Hi,

Im wondering if someone had a similar problem knows what could be the reason for the sudden misfiring of the engine in lexus gs450h. The failure occurred suddenly at a speed of about 50mph the engine suddenly lost power and began to work unevenly as if was misfiring.

The car was towed to a mechanic, hooked up techstream and error P3090 Camshaft Position Sensor 'B' Circuit Bank 2 popped up. The mechanic said that maybe it was the spark plugs and not the sensor and replaced all the plugs, but the problem remained.

The sensor will arrive after Christmas and will also be replaced, but I do not know what to do next? The mechanic said that it could be a pulled timing chain or jumped one tooth and he doesn't know really and advised to sell a car as it is LOL

Has anyone of you had a similar problem ? the car starts engine without eny problem but it seems as if it is not running on all cylinders. Mileage is 168k.

What else should be checked to try to remove this fault ? Anyone knows any good Lexus mechanics in Hertfordshire , UK ?

I am attaching a video of the engine running

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You can start the car with it misfiring, and disconnect each coil pack connector and if the it gets worst then that coil bank is good. If you pull the coil plug and the car runs the same then that cylinder is where it is misfiring. You can then swap out a good near by coil pack into the location of the bad one. If the issue moved to the replacement spot then the coil pack is probably bad. If the issue still stays on that same coil pack then is plausible that the cam shaft sensor is bad. What you can do is visually inspect the plug on the cam sensor, and or swap out the camshaft sensor from right to left. Then see what code pops up.

The worst thing you can do is throw parts at it in hopes of a repair without properly diagnosing it with a good mechanic. A good mechanic will save you time and money

 

Start with "P0390" and a lot more things will pop up.

Since you've already ordered the sensor, wait until it arrives and swap it it. Wouldn't drive the car like that for obvious reasons.

Not sure if you'll find service recommendations for the UK here.

 

I agree if you drive with that bad of a misfire you risk destroy the catalytic convertor.

 

Hi all,
many thanks for you replies.
Camshaft position sensor B has been replaced with no good results, also tested all ignition coils and they work good.
Used my endoscope and suspect stretch/worn timing chain on VVT sprocket as it looks very loose or tensioner went bad
The place where i use my endoscope is highligthed in yellow on one of the pictures.

Called lexus specialists near me and they are not willing to replace timing chain kit and send me to lexus, but said at lexus it will probably cost as much as the car is worth lol as miles is quite hight 168k miles.
Really dont know what to do, may sell is as it is or do breaking and sell parts only







got also a video when engine is running so if any of you is good with diagnostics you can see the stats while the engine is running.
its visible on video that misfire count is rising while im reving up engine.


bart

 

"With no good results" = "still throwing the code"?

 

So all 6 ignition coils are firing, how did you verify this? Did you try running it and undoing each coil while running, you should see rpm drop when you unplug the plug on each coil. If you do not see a drop in rpm then that would be the dead cylinder.

As for the cam tensioner, I wouldnt rush to replace parts unless you properly diagnose the car with a knowledgeable tech. Worst thing to do is throw parts at it in hopes of a repair. Not sure what style tensioner is on that engine. I would take it to the dealer and pay for diagnostics

 

Lwerewolf - yes still throwing the code
ibidu1 - yes i was undoing each coil while engine was running and could feel big difference every time coil was disconnected.

I'll call couple of independent lexus mechanics this week and see if they can diagnose it properly

 

Sorry I didnt view the first video you posted. But to me the sound of the engine and the way its running it honestly sounds like a vacuum line is broken. I would go through the whole engines vacuum lines especially the ones past the maf sensor. Theres a vacuum line that runs on the side of the left frame rail, deep low make sure thats connected. Certain times when the airbox is removed forcefully that hose comes off.

Theres an idle air hose aswell its best to check that. You can also spray carb spray on the engine and the motors vacuum will suck in the carb spray and raise the rpms, this helps you track hidden vacuum leaks.

 

OK, then. Check the harness:

E62 is bank 2's harness connector. E76 is one of the connectors of the engine ECU.

P0390 is for bank 2. EV2 is for bank 2. For RHD cars, this is the passenger side.

Pin1/Pin2 in the following context means Pin1 of E62. If it was bank1 it would've been E56 & EV1.

Disconnect the harness from the sensor first.
With ignition ON (double press the power button, don't hold the brake pedal - you don't want to go into READY), measure voltage:
Pin3 -> Ground should be ~=4.5-5v

Now disconnect the ECU-side as well.

Check that the following are connected (<1ohm):
Pin1 -> EV2+
Pin2 -> EV2-

Check that pin1, pin2, EV2+, EV2- are all isolated from ground. Shouldn't be a need to reconnect the connectors, you haven't disconnected the whole harness.

If you get the car to somebody who has a scope, they can check the waveform while the engine is running.

Beyond that, it's fun time (i.e. taking off the head covers). I'd still thing hard about ways to check EVERYTHING else before opening the engine, though. It is extremely rare for these to do anything of the sort.

 

BTW there is no misfiring, all the counters are zero. The car is seeing more intake air, so thats throwing off the maf sensor allowing the idle to bounce around and the bouncing idle is triggering the cam sensors. Go through all your hoses! Theres a small tear or one is loose, I would check the evap hose thats coming off the intake tube.

 

1) "No misfiring" on the counters just means that it hasn't tripped the car's misfire threshold
2) 1:01 on the video - misfire counters are not zero
3) this adapter isn't known for its update speed

 

Uhh... Check how your pictures uploaded. I just saw them somewhere else and that's definitely not normal. You should be able to take off the bank 2 cam cover but I guess the car's going to a mechanic regardless.

 

just to update everyone there are 3 timing chains and one of them, exhaust valve chain snapped in the middle.

Garages quoted me about £2500 to replace it all as it requires to take out an engine from engine bay, although it is possible to do in without.

My friends managed to replace it on driveway for £700 and then I sold a car.

 

The chain snapped yet the car was still running and there was no damage to the cylinders?! O_O