HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Hard to get good idle

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Hard to get good idle

Post  jpr on Tue Jun 24, 2014 8:16 pm

I have been trying to tune the idle of the car without luck. If I turn the idle to 800 to 900 rpm, when the car is rolling to a stop, it wants to die. If I turn the idle up to about 1k, when the a/c compressor cuts out, the idle goes to 1.2 k or higher. What's the trick in making the car idle normally. The idle air valve is working well but it seems it is not fast enough to keep the engine running when the idle is set low. (im adjusting the idle on the stop screw on the throttle body).

Thanks

Jpr

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Re: Hard to get good idle

Post  99sierra4x4 on Tue Jun 24, 2014 8:45 pm

What engine are you running, intake setup, and throttle body style (ie cable or electronic "wire").

Also do you have a VSS kit on your car?

Andy

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Re: Hard to get good idle

Post  Admin on Tue Jun 24, 2014 9:29 pm

Unless you have a carb on your motor you do not adjust that screw!
If we are talking about a cable LS throttle body, you will need a VSS installed and working to let the ECU know if and when the car is moving. The problem is if you are turning the blade adjustment screw the ECU will use the IAC to re adjust the correct idle that is set in the ECU. once you get to a certain point with the screw the IAC cannot compensate for the incorrect adjustment of the screw. You have to adjust the idle in the ECU, no other way to do it right. You need to make sure the AC input wire is hooked up to the ECU to help correct the idle when the AC is turned on.

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Re: Hard to get good idle

Post  jpr on Wed Jun 25, 2014 10:07 am

Thanks for the replies.  I have a vss that is currently feeding the AIM pista in my car. Is there a specific port for this signal in the ECU terminal block? I have an LS1 with cable throttle body.  ECU has the idle set for 900 rpm.  The engine dies mostly after the deceleration period when approaching an off-ramp or stop light. I don't know about the A/C wire but I notice that there is what appears to be a normal rise (about 100 rpm) and fall of the engine speed when the compressor is engaged or disengaged. Is there also a separate wire connection point in the ECU for the a/c?

TIA

Jpr


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Re: Hard to get good idle

Post  Jim7 on Wed Jun 25, 2014 6:56 pm

According to Steve Frost ( tuning by Frost) it takes awhile (100 mi) for the computer to learn the air density properties and in that time the idle can be weak.

Jim7

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Re: Hard to get good idle

Post  jpr on Thu Jun 26, 2014 2:00 pm

Yes, but my problem is more of the car not being able to stay on when running down from speed to a stop. Once stopped, the idle is high

jpr

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Re: Hard to get good idle

Post  jpr on Tue Jul 08, 2014 6:09 pm

bump for some ideas to get this thing to idle.

Thanks

Jpr

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Re: Hard to get good idle

Post  Jim7 on Wed Jul 09, 2014 9:07 am

I have connection diagrams for 98 and 02 PCMs, the ports are a bit different. What year is your PCM, maybe I email you a scan of a diagram.

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Re: Hard to get good idle

Post  jpr on Wed Jul 09, 2014 9:50 am

Thanks, Mine is an 02 z28ss ls1.

As scan would be very useful.

Thanks Again

Jpr

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Re: Hard to get good idle

Post  Jim7 on Wed Jul 09, 2014 1:39 pm

PM sent

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Re: Hard to get good idle

Post  applebit on Sun Jul 20, 2014 10:43 am

Correct me if I am wrong, but do you also not need a transmission switch detector to determine if you are in gear or not? I believe that might be my reason when I let off the throttle quick the RPM's hunt for a little before settling out. I am planning on a number of resolutions to this and other stuff this upcoming winter.
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Re: Hard to get good idle

Post  jpr on Sun Jul 20, 2014 10:55 am

The engine shut down on the off ramps was due to having the throttle blade on the throttle body too closed and the idle valve could not react in time to keep the engine alive. that I have already resolved. but now, I have narrowed down my problem to the Idle control valve.  At start up, the valve opens to help the car idle when cold, sometimes it closes after the engine has warmed up.  But then, in normal use, it opens again and gives me very inconsistent high idle.  Since the climate now is very hot, I have disconnected the idle valve and the engine runs great but I know the function of the valve and see no reason why it would want to open when the car is warmed up (idle around 1500 rpm). Fearing the at the valve I had was bad, I bought a new Delphi one and it does the same BS.  Any ideas?

 Rolling Eyes

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