Autotap and boost ?

[Grover03]

The intake manifold absolute pressure (PSI) keeps pegging at about 30psi no matter what size pulley I have on. Tried a 3.0" and 3.5" upper with the 6lb lower tonight and the autotap graph looked exactely the same for each?? What gives? It goes to 30psi and flat lines till I get off the boost.

Grover

 

[Shadowgray03]

Which parameter are you using?

"Intake manifold absolute pressure" or "Manifold absolute Pressure(MAP)" If youve only tried one, maybe try switching to the other.

Also note that (if I remember correctly) absolute pressure at sea level is like 14.xx so if your running 17psi you should be hitting a MAP of 31.

 

[Grover03]

Tried them both. MAP pegs at 60, intake MAP pegs at 30 - regardless which upper pulley size and that can't be right.

Grover

 

[DPS]

I'm not sure what you mean by absolute pressure, but I believe barometric pressure at sea level is 29.9X. Don't know if this helps or not.

:beer:

 

[Shadowgray03]

Originally posted by DPS
I'm not sure what you mean by absolute pressure, but I believe barometric pressure at sea level is 29.9X. Don't know if this helps or not.

:beer:

Ok, I found out what I was thinking when I said absolute pressure at sea level. When the car is not running but autotap is connected, MAP should have a reading, this reading (which is approx 14.xx or so) minus the MAP reading should be PSI or boost when car is running.

 

[Grover03]

Originally posted by Shadowgray03
Ok, I found out what I was thinking when I said absolute pressure at sea level. When the car is not running but autotap is connected, MAP should have a reading, this reading (which is approx 14.xx or so) minus the MAP reading should be PSI or boost when car is running.

I agree. 30-14.2 (where I am)=14.8lb boost I believe.
However, the autotap pegs at 30 regardless which upper pulley I have on (3 or 3.5"). Could the autotap be faulty? Can't rely on my boost gauge - has been sent back to Autometer as it was faulty - should have a new one in next week.

Grover

 

[Shadowgray03]

Originally posted by Grover03
I agree. 30-14.2 (where I am)=14.8lb boost I believe.
However, the autotap pegs at 30 regardless which upper pulley I have on (3 or 3.5"). Could the autotap be faulty? Can't rely on my boost gauge - has been sent back to Autometer as it was faulty - should have a new one in next week.

Grover

If anything I would say its a limitation of the autotap software itself. The autotap isnt really monitoring any of the ODB stuff itself, it is just pulling data from the EEC which in turn gets it(or calculates it) from sensors in the car. You may want to post on autotaps forums and see if they are aware of any problems with that parameter. Also make sure you are running the latest version of their software(2.04 I beleive).

 

[2K3BRA]

I lent Prasad IRageATMI my software and hardware for autotap I wonder if it worked for him maybe he will chime in with some advice hes running aftermarket levels of boost on his. I think he said it worked.

 

[Dana]

Maybe you're only getting 15lbs of boost and the AutoTap is correct?

Dana

 

[Grover03]

Ok, but are you saying that I am getting exactely 15lb of boost with both the 3.5" and 3.0" uppers?

 

[Dana]

Maybe.
Having any problem with belt slippage?
It probably isn't the case, but it is possible.
Are you using different belts for the 2 different sizes pulleys?

Or the PCM is dumping boost on you for some reason?

I guess the best thing is to wait until you have the boost gauge back and can check.
Just a couple of more ideas.
Dana

 

[Grover03]

Thanks Dana. I don't think I am having a problem with slippage. Using same belt. It's super tight with one and half tensioner with the other. I have thought the pcm or KB might be dumping boost. Just have to wait for the new guage.

Grover

 

[Dana]

Wasn't there an issue with the KB dump valve being out of place or loosening up somehow?
I know I read about the valve problem, just don't remember exactly what it was or if it would apply in this case.
Maybe someone else here remembers?
Dana

 

[Shadowgray03]

In some cases the arm from the selenoid to the valve became lose and arm fell of meaning valve was open all the time, when that happened though boost was dumped all the time. SOme had the arm come partially off and it wedged the valve at a partial position so all boost wasnt seen.

Also, for me my 17psi isnt seen until ~4500rpm. I pegs 13psi fast and slowly climbs to 17psi at approx 4500rpm. So, if you are running the 6lb lower and 3" upper and not taking it to higher rpm, you may not be seeing full boost.