CEL appear and disappearing
 

So after about 15 mins of driving or about 20 miles my cel comes on, however after I turn the car off and come out again. No codes.....
I've checked my battery not like its resetting. Previous codes were 51, my idle turns to shit when it comes on. Idles at about 1100.
Any suggestions?

Could be knock. Not all runtime errors are recorded and from what I understand some require a certain threshold to be surpassed in any given instance before it's recorded. There is no code for "OMG there's a hole in the #1 piston and your rods are a knockin!". You can try driving around with the diagnostic mode set and see if any additional codes show up. Naturally there will be a code 51.

Power loss at the ECU to the point of clearing the codes is a possibility but usually this isn't consistent and you'll see a code for inconsistent power show up sooner or later.

Code 51 is just indicative of the IDL switch being open the A/C circuit reporting as "on" and it clears as the trigger condition is resolved. So, it'll show up it you step on the throttle, have the A/C on or the TPS is misaligned but once the condition is remedied it'll go away after a few seconds.

Well as far as vocal noise I can't hear a knock. Everything seems to be good. When I got my car the tps was loose so it was moving and my connector is shit, im gonna replace both of those with oem parts from driftmotion since there right down the street....and cheaper than vatozone!!!! Thank you cre. Im gon a jump the block and drive and see what happens.

Okay so codes 21, 31, and 51

21 - I have a brand new o2 sensor
.....so im not sure there

31 - is the afm correct? Now I've read the FAQ section on adjusting. However when you say the screw has to be a certain distance you mean from the top of the screw to the top of the housing or ? I could use some more insight on this one.

Thanks guys

Well, I'm not there to look at it for you so get your ass moving and do what makes sense (inspect the connector, wiring, sensor for crap stuck to ir, rattling noises when turned, bad gasket).

There was another part in that thread which said NEVER TOUCH THIS SCREW! That thread is only there so you can reset the screw is someones f'ed with it. At any rate, even if someone f'ed up the fuel mixture by dicking around with stuff like an idiot it still wouldn't cause a code 31. RTFM for diagnostics on the AFM.

I've checked all that. And I read that as well however the cap covering the screw is missing. So there is another cause for code 31?

Code 31 is an electrical failure. Nothing to do with the housing or trim screw.

<snip>

Forgot to mention im NA :[

Oh god... sorry. mixing up posts.... Just trying to check in while dashing from one place to another.


Forget everything except that 31 is an electrical failure. Resetting the idle/bypass air screw isn't going to fix that. Test the AFM as detailed in the TSRM.

rotflmao..

Oh okay lol. Well okay so electrical issue.....i
Are you meaning the unit itself or the wiring harness?

http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx

the black box is sort of hard to break unless one goes dicking with it.. trying to "clean" it's optics by spraying something in there and wiping it off.. most likely cause is a faulty wire. I'd start there.

helping to rule things out.. your ecu is not the culprit.. those things don't generally break.. So that just leaves.. your afm. or your afm circuit.. the box or its wires.. check the voltage and you have your answer

My turn.... ROTFLMAO, I believe...

He's got an N/A which means he's got a VAFM (Vane AFM).... They are a wear component and do wear out. ;) But really 20+ years of vibration and bouncing around can take a significant toll on the KVAFM as well. Regardless, the issue here is most likely the AFM or the harness.

missed that..
touche

agreed on the years of vibrations.
I always found it interesting that in the lexus the kvafm wires are held in place more securely then the poor supras..

Can't say that I've witnessed that. They're just newer and more elastic.

the one I have of a ls400 has a nice rubber boot over the connector instead of just the hard plastic the 7m has. also has a secure point directly to the side of the connector to stop wobbles.. they just look beefier. =)

We're getting further and further off topic. I'd be interested in seeing pictures comparing the two though. Perhaps PM me or post a thread about it? I'm sure replacement plugs are still available for the Lex and it may be worth it to hunt down the part numbers for the connector, boot and pins for those who want/need to replace their worn out connector.

Well my question is with all these codes at once, doesn't that kinda hint to the ecu? I mean I replaced the gasket on the O2, checked the connector and wiring and still the code 21. I checked the connector on the afm, i also checked the resistance on the tps and afm and all values were off.

I'm just going based on how common each failure is. AFM, TPS, O2 sensor failing is quite common. Wire harness failure is fairly common. ECU failures do happen but it's not a very common occurrence. BUT, a bad ECU isn't going to make a TPS or AFM fail. So even if the AFM is bad... then you can add that to the existing list. :( If you have access to another ECU to try out then by all means do so but a bad AFM is still a bad AFM....

Which O2 sensor did you replace? The Cali spec vehicles have two, one before the cat and one after. They're not the same. Additionally, if you replaced an O2 sensor which had a heater circuit with a generic sensor which doesn't the ECU will throw an error code for the O2 sensor (GTE models do use these and GE don't but I don't know about Cali spec GEs).

Well although I am in cali this wasn't a Cali car so I have one O2. And its the one just below the manifold

well im gonna have to get the denso O2 sensor from driftmotion when they get them in. i ordered the TPS and new TPS pigtail from them today so im gonna go back tomorrow and pick them up. ill let you know if that helps any of the codes. next will be the afm. i wish i knew people in my area that could swap one with me so i could test it. :wtc:

well guys as shocked as i am the brand new oem toyota tps and tps pigtail from driftmotion fixed my issue. no more check engine. and the car is running awesome. idk but ya. those guys are awesome down there so anyone who can send them your support. :dance:

we always do.. glad you got it sorted.

Okay so very frustrated, the light came back on after numerous drives with no light after the new tps and connector installed. Again I checked codes and 21,41, & 51. How do I know which code is current and which are just stored?
I put the new Tps on and adjusted it, idk if I did that correctly however.

Im just confused and very regretful of buying this damn car. Plz help lol

Code 51 won't cause the check engine light to appear under except while the ECU is in diagnostic mode. Improper TPS calibration will not cause a code 41 either.

Have you tested the wire harness? I would inspect and clean the ECU grounds and grounds from the battery. Test the alternator. Test the Vc pin at the ECU, the TPS, and the AFM connector; It should read 4.8v or so when the ignition is in the "on" position.

The ECU is still a possibility but unless you've got a known good one you can swap in to test with I wouldn't spend money on one without testing as much as possible first... Start with the cheap stuff or this car will sink you financially.



EDIT: Clear codes by removing the EFI fuse in the engine bay fuse box for 10 seconds or more.

thanks cre for the speedy response, well i didn't do anything after the code came on. just parked it and went into work since i didn't have time to mess with it. came back after i was off and drove it home.....no code. hmmm.....well anyways while i was at work i decided to splurge and buy a new AFM since currently i work at a parts distributor and scored a reman one for 100 bucks out the door! :bigthumb: way better than buying retail from vatozone, same part too!.

I went home with no codes on, installed the new AFM. started the car and wow what a difference. no more crazy surging idle. however the idle was up too 1500 and steady, so i re adjusted the tps and knock on wood the car has been running great the past day or so at about 700 to 800 steady idle. i will keep up on this and let you know if more codes continue under driving.