Problem with Plenum & TB Install ...

[PULMEOVR]

Hi Guys,

So today I installed my Accufab 70mm TB & plenum on my car. I followed Helty's install guide posted on here (http://www.stangnet.com/mustang-for...plenum-install-write-up-biggest-duw-ever.html). The directions and write up are great!

Once everything was installed, I started the car up and I noticed the engine revved up quite high and slowly dropped down to about 700 rpm at idle. The car idled very rough, like it had aftermarket cams. I adjusted the throttle screw located on the TB at different settings with the same results. It seems no matter how I adjust it it idles like it's cammed. I un-installed everything and re-installed it all and it does the same thing. I checked for leaks, and made sure everything was connected and it looked good.

So I said screw it, and put the stock TB & plenum back on. Now it idles perfectly fine .

Any ideas?

 

[joshjwc9]

Is the Accufab TB closing all the way? As you absolutely sure the stock intake tube made it all the way around the new TB opening? My 75mm had a ton of trouble and me cursing trying to stretch it over the TB opening.

Also, check Helty's writeup for the issue with the vaccum line that the size is different for certain years. You may need to purchase some small vaccuum hose to adapt it to your applicable year car.

 

[trombonedemon]

Your car seems to sound like mine did when I put the lower intake gasket on the wrong side, which made for one hell of vacuum leak and a cammed sounding engine. Make sure all of your gaskets are sealing.
P.S.
There is no adjusting the idle on our cars, the idle is computer controlled.

 

[fiveoho]

when we installed my TB and upper plenum, i had directions to let the car idle for 15 minutes on the initial startup. also was made mention to not touch the throttle during that time. it did idle a little differently after the install but nothing dramatic. however, it took every bit of 100 miles for the computer to adjust to the changes. after that, the car runs great. much snappier now.

maybe the computer was just adjusting to the changes?



fwiw, this was a FRPP 70mm that had been ported/polished and a oem plenum, also p/p.

 

[GDawg]

Sounds like a vacuum leak to me. Before I installed my blower I put in an Accufab 75mm TB and a C&L plenum and everything worked fine from the get-go.

 

[PULMEOVR]

Your car seems to sound like mine did when I put the lower intake gasket on the wrong side, which made for one hell of vacuum leak and a cammed sounding engine. Make sure all of your gaskets are sealing.
P.S.
There is no adjusting the idle on our cars, the idle is computer controlled.

A gasket that goes underneath the intake plenum that attaches to the intake manifold? If so, I either didn't notice one in the box of Accufab stuff or my stock gasket got stuck to the bottom of my stock plenum and I didn't notice. Maybe thats it? I should have time to work on this on Tuesday, so I'll let everyone know what happens.

 

[YardSpecial]

LOL....................

 

[trombonedemon]

There is a lower intake spacer that required a gasket for the upper intake. My lower intake already has a rubber ring on that side. Sooooo, I put the gasket on the wrong side and Juala, one hell of a vacuum leak.

Your leak can come from the throttle-body gasket.

 

[PULMEOVR]

Hey guys,

I FINALLY got around to installing the TB & plenum again. It turns out the initial problem was a vacuum leak somewhere. I also adjusting the idle set screw so it is backed out 100% all the way. This fixed how long it took for the rpm to drop back down to idle (it no longer hangs). On the first install, I had it adjusted forward maybe 25%.

(not my image, but for those that don't know what I'm talking about).

I notice a small power improvement too. When I punched it from a roll in first gear before the install, the tires would just slip alittle. Now, the tires slip alot more (same tires, worn the same amount) almost like reving up in neutral and 2nd gear pulls harder too. I didn't notice much improvement on the throttle response which most people claim is improved significantly.

Hope that helps for anyone in the future if they search this thread.

Thanks guys!

 

[mustangjoe02]

did you find where the vacuum leak exactly was?

 

[PULMEOVR]

did you find where the vacuum leak exactly was?

Nope! I just re-installed everything, using the same gaskets as the first time. No leaks.

 

[mustangjoe02]

does your idle hang anymore or bounce?

 

[PULMEOVR]

I had to disconnect the battery for the install. Once I hooked everything back up, the ECU re-learned the idle pretty quickly after driving around for a few kilometers. Now it idles as smooth as stock. No bouncing around or hanging idle what-so-ever.