Signalmtb

1988 944 Turbo S,


Car was running very rich with 3.0FPR and autothority chip set to +12.5%. Reduced it to stock setting at +0%. Was boosting to 14-15psi.


Had a 3.0 FPR, and just installed a new FPR (2.5), no other DME changes, now the boost is barely 10-11. Would a 2.5 (vs 3.0) FPR reduce the boost like that? Again, have not changed the DME setting, so it's still at stock 0%.

AlphaOmegaPower

Sounds like the 3 bar you had. It should have been replaced with another 3bar. Check for vacuum leaks.

Signalmtb

does anyone know if setting my FQR back to +12.5% would help? I hate to pull all that DME crap out only to be a silly thing to try.

AlphaOmegaPower

Yes it would reduce boost as you need certain fuel pressure to keep up with higher psi.
Get a good 3 bar.

lart951

the possibility is that you are getting less fuel, causing a lean condition causing knock and the ignition is being retarded

Signalmtb

thanks to the responses...to clarify though, will setting the FQR to +12.5% potentially help given the FPR is a 2.5 bar and not a 3.0? I'm just not clear on that point. I could get another FPR 3.0bar but having just dropped $100 on this one, I'd like to avoid it if simply changing the FQR would help, so just curious before I go rip it out again.

AlphaOmegaPower

No disrespect intended but read what Lart said.
If everything is set up like it sounds like it is and you do not have a proper 3 bar you could potentially damage the engine. Get a working 3 bar. If there is an issue I would look at vacuum leaks.... Then at adjusting the fqr. I'm pretty sure that's not for that though. Swore that was for if you are at a different elevation compared to sea level.

Lart is acting like the grim reaper right now. He warned you. Heed it or he will materialize and spirit your Porsche away...

A 3 bar is the most standard and basic change we make when doing any modifications to the engine. Even with just an autothority chip and nothing else you use a 3 bar.

https://rennlist.com/forums/944-turb...regulator.html

Read each post closely in that thread.

Signalmtb

hey man, no disrespect taken or inferred at all, I appreciate all the help and input! This forum is awesome. Just wasn't sure with my setup if it was a problem, with a 2.5bar which is stock, and stock boost is around 11 (all of what I was seeing), it sounded normal just not as great as it was with the 3 bar and FQS dialed up. And, my prior setup was running so rich I failed emissions and fouled new plugs in 2 months. So I was thinking with the reduced boost and stock 2.5 FPR...oh, so this is what a "normal" turbo should feel like. Which kinda sucked to be honest...I lost the feeling of putting you in your seat.


So sounds like a 3bar is in order given I have it chipped.


Anyone need a brand new 2.5bar??

Tom M'Guinn

It's really not a good idea to make these kinds of changes without knowing your AFR and if/when it's knocking. I'd get a wideband O2 sensor and knock counter if you plan to modify the car (or go to the dyno). Without data, you're shooting in the dark. A car can be super rich a low smog loads, yet super lean on boost, or vice versa. Once you see where you really stand, you can figure out how to tune it. The alternative is to revert to bone stock, or to chips or a maf kit with a known-good tune. Trial and error tuning on these cars is like playing Head Gasket Roulette.

bw993

You need to get a new 3 bar FPR, since the Authority maps are based on 43 PSI of fuel.

Using a 2.5 bar FPR and increasing the FQS to +12.5% does not increase the physical amount of fuel available, beyond the max. limit of your 2.5 bar FPR. It only increases the scaling used in the maps, not the absolute amount of fuel you get to the injectors, which is mechanically limited by the FPR.

AlphaOmegaPower

where are you located and where was the car before you got it? It's strange to me someone tweaked the FQS. One of my turbos had the same set up when I got it. Ran fine but a little rich. No FQS adjustment.
I do not have emissions here though. To pass I would put stock 2.5 and stock chip.
Then 3 bar and chip back in.
Pretty sure several venders modified set ups can pass. I would look at upgrading to have more power but also more control and safety features.

Signalmtb

thanks to all the input above, I ordered and received my new 3.0bar FPR today. Car is in TN and spent most of its life in SC. I passed emissions fine with 3.0 bar, chip and 0% FQS setting. So installing the new FPR now to get back to that setup.


Question: procedure calls for removing fuel pump relay and running it out of gas. Is this necessary or just one of those recommended things? Just wasn't sure how much fuel would actually spray out once I unclamp it. TIA.

AlphaOmegaPower

Good to hear. Pull that or the fuse and crank your engine a few times.

Where in Tennessee are you?

Signalmtb

Chattanooga. You nearby??

AlphaOmegaPower

Up there interstate hour south of Nashville in Shelbyville.