Toyota Nation Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
Greetings,
New to the forum, I have owned several Toyotas over the yeas and have always been impressed with their reliability and longevity. I recently acquired a 2000 Lexus RX300 with 230k in poor running condition. That being said, it is a Colorado car, there is no rust and the interior is very clean. The guy who sold it to me, told me that his mechanic says it needs a new computer. It starts up just fine, the engine sounds good at idle. I was able to drive several miles with no issue, but when the car reached operating temperature, it ran poorly. Which was consistent with the description of the vehicle when I got it.
After reaching operating temp, the car seemed "bogged down" . It never stalled, but felt like it had no power. I need to floor the gas pedal to get the car to go. At full throttle the car would accelerate quickly, but at anything less than full throttle the car won't do anything more than crawl along. It seems like it may be in "limp mode".
After one driving cycle, I pulled the following codes:
P0172 Too rich bank 1
P1150 A/F sensor bank 2 sensor 1
P0330 Knock sensor bank 2
P1130 A/F sensor bank 1 sensor 1
The Previous owner had changed the MAF and the A/F sensors (I usually call the A/F sensors O2 sensors, but what do I know).
I wonder if the knock sensor could be the culprit. I read about a hack where you can wire the bad sensor's wires into the good sensor and trick the ECU into thinking that it's good.
I would appreciate to hear your thoughts. No one is smarter than all of us.
 

·
Registered
Joined
·
19 Posts
If I am in same situation, I will:

1. Replace all sensors, I bought all sensors on engine from eBay and Amazon, Toyota OEM quality, for about $200. Two Knock sensors only $30.
2. Buy a used ECU from eBay and replace it. I bought one for my Highlander for $30. Finally, I found ECU is not problem.
3. Run engine to warm temperature and measure engine compression.

Engine runs poor relate to few things:
1. compression low, (sensor, ECU, piston, valves, timing, VVT).
2. fuel (Injector, ECU).
3. ignition (Coils, ECU).

Good luck!
 

·
Registered
Joined
·
5 Posts
Discussion Starter #3
Update,
I did the knock sensor wiring hack, very easy. It eliminated the P0330 code. However it did not fix the problem. The engine starts great and runs fine when cold, but once it reaches operating temp, it doesn't want to go. It idles fine and never stalls, it creeps along but the throttle is unresponsive unless I floor the accelerator. Shifting seems erratic as well.
 

·
Registered
Joined
·
394 Posts
Do you still have the other codes? Do you have freeze frame data? Any misfire counts? Anecdotally 1MZ-FE seems to be pretty sensitive to the AF sensors so if they are not Denso I would consider them suspect. Same with MAF.
I assume the throttle is by cable on that. Look at data from the TPS and fuel trims when warm.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #5
I have two pending codes, the P0172, too rich bank 2, and p1130 A/F sensor bank 2. I know the A/F sensors, and the MAF were replaced after the problem occurred. I don't know what brand they were replaced with. There aren't any markings on the sensors that I can identify. No misfire codes, I have a cheap wifi connector and a free app. I can try the freeze frame feature, but I'm not familiar with it.
 

·
Registered
Joined
·
394 Posts
If you can’t read and graph real-time data you may want to invest in a more capable scanner. I like the OBDLINK MX+ with OBD Fusion app. The OBD Fusion app has a Toyota/Lexus enhanced PID package that you can buy that allowed me to access additional engine and transmission parameters as well as ABS, SRS, and more. I think the scanner, app, and enhanced PIDs were under $120 at the time.
OBDLink comes with a good app that is probably sufficient for what you are doing now.
 

·
Registered
Joined
·
394 Posts
Bank 2 is the front so easy to try a few things.
My theory is that the system works with ok with default values when open loop but once it goes closed loop a bad AF sensor in bank 2 gives bad data and sets the code.
I would first check the signal wiring back to the ECM and grounds from engine to chassis. If that doesn’t fix it then I would get the Denso part and try it. Other options are to use a lab scope to verify the AF signal at the ECM With the procedure in the FSM or to swap the bank 1 and bank 2 AF sensors.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #8
Another update,
Thanks CR, I learned a ton about Fuel Trim Values, from a video I found on this site.
It is actually bank 1 (my mistake) that is running rich. As suspected I saw the long term fuel values in bank 1 that were way off, in the -40 range.
If I disconnect the battery for a moment when the car is cold it will run great, until it enters into a closed loop state it, goes back to running rich.
Another piece of potential info is that I have a significant exhaust leak from somewhere near the front of the car. I need to investigate further, but I suspect that it may be causing air to get in and corrupt the A/F sensor reading.
 

·
Registered
Joined
·
394 Posts
You do need to track down and fix the exhaust leak, but Hig also has a good point.
There are YouTube videos on how to do a test for a clogged cat using a intake manifold vacuum gauge. The Haynes manual also has the procedure. Check that out and get back to us. If it looks like a clogged cat there are exhaust pressure gauges available to quantify and be certain.
 

·
Registered
Joined
·
394 Posts
But going back to my original statements- that P1130 is a sensor signal failure code. A bad cat should result in a P0420. But it is easy to do the vacuum test and worth trying
 

·
Registered
Joined
·
6 Posts
I'm no expert, just reminds me of my bad cat experience. Bad sensors and rich mixture may be cause of cat failing, but IMO failed cat is causing "limp mode" performance. As soon as my cat was replaced she turned back into a rocket. I don't remember having to replace any sensors, but either age or system problem can be reason for cat failure. I figured it was age at 125K miles. Damn things are expensive, I hope you find out I'm completely wrong.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #13
Hig, Interesting you mention the cat, now I remember the po told me had changed the rear cat, I haven't had a chance to really take a good look at it. but I could see a new y pipe and the connector to the front cat. I would guess that they did a poor job sealing the system as there seem to be new parts down there. Hopefully the didn't break any manifold studs. Cracked exhaust manifold could also be a possibiity, as it would mix fresh air with the exhaust gas, and throw off the A/F sensor. Won't know until I get a chance to really look but this is my first order of business. I may need a good exhaust shop.
My thought is that the p1150, and p1130 codes aren't necessarily saying the A/F sensors are bad, but the parameters they are measuring are out of whack. Especially since the only other code is for the too rich condition in bank 1.
 

·
Registered
Joined
·
394 Posts
Look for air leaks between the MAF and TB.
If your scanner can log real time data, log the actual AF sensor voltage on both banks and the MAF signals
 
1 - 14 of 14 Posts
Top