[Supras] Help! Idle cutoff cycle

[Harley]

I had the same problem after i installed my lexus afm. I replaced the fuel 
filter and the problem went away. But the thing that cause that are ISC, 
cracks in the intake, a faulty AFM, a clogged air filter would do it. But it 
sounds like yours would be a fuel filter. Yours is doing EXACTLY what mine 
was doing. Same RPM range too. If its the TPS it would normally die though. 
ISC will cause the problem but its usually speratic and you can normally 
test this by tapping on it with the end of a screw driver. Cracks in the 
accordian hose would normally cause the car to idle out and die if you gave 
it a good rev and let the idle drop off. But then again the fuel filter 
would do the same. Try replacing the Fuel Filter that should do the trick. 
Youll need to get the car high though as the Fuel Filter is a bitch to get 
to.

-Harley(87t)
----- Original Message ----- 
From: "Hacker J" <jonbhacker at yahoo.com>
To: <supras at supras.com>; <berniek at technicaldevelop.com>
Sent: Thursday, June 28, 2007 1:49 PM
Subject: Re: [Supras] Help! Idle cutoff cycle


>
> There are no codes for the ISC. Its a stepper motor driven pintle valve. 
> When you shut the car off the ECU homes it back to wide open, you should 
> be able to hear it. Often the pintle gets gummed up.  Try cleaning it 
> first.
>
> The surge is probably because with the ISC full open you are revving above 
> 1600rpm with a hot engine. This engages the trailing throttle fuel cut. 
> The ECU will cut the fuel back on when it hits 1200rpm.
>
> Easiest way to confirm is to disconnect the TPS connector. This will open 
> the IDLE switch and the ECU will not actuate the fuel cut. More details 
> here.
>
> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=125
>
> Jon
> 90T
>
>
>
> ----- Original Message ----
>
>
>
> Don, Joe, Bob and and group:
>
>    I wrote before about a hunting idle condition in a '91 turbo between 
> 800 and 100 RPM.  I have not had the time to dig into it more yet, but it 
> appears to be the ISc, but no codes are set.  I was going to manually 
> "throttle" feed to the ISC from the accordian hose by inserting a piece of 
> soft Tygon tubing in series with the tubiing to the ISC and then pinching 
> it with pliers as a test.  After tubing insertion, the flow resistance was 
> enough to bring the hot idle down to about 1000 RPM.  It does droop when 
> the A/C or lights are turned on, so apparently the ISC is not working. 
> But the mystery is that no codes are set.
>
>    Anyone have any ideas?  I'm going to try to get through NJ inspection 
> on Thursday with it as it is.  There are hints of a BHG:  Misfire after 
> startup and pushing water out of the radiator.  But I intended to change 
> the HG next week any way.  No sign of antifreeze in the oil.
>
>        BernieK
>
>
>
>
>
>
>
>
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