frito1

iTrader: (12)

I had my engine tuned today. The only thing the tuner struggled with was the idle. It wanted to hunt for a little bit before it finally smoothed out. Never did get it right. He happened to study my PCV system and noticed I didn't have the PCV valve in. He said that was most likely causing my issues. So as soon as I got home I went and found a generic PCV valve and stuck inline between the valve cover and intake. I put it so that the check closes when the intake pulls vacuum. Is that right? Now, it won't idle at ALL! Not drivable at the moment. Does it need to be re-tuned with the PCV valve in? What am I missing here?

TIA
Adam

Doc

iTrader: (9)

The "tuner" should have stopped the tuning process and fixed the problem (or at least given you the opportunity to in this case since the problem was so simple) before going any further.

I'd be looking elsewhere for a competent organization to help you out with your car. You are going to need to have the car tuned.

Uncomanded airflow in the path of the intake or exhaust cannot be "tuned" out.

LS1-450

iTrader: (33)

Your PCV valve is installed backwards. Turn it around.

Can't say for sure without looking @ your car run while scanning, but, the hunting idle is probably an anticipated airflow setting issue during idle, an air pump or purge related to anticipated airflowissue. Could also be an IAT, ECT, or commanded timing issue. Does it happen more on a cold start or after the car has warmed up? In any case, turn the PCV valve around. Also, tell us about your PCV system. Describe how everything is connected. For example, stock arrangement, or PCV system has been modified & there is now a breather in a valve cover....etc..

frito1

iTrader: (12)

I was told to put it in so that it "checks" or stops pressure from going into the intake. Basically making it a controlled leak into the intake. This is the way that I have it. The way you describe would be checking or stopping pressure from going into the crankcase. I'm not sure how I would be sending pressure back that way.

frito1

iTrader: (12)

I guess I could blame myself just as much for being ignorant and not having everything up to snuff. I now see how that uncontrolled vacuum leak is a big deal.

They are a pretty good size dyno shop in the KC area with lots of LS experience. I didn't know where else to go....

On a side note, he got my WOT tuning flatlined and perfect on the dyno sheet at 13:1 AFR range.

frito1

iTrader: (12)

I so badly wanted to run to a auto parts store quick to put one inline to see if we could work the deal out. Partly my fault for not pushing to make that happen. Now I have to reschedule to go back

frito1

iTrader: (12)

More stuff to look at. This is just how it was tuned. I understand the problem now.....






My weak dyno sheet through my loose converter.....

frito1

iTrader: (12)

Also, the car is "bucking" at around 30mph or ~1200rpm in city driving. It does the same under decel. I just noticed this today. I have a mild 231/235 cam. This shouldn't be a problem to get tweaked out should it?

LS1-450

iTrader: (33)

The way I have described it is the correct installation. What someone told you to do is to put a band-aid on the vacuum leak that was caused from connecting the valve cover breather to the intake. No sense in me replying in two different threads regarding the same issue. So, am gonna stick w/ the thread in the external engine section after this post.