CEL code 31 only at idle

[quark]

Hi guys

I have a problem that I dont understand.

I´am running a gt3076r turbo with 3" open exhaust all the way out.

The car starts to idle very bad and gives me code 31 at idle. When I give it some gas the CEL goes away and the car drives fine. What is the problem?

TPS is new due to a missing IDL signal and installed within specs.

Some times it starts up and dies, I then have to push the throttle to make it run, if the AFM was bad, wouldt that give me a code all the way up on the rpm scale? I have also tried with another AFM we took of a working car, and I still had the bad idle. (The AFM had another serialnumber (older), but I am pretty sure that they work the same.)

I am thinking of the Narrowband sensor, could that cause the fueling to go furbar and tricking the ECU into beliving that it is the AFM who is giving a bad signal?

Hope you guys can help me out.

 

[ben1984j]

Hi guys

I have a problem that I dont understand.

I´am running a gt3076r turbo with 3" open exhaust all the way out.

The car starts to idle very bad and gives me code 31 at idle. When I give it some gas the CEL goes away and the car drives fine. What is the problem?

TPS is new due to a missing IDL signal and installed within specs.

Some times it starts up and dies, I then have to push the throttle to make it run, if the AFM was bad, wouldt that give me a code all the way up on the rpm scale? I have also tried with another AFM we took of a working car, and I still had the bad idle. (The AFM had another serialnumber (older), but I am pretty sure that they work the same.)

I am thinking of the Narrowband sensor, could that cause the fueling to go furbar and tricking the ECU into beliving that it is the AFM who is giving a bad signal?

Hope you guys can help me out.

Not necessarily, seems like most of the AFM issues I've read about, the illumination of the check engine light actually is throttle dependent. Not that it really matters since the code remains stored regardless of whether the CEL stays on or not.

Pretty sure your problem has to be AFM-related, if you're sure the AFM you swapped in was working (which you can verify: http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=96) , then I would say the next thing to check would be the plug and wiring...

 

[quark]

Thank you for the reply. If its not RPM based, and its possible for it only to have problems at low rpm, then it could be the reason. The gt3076 moves alot more air than then ct26 at idle, and I was thinking that it maybe creates shockwaves in the intake. Also I am pretty sure that I have 2 problems in one. Wires have been checked.

 

[3p141592654]

What's in front of teh AFM? If you have any disturbance from an unshrouded fan or other air flow and the AFM input is not well shielded from it then you will see problems. Hook up a DVM, or better a scope, to the Kv signal and see how stable the pulses are at idle.

 

[IwantMKIII]

^disturbances? how do you figure? Any air entering the AFM will be METERED and should not cause issues, fan shroud or not. When you're driving 80mph down the highway do you really think there won't be massive fluctations of airflow and temp under the hood?

 

[3p141592654]

If you don't know don't post. The flow of air into the KV AFM must be laminar, hence the egg crate in front of it, but if there is an aftermarket filter bolted to it and buffeting from external sources (such as from a missing fan shroud) the flow can be beyond straightening with the egg crate resulting in degraded performance, especially at low flow such as idle.

 

[quark]

IwantMKIII Who is talking about switching to a narrowband sensor, do you even know what a narrowband is??? Advice like yours is dumb and unwanted. Go somewhere else.

I have nothing in front of the intake. Wires have been checked from ECU to AFM. zero resistance. AFM have been taking of a working car and still the same fault.

 

[3p141592654]

When you say nothing, do you mean it is open to the atmosphere without a filter or stock air box?. May be you can post a picture.

 

[quark]

I have build more supra/celica engine´s than you have farted. This is not a simple code 31, but if you care to read what I am writing, you would know that, so kids stay out of this.
Web moderators. Please move these spammers from the thread.

Everybode else I would love to hear your comment on the original subject.

I run on the original intake with a Lexus AFM, even a original airfilter. Offcouse my intake pipes have been changed from turbo to lexus. But this started suddenly. So I have good wires from ECU to AFM. I have a good working AFM, thats why I have an idea that the Narrowband is reading very lean og rich, and for that reason the ECU thinks that is the AFM giving a wrong signal, but it only theory.

Another theory is that I have shockwaves in the intake. I have a very high flowing hotside, with porting all the way, so even in idle this turbo pushes alot of air.

 

[Poodles]

Cut the crap, this is my only warning.

 

[quark]

Pictures

The bov has been put into the Intake since then.

 

[quark]

Who says that i builds boost? Now you make up things in your head to? It blows air around the system at idle, something like a hairdryer. More than a ct26 would ever do.

Why dont you shut up, who do think YOU are, do you think you are all that?

Just stay away and let people who knows something write here.

And last time would you please keep your head out of this thread. Nor you or your friend has been anything but talking down to my, so íf you don´ understand anything anyway, then just stay away.... Please STAY AWAY..

 

[jetjock]

1) 3p is right.

2) Contrary to what you may think it *is* a simple code 31.

3) The NB theory is not possible.

 

[3p141592654]

Quark, you are not getting a good AFM signal at low flow. Since your intake is stock, its not a laminar flow issue. Best bet is to look at Kv with a frequency counter DVM, or better a scope to look for inconsistent pulses. With the lex AFM, the flow rate is below the designed value at idle with the 7M compare to the UZ. You could try playing with the bypass screw (close it off) to get a little more margin.

It seems unlikely the turbo is playing a role given its at idle.

 

[quark]

Okay.. That I will try to do

"With the lex AFM, the flow rate is below the designed value at idle with the 7M compare to the UZ. You could try playing with the bypass screw (close it off) to get a little more margin." Makes sense.

 

[quark]

By the way,made 313hp at 5368 rpm today and a massive 471nm at 3052rpm, only at 0.97 bar.... That was nice, going to the dyno was also the reason Í have been fighting to solve this idle problem.

http://www.snupa.dk/video/MOV00076.MP4

 

[quark]

I´am pretty pleased with this.. :naughty:

0.97 bar is 14 psi