civtec89

i have a 1989 civic si with an obd0 b16 pr3 ecu not tuned. i put in an lsvtec with a garrett t25 dsm turbo stock internal wastegate, ebay intercooler and bov. autometer air/fuel gauge and boost gauge and b&m fuel pressure gauge in it. it has dsm bluetop injectors, a synapse missing link map bypass, and a synapse fpr/fmu. i was told it has a walbro pump in it from the previous owner. the problem im having is when i drive it it starts to buck when it makes boost. and most of the time when it does this the air/fuel gauge goes lean. when i tried to keep it out of boost while driving, the air/fuel gauge would fluctuate between rich, and stoich and sometimes lean. i think the synapse fpr/fmu is bad somehow. because when it idles after driving it, the fuel pressure gauge goes from 65 to 30pounds. i was going to call synapse about their fpr/fmu to see if they can replace it, or get a vortech fmu.
does the fmu sound like the problem, or could something else be causing this. thanks.

busa4

do u have it hooked up correctly? stop driving it lean as it doesnt take much to melt a stock piston.

your static fuel pressure should be set up at stock fuel rail pressure. usually 43psi then you need to adjust the top bleeder screw. the more boost you vent from the top bleeder screw the more rising rate you will get. where are you getting your boost source to the fmu? how is the fmu hooked up to the fuel lines. post pics.

civtec89

as soon as i seen it go lean i coasted it. im getting my boost source from a line i tapped into the intercooler pipe, a few inches away from the throttle body. it hooks up to the fuel line the same way as a stock fuel pressure regulator. the return line on the bottom, and feed through the rail. i set the static pressure higher than stock, about 55 pounds, i figured id go down from there if needed. i called synapse today and i am sending it out to them tomorrow, to have them check it. there instructions are really vague, they give you 2 extra fuel bypass fittings, but it doesnt say why you would need them. sorry i cant post pictures, computer wont upload pictures when i try.

busa4

do u have an air compressor? if so run some air pressure through the boost signal fitting into the fmu while the engine is running. you should clearly see the fuel pressure rise. make sure your air compressor has a regulator valve and set it low at around 10 psi. you do not want to blast 80 psi into the fmu.

MAJORAHOLE

did you gap your plugs correctly?

hard2obtain

You said PR3 not tuned.... that does it mean STOCK? or just with a basemap

If are stock then just remove thos 450s

If got a basemap then remove the missing link and FMU

civtec89

i do have an air compressor, but i sent the fmu out today. the plugs are gapped right, and are one step colder. its a stock pr3 ecu, the car did the same thing when i had stock ls injectors in it, i was hoping that was the problem when i changed them, but it wasnt.

hard2obtain

This is the part you dont understand

450s + chipped ecu + tune = way to go

450s + stock ecu = bad

stock inyectors + missing link + fmu = barely good for max 6-7 psi (check the missing link for any leaks)

civtec89

i do understand but it is what i have to work with right now, the reason i put the bigger injectors in is because i thought the stock injectors would be way past there maximum duty cycle. i have another pr3 that is supposedly chipped but im not sure, i had it in the car without the turbo and it ran fine. im only looking to make 7 psi. i am going to check the missing link for leaks like you said.