Codes 12,13, & 31?
05-05-15, 05:01 PM
#1
Codes 12,13, & 31?
Thanks for looking in guys. So about 2 weeks ago, I decided to change out my IAC due to a 3-4 times a month random engine shutdown. Usually would happen while sitting at a stoplight while the engine was at idle. I picked up a used idle air controller and installed.
Car ran good for about 2 weeks, then all of a sudden it would "buck" while driving. Car would go 2000rpm to 800, then back up, then turn off. I had to have the car towed home, let it sit outside overnight. Next morning it started, but only enough to get her into the garage. I changed out the IAC for 1 other spare, no fix. Put back on the original, again, no fix. I have checked all connections, plug wires, swapped out coils, etc. Can't seem to find anything easy. Pulled codes tonight and got 12, 13, and 31. No RPM signals and Air flow meter signal. Everything is plugged in as it should. Any suggestions? Thanks in advance.
All ignition parts (coils, plugs, wires, caps, etc have less than 15k miles).
Car ran good for about 2 weeks, then all of a sudden it would "buck" while driving. Car would go 2000rpm to 800, then back up, then turn off. I had to have the car towed home, let it sit outside overnight. Next morning it started, but only enough to get her into the garage. I changed out the IAC for 1 other spare, no fix. Put back on the original, again, no fix. I have checked all connections, plug wires, swapped out coils, etc. Can't seem to find anything easy. Pulled codes tonight and got 12, 13, and 31. No RPM signals and Air flow meter signal. Everything is plugged in as it should. Any suggestions? Thanks in advance.
All ignition parts (coils, plugs, wires, caps, etc have less than 15k miles).
05-06-15, 09:23 AM
#6
Three things combined to eliminate hesitation and bucking on my car: TPS adjustment, IAC servicing, and replacing the ignition coils. New upstream O2 sensors made no difference whatsoever (including for mpg's), and it's not like they're the easiest or cheapest thing to replace on a whim.
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Wouldn't hurt to crack the ECU open and check for leaking and corrosion.
05-06-15, 11:45 AM
#9
The ECU is my best guess, as mentioned with the earlier MAF comment, but you might also try the temporary bypass (+b and Fp jumpered) to see if the fuel pump ECU is dying/dead. I had some stalling issues that went away after servicing the ECU and bypassing the fuel pump ECU.
05-06-15, 02:03 PM
#10
The ECU is my best guess, as mentioned with the earlier MAF comment, but you might also try the temporary bypass (+b and Fp jumpered) to see if the fuel pump ECU is dying/dead. I had some stalling issues that went away after servicing the ECU and bypassing the fuel pump ECU.
05-10-15, 09:57 PM
#13
Driver School Candidate
I had the same EXACT issue with my 92 5spd for the the past few weeks. Blew the head gasket , pulled motor, new water pump, oil pump, gaskets, etc, etc... and threw the same series of codes. What you should do is check resistance at ignition coil, distributor and igniter. but its most likely your MAF is bad. MAF sensors are EXTREMELY sensitive, so if you had one just laying around in a box with other parts picking up dust and getting thrown around, chances are its no good. I went through three junkyard MAFs before getting one that worked, all had the same issue. . It would start and run fine for about 9-10 sec. then fall on its face and run like crap. When the ecu doesn't see the signal, it throws it into a fail safe mode so you can still drive the car (barely). The ecu doesn't see MAF/ Intake temp signal for about 9 seconds and inputs its own constant. I wouldn't recommend using MAF cleaner either. I was on the fence about using it. Heard good and bad things, and now I'm convinced that's what caused my original one to go (off a perfectly running motor before head gasket issue). Aftermarket MAF runs about $200-$300, OEM $500-$700. I decided to search the junkyards. And people love breaking other stuff trying to gee what they need...I have the lexus service manual at our shop. Ill post the diagnosis procedure with resistance tolerances for you later tonight, but I would start looking into a new MAF. You should check the MAF housing as well. There is a screen designed to create an airstream (karmen vortex) for MAF sensor. Make sure its not bent or dirty. Luckily, I found that had been on the yard for only few days. Engine Looked very well taken care of (despite the fact it was at pick-n-pull) cleared the codes, plugged it in and
I couldn't have been happier. I tend to grab ignition coils and igniters as well. they seem to be good things to keep around. early model GS300 has NA 2jz as well. Those are a little easier to come by than the SC
I couldn't have been happier. I tend to grab ignition coils and igniters as well. they seem to be good things to keep around. early model GS300 has NA 2jz as well. Those are a little easier to come by than the SC
Last edited by NPHendo42; 05-10-15 at 10:01 PM.
05-10-15, 10:56 PM
#14
The MF can be cleaned it's just delicate and requires a bit of finesse on the older SC's (92-95). The older SC's have a Von Karmann vortex sensor MAF which is basically a laser reflecting off a mirror and the disruptions in the laser's reflection are measured to determine airflow across the laser. If the mirror/reflective surface starts to get dirty the older MAF's will stop working properly.
To be cleaned, the best product to use is compressed air to remove surface smudges if possible. The surface needs to be perfectly clean for it to work properly. Any sort of oily spray or spray that leaves residue will cause problems, especially since the reflective surface is hard to reach and most products that require wiping are pretty much ruled.
If you have a 92-94 DO NOT USE MAF Cleaner or anything of the sort, it'll leave deposits on the mirror and will not improve the surface at all. Glass cleaner will be less damaging and work better than MAF cleaner.
Now if you're dead set on fixing it, follow the instructions in this thread for cleaning the MAF
https://www.clublexus.com/forums/per...rywhere-2.html
SCFrogger describes the process partway down page 2, here's the cliff notes.
-one or two drops of contact cleaner on the mirror
-tiny screwdriver wrapped in bits of paper towel
-lightly rub at reflective surface with paper towels on screwdriver until dry
-spray with compressed air
-hair dryer at distance to dry the unit
-leave it to dry overnight
-wipe one last time with paper towel
-one more spray of compressed air
It's quite a bit of work, and can be touchy, when I did it, I had to clean it twice to get it working properly because I still left some residue on the mirror. But it's definitely the way to go, as most Karmann MAF's you find now are most likely also dirty.
To be cleaned, the best product to use is compressed air to remove surface smudges if possible. The surface needs to be perfectly clean for it to work properly. Any sort of oily spray or spray that leaves residue will cause problems, especially since the reflective surface is hard to reach and most products that require wiping are pretty much ruled.
If you have a 92-94 DO NOT USE MAF Cleaner or anything of the sort, it'll leave deposits on the mirror and will not improve the surface at all. Glass cleaner will be less damaging and work better than MAF cleaner.
Now if you're dead set on fixing it, follow the instructions in this thread for cleaning the MAF
https://www.clublexus.com/forums/per...rywhere-2.html
SCFrogger describes the process partway down page 2, here's the cliff notes.
-one or two drops of contact cleaner on the mirror
-tiny screwdriver wrapped in bits of paper towel
-lightly rub at reflective surface with paper towels on screwdriver until dry
-spray with compressed air
-hair dryer at distance to dry the unit
-leave it to dry overnight
-wipe one last time with paper towel
-one more spray of compressed air
It's quite a bit of work, and can be touchy, when I did it, I had to clean it twice to get it working properly because I still left some residue on the mirror. But it's definitely the way to go, as most Karmann MAF's you find now are most likely also dirty.
Last edited by eknine9; 05-10-15 at 11:02 PM.
05-19-15, 05:08 PM
#15
So I got the ECU back from Tannin. They opened it up and saw no visible issues. I had them rebuild it anyways since they offer great service at a good price. Highly recommend them.
Problem not solved! Started digging a bit more into it. Tonight I pulled a plug wire, no spark. Pulled that same side coil wire, no spark going to the cap. Both coils were replaced about 18 months ago as preventative maintenance and have less than 10k miles on them. Codes 12 and 24 showing now showing when I pull them (no RPM and no IAC).
The IAC that is back in the car is the one that I had changed out a while back because of low idle and an occasional stall. (I had gone back to a known somewhat good one to try and isolate the issue). I will change that back out tomorrow and see if anything changes. If no one has any suggestions, I will likely take it to the dealer this week. Towed of course. Lucky for me, even though I will have to pay dealer prices, there is an excellent tech there that I fully trust.
Problem not solved! Started digging a bit more into it. Tonight I pulled a plug wire, no spark. Pulled that same side coil wire, no spark going to the cap. Both coils were replaced about 18 months ago as preventative maintenance and have less than 10k miles on them. Codes 12 and 24 showing now showing when I pull them (no RPM and no IAC).
The IAC that is back in the car is the one that I had changed out a while back because of low idle and an occasional stall. (I had gone back to a known somewhat good one to try and isolate the issue). I will change that back out tomorrow and see if anything changes. If no one has any suggestions, I will likely take it to the dealer this week. Towed of course. Lucky for me, even though I will have to pay dealer prices, there is an excellent tech there that I fully trust.