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vacuum line diagram for '98 gtp

leo

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Does anyone have any pictures or diagrams for proper placement of all the vac. lines for a '98 gtp. The car runs, but as soon as it boosts, it seems like a severe missfire or cutting off power or something... it is very annoying to drive the car under 1/2 throttle at all times and not have enough power to make a pass or even merge on the highway... any1 else have this problem in the past any fixes or pics/diagrams of proper vac line routes??? Thanks in advance!
 

smug

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check your plugs and wires first. My GTP did that once and I had a bad plug wire.
 

leo

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ya, i planned on doing a whole tune up tomorrow including the plugs and wires. I just wanted a reference diagram to make sure iv got them set properly... thanks!
 

TommyGloves

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See attached PDF for diagram. HTH.

(1)To EVAP Canister (At Rear of Vehicle)
(2)PCV Valve
(3)To Vacuum Brake Booster
(4)Throttle Body
(5)Supercharger Bypass Actuator (Bypass Valve Actuator)
(6)Supercharger Bypass Solenoid (Boost Control Solenoid)
(7)Fuel Pressure Regulator
(8)Supercharger Assembly
(9)EVAP Canister Purge Valve
(10)Manifold Absolute Pressure (MAP) Sensor

Make sure to check the rubber "T" fitting under the SC snout. They tend to become brittle and crack.
 

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Bru

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check your plugs and wires first. My GTP did that once and I had a bad plug wire.
X100

I've had the same thing happen to me. Was a burnt plug wire on the headers.
 

leo

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question... if it was a bad plug or wire, wouldnt it be creating "missing" all the way through the power band... not only upon boost? my "bogging" happens ONLY when the car boosts. thats why I was curious about the vac line set-up. I will check the plugs n wires tho.
 

Turk

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question... if it was a bad plug or wire, wouldnt it be creating "missing" all the way through the power band... not only upon boost? my "bogging" happens ONLY when the car boosts. thats why I was curious about the vac line set-up. I will check the plugs n wires tho.
I'm not sure about GTPs, but when my SS had a bad wire, it was missing only at idle and when I first accelerated. Everywhere else it was fine.
 

Bru

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question... if it was a bad plug or wire, wouldnt it be creating "missing" all the way through the power band... not only upon boost? my "bogging" happens ONLY when the car boosts. thats why I was curious about the vac line set-up. I will check the plugs n wires tho.
Not always. My wire was burnt halfway through and it ran fine as long as I wasn't in boost. Once boost hit the engine started to break up.
 

Freebeer187

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question... if it was a bad plug or wire, wouldnt it be creating "missing" all the way through the power band... not only upon boost? my "bogging" happens ONLY when the car boosts. thats why I was curious about the vac line set-up. I will check the plugs n wires tho.
You would think it would but im my situation it was not. I had the EXACT problem. The spark plug housing cracked. The actual metal inside appeared to be untouched (of course it was used and needed to be replaced) but the housing was causing the problem. When the plug was removed it collapsed into pieces.

Look at the thread I posted for more info. You can see all the troubleshooting I went through.

I had the car scanned while driving. At a small idle to wide open throttle there was 0 missfires being reported and 0 knock. We tried allot of things but for some reasons me and the guy I was working with forgot to check the plugs.

Before you jump to conclusions, purchase new spark plug wires and new plugs. Dont forget to gap them. Even if it does not fix your problem, it still is never a bad thing to have new plugs/wires.
 

leo

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ok, thanks guys! I will try it out.
 

leo

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ok, set all the vac. lines properly now... they were a mess and not all accurate, but it runs smoother now... Still has the main missfire on boost... had no time to do plugs n wires today, hopefully il get to it tomorrow, but good thing I got the vac lines in order now at least...
 

leo

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before i did anything today i got these 5 codes...

P0134- something to do with O2
P0135- another O2 code
P0300- engine missfire
P0446- some Evap code
P1133- S1-S2 and B1-B2 or something like that... sorry, i didnt memorize them.

cleared everything and il drive it home from the shop and back tomorrow to see if i get more codes or repeaters.
 

leo

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ok... next step please... wires are all good, and plugs are all good... grrrrrr.
 

SaturdaysGS

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My grandmothers 98 Buick LeSabre (3.8 N/A) had an EVAP code that caused the car to have a random misfire. I was only able to hook it up to a scan tool before she went and had the car fixed. Don't even know what they replaced (wasnt plugs/wires, it was some EVAP sensor she said) but now it runs fine.
 

leo

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ya, iv been driving it around like mad to get it to throw me new codes, but nothing yet... i was guessing that would be the next thing...evap system check
 

SaturdaysGS

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I'll see if I can dig up the reciept from her to see what exactly what was replaced, but thats already probably been misplaced.
 

TommyGloves

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P0134, P0135, P1133 - Either the front o2 is bad or was unconnected and you ran the car.

How old is the fuel pressure regulator and/or fuel filter?
 

Freebeer187

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P0134, P0135, P1133 - Either the front o2 is bad or was unconnected and you ran the car.

How old is the fuel pressure regulator and/or fuel filter?
Good idea. Replace the fuel filter. Even if its not the problem, once again its a good idea to do. You can also check the fuel pressure while the car is running. You need a tool for it (i had a friend check mine).
 

leo

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does anyone else have a pain in the ass time pumping fuel and have the nozzle unclick every $0.48... and have to costantly re-click and re-adjust the angle ur pumping and speed and pitch of the nozzle??? wtf... il check fuel filter tmw, depending on price for new 1, i may replace it... but its a spark/misfire issue tho.
 

Yaj Yak

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nope i have never had a problem like that.
 

Freebeer187

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does anyone else have a pain in the ass time pumping fuel and have the nozzle unclick every $0.48... and have to costantly re-click and re-adjust the angle ur pumping and speed and pitch of the nozzle??? wtf... il check fuel filter tmw, depending on price for new 1, i may replace it... but its a spark/misfire issue tho.
Never have I heard of or have had this problem
 

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