wallyman42

Hey guys, just picked up a 1999 ES300 that is having a strange issue.

When you accelerate from a stop at full throttle, the car feels very sluggish moving up the RPM range, and acts as though it is missing the entire way up. If you do the same acceleration at lets say 70-80% throttle its much faster and much smoother (like the car is supposed to be). Works just fine until the car hits like 55mph, then power just cuts out.

If I'm revving the car in park or neutral its the same story. Works well at part throttle, but full throttle it misses as its revving up.

To me this seems like 100% some kind of weird electrical issue. I'm having a tough time tracking it down though.

Things I have done:
1. At one point i had an VVTi OCV code for the rear bank, so I've replaced both OCV filters, and removed tested and replaced the RH OCV valve (they were both working to spec, but the rear one had a little more play in it).
2. No codes by OBDii scanning.
3. Cleaned MAF
4. Checked intake hoses for rips (there are none)
5. TPS seems to be working well based on OBDii diagnostics.

I'd appreciate any other ideas you guys have.

PFB

Could be fuel starvation caused by a partially blocked fuel filter, and/or the fuel strainer in the tank

wallyman42

Good thought, the only thing that made me not really consider that is this.

If I accelerate at full throttle and its stumbling through the rpms, if i decrease the throttle to 80% the car actually picks up and accelerates faster. I'll probably replace it anyways since its cheap.

Could a vacuum leak cause symptoms like this? I'm under the impression that the 1999 1mz-fe vvti doesn't have EGR, so that isnt a consideration correct?

PFB

Mine is a 2001. We have the same engines, in which case you do have an EGR. I would still start with the fuel filters however. Also make sure that your air filter is clean, and that you didn't pick up a bad batch of fuel

wallyman42

Air filter is clean. I could've sworn the early vvt-i 1mz's didn't have EGR. Wheres the EGR valve on the intake manifold of the vvti engine then? thanks

I'll swap the fuel filter tomorrow.

wallyman42

Newish development:



Was tracing all of the vacuum lines and noticed that several were just flat out cut through. The two going to the vacuum tank were folded back on themselves and ziptied and the other two were just sliced.

Could this be the source of my problems? I shall fix it tomorrow and see.

wallyman42

Unfortunately no dice. Changed fuel filter, cleaned IACV, reset computer, replaced vacuum lines and still nothing. This is driving me nuts.

PFB

You still need to verify the fuel strainer. There are several similar symptoms as yours on this site where the problem ended up being the Fuel Strainer Do a search, but here is one example below:


https://www.clublexus.com/forums/es3...finally-d.html

mdbrown

You need a scan tool that shows streaming data so that someone can ride along and see what the engine is doing while you drive. Sounds like it might be starving for fuel. I'd check fuel pressure while driving. Could be a failing fuel pump. Hard to say without more information. You don't have an EGR valve and that wouldn't cause any high speed driveability issues anyway. You might consider a clogged catalytic converter as well...

wallyman42

Clogged cat is my best bet at this point. Im gonna drop the exhaust tomorrow and inspect.

I also noticed a sulfery smell from the exhaust when messing with the car today. I bet its the cat.

wallyman42

Turned out to be a combination of a crusty fuel strainer and moreso a faulty fuel pressure regulator. Only sign that the fuel pressure regulator was going was that the fuel pressure was 51-52 instead of just below 50.

Car runs like a champ now.