deanshark

Just b/c the code cleared after you changed your T-belt does not mean that the T-belt is the cause for all code 13s. Although in the manual, in the "trouble area" box it does mention (skipping teeth of T-belt, belt stretched) that is only 1 possibility. It also mentions the crankshaft and camshaft sensors, or a short in those circuits.

atropine; When you check the cam and crank sensors, the resistence is
cold 835 - 1400 ohms
hot 1060 - 1645 ohms
Don't go changing your T-belt unless you check the timing marks and they don't line up, or if the belt looks bad. If the timing was off (jumped a tooth) it would run bad all the time, not just up hill with a load. Check the AFM, sometimes that doesn't throw a code when it is bad b/c the ECU is still getting an electrical signal. Clean the throttle body. (tutorial from lexls.com) Another thing that could be one of your problems is the ECT sensor. (Engine Coolant Temp) It's the main sensor for the fuel system and only cost 20 - 30 bucks, plus it's easy to change. It could be one of the causes for your other codes (25-26) Do a search for the ECT, you'll get some good info.

atropine

Hey guys-
I still haven't had time to spend in the garage working on this thing yet. But I have been driving it a little more; I drove it another 150 miles today and it is getting worse. It was hot here in Vegas today; prob 90-91 degrees. Above about 2800-3000 rpms it usually gets smooth and strong, but it is really misfiring and shaking/sputtering up until then. Also, today was the first time I have driven it in stop and go traffic in town; I noticed that the temp gauge was climbing dangerously close to the warning light. Once I was back moving again on the freeway, the temp came down to normal. Gonna read up on the ECT. I did a quick search for "ECT" and didn't find exactly what I was looking or but I'm sure with a little more searching I will figure it out. My fuel mileage is now down in the 18-19 range.

atropine

I had just a few minutes to work on the car today. So I replaced the ECT sensor ($14 at Autozone). Amazingly, this probably cured my problem about 75%. I just did a little test drive down the road a couple miles, but it was clearly a MAJOR improvement. I can still feel just a little of the same original issue anytime I go to accelerate, and the car does not accelerate with the power that it should. Clearly there is still something else wrong but I am amazed at what a difference there was with just a simple ECT replacement. I also cleared the ECU codes and will wait to see if any codes return.

deanshark

It's amazing how much that little sensor does, isn't it? And it will save ya some gas too. Hope ya figure out the rest, check out the things we mentioned. GL

atropine

Thx for the help. As soon as I get some more time I will start checking all the other things you guys have suggested. After spending a little time with it in the garage today, it smells like it is running a little on the rich side (even after the ECT sensor replacement). I am tempted to drive it back and forth to work for a couple days to see what my fuel mileage is now, but with all the plastic cover crap off the engine I kind of just want to tear down and inspect all the above mentioned items....

deanshark

Hey, just for ****s and giggles, try this if ya have a few minutes. Take out the fuse for the ECU, unplug the AFM, replace fuse. That puts the ECU in "fail safe" mode and bypasses the AFM. Drive it and see if the problem goes away. If it's still there then it's not an air/fuel mixture problem and you can rule out the AFM. It seems like the AFM is a common problem though. I've been pointing this out to alot of people lately. https://www.clublexus.com/forums/ls4...nging-too.html

atropine

OK. Only had a couple minutes to look at it tonight; I drove it for just a couple miles today and the CEL came on for a minute but then went away again. Retrieved a #13 code tonight, but that is the only code. So I tried unplugging the MAF after removing the ECU fuse (wasn't sure which one so I removed ECU B and ECU Ign from the inside fuse panel and also EFI fuse from the engine compartment fuse panel). No change. Smells rich standing near the back of the car and smelling the exhaust. Next step is to try cleaning the throttle body and testing some sensors with a multimeter. If only I had more time to spend in the garage...

atropine

BTW- can anyone confirm the # and location of the cam sensors on this vehicle? i thought there were 2 cam sensors and 1 crank sensor. i will do some more searching through the above links but it would be nice if anyone could give me some quick pointers!

JAndersson

See picture below. Hope this helps.

deanshark

Good job trying to search first. Seeing how I'm just sitting here I'll point them out to you. lol The #1 cam sensor is drivers side and #2 is passenger. In this link you can see the cam sensor connectors in #10 which you can unplug and check with an ohm meter. You can see the sensors in #13. They are on the distibutor itself. And then ya got the crankshaft sensor down by the crank pulley. You can see it in #18 to the right and below the pulley. http://www.lexls.com/tutorials/engine/timingbelt.html
Check the resistence of the sensors before just replacing them b/c it can get expensive to change parts that don't need to be changed.

atropine

Thx guys! That will speed things up for me immensely. I definitely don't want to just start replacing sensors randomly, as I am trying to make this a low-cost project. I will start testing sensors as soon as I get the throttle body cleaned and inspect the spark plugs. Thx again!

atropine

OK- quick update. Spent a couple hours in the garage last night. Prior to last night car was starting to run very poorly again-- I am a little frustrated how the car runs better after fixing/changing some things, but then after 15 minutes of driving starts to return to its poor behavior. Prior to last night it was actually starting to die on me when I would let of the gas just cruising around the neighborhood. So I cleaned the throttle body according to the LexLS tutorial; no change. Cleaned the MAF sensor, no change. Checked the resistance on the crank sensor and it was in spec at 1130 ohms cold, but I went ahead and put a new one anyway; this caused a significant improvement and no more stalling issues now. Pulled the spark plugs and examined them-- they all looked good until the last one (driver's side, most rearward one, not sure which cylinder # this is). This spark plug looked "oily/wet", like it hasn't been getting a good hot burn like the other cylinders. So I cleaned it up and reinstalled it, but I still fells like I have an intermittent misfire below 3000 rpms. I checked the resistance on the left cam position sensor and it is in spec at 1313 ohms, but I am tempted to swap it out anyway after seeing an improvement with a new crank sensor that was reading in spec also. I inspected all the spark plug wires/coil wire on the left side and it all looks fine. Previous owner replaced all the spark plugs/coils/caps/rotors already, but I really suspect an ignition problem in that cylinder. I plan to run a compression test on it, but I doubt that is the problem since I have such great power/smoothness above 3000 rpms. I still plan to run electrical tests on the MAF, TPS, and EGR sensors- just haven't had time yet. I unplugged the left side cam position sensor and drove around for 10 minutes and the car didn't act any differently--still has an intermittent misfire at idle and sputtering while accelerating under a load below 3000 rpms. It is overall better than when I bought it but something is still not right. With this info do you think replacing the left cam sensor has a decent chance of fixing my problem?

chadr

"Cleaned the MAF sensor" has caused problems for others as I've read here on the forums.

crank and cam sensors would be the very last thing I suspect, especially if the resistance is in spec. The oily plug and rough running could be from an injector not firing (this was the case for me). Mine had a connection issue following the valve cover gasket replacement I did. You can listen to the injector pulses by using a long metal rod against a cup on your ear or mechanics scope. See if that injector is clicking or sounding like it should. You can measure the resistance of the injectors too but none of this will actually guarantee it is working correctly. It may give you some ideas though.

radiohound

I too am having the same problem ...and like the other gent ... I too have changed coil #2 ... have recent new plugs, dist cap, rotors, wires, etc. It just started doing the hesitation dance.

Changed out the fuel filter and the MAF sensor. I also don't have the EGR valve and filter as it shows in the tutorial .. but have the same set up as the poster. Today, I was looking at a wrecked 94 and they have a very different set up,. I have a non traction control car s maybe they route these things differently ...

But I am at a total loss at what is going on ... I am ready to start looking at the ECU ...

Any help would be appreciated because either I get this working or I have to go find another Lexus

atropine

thx- i am going to pick up a mechanic's oscilloscope and listen to the injectors this weekend. i unplugged the spark plug wire going to that #7 cylinder and the engine didn't behave markedly different. then i removed the spark plug and reconnected it to the wire and started up the car; watched it spark and it looked just like it should. a faulty injector at that cylinder would make sense.