1994 FZJ80 Recent Refresh 240k miles, failed emissions

[Battlshp]

This car was recently moved to CO and I had no way of testing emissions prior to the move. It has one new O2 sensor, other tested fine. As part of the refresh the EGR got overhauled with a new VSV, all vacuum lines were replaced, there are no apparent exhaust leaks. It has new plugs, new air filter, recent distributor cap and wires (Toyota).

From other threads, I sense 40 vs 20 gpm is not a huge miss but I am not certain where to begin.

I have not touched the timing, but I will confirm it is at 3 deg BTDC.

Other thoughts would be appreciated

 

[Capriblue45]

Those numbers are very similar to what my Troopy with a 1FZ tested at. I ran it almost empty put in 7 gallons of E-85 got it good and hot on the way to the test station. Retest CO went from 47 to 2.4 and Nox only increased about a point. You will want to dilute the E-85 as soon as you can to reduce the risk of damage to rubber parts. Good luck.

 

[Battlshp]

Thanks, I was thinking about going this route.

 

[Battlshp]

Ok, I got a bit more clarity. The car went through an initial inspection that failed on the gas cap but passed CO with 10 bpm.

They had her get a new gas cap and after that the gas cap passed but the CO came back at 40 bpm and failed.

I am a bit confused about the gas cap. What is the test? It seemed to seal well here.

She drove from home to the test center so I will have her add some E85 and drive it for a day prior to retesting Friday. She understands that it will need 30 minutes on the highway prior to testing.

Thanks

 

[Battlshp]

Okay, we have yet to establish a relationship with a Denver area Toyota repair shop, so we took the emissions inspection station up on the offer of their diagnostic services.

This is what they came back with. O2 Sensor #1 (outboard) is brand new, Sensor #2 is 7 years/25-30k miles old. I have a spare, so replacing #2 is an easy step logically. The car has an intermittent Code 25 so we will test the wires/connectors as well.

As to the VAF, other than to test the resistance per the FSM and broadly confirm the flow across the RPM range with my Toyobd1 app I I did nothing to clean or disturb it. All I could do with the Cats was verify the exit temps at the back were higher than the front.

I would appreciate any thoughts.

 

[Battlshp]

I spoke with the technician an aside from replacing the other O2 Sensor, his main concern was the VAF was not "returning" or closing after acceleration quickly enough leaving the engine running rich. This in his mind is a spring that needs tweaking.... he recommended two area shops with experience with the VAF: Stang Automotive and the Toy Doctor.

Any thoughts? I thought the VAF was a pretty delicate gizmo.

 

[RayRay27]

I spoke with the technician an aside from replacing the other O2 Sensor, his main concern was the VAF was not "returning" or closing after acceleration quickly enough leaving the engine running rich. This in his mind is a spring that needs tweaking.... he recommended two area shops with experience with the VAF: Stang Automotive and the Toy Doctor.

Any thoughts? I thought the VAF was a pretty delicate gizmo.

Definitely replace your second O2 sensor before doing any other troubleshooting. I had a similar issue a few years back and once I replaced both sensors, my numbers came down. My sensors were only 7 or 8 years old and they were both bad. I'm assuming you have checked your timing?

 

[Inukshuk]

I have NEVER heard of a bad VAF causing emissions failure.
NEVER heard of anyone adjusting one.
I have fixed my own VAF and been inside two.
What happens is the thin metal strip used to make the connection between the connector plug and circuit board fatigue and fail. The fix is a quick solder job.
The critical thing to know is DO NOT remove the screws at the connector. That WILL break it.
It opens by cutting the silicone that holds the plastic top cover on. First time is scary. Then you see how easy it is.

VAF is NLA from Toyota.
Run the FSM diagnostics on the VAF. If it passes, leave it alone. If it fails, I'm happy to help you open it up and take a look.

 

[Battlshp]

Timing was first item - confirmed at 3 deg BTDC. O2 sensor will be replaced.

Before moving the car out there I did the FSM test on the VAF, my notes are sparse but VS-E2 400 & THA-E2 500 (Hot) I assume this is resistance but I am away from the FSM. I also recall watching a measure of flow on my ToyoOBD1 device and finding nothing remarkable.

The specific observation was the data the tech saw indicated the vanes were closing slowly after letting off the accelerator- it led med to wonder if cleaning and perhaps lubricating the vane mechanism would suffice?

 

[Battlshp]

Just as a follow-up. This has been slow due to work and the fall climbing season. I wanted to provide an update on the resolution. She first took the car to a Colorado emissions diagnostic facility and they came back with this:



I had see the Code 25 intermittently on the trip out to Denver, the 26 I thought was gone. The outboard O2 sensor had been replaced due to a bad heater circuit. I was going to replace the inboard while I was there, but to be honest I could not get to it. That sensor appeared fine per the FSM test and was only 7 years and 30,000 miles old. So, I left it. MISTAKE

Justin at the emissions center was great and offered to stay in touch while we got ahead of this. She had the new O2 sensor in her spare kit and got it installed Thursday. On Friday this was the result:



This was on regular fuel after 30 minutes of warm-up. I am greatly relieved.

 

[twentyfooteighty]

New numbers look great!

 

[Battlshp]

That is what I thought. Kinda of relieved, began to think I had handed her a pile of problems