We have a 2002 ES 300 that has simply been the most rock solid car imaginable at 225k miles. It is right up there with a '94 Landcruiser elsewhere in the family.

Late last week we started to take in on a 600 mile trip. In the first 50 miles I notice the fuel mileage per the dash display was way down. Then engine power seemed down as well. About 110 miles into the trip the engine started to vibrate and run poorly. I pulled off and shut it down. Nothing obvious under the hood and after a bit of debate we turned around and drove home.

The engine will not idle, it runs terribly and then conks out. After 225 miles, I am not certain our fuel economy was as bad as the display suggested -- that is the guage was in about the right spot for 220 miles of highway driving. I pulled the codes with my Innova 3150e (yea, I know it is cheap). It reports misfires on cylinders 2,4,6 (P0300, P0302, P0304, P0306) and nothing else. There is also nothing reported under the Lexus extended codes. I replaced the bank 2 oil control valve as there was some oil under it, not much just a sticky surface. I replaced the plugs as they were old anyway. Voltage testing of the coil wires and the fuel injectors seem on speck.

So, I am about to dig into fuel pressure, but I spot this on the rear bank valve cover:

Does anyone recognize it? It was lying on the valve cover in line with the middle of the car, arguably under the throttle body. Ideas?

Thanks in advance for your assistance. My other car is an Audi, I am far more active on those forums....

 

Does your scanner have a live data feature for fuel trim and oxygen sensor voltage?

I recently solved a long standing issue with random misfires and a poor running engine that took about a year to figure out.

My codes were either random misfires across bank 1 cylinders or System Too Lean for Bank 1.

I figured out that the issue was with Fuel Trim on bank 1. Every time the engine ran poorly, my fuel trim would spike on bank 1 only. So after some digging around, I discovered chew marks on the Bank 1 Air/Fuel sensor wiring. The sensor wires were exposed and making intermittent contact with each other.

I would advise to check the response of your Air/Fuel sensors and check the wiring especially for Bank 2 (near the radiator), because Cylinders 2,4,6 are on Bank 2.

p.s.: the piece of hose is a vacuum line. It would’ve come from the EVAP lines across the intake manifold, the throttle body, or the charcoal canister. Maybe it was replaced but somebody left the old one behind? Check for vacuum leaks to be sure.

 

Could be the line that comes off the VSV see here
https://www.japan-parts.eu/lexus/us/..._vacuum-piping

 

Looks like the one from airbox (highlighted in attached PDF)



The below pic another possibility. Its located under the engine cover

 

Here's another photo. Ignore the text block & circle, I couldn't edit it out...

 

Fortitude,

Thanks for the vacuum diagram, by the process of elimination, I have accounted for all vacuum connections and discovered the piece you identified by the airbox was newer than surrounding bits. It is a replacement and my original was on the valve cover.

Hayk

Your comment about critters scares me - a lot. I found half a dozen acorn shells in the engine area. I have checked the spark and fuel injectors as well as I can with a multimeter and eyeballs. I assume that if I have an O2 sensor issue it is with a newer Denso unit I put on the front (Bank 2). My scanner says it has live data, but I have not seen any, I will read the manual tonight. The wire up to the vehicle connector appears fine. Once it hits the connector, I very quickly lose sight of it.

I guess the O2 sensor could create these symptoms, just a bit odd the starting point was well into a highway drive. Unless said critters were onboard when we departed.

I am just guessing right now, which is frustrating. What about fuel pressure regulator? O would that effect all 6 cylinders?

Many thanks to both of you for responding.

 

BTW, that engine bay looks like you could eat off of it! Remarkable condition congratulations.

 

Chewed wires is just one possibility. In my case the car drove fine 90% of the time. I guess if I hit a bump or there was just enough movement between the wires, they would make contact with each other. I was able to get it to stop misfiring by letting go of the gas pedal and coasting for a moment. I think that made the engine move and spread the wires.

If you monitor your live data while the engine is running poorly, you should be able to spot data that’s not normal and that should clue you in.

Definitely start with Long Term and Short Term fuel trim for for both banks. Each bank’s total fuel trim % should be under 15. Then once you have those numbers you can start checking sensors and individual components.

Do you know if your car is California emissions (not sure if they still did that for 2002)? There were two different sensors for 1MZ-FE for the 3rd ES generation, I’m not sure if they did the same thing for the 4th gen. One sensor type was a wide-range Air/Fuel sensor that works on a 5V reference, the other is a standard narrow band Oxygen sensor that works on a 1V reference.

 

I have a friend coming over with a scanner that will show live data. This has been a weak point in my tool kit and I have know it. 90% of my work is on an Audi and for that I use VCDS which is great but useless outside the VAG world. I believe the 2002 still uses narrow band sensors. It is a 4 wire and from recent work on the Audi their wideband sensor is 5 wires.

I did discover that the #4 coil pack was different from the other 2. It was put on a couple of years ago by a shop in PA when my wife was up there visiting. It checked out low at 8 ohms on my meter and barely fit in the tube. I have ordered a Denso replacement, but this is little more than throwing parts at it. The front O2 Sensor wire does not have an obvious issue visually. It runs between the airbox and the block into a jacket and then into corrugated plastic all of which to my eye is in good condition. I did the old test of spraying water over the coil wires with the engine running and saw nothing. I do not think that is relevant in the low voltage systems, but I tried.

 

Both Wideband and Narrow band Denso/Toyota sensors are 4 wires. Two for the signal circuit (usually white and blue) and two for the heater circuit (both black). Yeah having factory scan tools are great, but like you said useless if you need to check another manufacturer.
If you get the time find a way to setup Toyota Techstream, they sell kits online so the hardest part is getting it setup.

With misfires on all three cylinders on one bank, you gotta have one major source thats causing that.

1. Air/Fuel sensor not responding/stuck.
2. A gross air leak (failed gaskets, torn hoses)
3. No fuel supply (wiring issues)
4. Engine timing issues with that bank (jumped timing belt)
5. Exhaust issues (plugged cat in the Bank 2 manifold)

Live data should tell you if the voltage is normal and you can test it by introducing a vacuum leak or adding more fuel to the intake.

You could check if the fuel injectors are working by listening to each one with a long metal rod

Timing can only be verified by looking at the timing marks. When was the last time you had the timing belt replaced?

Exhaust back pressure is trickier to test, you would need to remove the oxygen sensor but then it wouldn't be able to run smoothly.

 

Hayk,

Thanks so much for the tick list. I will do a propane test as soon as I achieve a rough idle today on the initial cold start. I used Fortitude's vacuum digram to inventory and inspect each line previously. Lots of hard rubber, but no noticeable cracking.

The timing belt kit and cam seals were done 20K miles ago. I guess the crude check is to pull the upper cover as see if by turning cams both the front and rear banks line up simultaneously.

I see zero evidence of coolant in the oil or oil in the coolant and it has 100 miles or so of highway driving after I noticed the problem. So, I am putting that one way down on the list.

My game plan for the weekend is to grovel for help from a friend and see if we can test fuel pressure and injectors.

Then it is down to the pre-cat sensor (NGK replaced 2 years ago or plugged CAT) as the high probability items.

I need to read about TechStream, VCDS for the Audi is a godsend.

Many thanks,

 

Fortitude, saw your hint on another post. Is that bluetooth OBDII reader good at getting the right data with one of the iPad apps? If so, thanks cheaper than a dedicated scanner! Here is what I get from live data at as low an rpm as it will run. Specs are off the scanner, so I am not clear on the accuracy. The one that jumps off the page to me is the MAF Sensor? I am going to try and get a read with my multi meter but my understanding is it should rise from 2 - 7 g/s, so 5.03 at Idle would be very high...



Foxwell 530 scan at near idle.

 

Not sure regarding iPad but it works on my iPhone and it pulls the relevant live data (fyi it does not read fuel pressure), with a caveat, its not on the same level as professional ($500+) scan tool. This app has more features with newer vehicles. On my '05 F250 SD, it shows a ton more data even potential code fix solutions.

Fuel system needs to enter CL = closed loop before a good assessment can be made of live data fuel trims. Engine needs to reach operating temp
If CL is not achieved after warm up, then aim at coolant temp data

'02 has MAF. After achieving operating temp and closed loop

• Idling: 3.3 − 4.7 gm/sec.
• Racing without load (2,500 rpm): 10.4 − 15.4 gm/sec.

What brand OCV did you buy for bank 2?
What brand of spark plug and part number did you buy?

 

Here is what I have - interestingly LT Fuel trims #'s relatively large and opposite signs

 

Four more graphs that might provide some insight



Bank 1 & 2 Sensor 1 @1,000 RPM

Bank 1 & 2 Sensor 1 @3,000 RPM

Bank 1 & 2 Sensor 2 @1,000 RPM

Bank 1 & 2 Sensor 2 @3,000 RPM