1933beer

Hi new to this forum. My son purchased a first gen rx with 200k and some issues. He replaced the valvcover seals and the back 3 coils and plugs. This stopped leak and made the car run on more cylinders. The problem is even with a knowm good coil in #2 it does not do anything. We did replace all plugs. And 3 denso coils.

I tested to see if injector was good it ohms out to prper level. I stuck a knoad light on and it gets signal. I know the injecor could be fouled out but i dont want to pull the rail unless cant find anything else.
has any one seen a solution to this? Is there a way to rule out the wiring to the #2 coil#2
i have looked at Some threads about this issue but have not found that points to this problemproblthere is one please direct me.
thanks

maxSteel

Pull out the #2 plug and coil, ground the plug, crank the engine to see if plug is firing

salimshah

Plug#2 is passenger side towards the radiator. 1,3,5 on the firewall side 2,4,6 on the radiator side. Counting starts passenger side. Please stick to OEM plugs. Suggested replacement interval is 110K miles. Once everything is OK, you can experiment with other brands.

For debugging purpose, swap combination of ignition coil and spark plug. You are fortunate that the issue is with bank 2 [radiator side ..more accessible], so you can swap #2 with #4.

Also RX uses port injection and not cylinder injection.

Salim

1933beer

yes, glad this issue is on front bank. I dont remeber what sparkplugs we put in all 6 where replaced. We only replace the back side coils. When he got it at least one of those also was out. We have swapped 2 nad 4. With the car running you can unplug coil 2 and there is no change. When you unplug 4 it misses more.

salimshah

You can try different combinations of coil from 4 and plug from 2. If the problem stays with 2, compression test would be the next logical step. If compression is good, then revisit the injector ... as the 2 is at the end.

Salim

1933beer

Yes i plan to test the compression on to now. I wiill say it doesnt run like its low crompression.

salimshah

Just make sure the spark is there.
If it is misfiring, you are getting no power from that cylinder. We are trying to determine reasons for no/low combustion.

Salim

1933beer

Update, yes we have spark, yes injector gets signal, yes the injector sprays. But still misses. We did find out that the o2 sensor was plugged in but not bolted in causing the exhaust leak. We need to find the right nuts and bolt in. I dont know if this would cause just 1 cylinder to misfire but the ecu had to be messed up.

salimshah

I would suggest investigate the misfire first.

If necessary do a controlled swap with a good cylinder yet again. two step, coils only, and then spark plug.

Examine the wires to the coil very carefully.

Do a compression check on the suspect cylinder.

Do a leak down test.

Access the situation and then take the next step.

Salim

1933beer

So we hooked up the o2 sensor. Cleared the codes only p1135 comes back. Is there a way to tell which O2 sensor has failed? I know there is 3 the 1 that was plugged in but not bolted in was the 1 after the cat. I have not checked compression in the cylinder that is work working. I cant remeber where i put tester.
We did drive the rx for 5 miles to see if it would do anything. No change.

salimshah

Compression test and leak down test is conducted by removing the plug of suspect cylinder and fitting the pressure gauge in there. There are two numbers of interest the max pressure of the cylinder under test and difference from other good cylinders. Leak down is more elaborate. There are plenty of stuff on the net. Get a shortest hose as possible for the tests.

The error code will tell you which sensor it pertains to. One is right by the filter/intake, common for both banks. The next two are by the first cat [one each for each bank] and ht least one is below the driver seat in the exhaust plumbing. [bank 1 is the firewall side]

Salim

Misfire typically lets out unburnt fuel which can generate a non-normal sensor readings. I would therefor ignore the O2 sensor readings till the misfire is fixed. Others may disagree with me.

1933beer

If / when i find my preasure gage i will be able to test. I understand i can test the o2 sensors. Will try to do that today.

salimshah

There is valve in line to the pressure gauge.It ends up as a special test equipment.

Salim

brandonfpv

I’m 20 and i purchased this moldy, high mileage, old Lexus . It had a water leak, an engine leak, from yes the valve cover, cylinders 1 3 5 misfire, exhaust leaks (bad from rust) basically not a good investment idea.. unless?

I fixed the water leak (sunroof drains)
engine leak gone from a loose valve cover screw (mechanic was shot)
the misfire was caused by the entire firewall side being ungrounded
however, there’s still a lot of misfiring. I only dumped $450 in addition to the $1,100 I paid, for both parts and because I don’t have a lift at my house.
Anyways, I can relate to your son. He made, to some, a controversial investment decision, getting a used vehicle with 200k+ mi, but with the right care, I think buying a used Toyota/Lexus is one of the best investments a young person can make. I’m happy to be joining this forum.

1933beer

i found the preasure gage and will test pressure.