Gm847 355 ported heads idle.

**anniversaryss** · 07-18-2016, 08:44 PM

I'm have a 355 lt1 with gm847 cam and ported heads with other goodies.
I got my second tune back from my second tuner and my car will idle fine in park and in gear with some fluctuation.
It's only when i drive and come to a full stop does the idle dips down to about 500 catches then back up. Sometimes it stalls.

From what I know this could be bc of iac counts.
Being a 97 I don't have any software to log it but I would like to make this better.
I know drilling the IAC hole bigger may improve it or cracking the throttle blades and adjusting the TPS will help to.
What method would be the best without a scanner?
And if I do the IAC port how big a bit should I use?

**Camaro96** · 07-18-2016, 09:13 PM

I would recommend a tune adjustment. @MoeHorsePower. He is a member hear and an excellent tuner.

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**NightTrain66** · 07-19-2016, 08:41 AM

i agree, getting some data logs of what the PCM is saying/doing underf these conditions might allow the tuner enough info to know if they can make some adjustments to correct the problem.

If the current tuner is not able to help I am sure that Moe would know the answer.

Lloyd

**Z28pr0jekt** · 07-19-2016, 10:14 AM

When I first installed my cc306, the car would stall every time I was coming to a stop. My tuner at the time told me to check the IAC sensor so I datalogged the car. The IAC counts read normal and fluctuated as they should. I disregarded my tuner's advice and drilled the IAC hole larger. This did fix my problem HOWEVER, when I started a motor tear down, I pulled out my IAC sensor and found that it was stuck compressed, the spring no longer had any tension in it and it was caked in carbon. I could've saved myself the headache by just pulling the sensor when I was first told.

As a quick check, I would do what I failed to.

**anniversaryss** · 07-19-2016, 10:38 AM

Thank you guys I will pull my iac and check that to.
I cleaned the throttle body a few weeks ago but neglected to check the IAC.
What are good ways to data log an obd2 lt1?

**anniversaryss** · 07-19-2016, 11:08 AM

Originally Posted by Camaro96

I would recommend a tune adjustment. @MoeHorsePower. He is a member hear and an excellent tuner.

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You mentioned moe in here so I assume this will get his attention and maybe chime In?

**MoeHorsePower** · 07-19-2016, 11:38 AM

There is never no need to drill the throttle blades, now some after market throttle bodies need the drill mod in the iac passage, If you have tuning software, your problem will probably be as simple as the throttle follower tables or running airflow..

**anniversaryss** · 07-19-2016, 01:11 PM

Originally Posted by MoeHorsePower

There is never no need to drill the throttle blades, now some after market throttle bodies need the drill mod in the iac passage, If you have tuning software, your problem will probably be as simple as the throttle follower tables or running airflow..

Wish I had tuning software

***SSlowBoat*** · 07-20-2016, 08:33 PM

Originally Posted by anniversaryss

Wish I had tuning software

Jet dst, it's not cheap and acts up sometimes

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**anniversaryss** · 07-20-2016, 10:13 PM

Originally Posted by SSlowBoat

Jet dst, it's not cheap and acts up sometimes
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I have the opportunity to get the jet dst from an affiliate of mine he said there's one or two more left on it. Im unsure what he wants for it.
If anything I could get it from the ws6 store for under 400.
I have no clue how to use it.
I'd like data logging to I know it doesn't have it.
But again id have no idea what I would be looking at.
On top that I want the 24x kit. I'm extremely close to buying it.