New 80 series 1FZE owner please help!

[garrett96]

Please help I’m new to owning a 80 series, and I have a small problem I cannot figure out. So upon buying this 1997 lx450, it did have a small hole in the top of the fuel tank, I patched it and and pressure tested it and while I was there I threw on a new fuel pump. I also installed new spark plugs while I tended to installing new valve cover gaskets. So here is my issue, when I crank it, it starts right up and idles at 1000 perfect no issues for however long I want to leave it running. I put it in drive and start off slow and easy it shifts fine and drive perfect one I get a couple minutes down the road mainly when I let off the gas and it tries to down shift the RPMs will bounce like crazy and it tries to go down to zero and stall out, if I hammer the gas it saves itself and keeps driving. Sometimes I can just hammer the gas and let off and cruise and it’s fine. When the rpms bounce it does a little jerking as well. It seems like maybe it’s a fuel issue. If I leave it in park and keep it at 2-3 RPMS it will white smoke a little and then the RPMS will eventually try to drop out. It had a code for both O2 sensors I replaced them although the only ones I could find didn’t look like the ones that come out of it but the harness fits perfectly and it bolts right up. But every time it does stall out and dies it gives me the same code. Any help will be appreciated please and thank you! I’m not sure how to post or attach a video to show what it does but if someone wants to reach out maybe I can send it another way

 

[DamoFZJ80]

MAF sensor? Throttle position sensor? Is the throttle cable adjusted correctly? O2 sensor connectors bad/corroded?

Side note: When you open your gas cap do you hear hissing? Want to make sure your charcoal canister isn’t clogged up. That caused my gas tank issue (in part)…

 

[Kernal]

A few dozen possible answers but start with the basics, check all the large vacuum/air hoses on top of the engine for damage, two from the valve cover and the larger pleated rubber air intake tube which is known to develop cracks between the pleats allowing un-metered air into the engine.

If the Oxygen sensors are anything other than Toyota(Denso) or DENSO brand all bets are off, Denso O2 sensors are known to work in the models that came with Denso/Toyota sensors, other brands like Bosch not so much (RockAuto usually has the correct Denso O2 Sensors in stock). Looks like the OEM Toyota front (#1) sensor is still available. The most important O2 sensor is #1.

What code are you getting and are you seeing any other engine codes, misfires??

Is the engine using any coolant, radiator overflow tank bubbling/boiling??

Have you observed the engine temp gauge ever go above the middle horizontal position?

Do you have any history for previous service or repairs on your 97 LX450?


RockAuto links for Denso Oxygen Sensors:

More Information for DENSO 2344153

More Information for DENSO 2344157

 

[effjay80]

Yes start with the correct O2 sensors as Kernal stated.

 

[garrett96]

MAF sensor? Throttle position sensor? Is the throttle cable adjusted correctly? O2 sensor connectors bad/corroded?

Side note: When you open your gas cap do you hear hissing? Want to make sure your charcoal canister isn’t clogged up. That caused my gas tank issue (in part)…

It’s not MAF I don’t believe it’s TPS but will look into it more, and as far as the canister you are talking about the purge canister or the fuel vapors right? I’m assuming I can take that apart and maybe clean it? I did bypass the VCV the small check valve under the intake which is downstream of the price canister and it acted like possibly it got better but I’m not certain yet. But I will look into cleaning the canister for sure thank you

 

[garrett96]

It’s not MAF I don’t believe it’s TPS but will look into it more, and as far as the canister you are talking about the purge canister or the fuel vapors right? I’m assuming I can take that apart and maybe clean it? I did bypass the VCV the small check valve under the intake which is downstream of the price canister and it acted like possibly it got better but I’m not certain yet. But I will look into cleaning the canister for sure thank you

Purge canister** my typing sucks

 

[garrett96]

I did get them off of Amazon starting to learn I can’t do that with this truck, so I will try to order some denso brands and see if that helps! But nosir it’s not overheating at all and the truck was a one owner but he didn’t drive it at all the last year. He put a new battery in it, I drove it for 2 hours before purchasing it then drove it 2 hours home with zero issues it wasn’t until after doing the work I stated above it started acting up on me I will try for sure new 02 sensors thank you

 

[garrett96]

MAF sensor? Throttle position sensor? Is the throttle cable adjusted correctly? O2 sensor connectors bad/corroded?

Side note: When you open your gas cap do you hear hissing? Want to make sure your charcoal canister isn’t clogged up. That caused my gas tank issue (in part)…

And I do notice a hissing so I will look into the canister

 

[Kernal]

None of the original vapor canisters are likely working after 27+years but IME they do not change how the engine runs. Some people, especially at higher elevations, have problems with gasoline spitting out the filler tube when the cap is removed after a drive on hot days. On the other hand I live/drive at sea level (similar to Beaumont, TX) most of the time and even though the vapor canister hasn't worked properly for years the engine runs fine.

Point is, IMHO I'd focus on what you worked on just before the issue started.

 

[BILT4ME]

Sounds to me like the wiring harness at the EGR valve.

Grounding out the injectors, dumping fuel, causing white smoke, also causing the O2 sensors to code.

 

[mudgudgeon]

it wasn’t until after doing the work I stated above it started acting up

Start by rechecking everything you worked on.
You said you did valve cover gasket. To do this, you needed to remove intake air hose, throttle body, upper intake manifold??, PCV hose, various vacuum hoses.

Did you install new pressed metal gaskets on the throttle body, intake etc?
Or paper gaskets?
Or re-use originals?

Did you replace spark plug tube seals in the valve cover? These are likely rock hard, and may not reseal when valve cover goes back on.

Every vacuum, pcv, intake hose you removed is a suspect.

The intake hoses get brittle and can crack in the folds.
Vacuum hoses, and PCV hose etc get hard. They often won't reseal on the hose barbs (too hard for the clamps to squish them)

PCV grommet in the valve cover can crack when disturbed.

All these things can create vacuum leaks meaning you have unmetered air getting into the engine. The ECU doesn't know there's extra air getting sucked in, so doesn't add fuel.

 

[garrett96]

UPDATE:
I have replaced my o2 sensors with DENSO. The truck no longer has the codes but still drove the same. I had people mention the Evap canister so I replaced it with the VC120 I believe is the part number. and all is good drives perfect right away, except for after about 2-3 hours it built up pressure in my fuel tank and send fuel to the canister and it was leaking, so I went to the gas cap and opened it and sure enough there was positive pressure ( a lot) so is my issue with the gas cap not releasing pressure when it needs to or do I need to look into my breather tube in the back of the vehicle??
Once I took pressure off and leave the cap off it drives perfect

 

[60 toy ota]

I'd check for clear passages through your evap lines