A couple of weeks ago, I drove my car for about an hour. When I went to start it up again, it sputtered at 200-400 rpms and then died. Cranked fine, but would not stay running. I had it towed to my mechanic, who said it started up fine with no issues. He cleaned the MAF sensor, and said it was probably just dirty. I noticed a much stronger idle after the cleaning, so figured that fixed the problem.

This weekend, after about an hour of driving, the same thing happened. Once I went to start the car back up (after a short break), it ran at very low idle, then died. I tried to crank two more times with no success. I let it sit for ten minutes, and then tried again and it started up totally normal. I drove it for another 45-60 minutes after that without issue.

So this is clearly something that only happens when the engine is warm.

I have no codes, and the mechanic didn't pull any either. Everything is perfect otherwise.

All maintenance up to date.

2004 with 120k miles.

Thoughts?

 

Charging, battery , fuel pressure, throttle body they are ok the only think I'm thinking spark, spark is control by ECU if it gets hot and expends it could be a simple circuit or cold solder joint . Net time it happens open the cover and spray freeze spay to lower the temp down .
If had your issue I start looking first at ECU.

 

Next time after a longer drive try to open your fuel cap when you stop. If you hear hissing/air being sucked in you may have a clogged return line which will cause vaccum in the tank and pump is unable to suck the fuel out. Just a maybe

 

My gut says it sounds like fuel starvation from the symptoms, and quite similar to those if you disconnect the fuel pump resistor while the car is at idle. I'd start by looking at the fuel pump relay and the fuel pump resistor circuit (It's the heatsink mounted under the left hand side strut tower cover.).

If they check out ok, then check out the fuel pump/pressure somehow when the problem occurs. Possibly cycle the key in the ignition from off to on (ignition on, engine off) a few times before turning it all the way to start the engine. If that fixed it the pump might well be on it's way out.

When you say there is no codes - do you have a code reader like a techstream cable or and elm327? If so what the sensor readouts when the problem is happening? Ie volts, rpm/ cam position sensor readouts, throttle position sensor etc. Unfortunately, I haven't found a fuel pressure sensor so it is a manual check with a Toyota/Lexus specific physical pressure gauge.

 

To diagnose this properly, you should have Techstream running on the engine monitor screen so you can see what is going on with everything right before the engine cuts out. Then you'll be able to see all the sensor readings leading up to the stall. This should greatly help with pinpointing the problem. Otherwise you are flying blind and diagnosing based on speculation instead of hard evidence. There are dozens of sensor readings that can help you troubleshoot this. Long term and short term fuel trims could give you hints as to what the problem is, but if you reset your codes, your LTFTs may not be correct until you drive around more.

Low idle could be caused by improper cleaning of your throttle body plate. The proper way to clean is to use the electronic motor to open the plate. The improper way is to force the motor and plate open by pushing it with your finger. Maybe all you need to do is to adjust the throttle position sensor to increase your idle and standard opening %.

Yes, you need a manual gauge (SST 09268-45014, 09268-41190, 90405-06167) to check fuel pressure. Access via removing the fuel pulsation damper on the RH pipe. Idle spec is 304-343kPa (44-50psi). Stop the engine, wait 5 minutes, then check again. Pressure should be at least 147kPa (21psi), and if not, check your fuel pump, pressure regulator, and injectors.

Fuel pump check is resistance across terminals 4 and 5, should be 0.2-3.0Ohms at 20C.
Fuel pressure regulator is inside the fuel pump.
Injector check is resistance across the 2 terminals, 13.4-14.2Ohms at 20C, and when battery voltage is applied, injection volume is 60-73 cubic centimetres per 15 seconds, and each injector must not have a greater than 13 cubic centimetre difference with any other injector. Injector leakage must be one drop or less per 12 minutes.

A 2002 Honda Accord V6 that I fixed up had this same heat soak problem (and many other engine/fuel problems including random misfires). I changed a fuel pressure regulator and/or fuel pulsation damper near the fuel rail on top of the V6, also changed all 6 fuel injectors (and noticed they were all mismatched from a previous owner trying to fix the problem, and then I had to redo the job when 1 of the 6 remanufactured same-brand injectors was actually defective).

The Honda heat-soak problem was experienced by tons of other Honda V6 owners on the Internet. Something to do with the fuel rail being located too close to the engine block and a defective FPR/FPD, Honda released a revised version sometime after the car was made. I also replaced all 6 ignition coils and spark plugs, did an ECM reset and then the Honda ECM relearn procedure, involving driving at certain speeds at certain rpms for certain durations in certain gear selectors.

 

Just thought I'd add a quick check to help determine the source of the problem being spark or fuel the old fashioned way.

(As mentioned before my gut says fuel related)

Grab a can of starting fluid and carry it in the car. When the symptoms present, spray some starting fluid directly into the intake manifold. Then crank the car to see if engine fires up for a bit until fluid is burnt up.

If it does, it is fuel delivery related in which case look at relay circuit (see FAQ thread) and/or pump.

If it doesn't, it is something else ignition/computer/sensor related.

 

Great info, I appreciate that.

I did have the TB cleaned by my shop (just as maintenance) about a year ago.

These days I do little work myself anymore, simply no more time and after 20 years of wrenching, I don't enjoy it like I used to.

Just curious, what is a "heat-soak" issue?

I'm just going to take it to an Indy these weak and let them sort it out I guess. Other than that, this car drives perfect. This is the first problem I've had in the 3+ years I've owned it. Not bad for a 15 year old car!

I suspect fuel pump or something related to the fuel system as well. I appreciate the input, I probably could bother to take some of these steps before I take it to a shop.

I mean no codes from an OBD II reader. Although the shop I had it towed to a couple of weeks ago, also hooked it up to their computer and didn't get any codes on their end either. They had a MAF code however, and that's why they cleaned the MAF.

 

By reader do you have your own or is it one from the shop?

 

I have my own OBD II scanner.

 

Cool.

Does your code reader have they ability to see more than one sensor readout at once? What about record data?

If so I'd take it for a drive when everything is working normally record
the volts,
tps,
engine temp,
both banks primary o2,
both banks ltfts
and maf

To have a baseline to compare with the data when/if problem returns.

If not, I'd recommend picking up a elm dongle compatible with your phone (WiFi for iPhone, Bluetooth for Android) and leaving it plugged into the car permanently. You'll need an app on your phone running when driving (I use car scannerbfrom carscanner.info) to read and record the live data. The data from the sensors help paint the picture as to what is going on.

The other thing I'd recommend (and am about to do to mine) is have a fuel pressure gauge installed permanently in the engine bay. That way you can see straight away if there is and how much fuel pressure present just by popping the bonnet.

 

Great info thanks. I don't have the time to do my own work these days, so I just have Indy's I trust do it.

I took it to the top rated Indy Lexus shop here in town-my first time there. He kept the car for three days and could not replicate the problem. He said everything was perfect. He did send me home with a wire to bypass the fuel (regulator? can't remember, it's on the driver's side of the engine) if it happens again to see if it's the culprit.

On a side note, I got the 120k service done, which included all kinds of goodies, including cleaning the TB, air induction system, fuel injectors, fluids (Brakes, coolant, power steering), new brakes/rear rotors, alignment etc. The idle is stronger (800 RPM) and you can't even tell the car is on while running. Just incredibly smooth now. Probably the best it's ever run since I've owned it. What a joy to drive and what a well built car. The mechanic told me it was one of the nicest ones he's seen of that age.

Curious to see if this happens again. Hopefully not, but we'll see. Thanks everybody for the input.

 

That is quite the service! Glad it's running super smoothly now.

 

I would check out your temperature sending unit. Could also cause same symptoms

 

Very similar to problem I had about 3 weeks ago with my 2002 LS,139000km
Had to have it towed. Electrical wire to MAF sensor had been chewed through by a rodent. Had that replaced and all good. I had no codes but VSC and check engine came on. Maybe check the wire to MAF sensor.

No issues since