98RedBird

iTrader: (77)

I just got the motor FINALLY together and running with great oil pressure but the tune seems a bit off. It drives okay but seems to idle really high and then moves up and down from like 1300-2300RPM. It's with the mods in sig. Also, when driving and letting off the gas it jerks almost like a really big misfire or like it's running out of gas (this might be what is called bucking I'm not really sure). I'm just wondering if maybe there's a vacuum hose that I forgot to hook up on the intake or something that might be causing this? I'm not going to mention who tuned it because I'm not sure if it's in the tune or if it's my fault.

Thanks guys.

Soul TKR

iTrader: (4)

If you had a vacuum leak you would most likely hear some sort of whistling noise... it would definatly cause idle issues if you had one... But most likely it's in the tune. What kind of throttle body do you have?

98RedBird

iTrader: (77)

FAST 90. Well here's what I'm wondering, I just realized that when I deleted the HVAC that I didn't plug the rear plug on the intake that controls the switching of air flow in the cabin to the floor. I don't hear a whistling but then again, it was running open headers so I probably wouldn't hear the horn if it was going off...

98RedBird

iTrader: (77)

The other thing is that port is right in the area of the MAP sensor, maybe it could be throwing off the reading for the MAP?

nobreaks254

iTrader: (50)

I have a similiar problem with my new build. I'm pretty sure I dont have any vacuum leaks. But I have the same symptoms as you. I would think you need to plug the port at the back of the intake.

98RedBird

iTrader: (77)

Yeah, I know. I need to do that regardless. Sounds like it's in the tune though...

98RedBird

iTrader: (77)

Yep, nevermind, I just checked and all of the vacuum lines are plugged in and ready to go... Must be in the tune. How do you fix the idle issue though and why does it do it? It's just all over the place, up, down, idles great for a few seconds, then shoots back up to like 2000, then just hangs there....

Also, I'm a little worried about the bucking issue. I'm not even sure that's what it is, but I'll be driving along with the throttle down a little bit just cruising and it'll start jerking forwards almost like it's trying to die, then it'll clear up and drive fine for a little bit...

johnLs1camaro

iTrader: (28)

did you remove all of your air and e.g.r bullshit?? i had the same issue with the because my hose that went into the top of the intake manifold had a leak and it caused the same issues due to loss of vacuum and then i removed all of that **** and it fixed everything...

Soul TKR

iTrader: (4)

do you have any sort of hole drilled in the throttle body blade?

98RedBird

iTrader: (77)

I did remove both my AIR and EGR. But all of my hoses are gone and they've been tuned out.

No, I don't. I wish I could get this figured out though, this engine build has been headache after headache so far it seems. If it's in the tune, I'll just send the PCM back and see if they'll fix it.

johnLs1camaro

iTrader: (28)

ok i didnt know if you still had the stuff on there....so you have a send off tune where you mail your pm??if so i would really recommend getting a dyno tune from a local tuner or something..

98RedBird

iTrader: (77)

I know, I would recommend that for me too... But the nearest tuner is like 3 hours away and I bought the head/cam package from this sponsor that I have the Mail Order Tune from so I figured they'd be able to hit it pretty darn close.

nobreaks254

iTrader: (50)

Let me know what you find out. Sounds like we have the exact same problem. We also have similiar setups only mine is a 383. We probalbly have the same sponsor mail oarder tune too.

98RedBird

iTrader: (77)

PM me who did your tune. I'm curious. I'm going to call them this morning.

Sales2@Texas-speed

iTrader: (5)

Have you tried to adjust the idle set screw on the TB? Most people assume they are set perfectly right out of the box, and that's not the case all the time. You might need to back it off a bit.

I'm not sying it can't be the tune, but yours is a straight forward every day set-up that Jason tunes daily. He usually hits them pretty close on the first try! I'd make sure there are no more vacuum leaks as they wreak havoc on several systems! Let me know if that doesn't clear it up, and we'll figure it out one way or another!!

YellowToy/A

iTrader: (1)

It is a vacuum or exaust leak. Look harder

98RedBird

iTrader: (77)

I'm beginning to wonder if it's that damn MAP sensor on the FAST intakes. Come to think of it, it was doing a little bit of surging after the FAST install a few months back, just not as intense as it's doing now. I never RTV'd it or anything, and it was kinda loose in there. Maybe that's the problem here.

98RedBird

iTrader: (77)

I went ahead and RTV'd the MAP sensor and reinstalled it. I'll give it some time to setup and we'll see what happens later tonight.

stevied916

iTrader: (30)

buy a couple cans of carb cleaner and spray all over the vaccum lines...you will probabally find a leak somewhere

07gsxr750

iTrader: (2)

its probably that map sensor, mine was loose and fell out a few times before rtv.