Major vacuum/boost problems, I think....

fbodlovr

1/4 Mile Freak
I guess ill start off listing everything that is on the car RIGHT NOW.

-84 Gn
-36lb blue tops
-Adjustable FPR-set at 30lbs with vacuum hose on. Only way to get it to rev all the way up.
-ACDelco cr43ts spark plugs
-TA33 with te61 guts
-Ported intake
-92 Thrasher Chip
-MAT Temp. Sens
-86 87 ECM
-Autometer Electric Fuel Pressure gauge
-Autometer Mech. Boost/Vacuum gauge

I have new plug wires, new ignition coil and the other goodies needed to install that, walbro340 pump, hot wire kit, fuel filter, and I beleive thats it WAITING to be installed. I know for a fact that I have a cracked pass. side header.

Heres the problem. The car is really really sluggish. The slip that came with the FPR said from 15.0 to 13.5 quarter mile times should be set to 42lbs with vacuum tube off. It would stutter badly in the upper rpms when like this. The only way we could get it to rev up completely is to drop the pressure to about 30lbs with the vacuum hose on. When looking at the boost/vacuum gauge, it sits at 10lbs vacuum. WHen I get on it, it only goes to 0. I can hear the turbo spooling, but it isnt screaming like I'd think it would. The puck is completely closed when sitting there because I can barely get it on normally. Now, what is the problem??????????? I have a scanmaster coming that should be here this week. But, until then what do you guys think?

Oh yeah, I have my boost gauge t'ed into the hose coming off the back of the vacuum block towards the drivers side. Hope that helps. :)
 
What does 30lbs vac line on translate to idle and vac line off? Whats fp reading at wot?Gauge may be inaccurate.How long does fp reading hold on gauge after shutting car off?
 
I think with vac line off it goes up to around 40lbs. Im not sure what it read at wot. I was also using a seperate fuel pressure gauge kit. I didnt check to see how long it held it after it was off, but earlier it held for quite some time. I do have a walbro sitting hear waiting to be put in.
 
you need to know fp at wot,that should be-static plus boost-pressure.Im not sure if youll runing too rich due to a faulty gauge or too lean due to bad pump,fuel filter,vac leak or header leak.Id hang tight to you get some scan tool readings,that should help narrow this down.
 
Well, i dont really know what boost im running because it doesnt go anywhere above 0. What should i do if it wont go above 0?
 
Youll have to ask others on this board about boost gauge hookup for your yr car.It may be hooked up wrong or gauge is bad.Get pump,hot wire,filter and header fixed.O2 wont read correctly with that leak.
 
Hey
Few things. The thrasher chips are set up for 45#'s fuel pressure. Is it a chip for 36# injectors? Thrasher chips need fuel. Move your boost gauge tie-in over to the line to the map sensor. Back of the vacuum block isn't where you tie-in. Could be the need of a better fuel pump as stated. Could be a bad maf sensor. You have a couple seperate issues.

suicide six wrote:
you need to know fp at wot,that should be-static plus boost-pressure.Im not sure if youll runing too rich due to a faulty gauge or too lean due to bad pump,fuel filter,vac leak or header leak.Id hang tight to you get some scan tool readings,that should help narrow this down.
Good Advice.
 
Well, i bought the turbo, chip, and intake off of a guy oh here. He said he was running the chip with this combo. Im fairly sure its for 36lb blue tops. I THINK i remember seeing it on the back of the chip also.
 
sounds like a vacuum leak and a pretty big one as well. If its 0 under boost, somewhere a line is loosing it. does the stock gauge show anything? Another thing i would consider is to get rid of the thrasher. I used to think they were great, but with the new chips out there you can see a big gain. I had a friend drop 1/2 a second going to another street chip compared to his thrasher. They just aren't aggressive enough.
 
The T-body never sees boost, only vacuum. That's why your guage only goes to 0. You have to tap in somewhere that gets it's vacuum/boost after the turbo like the FPR vacuum line or MAP sensor line.

The header leak can make it run rich all the time vs a vacuum leak which will make it run lean under vacuum and rich under boost. Usually the idle will be high if the leak is bad enough to make it run bad. 10" of vacuum is not enough, something is wrong with that. Even with a bigger cam, mine pulls nearly 18" at idle. Did it start doing this when you installed the mods?
 
JDSfastGN said:
sounds like a vacuum leak and a pretty big one as well. If its 0 under boost, somewhere a line is loosing it. does the stock gauge show anything? Another thing i would consider is to get rid of the thrasher. I used to think they were great, but with the new chips out there you can see a big gain. I had a friend drop 1/2 a second going to another street chip compared to his thrasher. They just aren't aggressive enough.

Ive actually been thinking about getting a turbotweak chip. I hear nothing but good about them. The stock gauge i hear is crap, and ive only got it to read.....maybe 5 lbs of boost when reving it up suddenly.
 
cool 84 said:
The T-body never sees boost, only vacuum. That's why your guage only goes to 0. You have to tap in somewhere that gets it's vacuum/boost after the turbo like the FPR vacuum line or MAP sensor line.

The header leak can make it run rich all the time vs a vacuum leak which will make it run lean under vacuum and rich under boost. Usually the idle will be high if the leak is bad enough to make it run bad. 10" of vacuum is not enough, something is wrong with that. Even with a bigger cam, mine pulls nearly 18" at idle. Did it start doing this when you installed the mods?

I hate to ask this, but where is the map sensor on these cars? The idle isnt bad. When i take off a hose it speeds up a little. Im only reading 10lbs of vacuum where it is t'ed into now. I wonder if thats why it isnt reading enough. When we bought the car it had small issues. This has been one of them. The car actually came with a stock turbo, and its exhaust side impeller was busted off. I guess once i move the vacuum line, i will be able to see what the true boost is huh.

Also, the line that came with the autometer gauge was pretty short. What are you guys using to get to places further away? I could only get from the top of the pillar to the turbo area. The hose that came with it is the white, small, hard hose.

One more thing, when i move it, and if i dont see any difference in boost or vacuum, what would be your guys assumption?
 
The map sensor is on the passenger side fender well. Rectangle with a vacuum and electric plug. The vacuum line for it runs from the sensor, along the firewall to the back of the intake manifold. You can tap into the fuel pressure regulator line, I don't like doing that on the chance that if something happens to the boost guage line like a leak, it could lower your FP under boost.
 
Well, i found the hose to the map sensor was actually off. I put it back on, i noticed that it was sputtering real bad when revved up. When i took it out, it also sputtered when i got going a little. When we pulled it back in, i smellled gas really bad. Turned out the shrader valve is bad on the fuel rail. Im also not getting any fuel pressure now. I cant hear the pump priming either. Think the pump is just going out? I have a walbro im going to put in, just havent had the chance.
 
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