

 

[edge10]

That could be why the fuel trims are up on bank 1. It happened after the car sat for several weeks.

Is cleaning worth a try ? Though,Looks like a popular replacement part on rock auto (Standard Motor) .

I'll check the A/F sensor and maybe an injector cleaner, since it is a pricey fix to replace them . Any brand injector you recommend?

 

[Oliveoil2]

Sounds like bad gas. How old is the gas? A 99 with 35k?

 

[SC Maintenance]

Is 1 and 5 on the same bank?

It won't throw a lean code until either 20 or 25% - I can't remember which. Your at 19.5% so you may just have not gotten a code yet.

I agree that sticking injectors could be a thing. You could try a double dose of techron and fresh gas. It won't fix it, if the injectors are sticking, however it might free them enough to make the LTFT a little better, in which case you will know what your problem is.

Can those injectors be rebuilt?

 

[edge10]

The gas was about 6 weeks old. I filled up, did a short trip - 7 miles and parked it with the battery tender for 6 weeks. Yes, it has 35K.

 

[edge10]

Yes. 1 and 5 are on the same bank. Not sure if the injectors can be rebuilt.

 

[Marcozi]

Yes. 1 and 5 are on the same bank. Not sure if the injectors can be rebuilt.

Contact this company. It's very highly rated.

https://www.rcfuelinjection.com/

 

[SatinSilver]

Trav, above cleans and services injectors. I'd send them to him.

 

[zzyzzx]

5S-FE engine?

 

[BC1]

I would suspect the O2/AF sensor based on the info presented. 30% lean on that bank, smells rich and 17 year old sensor. Can you get real time data?

 

[Lawnman23]

5S-FE engine?

1MZ-FE

 

[edge10]

I would suspect the O2/AF sensor based on the info presented. 30% lean on that bank, smells rich and 17 year old sensor. Can you get real time data?

Not with this reader. Any recommendations for a reader that has real time monitor ?

 

[SC Maintenance]

Not with this reader. Any recommendations for a reader that has real time monitor ?

Torque Pro if you have an android. You need a generic dongle and the $8 app. You can spend a lot more, but this setup has worked for me so far.

 

[BC1]

I use a cheap $50 topdon topscan run off an old tablet. It has bidirectional controls also. Only downside is the $50 annual fee.

 

[SC Maintenance]

I use a cheap $50 topdon topscan run off an old tablet. It has bidirectional controls also. Only downside is the $50 annual fee.

Does it do all modules - ie trans, ABS, etc?

 

[BC1]

It shows wheel speeds, reads codes and runs the ABS valves. I drive old junk so not sure about transmissions.

 

[iCurious]

There is a large vacuum leak on bank 1.

 

[michaelluscher]

Check the injectors against this TSB
https://charm.li/Toyota/1999/Avalon XLS V6-3.0L (1MZ-FE)/Repair and Diagnosis/Technical Service Bulletins/Customer Interest/Powertrain - Rough Idle/Single Cylinder Misfire/

Trav did me right with my 2AZ injectors in my xB

 

[Skid]

I would start with the VVT solenoid for bank 1. You can get misfire codes when a solenoid starts getting lazy without getting the specific codes for the VVT, then when it gets bad enough, you'll see like P1130 and P1349.