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Boost Issues!!??

Bought a 951 a month ago....so I know little about trouble shooting problems with turbos....so please bear with me as this may be a stupid question:

When I bought the car the boost level was great...didn't have a problem hitting roughly 2 bar pretty consistently.

Now in first gear it only goes to about 1.5 bar at best, 2nd about 1.75 bar, and the rest almost 2 bar.

What would cause this change? Temp? Leak somewhere?

The car feels quite a bit slower in first gear now that it pushes only 7.5lbs in first gear!! Any help would be appreciated!

Thanks

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Old 12-04-2003, 09:24 AM
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1) Check all vaccume lines
2) Check Cracks in Intake Boot
3) Check to make sure al the line going to and coming from your Cycling Valve are connected and in good shape.
4) Check your turbo's shaft for play in any direction.
5) ....Theres an assload of things that could be doing it.
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Old 12-04-2003, 10:27 AM
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ScottR...the previous owner has recently replaced the following:

Vacuum lines
Intake Boot
Turbo

So I doubt the problem is stemming from those...although it could be. I will check the Cycling Valve as you have suggested.

Thanks
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Old 12-04-2003, 12:44 PM
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I think he used an afterburner in that car that he probably bypassed the cycling valve...
What else do you have on that car? Modifications?
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Old 12-04-2003, 01:10 PM
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Right...he has a Manual Boost Controller from Lindsey Racing! Forgot that bypassed the cycling valve!!

Other than that....everything on it is in the signature line
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Old 12-04-2003, 02:07 PM
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Re: Boost Issues!!??

Quote:
Originally posted by will944
Bought a 951 a month ago....so I know little about trouble shooting problems with turbos....so please bear with me as this may be a stupid question:

When I bought the car the boost level was great...didn't have a problem hitting roughly 2 bar pretty consistently.

Now in first gear it only goes to about 1.5 bar at best, 2nd about 1.75 bar, and the rest almost 2 bar.

What would cause this change? Temp? Leak somewhere?

The car feels quite a bit slower in first gear now that it pushes only 7.5lbs in first gear!! Any help would be appreciated!

Thanks
I don't own a turbo so forgive me if I am wrong. Don't the 951's run about .7-.8 bar of boost stock? I remember hearing that 1.0bar is hardcore and 1.3 bar is near the limit. How could you be running 2.0 bar on boost pressure? Isn't that almost 28psi? WOW! Maybe your gauge is not working correctly.
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Old 12-04-2003, 03:11 PM
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He's referring to the factory gauge reading.
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Old 12-04-2003, 03:34 PM
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What's the difference between the factory gauge reading and actual? If the gauge isn't accurate what good is having a gauge? Sorry for the ignorence.
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Old 12-04-2003, 03:47 PM
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The guage is close but it just doesn't give you the fine detail and doesnt seem to jump up as quick as aftermarket.... but 1 bar means at atmosphere, so 2 bar is ~14.5 psi.

Your numbers aren't bad. 15 psi in 1st gear is a challenge to begin with. You should reach it in 2nd, 3rd etc.....

at what rpm are you reaching boost (15 psi) in the higher gears... 3K, 4K rpm etc.....
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Old 12-04-2003, 06:45 PM
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Will, the factory manual says the boost must be 1.75 +- 10%, so your boost is ok,you shouldīnt reaach 2 bar with the stock car.Mineīs stock and never saw the gauge above 1.75 or so.

You need to check it at high gears,or according the manual tests,you need to be in 2nd,then you press full throttle at 2000 rpm,while with the other feet you brake the car.You do it for 2 or 3 seconds,and you should read the exact boost.You must use a good boost gauge,because the panel one is acceptable,but not very reliable. Be happy,you boost readings seems very good!
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Old 12-05-2003, 12:34 AM
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Manute....my car is not stock. It has chips which I thought increased boost levels right???

The car hits full boost in 4th and 5th gear around 3KRPM at full throttle...full boost being just under 2 bar. 2nd and 3rd come much closer to the same boost as 4th and 5th...

But again....just 1st gear only reaches 1.5 bar AT THE MOST!!! This was not the case when I purchased the car....it feels considerably slower....or maybe I'm just getting use to the faster car (a possibility).

Is there anything that would cause lower boost levels in 1st gear only? I am gonna make a call to ScottR and see what he thinks....he knows the history of work he performed better than I do.
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Old 12-05-2003, 12:52 PM
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Ask scott.... it seems normal

Its hard getting full boost in 1st gear. It may just be feeling slower... 2800-3K full boost is right.
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Old 12-05-2003, 02:16 PM
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Well,if you really saw it before you are right,but for me seems normal. About 2 bar is the normal pressure people use to set when car is not stock. As they said, in 1st gear is very difficult to attain high boost,i didnīt checked mine but 1.5 seems ok,even if itīs modified. You should noticed,in 1st gear and with full throttle,things pass very fast.

When i just bought my car i though i had more boost,but later i realized is a bit less,was only eye failure and emotion
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Old 12-05-2003, 02:57 PM
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haha.....things pass VERY fast in this car.....

I know what you're saying Manute. When I first got the car the speed kept my eyes on the road and not on the boost gauge. Now that I'm more comfortable with the car I notice the little things about it.

You could very well be right. I'm bringing the car to the dyno when I get my new Adjustable FPR. Any problems will be found and corrected then.
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Old 12-05-2003, 05:23 PM
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Will,just donīt forget to keep your eyes on the road,not in the boost guage,even when you get used to the car!!

Please inform us when yo do you dyno...iīm sure you car is ok.And think that,more boost,less reliability and duration! (thatīs what i think when i see my boost )
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Old 12-06-2003, 07:41 AM
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Thanks Manute.

I will definitely post my dyno run sheet when I get it done...1 month or so....I"m already excited as heck!! My girlfriend asked me what I want for Xmas....my reply...DAY AT THE DYNO!!!
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Old 12-06-2003, 04:53 PM
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LOL....not very romantic gift tho! But who cares,is useful!

How much it costs? I never asked for that thing here,I wouldīnt do because if i notice one less HP than expected, iīd turn mad!
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Old 12-07-2003, 08:21 AM
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$75 for 3 runs...so I'm going $150 for 6! You're right....not so romantic....but at least I'm honest as to what I want right??!! haha

I agree...when the car puts down less than I expect I'll be pretty disappointed...but hopefully that won't happen!

Just opened up the airbox on this car and I think a dead animal is in there....well not really. But the airbox was full of dirt and stuff....I have never seen one so dirty!! (it's a K&N)....so I'm cleaning it as we speak. Hope it feels a bit better after the cleaning!
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Old 12-07-2003, 01:26 PM
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Not very expensive,maybe i should try dyno one day.

I never opened my airbox,seems strange to found such things there!Maybe the filter gets dirty very easily,good to know,i need to check that simple thing.Sure it will be better after cleaning it!

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Old 12-08-2003, 02:38 PM
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