intermittent trouble code

[dustin77]

I know i probably haven't been searching long enough, but i haven't been able to find it. I am wondering what trouble code will come on while driving and then go off without leaving a code stored? I believe a long time ago I read that a tps code will come and go?! When the light comes on I do loose power it doesnt matter if I am under boost or not. I have ohmed out the tps and it does check good. I am running the maf off of the lexus both housing and electronics with 550 injectors and a .57 trim just rebuilt from driftmotion! Timing is all set. I am running a little lean at 12.3 under 3/4 throttle too scared to go any more, and sitting at 14.5 at idle. I havent driven it more than half a mile at a time, and havent gone wot yet either. I am saving for a maftpro for tuning. I have read somewhere that the lexus electronics can make it run lean, and others have said it doesnt matter! so my other thought was a lean misfire/knock but I thought that if the ecu saw that it would store the code? any suggestions would be muchly appreciated! and sorry for the not so clear wall of text!
Thanks Dustin

 

[BryanDyer]

have you checked for codes even though the light comes on and off?

 

[raysupra]

could be your car is high mileage and your Fuel filter is just dirty... I thought that lex 550's setup ran (Rich) I'd look into other problems

 

[hvyman]

High mileage and fuel filters won't cause the check engine light to go on and off.


If there is electrical issues I would look I to that first.

 

[dustin77]

I don't think there are any wire issues. Fuel filter is new, I did just upgrade the fuel line from 1/4-3/8 don't remember to5/16. The motor is sitting in a 77 Celica. This just started happening after I got the rebuilt turbo and fuel line ran. I was more wondering what codes didn't store? And I have tried checking for codes. Would it be bad of me to jumper it and putt around the block and try and catch it in the act?
Thanks Dustin

 

[jetjock]

If the MIL came on steady after engine start a code was stored but if keep alive power (BATT) is lost thereafter (ignition wired for example) said code(s) will be erased. The second way the MIL will come on is if the system is in diag mode. Since 51 does not set, the system must be in that mode to display it. The third way is if RPM falls below 400 after reaching 500. That's it. The thing does not have a mind of its own...

 

[7M4EVR]

Food for thought:
http://www.supramania.com/forums/showthread.php?46793-Code-51

 

[dustin77]

well no codes are stored. it doesnt drop in rpm and I am not losing any power to the ecu, after the light comes on! I am not in diagnostic mode so I dont think it is that 51 issue, but maybe it is i dont know. The ecu may be stupid but it is smarter than me! I just dont know what would cause the check engine light to come on while I am driving than go off two seconds later, without leaving a stored code!
Dustin

 

[BryanDyer]

There are only 2 codes that don't get stored and are actual real time live codes iirc. JetJock will know.
But I doubt those 2 codes apply to your problem.

 

[7M4EVR]

Sounds like the possibility of an "intermittent" open in the idle circuit could flash the MIL. I posted the link on code 51 because with the information in that post by JJ he tells you step for step how to rule out the throttle plate, the wiring, and the TPS itself. Hell, even if this ends up not being your problem at least you can say you know for sure you have ruled out those things and can move on.

 

[jetjock]

...The ecu may be stupid but it is smarter than me!..

Unfortunately that appears to be true. Ah well, I tried...