gtoden1

I have a 1993 LS400, Today I filled her up with the high octane, drove about 140 miles and then notice when I step on the gas (to accelerate) she starts to sputer with no power. When I just give it a little gas she will come up to the speed I want but if I want to accelerate she sputers. I'm wondering if by put in a higher octane which I haven't been doing on a regular basis did I mess up something?

Is there a sensor the may have gone bad? Anyone had this problem or know what is causing this? Thanks for any help you can give.

enia1953

Hi, I just today joined the club. I have ls 400. It was riding fine. It has over 130,000 miles and my mechanic said I could use regular gas. Hence, I did. since then, I have the exact same problem. After that filling, I changed the gas to supper unleaded. I had a home mechanic come and look at it. he could not identify but to tell me it could be ecm or some electrical or master air flow switch of some sort. I hope some one knowledgeable advise us as to how to go about repairing it. Thanks.

PureDrifter

iTrader: (10)

f it happened after you filled up a fresh tank of gas my first suspect would be bad gas...

gtoden1

Pure, would it help to put some Sea foam in the tank?

gtoden1

Has anyone ever had this issue? Are there some sensors I should check?

deanshark

Air Flow Meter. My 93 was running like that and when I unplugged the AFM it ran fine. Not a good idea to drive too long with it unplugged, it runs too rich which will mess up other things, not to mention the real crappy fuel mileage. The AFM sometimes wont throw an engine light b/c the ECU is still getting a signal from it. Here's the specs on what it should be, along with the IACV and TPS; https://www.clublexus.com/forums/sc-...on-issues.html

steve2006

You could try pulling the EFI fuse for a few minutes to reset the ECU it will then allow the ECU to relearn and therefore adapt to the new fuel.
Better still it costs nothng to try it and may sort the problem.

gtoden1

Dean, what did you end up doing to your AFM?

deanshark

I still have it unplugged. (over a year and a half) I get crappy mileage, my last set of plugs fouled out quick, and Idk if it's related but, I can't pull any codes from the ECU now, it just flashes quicker then if everything was good. If I plug it in the car will barely run. I might have messed it up trying to clean it. I can't find one at the junkyard b/c they disappear fast. When I get back to work I'll get one from Ebay or something. No way will I buy a new one for $900. You can try unplugging it to see if your car runs better but if you do, you have to pull the EFI fuse first. And then again when you plug it in again. When unplugged the ECU will go into "fail safe" mode.

gtoden1

Did a check to see what codes I have, got three, a 31, 41 and a 24.

Wanted to ask if I should look at one of these that might be causing the others to show up. Going to get a OHM meter and follow some of the trouble shooting that I read here.

PureDrifter

iTrader: (10)

dean, check the supra forums (3rd gen), so supramania and supraforums for an AFM for your car.

the mk3 turbo supra guys ****** them up by the boatload since they use them to meter in extra fuel with bigger plugs on the stock ECU.

gtoden1

Pure, did you mean to post this here? Not sure what it is.

deanshark

The 24 is for the Intake Air Temp. sensor which is inside the AFM which is why you're getting the code 31. I'm not sure if you can change just the IAT sensor, I think the whole AFM needs to be changed. The 41 is for the TPS. First thing you should do now, seeing how you pulled the codes, is pull the EFI fuse for a minute to clear the codes and reset the ECU, put it back in, drive for a bit to see if anything comes back. You can get an Ohm meter cheap enough to check the AFM and TPS. I changed my TPS with one I got from the junkyard. That was real cheap, it somehow slipped in my pocket.

deanshark

Thanks PD, that's why there's never any at the junkyard, them bastards.