Need some help diagnosing this. Fuel Cut?

[Tcoat]

Originally Posted by Spartarus

My initial suspicion is your Walbro in-tank pump is failing.

.

Or we are back to my first suspicion and the filter is plugged even though a visual inspection says it looks fine.

[Ultramaroon]

Originally Posted by Tcoat

Or we are back to my first suspicion and the filter is plugged even though a visual inspection says it looks fine.

I don't think the filter itself was inspected. @Kiske, you just mentioned a sock, right?

[Kiske]

Originally Posted by Spartarus

Problem is, throughout the log, rail pressure and commanded pressure are always close and following.

My suspicion with the CP and FPDC jumping at the same time was that the HPFP suddenly lost supply pressure, pointing to the in-tank pump cutting out.

Forgot to clarify, that's HP rail pressure. The LP rail doesnt have a sensor.

That makes sense. I guess next step is to print out the repair manual and start with testing the fuel pump. Will also have to check the fuel pump o-rings. I never had an issue with then nor had to use multiple o-rings in my install but, the issue does sound similar to what others experienced. Wounld be odd for it to not have manifested sooner though. Thanks

[Kiske]

Originally Posted by Ultramaroon

I don't think the filter itself was inspected. @Kiske, you just mentioned a sock, right?

This car doesn't have an inline fuel filter, just a sock on the fuel pump inside the tank.

[Ultramaroon]

Originally Posted by Kiske

This car doesn't have an inline fuel filter, just a sock on the fuel pump inside the tank.

The diagrams don't help much but they call it a "fuel filter assembly." You don't still have your stock pump by chance.

[Spartarus]

Originally Posted by Ultramaroon

Here. I uploaded his log to datazap.

http://datazap.me/u/ultramaroon/log-...g=0&data=15-40

You can keep your graphs.

Mine are all up here.

I don't even see the code anymore.

[Kiske]

Originally Posted by Ultramaroon

The diagrams don't help much but they call it a "fuel filter assembly." You don't still have your stock pump by chance.

Yes, I still have it. Aswell as a spare engine and junk trans. :O I'd have to re-tune to use it though. The walbro pump reuses the stock housing, wiring, lines and filter.

Here is a picture of the sock.
http://www.ft86club.com/forums/attac...1&d=1397329474

[Ultramaroon]

Originally Posted by Spartarus

You can keep your graphs.

Mine are all up here.

I don't even see the code anymore.

Haha... Ok Neo. It helps the rest of us mere mortals.

[Ultramaroon]

Originally Posted by Kiske

Here is a picture of the sock.
http://www.ft86club.com/forums/attac...1&d=1397329474

Ah, I see. Ok, definitely not the filter.

As long as there is some positive pressure on the PI rail, the HPFP will supply and regulate the DI rail just fine.

30 seconds into your last log it appears to switch over to DI. The port injectors never fire after that. At 50 seconds you start giving it gas but the target and actual rail pressure never diverge.

I'm skeptical that it's a fuel supply issue. Still studying.

edit: The second time you give it gas, while you're holding it steady, the MAP shoots up and down like crazy. Is that real? It looks sketchy.

[Spartarus]

Originally Posted by Ultramaroon

Ah, I see. Ok, definitely not the filter.

As long as there is some positive pressure on the PI rail, the HPFP will supply and regulate the DI rail just fine.

30 seconds into your last log it appears to switch over to DI. The port injectors never fire after that. At 50 seconds you start giving it gas but the target and actual rail pressure never diverge.

I'm skeptical that it's a fuel supply issue. Still studying.

The ECU is cutting fuel. The injection time drops to zero.

All the speculation is about why... Something is triggering that fuel cut.

That much we know for a fact.

I was speculating that there is a momentary supply pressure drop to the DI fuel pump and the ECU cuts injection in some sort of protection scheme.

I seem to remember some issue with the pumps wiping cam lobes when the car was new... In this case the pump seems to be working fine.

[Kiske]

Originally Posted by Spartarus

The ECU is cutting fuel. The injection time drops to zero.

The speculation is about why...

Well unless I'm wrong, only the MAF and MAP can can tell the ecu to cut fuel if they are seeing too much air. The map sensor does seem to shoot up to 36.97 just before the direct injection is cut at 112.593 into the log

[Spartarus]

Originally Posted by Kiske

Well unless I'm wrong, only the MAF and MAP can can tell the ecu to cut fuel if they are seeing too much air. The map sensor does seem to shoot up to 36.97 just before the direct injection is cut at 112.593 into the log

Oh my god, how did I miss that. Boost fuel cut...

You have a faulty MAP sensor, because you obviously didn't build 2.55 bar of boost in 0.1 seconds at part throttle and no load.

[Kiske]

Originally Posted by Spartarus

Oh my god, how did I miss that. Boost fuel cut!

You have a faulty MAP sensor, because you obviously didn't build 2.55 bar of boost in 0.1 seconds at part throttle and zero load.

Quickest car in the driveway!

[Ultramaroon]

Originally Posted by Spartarus

Oh my god, how did I miss that.

You refused to look at my pretty chart.