I am confused here.....is this normal or not.

[Andrade08]

I keep reading how this car is set up to run 15.6PSI. When I floor my car in 3rd-6th I get a spike to over 15psi (can't exactly tell) and it holds steady for I would say 3 seconds & then it very quickly goes down and holds at 10PSI. And as I get closer to 6000rpms(say 5800 and over) it goes under 10psi but never below 9psi. Is this normal? I am at 10psi by 3500rpms no matter the gear (not counting 1st and 2nd here).
Now, if I am cruising at 65mph and down shift to 4th and nail it the boost spikes out to about 14psi (Never hits 15psi at all) and VERY quickly drops to 10psi. Is my car frigged up? As of right now I am bone stock because I didn't know if it was me or the mods on the car. I had a Forge BPV, ATP 3" inlet pipe, K&N drop in and a modded stock air box. Right now I have the stock BPV on, stock inlet pipe and a stock unmodified air box (I have two stock air boxes). Only non stock things are the boost gauge and my SU silicone boost tubes(car did this worse before the boost tubes and that is why I put them on). The PS gauge works because I put a vacuum pump/gauge on it and set it to 5..10..15 and 20" of vacuum and the PS gauge was right on. I made sure I held the vacuum for a while too, not just a few seconds. I then hooked a small air line to my compressor and put 10psi to it......gauge was right on.....15psi.....perfect......20psi.......dead nuts. I held those too. Not just a few second test. So I know my gauge is good.
My car does the same exact thing with all the mods on except I get alot more pull over 4000rpms from the ATP pipe no matter what the boost is.
Am I OK or is my car loosing more boost than normal?

 

[Hypnotized]

Dude, my car did the same. Get an intake and you will hold 15 all day long. I went with Cobb and I have an HKS BOV vented. I had a Turbo XS hybrid and had the same results.

 

[mrlilguy157]

thats typical and it sucks. its because of the small turbo for 1, and 2nd because of that closing throttle plate.

 

[ZooZoom]

not sure why it seems a bit lower than what my (mechanical) ProSport boost guage reads.

If I cruise along at say 70 mph in 6th gear and floor it, it will jump up to 16-17 psi for a few seconds then slower taper down to about 12 psi as it runs out of "gas" above 5,500 rpms.

I can routinely hit 15-16 psi jumping on it in 2nd, 3rd, 4th, & 5th gears. Now it won't hold 15+ psi forever. It always tapers down to around 12'ish psi as the rpms rise. But I don't recall it ever showing a "ceiling" as low as 10 psi.


Mods that probably make a difference: ETS 3.25" thk TMIC and Cobb SF intake. Exhaust is 100% stock.

 

[Falconx84]

Mods are probably where the extra boost is from, freeing up the intake tract

 

[Andrade08]

I keep forgetting to add that it is COLD out too. It was 28* when I tested stock yesterday. It has been a struggle for the temps to stay over 30* lately. Normal temps for late feb are mid 40s too so..............this weather is old already. I am more than ready for friggin spring.

 

[nypest]

I keep reading how this car is set up to run 15.6PSI. When I floor my car in 3rd-6th I get a spike to over 15psi (can't exactly tell) and it holds steady for I would say 3 seconds & then it very quickly goes down and holds at 10PSI. And as I get closer to 6000rpms(say 5800 and over) it goes under 10psi but never below 9psi. Is this normal? I am at 10psi by 3500rpms no matter the gear (not counting 1st and 2nd here).
Now, if I am cruising at 65mph and down shift to 4th and nail it the boost spikes out to about 14psi (Never hits 15psi at all) and VERY quickly drops to 10psi. Is my car frigged up? As of right now I am bone stock because I didn't know if it was me or the mods on the car. I had a Forge BPV, ATP 3" inlet pipe, K&N drop in and a modded stock air box. Right now I have the stock BPV on, stock inlet pipe and a stock unmodified air box (I have two stock air boxes). Only non stock things are the boost gauge and my SU silicone boost tubes(car did this worse before the boost tubes and that is why I put them on). The PS gauge works because I put a vacuum pump/gauge on it and set it to 5..10..15 and 20" of vacuum and the PS gauge was right on. I made sure I held the vacuum for a while too, not just a few seconds. I then hooked a small air line to my compressor and put 10psi to it......gauge was right on.....15psi.....perfect......20psi.......dead nuts. I held those too. Not just a few second test. So I know my gauge is good.
My car does the same exact thing with all the mods on except I get alot more pull over 4000rpms from the ATP pipe no matter what the boost is.
Am I OK or is my car loosing more boost than normal?

What sppring you running in the forge ??

 

[nypest]

Get rid of that bad stock intake, you will see alot of improvement there. Then get a bigger TMIC or go FMIC and you will see a huge difference in Boost.... With my TMIC on i run 17psi to about 6200 where she falls of a bit to 15.....

 

[Andrade08]

I do not have the Forge valve on right now. I went almost 100% stock. Only boost tubes and the Prosport Mechanical boost gauge are on the car. Yes, I spent a few hours taking the ATP pipe off......again....it will be on again by Thurs night though. I have another Cobb on order but I like the cut down Fujita short ram thing. I also really like the air straightener built into the Cobbs bellmouth syle MAF housing though. I am going to probably stay with the Cobb MAF housing and filter when it gets here then make my own mounting bracket and tuck the filter as far down as I can. I have aluminum intake pipe sections here and a ton of couplers so it won't be hard. Once this is squared away the ETS 3" or 3.25" TMIC is going to be next. I was torn between the TMIC or a cat back. Cat back is more for looks (tip) and sound which I do like because I am a car show guy but..........the TMIC has alot of good points to it that really out weigh the cat back. I am hoping that SCT comes out with some tuning software this spring eary summer. If not then I will do the MAP clamp/MBC route. Next spring I will do a full TBE but for now the car is a few months old with 4000 miles so I am going to leave most of the exaust alone.......I will just have an exhaust shop kill the middle resonator and the little muffler at the end and put a nice 4.5" tip on the end and call it a year.

 

[nypest]

I do not have the Forge valve on right now. I went almost 100% stock. Only boost tubes and the Prosport Mechanical boost gauge are on the car. Yes, I spent a few hours taking the ATP pipe off......again....it will be on again by Thurs night though. I have another Cobb on order but I like the cut down Fujita short ram thing. I also really like the air straightener built into the Cobbs bellmouth syle MAF housing though. I am going to probably stay with the Cobb MAF housing and filter when it gets here then make my own mounting bracket and tuck the filter as far down as I can. I have aluminum intake pipe sections here and a ton of couplers so it won't be hard. Once this is squared away the ETS 3" or 3.25" TMIC is going to be next. I was torn between the TMIC or a cat back. Cat back is more for looks (tip) and sound which I do like because I am a car show guy but..........the TMIC has alot of good points to it that really out weigh the cat back. I am hoping that SCT comes out with some tuning software this spring eary summer. If not then I will do the MAP clamp/MBC route. Next spring I will do a full TBE but for now the car is a few months old with 4000 miles so I am going to leave most of the exaust alone.......I will just have an exhaust shop kill the middle resonator and the little muffler at the end and put a nice 4.5" tip on the end and call it a year.

Nice to see ya got plans!


Yeah that TMIC will do way better for you performance wise then a cat back. I bet you gain 2-3psi from the TMIC

 

[Andrade08]

Sheesh.......All done. I started early taking breaks to warm up and type here and there on the Laptop. But, done. All back on. Battery is unplugged right now so the ECM resets. I am thinking of welding/brazing on a bracket so the ATP pipe is held in place were the stock inlet pipe was. Here is a PIC. Only difference is the stock valve. The forge is on now too. I left it in the house so I did PICs 1st and slapped on the Forge unit after.

 

[Andrade08]

And I run the blue spring with one shim in the Forge.

 

[nypest]

Sheesh.......All done. I started early taking breaks to warm up and type here and there on the Laptop. But, done. All back on. Battery is unplugged right now so the ECM resets. I am thinking of welding/brazing on a bracket so the ATP pipe is held in place were the stock inlet pipe was. Here is a PIC. Only difference is the stock valve. The forge is on now too. I left it in the house so I did PICs 1st and slapped on the Forge unit after.

nice work

 

[tru-boost]

wow, mine was never that low ! i used to spike to about 17psi and hols about 14psi. by 6k RPM it would be down to 10psi. if you are at 10psi by 3500rpm, i dont think it is normal. you may have a leak somewhere (SU boost tubes) maybe not the tubes themselves, but maybe a clamp is loose. i gues if others see similar results it may ne normal, but i know mine never went that low. you boost should hold solid to at least 5k. if it even starts to drop before that, i would think there is a problem.

 

[SwampAss]

wow, mine was never that low ! i used to spike to about 17psi and hols about 14psi. by 6k RPM it would be down to 10psi. if you are at 10psi by 3500rpm, i dont think it is normal. you may have a leak somewhere (SU boost tubes) maybe not the tubes themselves, but maybe a clamp is loose. i gues if others see similar results it may ne normal, but i know mine never went that low. you boost should hold solid to at least 5k. if it even starts to drop before that, i would think there is a problem.

Mine is the same way. I hold about 10psi in 3rd and up

 

[tru-boost]

hhhmmm that sucks guys ! not to rub salt in your wound or anything, but as a suggestion, maybe a MBC will make you happy ! i spike to about 22 and hold 19-20 up to 5k it drops to about 15psi to by redline, and even if i take it up to the rev limit i dont fall to 10psi now....13 at the lowest.