Overboooooost

[aliencurv]

how much max boost should i see with my first and second apr tune in my b5 s4 "stage 3"?

[R-Audi]

Re: Overboooooost

There is no set range.. (Due to temperature, density etc) but typically it would range from 19-23... what are you seeing??

And Im assuming tune 1 and 2 refer to 91 and 93 program?

[RSS]

Re: Overboooooost

One of us would have to have a properly running car to answer that but we own S4's so that will never happen

[R_Ethug]

Re: Overboooooost

LOL.. mine runs properly i think.. other than my fluttering gauge but then again i usually only boost 2-3psi on the daily

[Smarty39]

Re: Overboooooost

That is so true it's actually not funny...

One of us would have to have a properly running car to answer that but we own S4's so that will never happen

[The_Jerbel]

Re: Overboooooost

My car ran like a top. But then I went and sold it.

[The_Jerbel]

Re: Overboooooost

I agree with Mark (R-Audi), and would say that at our altitude you should see 20-21 psi peak.

[RSS]

Re: Overboooooost

Well today mine is running a solid 6-8psi limp mode FTL

[aliencurv]

Re: Overboooooost

ah okay so it does figure out the boost using some maths . gotcha .


In kelowna using Tune #2 with 94 octane,
well the issue is now that i fixed the boost leak, i'm seeing nearly 30 psi . and that frightened me so i let the foot off the gas quickly . openned the hood and examined to make sure i still had wastegate vacumn lines

got back in the car. and tired another pull . i was still seeing 25+ psi . but it was stuttering and then making a noise which i suspected was either detonation or spark blowout . but either way, the check engine light was flashing .

so i drove carefully from that point along the highway some hours.. then i tried another pull and it kept cutting out again. like jerking. and was about 25 psi (so it adjusted).

so of course i thought maybe bad gas or who knows . so i put myself in the 91 octane tune and continued on to calgary avoiding high boost.

i got near banff and tried a 91 octane tune pull with no problems . either the problem "fixed itself", or i had bad gas, or the plugs need changing, or it didn't like the altitude change.

either way i gotta find out what's wrong before i take it to ontario in 2 weeks.

[The_Jerbel]

Re: Overboooooost

That's too high.

Just so you know, Mohawk 94oct performs about like shell 91oct.

Have you experienced over-boosting or inconsistent boosting for a while now, or is it just recent?

If you wanna bring the car over some time I can figure out what's going on for you. Send me a PM if that's what you want to do.

[aliencurv]

Re: Overboooooost

That's too high.

Just so you know, Mohawk 94oct performs about like shell 91oct.

how can that be? octane is a measurement of how much pressure the gasoline can withstand before combusting . it's a pretty straight forward measurement and ethonal has very great pressure resistance properties like alcohol. my other cars i tune on 94 octane. i can tell you that i can't run 91 or i experience detonation. 94 mohawk definetly withstands higher compression then 91. all the cars that come out of the shop that tune on 94 have to stick with it or they will experience detonation on 91 also. i think it'd be illegal for mohawk to advertise an incorrect octane/ron.

Have you experienced over-boosting or inconsistent boosting for a while now, or is it just recent?

i've always seen around 23-25 psi until i patched a boost leak, now it bumped to 30 then went back down to about 25. strange thing is, after it throws a cell it limits me to 5 psi. which means the actuator and solenoid must be working.

If you wanna bring the car over some time I can figure out what's going on for you. Send me a PM if that's what you want to do.

where is here? i wouldn't mind someone with experience on these cars to take a look. i didn't build it, so i'm learning as things break lol

[R-Audi]

Re: Overboooooost

Jordan, this is my old car...

I wonder if the nozzle patch is holding well enough? I dont know much about the hosing for the meth kit, but could the air be coming out the hose that is typically in the nozzle? The one way valve is right before the splitter...(to the right of the drivers side nozzle)
Other then that possibly need a pressure test.. The N75 was replaced last year when I experienced some overboost.. and that solved it right away.

[aliencurv]

Re: Overboooooost

Jordan, this is my old car...

I wonder if the nozzle patch is holding well enough? I dont know much about the hosing for the meth kit, but could the air be coming out the hose that is typically in the nozzle? The one way valve is right before the splitter...(to the right of the drivers side nozzle)
Other then that possibly need a pressure test.. The N75 was replaced last year when I experienced some overboost.. and that solved it right away.

N75 - Solenoid Valve for charge pressure control
G31 - Charge Pressure Sender

Will vag-com monitor those pids? otherwise i can hook my voltage datalogger up to the wires.

[The_Jerbel]

Re: Overboooooost

how can that be? octane is a measurement of how much pressure the gasoline can withstand before combusting . it's a pretty straight forward measurement and ethonal has very great pressure resistance properties like alcohol. my other cars i tune on 94 octane. i can tell you that i can't run 91 or i experience detonation. 94 mohawk definetly withstands higher compression then 91. all the cars that come out of the shop that tune on 94 have to stick with it or they will experience detonation on 91 also. i think it'd be illegal for mohawk to advertise an incorrect octane/ron.

This is from Wikipedia, so take it for what you will:
"Definition of octane rating

Octane rating of a spark ignition engine fuel is the detonation resistance (anti-knock rating) compared to a mixture of iso-octane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. By definition, iso-octane is assigned an octane rating of 100 and heptane is assigned an octane rating of zero. An 87-octane gasoline, for example, possesses the same anti-knock rating of a mixture of 87% (by volume) iso-octane and 13% (by volume) n-heptane. This does not mean, however, that the gasoline actually contains these hydrocarbons in these proportions. It simply means that it has the same detonation resistance as the described mixture.

Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn rather than explode."

You are correct about what octane ratings mean, but there is more to fuel performance than its octane rating. I can tell you that I have done extensive testing using various fuels in my old VAST stage 3 S4, and Shell 91 and Mohawk 94 gave almost identical performance outputs.

i've always seen around 23-25 psi until i patched a boost leak, now it bumped to 30 then went back down to about 25. strange thing is, after it throws a cell it limits me to 5 psi. which means the actuator and solenoid must be working.

This is NOT normal. 25-30psi is not what an OTS stage 3 tune should be running, ESPECIALLY for 3900 feet of elevation. Your K04s won't last long at that output level.

where is here? i wouldn't mind someone with experience on these cars to take a look. i didn't build it, so i'm learning as things break lol

I'm a full-time student taking accounting at the UofC, but I work on Audi's on the side. I particularly work on cars with the 2.7T power plant. I work out of my garage, and I live right by Mount Royal college.

[The_Jerbel]

Re: Overboooooost

Jordan, this is my old car...

I wonder if the nozzle patch is holding well enough? I dont know much about the hosing for the meth kit, but could the air be coming out the hose that is typically in the nozzle? The one way valve is right before the splitter...(to the right of the drivers side nozzle)
Other then that possibly need a pressure test.. The N75 was replaced last year when I experienced some overboost.. and that solved it right away.

I figured that this was your old car, Mark. Have you taken possession of the new car yet?

If the hole in the bi-pipe is patched correctly, then there shouldn't be any air leaking out of the bi-pipe at all, even through the meth injection system.

The N75 may have crapped the bed on you again, but there's only one way to find out, and that's through troubleshooting a few different systems to see where the abnormal boost level is coming from.