After coming off throttle, stalls and code 31

[--Wolf--]

Freshly rebuilt 7mgte, done about 400kms since rebuild. MHG and ARP studs. Still running in engine. Car mostly stock. First problem with engine today.

Drove for about 5 mins, got to operating temperature and then came off throttle to come to a stop, saw engine check light come on and car started making struggling noises as if it was trying to die. When I came to a stop car died straight away. Started it up again, struggled then died. Started up again and quickly took off and parked up (died again). Checked the basics, couldn't see anything wrong. Gave it a couple of minutes then tried starting it, same problem. Had to get it home so started it and took off, first stop it died again. After that it was alright for a few minutes and then just before I got home I tried to see what was making it die.

Coming off med-hard throttle doing 50kmph and engine check light would come on and it would start to want to die, get back on the throttle and it would go away (both the light and the stalling).

Any ideas? When I parked up at home it didn't die.

EDIT:

Here are the error codes:

12
24
31
32
41

EDIT2:

Code 31 only now. Problem definitely seems to be AFM.

 

[ben1984j]

When the check engine light comes on it means you've thrown an engine error code, and the code remains stored from then on (at least until you reset the ECU), whether or not the check engine light stays on. So you should check your codes, that will give you (and everyone else on here) a lot more information about your problem. In case you haven't done it before...

http://www.cygnusx1.net/supra/TechTips/engine_error_codes.aspx

 

[--Wolf--]

Sorry, should've done that first, here they are:

12
24
31
32
41

 

[--Wolf--]

Cleared the codes, went for a 5 minute drive, was all good until 3/4 the way into the drive when it started doing it again, but didn't die this time. Same thing, came off med-hard throttle and would lose power and engine check light would come on, then would go away after a few seconds.

Checked codes after and this time I'm only getting 31.

 

[ben1984j]

All those codes after a fresh rebuild? Some of them might be leftover...you should try clearing the codes by pulling the EFI fuse for 30 seconds, then drive around for awhile and re-check to see which ones are still there.

However, I'm pretty sure none of these codes except the code 31 could cause the problem you describe; the code 12 only applies on start-up and the rest shouldn't be keeping your car from running altogether.


Edit:
Well looks like you beat me to it and already knew what to do But yeah it looks like the AFM is the problem...inspect it per the TSRM to make sure.

 

[--Wolf--]

Will do but don't have the tools here. Safe to drive a a distance of say 10, 20kms as is?

 

[ben1984j]

Yeah it's safe...you'll just be running really rich, shouldn't hurt anything.

 

[89supra7mgte]

I have the same problem, after letting off throttle car stumbles and cant regain idle all the time, has code 31, smokes bad and can smell the fuel. Tested afm and it appears to test good.

 

[ben1984j]

I have the same problem, after letting off throttle car stumbles and cant regain idle all the time, has code 31, smokes bad and can smell the fuel. Tested afm and it appears to test good.

If the AFM is good and you're still getting code 31, there could be a bad/loose connection at the AFM plug...try replacing the plug.

 

[--Wolf--]

What are the chances of rain causing it? Was raining for the first time today since I got the Supra back when all this started happening, but when driving it tonight and there was no rain it was fine?

 

[ben1984j]

What are the chances of rain causing it? Was raining for the first time today since I got the Supra back when all this started happening, but when driving it tonight and there was no rain it was fine?

That's just a coincidence...

 

[RiyadYar]

is you bov vented to the atm. make sure theirs no boost leaks or if it is vented to atm. that the nut is not loose .

 

[--Wolf--]

Apparently it is recirculated, but it sounds like I'm getting surge back. Will do those checks.

Also has started to back fire when letting off throttle now.

 

[ben1984j]

Yeah, the backfire is most likely a symptom of the same problem...since those are often caused by running rich...

 

[sparkplug619]

I had a similar problem when my maf (non turbo) came loose and too much extra air was going through the intake

Also had the same problem when I first bought my 90, my afm (turbo) connector had a piece of a leaf in it, it gave me a code 31 and 26, I cleaned it out with compressed air, it cleared the code and my car no longer cut off

 

[--Wolf--]

Alright had the AFM checked by a mechanic, including the circuits inside it and he couldn't find anything. Haven't put it back on but assume I'll still get the same problem.

What else can I check?

 

[Poodles]

Kinda doubt he checked the circuits inside it...

But, swap the AFM and see if it fixes it.

 

[89supra7mgte]

I replaced mine and now my problem is completely gone. Had 3 prior that tested good but were infact bad. so like said above try finding one to swap with to test.

 

[--Wolf--]

Will try and find another one to check. But I think he did check inside it, the black box has been sealed up with sealant.

 

[Poodles]

There's nothing to check in there, if you disturb the mirror it's trash...