[T76coupe]

hey guys..great site here. I have an 87 notch with a built 351w (makes 340 rwhp N/A) and it has a custom intercooled single turbo kit with a Turbonetics T-76 q-trim. I have a full fuel system with a 360 lph Kinsler pump,-8 feed,-6 return,Aeromotive rails,a1000 regulator and Aeromotive rails.

The car seems to run a good a/f ratio and idle and part throttle according to my Plx m300 wideband but at WOT the A/f stays in the 14:1-15:1 range at only 6 psi of boost. I had it on the dyno and it made 460 rwhp at 10 psi shutting down at 4300 rpm as the a/f was not dropping. The fuel pressure gauge was incresing 1 to 1 with boost and holding.

I'm running just a blowthrough 75mm pro-m bullet calibrated for the 50lb injectors. I'll be picking up a Tweecer this weekend so hopefully i can finally tune this car properly.

[88mustang]

Sounds like you are having the same problem as me. I hope you don't mind me posting here as we will probably get the same answer.

The turbo install is new and I just noticed this problem yesterday. I have been dialing in the MAF curve and no matter how much I increase the top end of the curve the computer calls for 11:1 and the wide band is reading 14:1 or 15:1 when in boost. I feel I am running out of fuel pump and most likely you are as well. If this is true the TwEECer alone will not fix it. You will need to increace fuel pressure or get a bigger pump. Then tune with your TwEECer. However if its just your MAF curve being off then yes the TwEECer can fix that.

(I dataloged injector duty cycle and it only hit 55%) This is at 8 psi and I want to try 14 psi at the track. Now my question for the board.

Should I even try increacing fuel pressure or just go with a bigger pump? My feeling is to go with a new pump that will feed my car at 14 psi of boost and still keep my fuel pressure at 39 psi. I also have a regulator increacing pressure 1:1 with boost. My tank is already sumped with an 8AN feed line and 6AN return line, so an Aeromotive inline will bolt right in.

Thanks for the help

Tim

[T76coupe]

Sounds like you are having the same problem as me. I hope you don't mind me posting here as we will probably get the same answer.

The turbo install is new and I just noticed this problem yesterday. I have been dialing in the MAF curve and no matter how much I increase the top end of the curve the computer calls for 11:1 and the wide band is reading 14:1 or 15:1 when in boost. I feel I am running out of fuel pump and most likely you are as well. If this is true the TwEECer alone will not fix it. You will need to increace fuel pressure or get a bigger pump. Then tune with your TwEECer. However if its just your MAF curve being off then yes the TwEECer can fix that.

(I dataloged injector duty cycle and it only hit 55%) This is at 8 psi and I want to try 14 psi at the track. Now my question for the board.

Should I even try increacing fuel pressure or just go with a bigger pump? My feeling is to go with a new pump that will feed my car at 14 psi of boost and still keep my fuel pressure at 39 psi. I also have a regulator increacing pressure 1:1 with boost. My tank is already sumped with an 8AN feed line and 6AN return line, so an Aeromotive inline will bolt right in.

Thanks for the help

Tim

I doubt i'm running out of pump. the pump i have is a 360 lph Kinsler pump which can support 650 rwhp or around 800 crank hp...same as an A1000. The guy who had this pump before me made 610 rwhp and it was a supercharged 4.6 4V car. I'm only running 10 psi of boost which should only make 520-530 rwhp on my car.

what pump are you running now?

[88mustang]

I am running a Bosch inline I bought from a friend, I think it is a 255lph. When I decided to go turbo I thouht I might need more but wasn't sure.

I am now looking at the Areomotive A1000. Thats probably what I'll go with, unless someone here has a better idea.

Tim

[T76coupe]

I am running a Bosch inline I bought from a friend, I think it is a 255lph. When I decided to go turbo I thouht I might need more but wasn't sure.

I am now looking at the Areomotive A1000. Thats probably what I'll go with, unless someone here has a better idea.

Tim

just a single 255lph in-tank pump? Are you running factory feed/return lines/rails? You said your tank is sumped?

[88mustang]

Its not an intank pump it is an inline pump just like the A1000 fuel line goes in one side and out the other. Other than that my setup is alot like yours (same lines, rails, and regulator).

[sailorbob]

The Tweecer will help you tune the ecu to your setup.

The fuel pressure gauge was incresing 1 to 1 with boost and holding.

Regarding this, you don't want a rising rate regulator with the early eec 's as they don't sense fuel pressure and cannot compensate. This will throw the fuel calculations out.

[mach1]

the point of the 1 to 1 on a regulator is to compensate for pressure conditions in the manifold. here is a example.
with the engine pulling vaccum the fuel pressure doesnt need to be as high because the vaccum is "pulling" the fuel through the injectors therefore if you ran the same fuel pressure as without vaccum then the car would be rich. on a boosted setup the boost is pushing the fuel through the injector(not exactly pushing it through but putting more resistance on it) so the FPR must increase fuel pressure to keep the same mixture. in the sitation of a fmu it just shoots the fuel pressure sky high which with richen the motor but if you pull fuel pressure under vaccum and add fuel pressure under boost (1:1) it should keep the injector flowing the correct amount the whole time, not make it lean or rich...

[T76coupe]

The Tweecer will help you tune the ecu to your setup.

The fuel pressure gauge was incresing 1 to 1 with boost and holding.

Regarding this, you don't want a rising rate regulator with the early eec 's as they don't sense fuel pressure and cannot compensate. This will throw the fuel calculations out.

You are thinking of one of those old style regulators like the cartech that use to double the fuel pressure under boost. The stock fuel pressure regulator is a 1:1 ratio.

[88mustang]

The fuel pressure gauge was incresing 1 to 1 with boost and holding.

Regarding this, you don't want a rising rate regulator with the early eec 's as they don't sense fuel pressure and cannot compensate. This will throw the fuel calculations out.

What is the difference between this and a regulator that pulls fuel pressure under vacuum? Many people on this board use this type of regulator. I for one like the extra fuel pressure under boost. Its just a bit safer especially if you are close to the limits of your fuel system.

[Shaker666]

There are several ways you could correct this problem by tuning with the Tweecer, the easiest attempt being to modify the WOT Fuel Multiplier setting to richen it up a bit. This saves you from modifying your fuel maps; the alternative of course, being to modify the fuel tables themselves. Of course, your issue could be as simple as having the wrong MAF calibration... which seems to be, at least 95% of the time, the culprit for rough running engines in my experience.

Datalogging with the Tweecer and inspecting your KAMRF and lambda readings will tell you whether your MAF is culprit or not.

[sailorbob]

You are thinking of one of those old style regulators like the cartech that use to double the fuel pressure under boost. The stock fuel pressure regulator is a 1:1 ratio.

Yep, you're right

[T76coupe]

There are several ways you could correct this problem by tuning with the Tweecer, the easiest attempt being to modify the WOT Fuel Multiplier setting to richen it up a bit. This saves you from modifying your fuel maps; the alternative of course, being to modify the fuel tables themselves. Of course, your issue could be as simple as having the wrong MAF calibration... which seems to be, at least 95% of the time, the culprit for rough running engines in my experience.

Datalogging with the Tweecer and inspecting your KAMRF and lambda readings will tell you whether your MAF is culprit or not.

thanks,i think my problem is i have a few bends in my cold side piping before the mass air meter and that could be throwing the reading off. It just sucks trying to reclock the meter on my car since the maf is in a tight spot.

The guys at Pmas told me that after 42s you really need to go into the ECU and change the maf transfer/injector slopes but some have had luck running 50# meters without a tuner but it could be that they had a lot of straight pipe before the meter.

I got my Tweecer yesterday and i'm waiting for the laptop i got off ebay to get here. The only thing is the version i got is just the base so i can't datalog so i'll just have to tune off my plx m300. Anyone know what it costs to get the base converted to an RT? I just got a good deal on this base.