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Old 07-18-2012, 12:23 AM   #1
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Ok.... car surging and dying again......

I had some perfect video of what it was doing but deleted it off my phone via PC by accident.

So let me get the conditions laid down.

NO CEL codes.

When I am at low RPMs and only sometimes, it will drop to below 500 rpms and die. In gear only. Usually on an incline probably because of the load on the tranny in gear at low rpm.

Instead of dying sometimes it will TRY to die but come close and then recover making it surge and buck up and down and up and down till it levels off. If I put my foot on the brake, it dies.

Same thing it was doing before it went to Vengeance.

Also, it seems that when it's hot outside is when it will do it. Not all the time but almost never when cooler out. Could be otherwise but as far as I recall. So maybe just cooincidence too.

This surging and dying is WAY worse when the headers are open with the diverters.

My air conditioner will only work when it's cooler out as well. When the air does work, it blows cold as ever. But when it's real hot out the AC just doesn't work. I wonder if it could be related at all?

Also, I found my EVAP line kinked right where it's braided and is coming out of the rail where the fuel line comes up. I unkinked it but might still be collapsed til I get another one.

I've done a number of things like a smoke test, on the entire manifold and adjacent lines. Checked the fuel pressure. Compression and leakdown test, looked for the header gasket to be leaking.


So my questions are:

Could a kinked EVAP hose cause this?
Could it be related to the air conditioning problem?
What else could it be?
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Old 07-18-2012, 12:32 AM   #2
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Quote:
Originally Posted by PQ View Post
I had some perfect video of what it was doing but deleted it off my phone via PC by accident.

So let me get the conditions laid down.

NO CEL codes.

When I am at low RPMs and only sometimes, it will drop to below 500 rpms and die. Usually on an incline probably because of the load on the tranny at low rpm.

Instead of dying sometimes it will TRY to die but come close and then recover making it surge and buck up and down and up and down till it levels off. If I put my foot on the brake, it dies.

Same thing it was doing before it went to Vengeance.

Also, it seems that when it's hot outside is when it will do it. Not all the time but almost never when cooler out. Could be otherwise but as far as I recall. So maybe just cooincidence too.

This surging and dying is WAY worse when the headers are open with the diverters.

My air conditioner will only work when it's cooler out as well. When the air does work, it blows cold as ever. But when it's real hot out the AC just doesn't work. I wonder if it could be related at all?

Also, I found my EVAP line kinked right where it's braided and is coming out of the rail where the fuel line comes up. I unkinked it but might still be collapsed til I get another one.

I've done a number of things like a smoke test, on the entire manifold and adjacent lines. Checked the fuel pressure. Compression and leakdown test, looked for the header gasket to be leaking.


So my questions are:

Could a kinked EVAP hose cause this?
Could it be related to the air conditioning problem?
What else could it be?
Stalling could be in the tune.

On the A/C.... Fall will be here soon!!
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Old 07-18-2012, 12:34 AM   #3
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Any chance you added a breather? My car had the same symptoms when we installed the breather. Ted needed to adjust the tune.
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Old 07-18-2012, 12:35 AM   #4
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Stalling could be in the tune.

On the A/C.... Fall will be here soon!!


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Any chance you added a breather? My car had the same symptoms when we installed the breather. Ted needed to adjust the tune.
No. It's the same CAI that was on it before and when it went to Vengeance. Nothing has changed.

Seems that Vengeance may have just masked an already there issue? Not intentionally of course but it wasn't doing this when it left them. Wasn't idling perfectly smoothly on the tach but I attributed that to the cam.
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Old 07-18-2012, 12:37 AM   #5
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How much gas do you have in the tank?

An overheating fuel pump can cause those symptoms...stalls out then when it cools off it will start working again
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Old 07-18-2012, 12:39 AM   #6
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How much gas do you have in the tank?

An overheating fuel pump can cause those symptoms...stalls out then when it cools off it will start working again
Full tank, low tank, never matters. It's done it both ways as far as I remember.

And don't scare me like that.

Car runs great when given gas. Even when held to the right RPM.

I'll try and keep notice though just in case.
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Old 07-18-2012, 12:40 AM   #7
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sounds like you need a proper tune. maf, ve, idle spark, base running airflow, proper idle rpm, etc. it takes a lot of time to properly tune idle. wot is the easiest, part throttle is easy, idle can take time to do right.
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Old 07-18-2012, 12:41 AM   #8
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I've ran into something similar working on an SS at a dealership. I found the electrical circuits going to the MAF sensor chafed on the coolant pipe right under the air duct. Also try checking your knock sensor circuits. They might be contacting your exhaust headers and making and breaking contact with the heat. I hope this hepls.
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Old 07-18-2012, 12:41 AM   #9
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sounds like you need a proper tune. maf, ve, idle spark, base running airflow, proper idle rpm, etc.
You'd think so but Vengeance dyno tuned it and gave it a clean bill. And it didn't do this when it first left them.

Can a tune regress at all?
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Old 07-18-2012, 12:42 AM   #10
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I've ran into something similar working on an SS at a dealership. I found the electrical circuits going to the MAF sensor chafed on the coolant pipe right under the air duct. Also try checking your knock sensor circuits. They might be contacting your exhaust headers and making and breaking contact with the heat. I hope this hepls.
I will take a look.

I'm not familiar with the knock sensor locations though.

After I installed my blower this same thing happened. Seems it's back. The MAF sensors wires were good. But I'll look again.
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Old 07-18-2012, 12:43 AM   #11
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You'd think so but Vengeance dyno tuned it and gave it a clean bill. And it didn't do this when it first left them.

Can a tune regress at all?
a dyno tune doesn't always men a good idle tune. I edited my last post....

and no a tune won't regress but idle issues can show under different circumstances when not complete.

any time you change the tb size or way air flows into the engine you should retune the idle. a cam drastically alters this. a tb alters this, even a ported one. most people rely on trims to try and compensate but it doesn't always work under all conditions.
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Old 07-18-2012, 12:43 AM   #12
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The knock sensors are right above the oil pan and the left and right sides of the engine. I'll see if I can find a pic and post it.
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Old 07-18-2012, 12:46 AM   #13
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a dyno tune doesn't always men a good idle tune. I edited my last post....

and no a tune won't regress but idle issues can show under different circumstances when not complete.
Hmmmm. Interesting. I do believe it was tuned for cold start. But not possitive.

The problem can come and go in one trip to the store. Engine hot and cold has no bearing. It's done it both hot and cold.

Just seems that the outside air temp can effect it. SEEMS anyway.

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The knock sensors are right above the oil pan and the left and right sides of the engine. I'll see if I can find a pic and post it.
Cool. Thank you.
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Old 07-18-2012, 12:46 AM   #14
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Yes on knock sensor is right above the oil cooler and the other is on the opposite side in the same location
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