So I get the plenum and install it, start her up and ahhhhh!!!!

Very rough idle, almost dies then when I do a light rev it sounds like someone under the hood blowing a New Years party horn! I noticed when I put it on that it didn't seem very flush, it kind of wobbled slightly....do these things tend to warp when welded? Does this sound like an air leak somewhere with the whistling, and, would that explain the rough idle?

Calling Doug first thing...may just drive to Nashvegas and let him mess with it but that's alot of work followed by an "Oh Crap!!!" All I could think of was that I left a bolt in the plenum loose and paranoia got the best of me.

Scared the hell out of me. Returned to stock plenum and everything is kosher now.

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

Wow! Sounds bad... let us know what happens. I am sure Doug will help you square it away... Good Luck..

TC

"There is a Very Fine Line Between "Hobby and Mental Illness"

 

You probably had the rubber ring around the oil cap stuck under the plenum which was causing you not to be able to get a good vacuum. It is hard to get a good seat on the plenum, the darn rubber piece wants to get in the way. Take a look at photo#1, it shows the oil cap, and if you look closely, you can see the black piece of rubber laying over the plenum. When you set the plenum down this rubber gets sandwiched between the plenum and the exhaust manifold.

300bhp??? We'll see... 5-22-2004

 

It wasn't that Neff, I double checked. The nipple cover was replaced, all the hoses were on good, the oil filler baffle was free and clear, the 4 bolts inside were on and lock tited.

Just got off the phone with Doug who says they all warp when welded, just a bit. That's why they're double gasketed. He said torque the outer bolts down good, 60 inch pounds is not enough. He said one other person had an air leak problem, sent it back, and it's sitting on Doug's car right now.

So, this weekend I'll attempt another install, leaving my torque wrench in my toolbox, and torque them all down real good.

One question, the two long bolts that feed all the way through, they have a little plastic sleeve. If torqued too much this sleeve deforms. I'm assuming these two should be "finger tight" bolts?

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

arrrghhh!!! All that wait just to get disappointment. Give me a call this weekend and maybe I can come over and help you out. I guess 2 heads are better than 1.

 

The symptoms you describe point to an airleak. I had the same issue with the first plenum I installed, and yes it was warped too much to seal properly. Doug does suggest using 2 gaskets to help, but if the warp is too great then a new plenum is needed. (make sure all the hoses are connected too)
I wouldn't suggest using more that 10 - 15 ft lbs of torque on the bolts, and the 2 in the middle should be more than finger tight. Don't worry so much about deforming the neoprene gaskets, but you don't want to deform the plenum.

<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

Catatafish

I bet I have got your solution... Did you forget to screw in the 4 small bolts to plug the holes in the lower plenum that are not being used anymore? That's what I did, and I had a leak that would cause my car to die while idling....

The engine is just sucking in air from below the lower plenum that is not being measured by the MAF--- hence you idle so lean that the combustion cannot be supported....

 

snicker snicker...gurgen forgot to screw in his lower plenum plugs

snicker snicker...


(bored post #2)


'03.5 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
Click for MODS or Vote at Online Showoff

 

60 ft/lbs!!!!!!!!! Is he crazy? We're talking about alumninum here. Most alum manifolds require about 15-20 ft/lbs. Anymore than that and you risk stripping the holes or cracking the manifold itself.


Dave

96 Maxima SE
14.40@97mph, 2.20 60 foot. Best mph 99mph.

JDM intake manifold, JWT ECU, Y-pipe, CAI, 2K Maxima muffler

 

I'm thinking that was meant to read 60 inch-pounds. Sorry, don't recall how to convert to Newton Meters. lol

Future G35C Owner... ...Never too soon to think about modifications!!

 

gurgenpb, catatafish said in his second post that the 4 bolts inside were properly tight.

 

40-60 INCH pounds, that's correct. I got those numbers from a post Neff made awhile back.

I measured the variance and it is a difference of 3/16th of an inch. I called Doug and he measured a few of his and said that was not atypic. He said to use a 1/4 inch driver and just "tighten her up good" or something like that.

I did remember to install the 4 bolts inside the plenum and all my hoses were connected. I believe my problem was torquing the outer bolts to 50 INCH pounds which Doug didn't seem to think was enough.

I'm going to try again this weekend and act like a 16 year old and just start cranking bolts with no regard for torque. That's what Doug said the majority of buyers are doing with great success. I guess my problem was thinking and caring too much about precision. I'll blame Neffster for this . Damn engineers.

If I break off a bolt in the manifold, I guess I'll just take myself out right then and there. I was up at 3 a.m. putting my stock plenum back on and I can tell you the sound it made will make you literally sick to your stomach. This may be the last self-mod I do to this car. Too stressful!!!

If all else fails I'm going to drive to Nashvegas and let Doug put it on himself. I have to say Doug has been great throughout all this and a standup guy. He has been immediately available and is willing to accomodate. I recommend doing business with him.

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

By the way,
Doug told me to take some brake cleaner, and while the engine was stumbling, spray it around any potential leak areas. He said when the engine revs higher, there's the leak. I guess brake cleaner will be sucked in and blow up real good, huh? I can't say I feel real good about spraying brake cleaner in my mix.


Hmmmm, note to self: look into a Brake Cleaner 100 HP spray kit and sell it on e-bay. Kit will include 2 cans of brake cleaner and a remote that sprays the cleaner right into the air cleaner.

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

If I'm paying $400 for a reconditioned plenum, it better be checked for warping before it's sent to me.

Having to use two gaskets or overtorquing is not a proper solution.

Over torquing could cause a bunch of other problems.

More warpage, heat warpage, cut gaskets, broken bolts, stripped threads...

If the front two runners are truely "staved for air" I'd like to see a few more aftermarket solutions.

jmo.



2004 G35C 6MT Black. I stare. And I am content.

 

catatafish- awesome idea, can I get on the waiting list?

PS- will the 100HP kit void my warranty?

'04 OB 6MT Coupe- Polished Vortech and Crawford Plenum, Kinetix Cats
'04 GSX-R 600