Been driving the GX now for almost 2 years. 13k miles since we bought it. Has been a great first car for my son. The other day he called me. Said it was running rough and "all the lights on the dash were on". Luckily it was running and he was 5 minutes from the house. He pulled over to a parking lot so I could head over and meet him.

Scanner - P0353. Coil failed cylinder 3.

Our original purchase thread: https://www.clublexus.com/forums/gx-...004-gx470.html

As we did not do plugs and coils since we bought it I fired up the parts cannon and ordered plugs and (4) coils. All OEM Denso. Replaced cylinder 3 and 3 other coils which looked the worst (cracks, discolored, etc. I did check the wiring harness at cylinder 3 for 12V and ground but I dont have a tool for the middle wires on the harness. I assumed it was good. Car ran great. For 1.5 weeks.

Same error code. Only this time I also had pending misfires for all the other cylinders. I unplugged #3 which made no difference to how it was running. It was def missing. Moved the new coil to another cylinder, no difference. Cleared the code. Car ran great except this time I noticed cranking time to start was noticeably longer than normal and the idle was as smooth. Asked my son as I dont DD the GX. He knows nothing about cars but confirmed it had been starting a bit slower for a few weeks.

Error returned in 1-2 days. Obviously coil/plug didnt fix it. This time though I had trouble getting the GX to start. Before I could do a "clear flood" start (gas pedal to the ground while cranking) and it would start. Id have to two pedal for a bit to clear up the idle. This time I could get it started, at 2k RPMs it would smooth out but trying to idle it wasn't happy.

At this point I suspected a fuel issue. I don't have a fancy scanner that does injector pulses and such. Couldnt hook up a fuel pressure gauge as he GX uses a connector I didnt have. Truck wouldn't run well enough to drive it to check fuel trims so parts cannon it is. As I don't suspect all the injectors failed at once, and I could get a fuel pump and regulator faster than an injector from rock auto, I went fuel pump and regulator. 202k miles, no record of a previous swap.

Let me say, the fuel pump job is no joke. Not many videos on youtube. The one video I did find was more of a walk through after he had done it (Hawkeye Garage). There are a couple small differences on the 04 from his 09 in the video. The video was a great help though. I dropped the tank to make the swap.

Bought the denso fuel pump and a beck Arnley regulator. Couldnt find an oem regulator- if anyone has a link to OEM. Also could not find a complete drop in assembled pump and sender so I had to take the old one apart and pump swap my sender. So far, so good. Been 2 days. Driven the GX a few places and put 20 miles on it. Haven't filled it back up with gas yet as I wanted to make sure the pump swap was good. Back to starting like normal. Idles really smooth. Throttle response and power seem back to normal.

Normally I don't like the parts cannon approach but the parts I replaced I had no records for previous swaps. At 200k others had said fuel pump is due and I am glad it is done. Hopefully it lasts another 200k because that job really f*!king sucks. Next I'll pull the fuel rail and send out the injectors for cleaning and testing if needed as I have a local shop that does it for $6-8 per injector.

Anyone been down this path and curious what they found was the fix? Cleaning injectors or just swap new ones in?

Any ideas appreciated. Ill keep this updated if it fixes the issue or I have to do more work.

 

That's cheap for cleaning injectors, and the shop should be able to advise if they were able to get them spraying properly or if any require replacement, I'd go the cleaning route 1st.

Tell your son to fill up at 1/4 tank going forward so the new fuel pump doesn't overheat and burn out!

 

Update. Problem not fixed. After driving today about 10-15 minutes, issue returned. We limped her home. Decided to check out a data log with some driving.

LT fuel trim for bank 1-2
34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375 34.375

Obviously there is an issue. I didn't bother making it a nice format as the number doesn't really change through the log. The ST trims were also on the high side and the CEL presented with p0171/p0174 now. Lean condition bank 1/2.

Cleaned the MAF using CRC maf cleaner. It is an OEM Toyota/Hitachi part. No difference.

Checked for vacuum leaks (visual) without finding anything out of place.

Found this thread - Link

Sounds similar but no resolution in that thread. Seems to be an LX issue also with the 2UZ engine which occurs to random vehicles. Cant find a resolution there either. Might have to break down and take her to a Toyota specialist.

Ideas appreciated

 

More updates. Still seems to be a fuel delivery problem. Harbor freight has a fuel pressure test kit with correct banjo bolt adapter. Went through some troubleshooting.

I found with cranking I am getting 10-12psi fuel pressure at the rail. Car starts and idles on this but any load makes it struggle. Applying 12v to the fuel pump relay, same result. 10-12 psi. Checked for 12v at the fuel pump plug, tested good. Removing 12v, pressure drops immediately to 0 or near 0.

Then I removed the #3 fuel injector as this was the original misfire cylinder. I suspected I had a bad injector maybe bleeding down pressure. Using some online instructions I got it hooked up to maf cleaner and a 9v battery using a couple clamps and some fuel line. Spray pattern looks excellent and no leaking. I didnt have time to remove the entire fuel rail.

Swapped back to the original fuel pressure regulator. Same. 10-12psi and drops immediately. Safe to assume both new and old are functioning the same.

I tossed the old pump as garbage day was friday and car ran great after swap initially. Can put it back in for testing.

Went around the fuel injectors with the engine running. They all click correctly both audibly and by touch can feel them cycling.

FSM lists checking fuel pump, regulator, lines, injectors if pressure isnt high enough.

At this point I have a couple options -

(1) drop the tank. Send by the Denso pump as I have no way to test it unless it is in the car. Assume it is a bad replacement.
(2) drop the tank - perhaps the fuel sending unit is bad/clogged. I found a thread where someone cut open the sealed filter and it was clogged. Maybe replace the entire unit if I can find an OEM
(3) drop tank. Remove pump. Spray fuel cleaner through the lines and try to clean out the sealed filter.
(4) pull all the injectors and replace/refurb
(5) send to a mechanic

Any other suggestions?

 

You do know there's a low & hi speed resistor inline with the pump, controlled by a relay? Check these.
If the pump can't get full voltage it can limit power at the time full pump power is needed. If you jumped the pump around that relay for full voltage on pump and getting only 12psi, then it might just be the pump itself. What psi does pump give with and without the inline resistor?

I suspect it's not fuel lines. Bad injectors maybe, but they don't typically make the engine limp, more like just some lost power you don't really notice.

You can measure pump Ohms from the relay box. Is that good?

Spray pattern by eye is only half the test. Flow will be 10x more important.

If you are gonna do injectors and can have the GX down for some time, send yours to RC Engineering in CA, they do a full service on them for about $300. Or option B, find 2UZFE used set from junkyard or online, send those to RC.

 

I jumped the resistor connector on the driver side engine bay. No difference. Was hoping that was it. Forgot to mention that.

I'll ohm out the pump. I did read that elsewhere. Meant to do that earlier but forgot.

 

That code is a coil pack code.

P0353 TOYOTA Code - Ignition Coil 3 Primary/Secondary Circuit

P0353 TOYOTA code possible causes
Faulty Ignition Coil 3
Ignition Coil 3 harness is open or shorted
Ignition Coil 3 circuit poor electrical connection
Faulty Engine Control Module (ECM)

Read more: https://www.autocodes.com/p0353_toyota.html

 

i know i posted quote a bit. Thanks for the reply but i already swapped coils and plugs. Checked the power and ground on the coil harness which was good.

 

Your description of it makes me think fuel pump or ECU. Of those two, pump is more likely. But if the pump has correct ohms then maybe (maybe) the mesh screen on pump is clogged? Mine at near 240kmi was absolutely clean.

You replaced pump fuse? You measured the ohms across the relay contacts? Worn contacts can reduce power at pump, etc.

 

Low battery voltage?

Chip H.

 

I had a similar issue with my T4R. Replaced coil and injector and it would fail again after a couple hundred miles. What finally fixed it was some good contact cleaner at the coil pack connector. I guess it had some corrosion on there that cleared just enough when I unplugged and put in a new coil to run well for a short time, then lose connection later. Try this:

 

Update - Back on the road.

As stated above, finally made an appointment at my trusted indy. Day before couldn't even get her to start to move her out of the garage. Called a tow. Pulled codes before tow got to the house. Now a new code P0335 crankshaft position sensor circuit. Had an idea what is causing this. Didn't have time to look over it. Looked under and sure enough the harness to the crank sensor is against the pulley. Don't see anything cut.

Mechanic had it a couple weeks. Found a short a bit higher where it was rubbing on the serpentine belt. Fixed. Cost me a tow ($75) and a couple hours labor but back on the road.

Few things I learned - electrical problems suck to diagnose. While I needed plugs and did find a bad injector and my fuel pump had 200k miles on it, none of this was the primary issue. I am glad to have new injectors, plugs, coils and a newer pump though. The MAF I got from Autozone is a POS and reads the wrong airflow out of the box. Went back to the OEM I removed as after we got her back she gave P0420/P0430 codes which we had not had before. I ordered an OEM MAF to replace it when it gets here.

 

Awesome thread
Many great posts.