HondaRegistry

I bought this Si from the original owner, about 2 yrs ago. In which he had a Drag 3 Turbo Kit installed back in 01-02? Anyhow, the car ran great with no issues. It became of weekend car for me, and I took out last weekend, and did a spirited 1st to 2nd gear shift and when I came to stop, the idled very low and progressed to shut off, when I would come to a stop.

So I popped the hood, and knoticed that one of the "check valves" had come off
where the stock map sensor is originally located.

So I went to an Auto Zone and replaced the one way check valve, and still the same symptoms. I changed the plugs to some fresh NGK iridiums, and again, still the same. What I am knoticing is how rich the car seems to be running now. Outside of the idling issue, the car on full throttle feels exactly as it always has at only 6 pounds of boost. I thought maybe I installed the one check valves the way, and have switched sides of them, several times and again, still the same issues.

The kit is un-modified, still runs the FMU, Delta-gate wastgate, stock injectors, additional fuel pump etc.

The car gets horrible gas mileage at the moment, and again the low idling issue and you can tell some non smooth RPM's when you hold it at 3k RPM's, which sort of bring a slight stutter.

I am at a loss of what it could be. I pulled the IACV off, and cleaned the filter and the ports in the intake manifold.

I have also done countless amount of searching, on this site and google with no luck. So I was hoping someone can point me in the right direction as to what might be the problem or anything I can do to see if I can cure the problem.

Thanks in advance for any help you guys can help me with.

wantboost

iTrader: (2)

check the injectors for proper flow and pattern. also, after driving the car feel the injectors and see if they are excessively hot. fmus are a horrible way of controlling fueling. they work fine for a bit but long term use can damage and/or destroy an injector as they were never meant to see such high fuel pressures

a 12:1 fmu will increase fuel pressure 12psi for every pound of boost. so you're looking at 72psi added to a.base pressure of 42psi. that's 114psi at the injector. that's way too high.

your injectors could be sticking open, not closing all the way causing a leak, etc. all of which would contribute to or exacerbate your issues or even cause them

honestly you need to ditch the extra pump, fmu, and checkvalves and get a real engine management solution

10psiLsEf2

You need a dyno tune to START

SilverEK96

iTrader: (11)

I know we all have to start some where, but it's time to get with the times. Get rid of the check valves and fmu. Buy a real tuning system and get a dyno tune before you blow your engine. Hell at this point even I would say get a tune on chrome if possible over what you have now.

HondaRegistry

Thank you so much, for posting such a clear way for me to further check into what you're explaining. As it makes complete sense. Thank you again, and I'll keep you updated


Tune what? I am runing a stock ecu, piggy backed by an FMU, Check Valves and external fuel pump. I am not running anything like EMS, Hondata etc.

10psiLsEf2

Get the car dyno tuned son.

Fmu,check valves is not a correct way of controlling fuel.

This will be my last post on this thread.

Take my advice and get your car tuned on a real ems like hondata,neptune,crome, etc etc

hybridpatient95

change the map sensor . that's it

wantboost

iTrader: (2)

That is what I'm here for lol. Also, do you have a pressure gauge on your fuel rail? I'm wondering if that extra inline pump has caused base pressure to increase... another possibility is that the excessive fuel pressure created by the FMU has slowly, over time, damaged the stock Fuel Pressure Regulator (FPR) so you need to attach a gauge to see what base pressure is at idle, it should be around 42psi (stock).

also, when was the last time you changed the fuel filter? sometimes a clogged/dirty filter can cause all sorts of issues
How would that change anything when he's using a check valve arrangement where the map sensor never sees positive pressure and the ecu still thinks it's NA? I could see over time the map going bad but with him having an OBD2 car it would throw a code

OP, do you have an obd2 scan tool? If so, plug it in and when you're WOT in boost take a freeze frame at that point, that will let you see all of the data the ecu is receiving... that will let you know if the map is bad, what timing is at, o2 sensor voltage, etc.

also check the map voltage at idle using a multimeter, then write down the value from the WOT data freeze frame and compare these two numbers to the service manuals values and see if they are within spec, if they aren't then the map sensor is bad