in need of help code 31

89supra7mgte

New Member
Sep 20, 2009
797
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colorado
Ok i have made one post earlier about code 31, got off topic and not much help so here goes again. Car starts and idles fine revs up but soon as you let off it dies, sometimes will regain and keep idling but rough. I have went through replaced the afm, checked and tested resistance and hz on it. Checks out ok. Set the tps to spec (tsrm) Checked vacuum leaks everywhere possible yet to find any. Is there any other possible reasons why the car is doing this? I am at a complete loss. I am going to check the egr system tomorrow, and engine vacuum. I dont know what else it could unless it is another faulty afm, or a false code please help
 

LamaRossa

One and Only LamaRossa
Apr 6, 2005
131
0
0
44
ct
i forgot what the hell its called

on the throttle body theres a spring valve with adjustable screw.. and when the throttle is close it rest on this valve... as a cushion.... adjust it up a bit... mine did the same dies after rev..... i adjusted it... sometime aftermarket bov lose screw will cause idle to die if its running pig rich...............
 

89supra7mgte

New Member
Sep 20, 2009
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colorado
I tried adjusting that but no change in how it acts everytime like clockwork same thing, even barely touching the throttle by hand it does it. and sets code 31. I have good vacuum in engine 12 inch, good fuel psi and doesnt drop when car dies. pulled turbo pipe off to intercooler still runs? have good flow. I dont know what else to check? did notice have no flow through egr cooler (head) egr works manually but dont seem to have vacuum at idle? Not to sure on how that system works through the vsv and ecu? When apply vacuum to egr at idle car revs u instead of dying?
 

89supra7mgte

New Member
Sep 20, 2009
797
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colorado
Ok post number 3 on this damn car still cant get any help to solve the problem. Ok here is the problem:

****Car dies when let off throttle, neutral or running. High rpms, or idle. sets code 31 when dies*****

The car: 1989 supra 7mgte all stock, with exception of hollowed cats(plugged) and egr delete(no emissions and not functional)

The tests/checks i have performed:
1. Test afm, ohms good. Have tried 3 now one being lex
2. Test inspect and reset cps.
3. Test inspect and clean isc valve
4. Inspect and test all grounds and wires from ecu out to engine
5. Check for vacuum leaks (none)
6. Check engine vacuum, steady 12 at idle
7. Check fuel psi 34 regulated 41 unregulated
8. Check dashpot for proper operation good

I am at a loss please help. I have read the tsrm many times but cannot find my answer. the car idles fine but touch the gas and let off and it dies, tries to catch itself around 500 rpm but cant regain. I need this car to run but cannot figure it out please help thanks.
 

89supra7mgte

New Member
Sep 20, 2009
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colorado
The entire system is stock, so no aftermarket blow off valve, what is the valve from the accordion to the 3000 pipe? has the vacuum port on it? how should that operate?

As far as the trouble codes i have none when cleared and engine idling hit throttle and release sets afm code like clockwork. but it only sets when doing that i can let the thing idle all the way up to full op temp and never have any code
 

IJ.

Grumpy Old Man
Mar 30, 2005
38,728
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I come from a land down under
You had 3 threads on the same thing I just merged them into one, I'll repeat myself this once, Don't Post another on this topic you won't like the outcome.

If someone had an idea they would have posted it by now.

All I can suggest is go back to the basics, Check the TPS Calibration for the Idle signal, Remove and clean the ICS, check base timing, check for any leaks in the intake manifold.
 

jetjock

creepy-ass cracka
Jul 11, 2005
9,439
0
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Redacted per Title 18 USC Section 798
89supra7mgte;1419080 said:
... I have good vacuum in engine 12 inch....

89supra7mgte;1420965 said:
Check engine vacuum, steady 12 at idle

Sounds good to me. :nono:

OP: although I'm retired from this zoo here's a one time tip: If you've tried 3 afms and none have solved the problem maybe it isn't the afm eh? Here's another shocker: you should be able to remove the air filter, afm, CBV, accordion hose and all the associated induction and ISC plumbing and the engine should still idle and run. Near normally in fact. When I had my car I drove it around town like that several times, codes and all. Even posted a vid of it. Since the engine is *supposed* to be able to do that maybe, just maybe, you're looking in the wrong place...
 

89supra7mgte

New Member
Sep 20, 2009
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colorado
Good call JET i am actually about to go and start pluggin some of those valves/hoses just to see. I have been kinda leaning towards a false code atleast that is what i am hoping for, before deleting the egr i found that when i apply vacuum to it it idles up leading me to believe i have a vacuum leak, but cant find it.
 

89supra7mgte

New Member
Sep 20, 2009
797
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colorado
Ok so i have a little update on my situation. Went through rechecked the basics timing, tps , cps, afm and so on. Found that when i tap throttle and right before car dies or attempts to the fuel pump relay clicks back and forth as the car is hesitating. I see the resistor in there and that my voltage is only around 10v is this normal? It is also running rich not sure if i can adjust fuel psi with stock reg or how i can fix that? fuel psi tests from before indicated

33 regulated and 40 unregulated.
 

supra22

New Member
Apr 15, 2009
9
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Knoxville, TN
Any update on this issue? I am having some of the same symptoms with my 87' 7mgte...code 31, car dies easily if cold not to mention a bear to start, I have no power and no boost. I have checked pretty much everything mentioned in this thread and I am out of ideas.
 

89supra7mgte

New Member
Sep 20, 2009
797
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colorado
Mine was actually faulty afm. purchased 4 and lucky number 4 worked. As for the egr testing i did, disregard it was plugged on back of head so i was creating the vac leak.

I should have updated along time ago, but my fault was the afm and the used ones i had purchased.
 

supra22

New Member
Apr 15, 2009
9
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0
Knoxville, TN
UPDATE: I had purchased a replacement AFM for my car and it too fixed all of the problems I was having. It looks like I got lucky and bought a good one the first time around. I still would like to test out my damaged AFM and see what the problem might be. It would be great if I could figure out how to fix it and maybe post a how-to...this seems like it would help a lot of Supra owners out.