AdamMak90

Hi,
I have 04’ RX300 (IIgen) and I’m struggling with a problem: my lex have different level of Fuel long-term trims. On bank 1 is about +15/20%, on bank 2 is about -5/10%. This causes to low idling and bad bibrations on dash. What I checked or/and replaced:
-new spark plugs (Denso)
-new valve cover gasket on both banks
-new air intake gasket
-set the right valve clearances
-all Ho2s sensors checked- all good- to be sure I changed the sides of the sensors- still the same issue with the fuel trims
-checked purge valves- all good
-time to time I get the check light with code p2196 (Ho2s sensor, signal stuck rich)
- changed ignition coils sides( from b1 to b2, and from b2 to b1)
- no intake leaks( checked with smoke, and foam)

my mechanic friend aks me to check the timing belt( i changed it 35kkm Ago), could I check it with TechStream? Like check the signal from camshafts sensors? Or I have to check it right on the belt?
or could exhaust leak could do this issue?
I have no more ideas what could happend to my engine

Mesquite77

WAG, bank 1 has a burned valve or broken ring, causing low compression, so high O2 in exhaust, therefore high plus fuel trims.

What does a compression test show for each cylinder, dry first, then with oil added?

AdamMak90

Hi, thank you for your answer. So I did the copression test, with some Yato’s tool, and it showed me between 14 and 15 bar on all cylinders. So if bank 2 and bank 1 have the same compression, I think problem is not from valves or from one of the cylinder, but from whole bank 1. Also all 3 sparks from bank 1 is darker than from bank 2.

Mesquite77

So good news with compression. Maybe electrical, some peeps here very good at deep diagnosis like: https://www.clublexus.com/forums/rx-...e-ckp-cmp.html

AdamMak90

Oh, so it could be only a dirt in my engine?
I will check it, with oil change
It started from oil change, I used Motul 8100, 5w30 ( my parts shop guy recommended this oil, I have been using Millers before)

AdamMak90

Sorry for the post right under the first one, but I think clearing the intake is working so far. I have got trims on minus on both banks right after heat up the engine. I will ride for some time and keep watching on trims.
and here I have the second question, on how level should be the idling? i have about 850 on neutral and about 550/600 on D, I gues that is too low, am I right?

Leeper

Have you checked the fuel injectors? Often times dirty or clogged fuel injectors can cause the symptoms you're speaking of. It is an easy fix by making a homemade cleaner adapter/tool or there are companies you can send them off to for cleaning, rebuilding, and flow testing that are not very expensive. You can also look at the fuel injector bases while the engine is running to see if there might be any leakage at the seal, not uncommon as these cars age and the rubber dries, cracks, and shrinks. It would be noticaeable as the fuel is under high pressure it will bubble up from the base of the injector, the solution if that is the case is simply replacing the seals but while there might as well clean each one.

*** if you do this job yourself, I'm about to do mine, I strongly suggest purchasing a set of new seals those run @$25 on eBay.

AdamMak90

Thank you for the answer. I tought about cleaning the injectors, but till now I only added the cleaner for incejtors to Fuel. Yeah, this car is not young anymore, so I could change those seals to be sure it is hard to take off the injectors?
my mechanic said that injectors shoudn’t be dirty only on the one side of the engine, but maybe it will be better to clear it.

Margate330

Already great posts.

Can I please add, as we can see you have one bank rich and one bank lean.

It's common on our cars for people to do new stuff on the easy bank aka front bank and neglect the rear bank.

Couple of things.

(1): your MAF should be at 3.3g at idle, engine fully warmed up as I can see it is by your scanner data.

(2): I bought a whole set of six flow matched OEM fuel injectors on eBay from a seller with good feedback rating. Recommend only get flow matched if buying used. It's critical to get balanced fuel delivery. New OEM coils were expensive and I didn't want aftermarket so that's what I did.

(3): weak spark from old or fake clone ignition coils can raise fuel trims.

Good luck, plz keep us posted.

AdamMak90

Thank you for your thougths!
1. Right now I have about 3.5g
2. I will clean the injectors by myself or I will send it to Company which will clear the injectors and fix it if it will be needed
3. I have all 6 new sparks Orginal Denso, bought in my trusted parts shop

tomorrow I will go for longer ride to check if this clearing of the intake will helped for longer time

adding last data

Leeper

This is what I made, worked great! I've used it on two of my cars so far will do the RX here shortly. As said though be sure to replace the seals and other small rubber pieces the kit runs @$25 USD on eBay. Lastly - be careful when disconnecting the fuel rail as it is under high pressure will squirt gasoline all over cover it with a rag


Good luck

Leeper

I just ordered a seal (Amazon $14 USD) kit so I'll do a comprehensive write up on how to clean the injectors and replace all the rubber bits either this weekend or the following

AdamMak90

Very nice! Could you send me a link for the set of those needed seals? There is many of it at polish ebay but I’m affraid to buy wrong or low quality ones

Leeper

This is what I just orderd, cannot confirm yet 100% that it is the right fit until I install. Also my car is a 2004 RX330 with 171K miles, you stated in the first post that your car is a2004 RX300 if that is correct I do not know if these are the right ones


This is good preventative maintainence if your car has decent miles/kilometers on it though it may not be your issue. In looking at your issue it would be more likely a clogged/dirty injector than a bad seal but they are cheap and should be replaced anyway. As I mentioned in a prior post while doing this good idea to clean off your O2 sensors (one one top of engine easily accessed, one below also easily accessed no need to unplugged just loosen, spray with carb cleaner, wipe down, spray again, reinstall but make sure you wind the wind backwards so when your finish threading it back in the wire is straight. You should unplug the battery for a couple minutes then hook back up this will reset the ECU to relearn your driving style. Reset your windows and sunroof and drivers seat memory. This is free aside from the brake cleaner. As a result of my doing this my gas mileage went up considerably. I'll do this again after messing with the fuel injectors in case they are flowing differently I will assure the engine ECU learns again.

AdamMak90

Thank you for the answer. I will clean the injectors next week, I already bought new seal for injectors, but OEM, and only those between bank and injectors. Despite the good lookin Fuel trims I still have bad vibrations on my cockpit and sterling wheel when transmissions is in D or R possition. There is enough oil in transmission box. I will clear also the camshaft sensors, maybe its have some metal filings on the magnet side. I Think I have to check the exhaust leak too, maybe from this the vibration comes