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6SENSE

Member
Joined
Jun 3, 2001
Messages
1,635
Havent been completely satisfied with how the car runs and performs since day one. Dont get me wrong, the car is fast, but not doing what I built it to.
One sign I never have been able to understand is the vacuum #s. Only 12psi in park/neutral, and 8-10 psi in drive!
I tried to not pay it too much attention, but after tons of tuning and everything else I could think of doing, including taking out double roller chain and replacing with GM O.E. (thinking that there might be slack or extra noise from metal cam gear), constantly checking for vac leaks, constantly taking apart exhaust parts to make sure no leaks, etc, etc. I am running out of places to look.
Like I mentioned, the car is fast, but something just doesnt seem right. I havent been able to get any timeslips this year yet with the TA33 installed, but last year (with the stock turbo) no matter how I tuned the car I couldnt make it run faster than 94mph in the 1/4. (Besides, with the TA33, I notice a difference, but still feel that all the power just isnt there).
Now Ive started to have backfiring from intake with boost levels no higher than 16lbs (certain chip settings react worse than others). Also seems like I cant reach higher boost levels anymore, even after cutting down wastegate rod some more!
I feel like I have checked over everything (including switching out EGR a couple times). Im just starting to think that those vac #s may have something to do with the problem.
COULD THE CAM HAVE NOT BEEN BROKEN IN RIGHT? I have been trying to ignore the symptoms pointing to the cam, but I am running out of options now. What do you guys think? If I do wind up changing the cam out, what would be a good one to go with my mods (the same one or something else?).
Any comments/suggestions are much appreciated. Thanks.
 
I run the postons cam and think it is great.If I spool just a little then let her go it shreds the tires then when it shifts into 2nd it actually fishtails the back end a foot or so! I have had plenty of built large v-8's theat are'nt even in the Buick's league.I did do some of my own intake mods and porting though and I think that made the bigest difference yet!! My vacuum is about the same as yours and I have a stock turbo still with a fresh rebuild.I have proven to myself that this stock intake we have sucks in the flow department to the point where it can't flow as much as the stock turbo can feed it.I will put up my times as soon as the weather permits a trip to the track(COLD COLD COLD).I have to disagree about the cam being the problem.
 
Thanks for replying Dave. Havent been able to get back to check until now. Dealing with these damn inspections, both my Ttype and truck's plates are expired!
Anyway, you say your vaccum reads the same, and you also run the Poston's cam? Thats good to hear, a little encouraging (hey, has your gas mileage sucked too?). I would hate to change out the cam and notice no difference.
Its getting to the point that I dont really want to drive the car anymore until I find out the problem. It is getting worse and getting on my nerves.
The main problems are constant popping from the engine when I get on it and for some reason I can not get my boost up (since I put on the TA 33). I have cut a little off the wastegate rod 3 times and I am not going to keep cutting. The last time I cut it I could not get the boost to go up anymore than before. I think the most boost I have been able to reach is around 15psi. I was able to run over 20psi with my stock turbo. Could something be wrong with the wastegate that came with the new turbo? (I figured that psi might be down a little with a bigger turbo flowing more air volume, but after cutting the rod down I should be able to get the pressure up!?).
Any ideas guys. I guess the popping is the worst thing, because there is basically no reason to drive the car if I cant get on it! The EGR system keeps coming to mind(?). Im running out of ideas. Maybe something simple like the fuel filter? (but what would that have to do with the boost?).
Just as I would hate to swap the cam for no reason, I would hate to take the intake off for no reason, but that is what I have been thinking of also doing. Just in case a vaccum leak from the intake is the problem(?). I have tried using some vaccum hose to listen for leaks around the motor in the past, but could never find one, but who knows maybe its somewhere I couldnt get to. If there has been a vac leak all this time Ive probably burnt my valves too, huh?
Any ideas? I am loyal to my mission of being the underdog with the hotair car around here, but this car has been really stubborn to get performing the way it should! Sometimes that '87 motor Ive had sitting on the engine stand looks like the way to go, but boy do I hate giving up on something I set out to do! With what I have done to this car it should be running 12s without a intercooler!
P.S. I have always had these ticking/clicking noises, even after welding headers and reclamping, welding, and replacing gaskets over and over again on the exhaust. I just cant get the noises to go away. Any chance these sounds could be vac leaks?
 
Fuel filters' relation to boost~If it 's dirty...no fuel+boost=:eek:

Do you have a scan tool? or Fuel pressure gauge to monitor pressure@WOT?

You have the parts for high 12's IMO just needs to be worked out.

Maybe your boost solenoid or something related coincidentally failed,things like that always happen with these cars it seems.

A local guy also runs the postons 107 in his basically stock hotair and the vacuum is the same or very slightly better but it may be due to his not being ported whatsoever.
 
Ive got FP guage staring at me (mounted on the hood). Pressure is there. Went ahead and changed out filter today anyway. Also found out that shraeder valve on top of tee fitting on rail was leaking, so changed that.
Changed out wastegate with the one that I had on my stock turbo, after cutting rod down a little more.
Just got finished driving car a little while ago and its pretty much doing the same thing. Boost was around 14 psi. Once when I stood on the pedal for awhile it finally went up to 16, but the rest of the times it seemed to like 14psi. Still getting the nasty burping and farting from the engine when I get on it. Its really frustrating driving this thing when it is obvious something is holding it back. Especially when it is having one of its belching attacks, its reving and sounding like its going fast, but not really going anywhere!

Hey, I noticed that the lever thing for the puck (that hooks up to the wastegate rod) seems like it catches or gets stuck. When pushing it forward (towards dirvers side) to hook up WG rod, it doesnt always go as far as it can. I pull it back and flick forward again and it goes a little further, then easier to hook up to rod. I noticed this awhile ago but didnt really trip off it untill now. Is this normal or could the puck be leaking after opening and closing and possibly not seating all the way? If so could this be causing the boost problems and backfiring from up front?
 
my call is that it's too rich.do you have any o2/egt #'s?

i had a funky popping/sputtering problem and leaning it out helped a lot.it was popping at part throttle as well as wot.

i leaned out the spoolup curve and the wot curve(16 pos maxeffort,the best chip on the planet:))and it made a huge difference.fwiw,i had my boost set at 16 psi and my o2's were mid-800's.i started leaning it out and it kept getting faster and faster,and as the o2's came down the boost went up!the spoolup got better and better too.i got it down to low 800's before my laptop battery died:mad: .i romped on it again tonight and it was hauling ass,20 psi,no knock!!!:eek: i hadn't touched the boost setting since i tuned it yesterday.leaning it out brought the boost up that much!

so,anyway,i think it's rich:D.


later,sean
 
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