Turbo chip without a rrfpr?

[Daeldalus]

I have been doing a large amount of research lately.
my goal is 7-8 psi small turbo super reliable DD-able on a budget
and it seems like all the turbo chips out there say you need a rrfpr
in order to make fuel come out right. why?
Unless I have missed something ecu chips for a 173 can change
the fuel map. So why would chip companies not test and tune
their chips so as to make rrfpr's unneeded? that would cut costs
for us and make their turbo chips very popular. Also would that not
be a more accurate means of controlling fuel?

even if chips cannot change the fuel map would you not then need
a AFC + wideband in order to know how to change the rrfpr?

I know that MS2 is a better overall option but I am wanting to go with
something pretuned, even if very conservatively, so that i dont have to
do a large amount of trial and error and all that extra work at first.

[Vincent Brick]

I didn't even know RRFPRs were still relevant at all in turbocharging, had one on my turbo Neon and don't blame anyone for wanting to avoid using one. I would look into using an AEM FIC before I used an RRFPR again.

Sorry, I know this isn't what you are looking for but subscribing for the knowledge. Good luck.

[ak-]

Believe me when I say to just go straight to MS. This isn't the 80's anymore!
You're going to save time, money, and headaches.
And even if you still have headaches after going F/I, you can still use it in your N/A powered car. It's a great investment no matter what direction you choose to go and you're lucky enough to have a guy on the forums who sells PNP units who also takes care of his customers via email/remaps/troubleshooting.
The guy above me, who I'm assuming isn't that familiar with the e30 boost game(no offsense!), is even telling you to ditch the RRFPR and go standalone..

Take advantage of what the community has to offer!

[Daeldalus]

thanks i figured rrfpr's were a mess.......
I guess the main question is. Is it possible to order a custom
tuned chip with the timing and fuel maps changed as to make
neither standalone nor rrfpr's required? I know eurotuning does
custom chips to your specs but not exactly about this

If i could do fuel management for 180-220 with a chip
instead of 650 for a reportedly nice whodwho PnP
then i would go with that first in order to save up

also I know I can get MS2 for ~350 but i am a little
daunted by the work involved with that

[TheTacoMan]

Don't mess with the turbo chips, go with ms to begin with. It can be done without it but ms is so much easier and so much more reliable.

[squidmaster]

The stock motronic ECU cannot read boost pressure, and therefore cannot increase fueling by boost. Instead fueling is increased by AFM open angle. Since this is not acceptable for a turbo application, fueling is set statically. Basically we have to extrapolate what psi your turbo is going to be at during every throttle angle and RPM using nothing but math. Therefore you cannot adjust turbo pressure up or down without directly affecting your AFR. Since the same amount of fuel is going to be dumped in at 2psi as it would 10psi, or 15psi, the tune would be made for a static pressure.

There is, however, an alternative-- using a RRFPR. While this, also, is not ideal, this will drastically improve the daily-driving and part throttle experience. A RRFPR (rising rate fuel pressure regulator) takes a pressure reading from the manifold and increases or decreases fuel pressure as applicable. And since we control injector open time (pulse width) via the computer, more pressure = more fuel in the short period the injector is open. This will mean you can adjust boost pressure up or down as you see fit and the fueling will adjust with it.

However, MegaSquirt is the best option no doubt about it.

[cleanasse30]

The stock motronic ECU cannot read boost pressure, and therefore cannot increase fueling by boost. Instead fueling is increased by AFM open angle. Since this is not acceptable for a turbo application, fueling is set statically. Basically we have to extrapolate what psi your turbo is going to be at during every throttle angle and RPM using nothing but math. Therefore you cannot adjust turbo pressure up or down without directly affecting your AFR. Since the same amount of fuel is going to be dumped in at 2psi as it would 10psi, or 15psi, the tune would be made for a static pressure.

There is, however, an alternative-- using a RRFPR. While this, also, is not ideal, this will drastically improve the daily-driving and part throttle experience. A RRFPR (rising rate fuel pressure regulator) takes a pressure reading from the manifold and increases or decreases fuel pressure as applicable. And since we control injector open time (pulse width) via the computer, more pressure = more fuel in the short period the injector is open. This will mean you can adjust boost pressure up or down as you see fit and the fueling will adjust with it.

However, MegaSquirt is the best option no doubt about it.

Good explanation. IMO, this is a band-aid for an extremely outdated method of measuring airflow. It will work okay but there are much better options available such as MegaSquirt as stated above. If you can't afford to do it right, don't do it at all.

[DesertBMW]

I have been doing a large amount of research lately.
my goal is 7-8 psi small turbo super reliable DD-able on a budget
and it seems like all the turbo chips out there say you need a rrfpr
in order to make fuel come out right. why?

I created a chip for 173 for reliable turbo application for low boost. Up to 10 psi max. I ran 8psi on mine 10 years ago. I sold these chips on ebay 10 years ago and people liked it.
In order for the Motronic to know that there is boost and to increase the fuel accordingly, the air flow meter must be a "pull trough", this means you must install AFM in front of the turbo and there is not lot of room. Then use internally BOV turbocharger. How does motronic know how to put more fuel with boost? It is simple, turbo pulls more air to create boost therefor AFM reads this and motronic injects more fuel. I used AFM from M30 because M20 is too small.
Stock 1991 Toyota MR2 turbo works the same way.



Note: boost pressure sensor is used only for safety fuel cut feature and it is not used for engine management.

Squidmaster
Basically we have to extrapolate what psi your turbo is going to be at during every throttle angle and RPM using nothing but math.

This tells me you are not the very good tuner. There are turbo cars made from factory that use barn door air flow meter and do not use any boost pressure sensors.

[ForcedFirebird]

There is nothing wrong with using Motronic for boost, I have tuned numerous turbo cars with a chip only. The only time you will have an issue is if you wanted to change the boost level. Turn down the boost, and it will run rich.

I have not tried going over 1bar with the stock ECU, but have tuned to 13psi on a daily driver that up until yesterday has been a daily for 2 or 3yrs (it was totaled on the highway from a rouge couch that fell out of a truck).

Porsche used the very same Motronic we have in their turbo 944's.

[ForcedFirebird]

This tells me you are not the very good tuner.

Coming from a guy that says that a stock engine can't be tuned to make more power. The guy above you wrote a chip that I tested on a dyno, same day same car, +7whp over a stock chip. Him and I both do extensive testing, we didn't just click the offset button and add universal timing/fuel like 90% of the chips offered elsewhere.

[DesertBMW]

Coming from a guy that says that a stock engine can't be tuned to make more power. The guy above you wrote a chip that I tested on a dyno, same day same car, +7whp over a stock chip. Him and I both do extensive testing, we didn't just click the offset button and add universal timing/fuel like 90% of the chips offered elsewhere.

+7whp but you can only use 91 octane. Stock chip is made with some safety margin. And as far as I remember you fist started tuning motronic with my free XDF.

[jalopi]

$200 for the chip, $100 for a decent fpr - you're pretty much halfway to a PNP megasquirt, $50 shy of a DIY kit.

'nuff said

[ForcedFirebird]

+7whp but you can only use 91 octane. Stock chip is made with some safety margin. And as far as I remember you fist started tuning motronic with my free XDF.

Wrong. I run 87, even in the race cars with zero effect or knock. There's no way a car with 8.8:1 compression needs premium fuel. The OEM tune is extremely conservative. The engine stops making power before the timing is advanced enough to knock.

Yes, I used your .xdf to kick start the Motronic tuning, but have been tuning far longer with other platforms.

Besides, there is a big difference between a tuner and someone who can manipulate code. If you want to throw stones, let me ask you how many times have you tuned on a dyno? How many of your tunes have been proven to make more power? Have you EVER put a car on a dyno?

You have no room to talk, anyways, you had people read their tuned ECU's to find the maps in OBD2, no? I saw you on e46fanatics gathering the info needed, all of a sudden you're a "tuner" when you were just copying others.

At first I thought it was great that someone was sharing information, the domestic tuning crowd shares everything and now have hacked the ECU's to be capable of some amazing things - GM OBD1 is now just as capable as a stand alone (3bar MAP, anti-lag, speed referenced boost etc). No such thing is going to happen with BMW's and it's sad, really. This is why I started the thread on e30tech, showing other people how to tune their own ECU.

[Daeldalus]

Thanks everyone.
I was not thinking about the afm as what controls the fuel map but
now that i am thinking that would be it and if it is all the way open at
2psi then it could not be more open at 10psi.

of course if you tune a turbo chip to run a specific turbo at one specific
boost level, say 8psi, and never touch it then i could see this working.
but then again that is not the kind of product that could be marketed
because it would be so very specific.

this has given me quite a bit of useful info and has cleared up issues
that i could not find answers to. basically the answer was the same
(get MS2 or 3 and be happy) but now i know both the why and that
my theory was correct, just a bit too inflexible.

Woo...... I guess back to trying to figure out how to build and run MS2

[DesertBMW]

Yes, I used your .xdf to kick start the Motronic tuning, .

Thanks for being honest.