Need some tech advice, BOV and bad FP signal problems

[datsunmotorsports]

Im helping another Hybridz member out with his ride. We have 2 problems to overcome still though. Im hoping to get some advice.

The first problem, the ECU won't put out enough amperage to kick over the Fuel Pump relay. I see 4.5v at the signal wire from the ecu with no relay. If you add the relay then I see .5V before the relay when I should still be seeing the full 4.5V. So I think the ECU Fuel Pump driver is bad. I tried to replace the relay. I made sure the other side of the relay coil had a good ground. It was still dead. So I bypassed it and hooked it to ignition on for now.

Second problemo, He is running the greddy style intake with the Q45 TB and a Greddy BOV. I chased vacuum around using my car as the template as it is stock. So now that everything is hooked up correctly and he is still having drivability issues. Once he hits boost the car stumbles. The variable in the system is the BOV. Its an adjustable type that discharges to atmosphere. I know its not correctly adjusted and I know that venting to atmosphere under boost will mess the A:F up. Recommendations? I suggested to find a stock BOV and install it as I dont have the tools or experience to setup the Greddy one. There is a Boost gauge and a Stoic gauge on the car so we can watch what it does. The A:F is all over the place when it stumbles and the boost is low.







These were taken before a few of the miss routed lines and the boost solenoid were hooked up. But it gives you an idea of what we are dealing with.

and just for referance since I couldnt have said it better myself in reference to replacing the OE BOV with an aftermarket one.

You should be able to just vent it to atmosphere yes. But keep in mind that under vacuum the valve will be open. 2 problems here: 1 unfiltered dirty air gets into your engine. You can throw a breather on it though. 2) the extra air is unmetered. So if using MAF still, then you will be running lean. Alternatively, when it actually blows off, you will run very rich. Long story short, MAF systems typically require a recirculation to avoid running issues. But if you've converted to MAP, then go for it! Mark

Anyone want to pile on some advice or confirmations? Questions? I know I leave info out sometimes that is crucial.

Thanks Guys!

I almost forgot to ask. The BOV is situated about 12-16" away from the turbo rather than 12-16" away from the throttle body. So if there is a pressure wave it would hit the butterfly plate and head all the way back through the system and almost get to the turbo before the BOV would release it. Its a little to much for me to contemplate at the moment. My guess is that it really isnt critical where it is on that part of the system because the BOV will be activated before the wave has time to hit or build up and hit the turbo. Just curious.

Thanks
Modified by datsunmotorsports at 8:46 AM 1/24/2009

[USMCgetsome]

s.o.b. finally someone with the same issue! Man i went passed the damn relay and put a switch to it. Basically used jumpers and where the gate closes i put in a manual switch. Only way to solve it. I tried grounding the #2 position because the voltage was low and wouldn't kick over the relay gate. Then i tried to bypass the internal resistor in the relay and soldered in a straight piece of wire. It helped but was inconsistent. start with that.

btw i also went through 3 different ecus just to ensure it wasn't the driver.

[Kansei240sx]

Probably simple stuff.

Gasket on the throttle body?Leaks in the FMIC piping?Tighten the **** out of the BOV untill it cant even open up and the turbo gets compressor surge, then start backing it off. Do a leakdown test of the intercooler system starting at the turbo inlet. Make sure the injector isolators aren't leaking, its common for those to leak air.

About the Fuel Pump relay signal, it has 4.5 Volts coming out of the PIN for the FPMP Relay on the ECU? Then when you plug it or turn the key to the ON position or even ACC it will drop to .5v?

[datsunmotorsports]

Probably simple stuff.

Gasket on the throttle body?Leaks in the FMIC piping?Tighten the **** out of the BOV untill it cant even open up and the turbo gets compressor surge, then start backing it off. Do a leakdown test of the intercooler system starting at the turbo inlet. Make sure the injector isolators aren't leaking, its common for those to leak air.

About the Fuel Pump relay signal, it has 4.5 Volts coming out of the PIN for the FPMP Relay on the ECU? Then when you plug it or turn the key to the ON position or even ACC it will drop to .5v?

Will have a check at the TB gasket. I forgot to check. The FMIC silicone piping is cheesy and I would personally upgrade to thicker stuff, but its got the nice clamps and they are all tight. How do you do a leak down test on the intercooler system?

I pushed the BOV screw all the way down and could hear the surge nailing the turbine wheel. I started turning it down but ran back into the bad fuel ratios long before I could get the surge to stop. (maybe it just needs to be recirculated) So I turned it half way out and called it quites with the hope there was no more surge even if the car would barely drive. At least it was safer than granading a turbo. There must be a way to put a gauge on the BOV and set it at a certain pressure or something.

I did check the injector isolators. They are sealed up pretty good.

Fuel pump, Thin black/pink stripe #AF73 and going to pin 18 on the ecu. it's a switched ground signal that you use for your ground to switch your fuel pump relay. When everything is off 0V. Turn the key to On position 4.5V for a few seconds then 0V as expected. Turn the key to start and you get 4.5V. Once its started you get around 4.5V out of it. It fluctuates slightly. Maybe .15V? Nothing to worry about. IF at any time you plug the relay in and test that pin on the ECU you will see .5V. What I should see is 4.5V-5V. The circuit is built so that the ECU is the power source as it has a voltage regulator built into it. The other side of the relay coil goes to ground.

s.o.b. finally someone with the same issue! Man i went passed the damn relay and put a switch to it. Basically used jumpers and where the gate closes i put in a manual switch. Only way to solve it. I tried grounding the #2 position because the voltage was low and wouldn't kick over the relay gate. Then i tried to bypass the internal resistor in the relay and soldered in a straight piece of wire. It helped but was inconsistent. start with that.

btw i also went through 3 different ecus just to ensure it wasn't the driver.

REALLY 3 ECUs and still the same problem? I even checked the resistance of the wire from the pin to the relay. Then I pulled the whole harness out and stripped it so I could make sure it was installed correctly. Then I moved on to power sources. I had no luck tracing it out. I need to find someone that knows the exact circuitry inside the ECU so I can trace it farther.

Thanks you guys for the really fast responses and the ideas!!!! You Guyz Rock


Modified by datsunmotorsports at 8:05 AM 1/24/2009