VVTI 2UZ-FE

[rckymtngx]

Hey guys,

I have an '08 GX and for the last few months, ive noticed in higher rpms it would hesitate/break up a bit, and I have been waiting on a misfire code, however im thinking it may be my fuel pump on its way out... I got in to go to work this morning and started it letting it warm up, and then idle dropped like it was going to shut off, unless I gave it throttle, it stayed running, got out on to the road, and it was like it hit a wall at 3-3500 RPMs, but then it cleared up... I am not gettting any CEL, other then p0456, and ive replaced the cap already so need to smoke test it i reckon tonight. im hoping you guys may be able to offer some insight, as i of course have family coming into town on wednesday, and need to get it fixed. thanks in advance!! im leaning towards a fuel pump, OR maybe clogged cat/s due to the fact it clears itself up??? i am stumped.

 

[LXfromTX]

An 08 GX...shouldn't you be posting this to the GX group? Perhaps you're thinking the 100 group has more experience in this engine?

 

[rckymtngx]

An 08 GX...shouldn't you be posting this to the GX group? Perhaps you're thinking the 100 group has more experience in this engine?

I 100% should have prefaced my og post, however yes I’m hoping to get some insight from other platforms possibly. I’ve had a couple of people mention similar symptoms say a fuel pump fixed their issue, but also get the response when I mention it, that (fuel pumps just die, they’re don’t get weak before etc) I’m going to be putting a fuel pressure gauge on it this evening to see how it looks.

 

[OEMGUY0720]

If the system (combustion) is running lean, it typically won't light up the CEL (the ECU tries to manage based on preset programs), but you can validate that the engine is idling/revving differently. If you have an OBD reader that will give you a better sense of what the system is experiencing. Even better to read the Short and Long Term Fuel Trims for both banks. The symptom as you indicated above it hesitates at higher RPM. The 2UZFE VVTi's fuel pump is a 2-speed type and pumps in more fuel and more pressure to the line feeding the injectors as you go higher RPMs. I think it's your fuel pump as well, but it's always good if you have data to support the hunch.

 

[rckymtngx]

If the system (combustion) is running lean, it typically won't light up the CEL (the ECU tries to manage based on preset programs), but you can validate that the engine is idling/revving differently. If you have an OBD reader that will give you a better sense of what the system is experiencing. Even better to read the Short and Long Term Fuel Trims for both banks. The symptom as you indicated above it hesitates at higher RPM. The 2UZFE VVTi's fuel pump is a 2-speed type and pumps in more fuel and more pressure to the line feeding the injectors as you go higher RPMs. I think it's your fuel pump as well, but it's always good if you have data to support the hunch.

Hey thanks for the reply! I’ll be sure to log them the next few times I drive the vehicle, my hunch is the intermittence of the problem. Drove fine all weekend, got in it to go to work Monday, and damn near died. Was like it hit a soft rpm stop at 3k rpm, and then would spit and sputter past. (I was only driving that hard to try and replicate the issue), and then it cleared out in the afternoon. So weird.

 

[OEMGUY0720]

Hey thanks for the reply! I’ll be sure to log them the next few times I drive the vehicle, my hunch is the intermittence of the problem. Drove fine all weekend, got in it to go to work Monday, and damn near died. Was like it hit a soft rpm stop at 3k rpm, and then would spit and sputter past. (I was only driving that hard to try and replicate the issue), and then it cleared out in the afternoon. So weird.

The p0456 you mentioned is also related to the fuel system and how all associated parts manages to properly vent pressurized fumes. When fuel gets hot, it expands (just like any liquid), and the vapor is highly volatile that’s why it needs to slowly vent to the atmospheric pressure (depends on your elevation/location). This is a safeguard to reduce risk of fire. However the specific p0456 error is not a big contributing factor when we talk about fuel delivery to the combustion chamber low/high revs. The near stalling can be attributed also to as simple as a faulty MAF sensor and/or vacuum leaks. Take your time to inspect all of your vacuum hoses for any loose connections, breaks and cracks including the hoses/clamps in your charcoal canister.

Another troubleshooting step you can try is when the engine is running on idle, try to briefly smell the exhaust gases from the catback, if it smells like charcoal, it’s running lean, if it has a strong gas odor, it’s running rich. The 2uz like any other Toyota has a unique sweet-smelling exhaust odor, that’s the product of a proper and well balanced mixture of air fuel combustion.