COLEVETTE

Recently the V has been on dd duty while I finish my other car up. Over the past few weeks it has just felt kind of unresponsive and has a very bad off-idle stumble when its cold and sometimes when its hot.

Backtracking a few weeks, I was at my tuners shop and I fired my car up and he thought I had a vacuum leak. We poked around for a while with a can of brake clean and found nothing.

So yesterday given how poorly its running, I dug a little deeper and found that when i spray starting fluid or brake clean right under the snout at the base of the rotor case it bogs the engine down. Shouldn't the idle pick up?

Other things I have noticed are that before I put the LT's on it I could peak at 9.8 lbs of boost. After the LT's it maxed at about 8.4 which I understand is normal with the decrease in back pressure, but now ill be hard pressed to reach 6psi.

What type of gasket (if any) is used between the rotor case and base plate?
Anybody else have this problem?

Edit: It dynoed at 488.3 hp and (im not making this up) 488.3 tq. It would melt tire 1-3rd gears but now it just feels sluggish and hard starts sometimes

DMM

No gasket there. Use threadlock to seal that area. Do you have stock valve springs?

raven154

iTrader: (14)

Like DMM said no gasket. I've got the Maggie apart off my dads V right now and its getting sealed up with red gel locktite.

COLEVETTE

I called Magnusen today and they said the same thing, 510 locktite.

Yes, the engine is completely stock aside from the maggie and LT's. I dont tend to beat on it too hard and it literally just turned over 50k last week. No strange noises to speak of either aside from a slight whistle/intake hiss under light load.

Edit: Thanks DMM, I started looking at valve springs and thought "may as well do a cam at the same time".....great

COLEVETTE

Another thought is that if there is a leak and I do fix it, the tune will be wrong if it were indeed present during the tune, correct?

raven154

iTrader: (14)

http://www.ls1gto.com/forums/showthread.php?t=382840

Has some good info on bearings and stuff if you want to go that far into it.

DMM

Not necessarily. I wouldn't worry about a cam since you're nearly maxed out on power now. I'd just get a set of LS9 valve springs and try to step up the HEX with a better pump and maybe meth.

I am offering these suggestions b/c your tuner probably has 20+ degrees of timing up top to get that kind of power which is not the best for longevity. Get your IAT's as low as possible and use meth to up the octane a little.

punishmentcycle

iTrader: (6)

Couple things to check.. By pass valve.. Make sure the by pass throttle blade didnt break the small screws. A leak anywhere after the maf will cause issues so go over and make sure u have no loose clamps or hoses anywhere

COLEVETTE

All I know about the timing is that it was at 15 and he told me that he pulled timing until he started seeing big drops in power.

Punishment, could you elaborate more on that bypass valve. Im standing in front of my car right now.

punishmentcycle

iTrader: (6)

With the car off the valve should e closed. It's on the drivers side of the blower. It has one vac line running from it to the snout. It works off of vacuum. So with the engine idling it will pull the valve open and bypass the rotors. When u go into boost it closes tht valve and all the air gets compressed thru the rotors. So take a look at the valve with the engine off and make sure it's closing all the way. When u start the car it will open. Sometimes those valve rip the diaphragm's in them and give problems. Check there first and go over all the lines.. These Maggie's don't have many lines so you should find ur problem fairly easy but if its the actual Maggie leaking then u need a tear down