17 psi too high?

[robbiepc30]

I just recently took my 91 eagle talon to a performance shop to get some work done to it. I got a 21/2 inch down pipe and 3inch back exaust from there. I had a 255 high pressure walbro fuel pump installed in it, and had it rewired, and last a manual boost controller installed, and I asked for it to be set at 15psi. I picked my car up a couple of days ago, and they told me that they had some problems adjusting the boost controller, and it is currently set at 17psi. The guy who did all the work, is a DSM guy, he owns too supped up talons, and I mentioned to him if that was a little high for running stock injectors, and intercooler and he told me it was fine. I find it hard to believe, because everywhere I read people say 15-16psi max, and I am using this car as a daily driver. I know people turn it up a bit more for track, but is this a safe boost to be running for my daily driver. The only thing I have done to my car is what I mentioned above, plus a hks super flow intake, boost gauge, and njk sparkplug and wires. I would just like other people’s opinions on this, thanks.

 

[theycallmedalgo]

yeah fuel is cut is about 16 just lower it

 

[pnishr]

your injectors are going to be flowing more than their standard rated amount with the 255 and having it rewired. 17 isn't going to be a big issue. If you are worried about it, just turn it down. But I wouldn't think too much of it. I had mine at 17 with no fuel controll on the 97 and it was just fine. You really can't know without some kind of logger to ensure no detonation though.

I wouldn't lose sleep over it, but if you are going to, lower it to 16

 

[theycallmedalgo]

ahha whoops did see the 255 there

 

[GraphiteGST]

If you install a manual boost controller on a 100% stock 2g gst, how high can you raise the boost level to run safely daily?

 

[omoral2]

14 psi

 

[2gGSX]

your injectors are going to be flowing more than their standard rated amount with the 255 and having it rewired.

This is completely incorrect.

The extra flow from the rewired 255 will cause overflow at idle due to the fuel pressure regulator not being able to compensate for the massive increase in flow, but at WOT this is definitely not a problem. His base fuel pressure will not change short of a malfunction with his stock FPR, and thus his injectors will flow exactly what they are rated for.

As per your problem now, my advice would be to procure a datalogger somehow (make one, buy one, borrow one) and monitor knock. This is the only way to truly answer your question.

 

[MyBeatGSX]

^He's right, or just find a wideband and see where you're at.

But for the record. I ran a s16g, 255hp, afpr, and stock injectors at @18psi with no problem. The injectors were MAXED out but the A/F managed to stay below 11.5:1. The was only a temporary situation, I'd get some bigger injectors or turn the boost down asap.

 

[Mikael]

You paid for this work, yes? Make him fix it.

 

[flashburn02]

I have a 95 tsi and at anything above 16 it starts cutting, it isn't horrible. Like you said, if it were track usage on a rarety not a huge deal, but for a daily driver back the boost off. How did they have trouble setting the boost? You should ask them that because if you paid for it you should have them fix it or get some money back.

 

[andymoraitis]

I certainly hope you added an AFPR otherwise that 255 will be overruning the stock regulator in a serious way.

 

[HustlerTalon]

I know that everyone has their own experience with this but when i first purchased my 90 talon, I only had a 255 pump, 2.5" UICP (from SLS), full 3" exhaust, and a bigger turbo outlet pipe, running the 14b at 19psi with no problems. I didn't have a boost controller, actually the wastegate was bad but since I didn't fuel cut, i didn't change it. it was my daily driver for about 7 months until I went all out and upgraded everything.

 

[EvilAWD10]

I've had the same situation. never installing a fpr. some of us do it the lazy way and dont bother purchasing the proper equipment. If your worried, especially it being your daily car do yourself the favor and lower the boost or get the required logger to really identify if its safe to keep at 17 psi.

 

[pnishr]

This is completely incorrect.

The extra flow from the rewired 255 will cause overflow at idle due to the fuel pressure regulator not being able to compensate for the massive increase in flow, but at WOT this is definitely not a problem.

You've just contradicted yourself. "this is completely incorrect" (regarding the flow being fine due to pump/rewire) to "but at WOT this is def. not a problem." If he's pushing 17psi, it WILL be at WOT. I don't think his concern was detonation at off-boost/idle conditions. Fuel injectors are rated in different ways at different PSI, etc. from company to company. Assuming that the stock FPR will not hold back ANY more fuel than what the stock pump can provide is a bit unrealistic. So, a 190pump is OK without an AFPR, right? That seems to be the general concensus. So, that means the stock FPR CAN regulate more pressure, thereby forcing more fuel through the injectors. Why would it completely allow ALL excess pressure produced by the 255 to bypass it?

I do concede that an AFPR is in order, but plenty of people can, and have, run a measely 17psi with NO problems, with no fuel or datalogging, myself included- years ago. And that is really the root issue here. Datalogging equipment and more fuel support are always the prudent thing to do, but where's the cause for concern in running 17psi...?

 

[AWD 90 Tsi]

I got a quesiton, i uped my boost to 18 and it pulls good in 1st and 2nd but in 3rd and 4th the car kinda sputters up top, is this fuel cut?? How do you bypass this fuel cut?

 

[HustlerTalon]

I got a quesiton, i uped my boost to 18 and it pulls good in 1st and 2nd but in 3rd and 4th the car kinda sputters up top, is this fuel cut?? How do you bypass this fuel cut?

Yeah that is fuel cut....I am assuming you don't have any fuel upgrades (pump, injectors, etc) since you are experiencing fuel cut....how to bypass it???? SIMPLE, either lower the boost or upgrade your fuel system.

 

[2gGSX]

You've just contradicted yourself. "this is completely incorrect" (regarding the flow being fine due to pump/rewire) to "but at WOT this is def. not a problem." If he's pushing 17psi, it WILL be at WOT. I don't think his concern was detonation at off-boost/idle conditions. Fuel injectors are rated in different ways at different PSI, etc. from company to company. Assuming that the stock FPR will not hold back ANY more fuel than what the stock pump can provide is a bit unrealistic. So, a 190pump is OK without an AFPR, right? That seems to be the general concensus. So, that means the stock FPR CAN regulate more pressure, thereby forcing more fuel through the injectors. Why would it completely allow ALL excess pressure produced by the 255 to bypass it?

I do concede that an AFPR is in order, but plenty of people can, and have, run a measely 17psi with NO problems, with no fuel or datalogging, myself included- years ago. And that is really the root issue here. Datalogging equipment and more fuel support are always the prudent thing to do, but where's the cause for concern in running 17psi...?

Read it again, that is not a contradiction. I said the stock FPR could not regulate pressure at idle, however at WOT this is not a problem--due to the fact the engine is consuming all excess fuel. That does NOT mean however that simply with a large fuel pump will he increase the set base fuel pressure which is what fuel injector flow is dependant upon (assuming it's still a 1:1 rising rate regulator like they're supposed to be). Without a fuel pressure gauge inside the car to monitor what is going on throughout the pull it wouldn't be safe to simply assume that you're getting excess fuel flow. Even if you do get extra fuel flow, what's the big deal? These cars already run stupid rich from the factory, and you're going to try to add another x% fuel to that?

The reason why the stock FPR would completely allow ALL excess pressure produced by the 255 to bypass it (at WOT) is because enough fuel is being used to the point where there is no longer enough to overrun it.

You ran 17 psi daily and assumed it was fine, sure. You yourself also said you had no datalogging equipment to see what was going on. Maybe you were getting 20 counts of knock throughout the pull, but how would you know? Is this detrimental to the car? Yes. Can it happen at 17 psi on a 14b? Absolutely.

 

[steve]

Yeah that is fuel cut....I am assuming you don't have any fuel upgrades (pump, injectors, etc) since you are experiencing fuel cut....how to bypass it???? SIMPLE, either lower the boost or upgrade your fuel system.

Please! Fuel Cut has nothing to do with the fuel system capacity

It's all about airflow! Too much airflow and the ECU turns off the the injectors.
The only solution is a modified ECU removing the test. You can work around it by making sure you don't have any boost leaks, installing larger injectors and a SAFC or such, to reduce the airflow seen by the ECU. Upgrading the fuel pump is something you might do to support larger injectors but won't address the cause of fuel cut directly.

Steve