Power restricted over 3000rpms

[Spencer87]

So yesterday I was sitting at the lights in traffic (red) waiting to make a left. Once the lights changed, traffic progressed through. Once I got it into second, I started to accelerate, I'm not precisely sure of the exact rpm but it was most likely around 3500-4000 when all of a sudden I lost most of my power. She doesn't idle right, where if I don't watch her, she'll stall. I managed to get her to the shop (didn't get her over 2500rpms on the way) but it was such a weird feeling (once you apply gas, its like nothing happens).

There are a couple things that we have come up with so far but I wanted to post what I experienced in case this has happened to anyone else.

Gas Pump (which I hear is common) - and if I'm replacing it, I'm thinking of replacing my stock GTST gas pump with the GTR (I want to convert it in the long run).

Mass airflow sensor? (I could be mixing up my sensors)

and to make sure its not something silly, spark plugs (I'm sure they're running through other possibilities as well).

[GTRC Admin]

Not particularly a problem special to the Eastern Region, moving to Skyline Tech

[judasentinel]

Fundamental question to ask at this juncture - are you able to rev the engine freely past 2500-2800 rpm without any problem? If you are, then your MAF is not dead...maybe weak but not dead.

Eliminate the most basic of possible causes - air leak in piping from after turbo to the intake manifold, faulty MAF (may need to resolder the connections inside it). Sounds like a loose coupler somewhere....possibly around the SMIC if you're still running stock setup.

A faulty fuel pump will make your car jerk and stall under acceleration/load. Usually when fuel pumps go, they do so in stages. If you are able to rev freely without issues then its more than likely not the fuel pump. Upgrading to a GTR one is a good idea anyways.

Sometimes, depending on where you go, dirty petrol/gas can also cause issues with loss of power.

You need to describe in a bit mroe detail as to what is happening with revs, with power, and boost. Any sputtering from the exhaust?

[RSi]

Could be kicking to safety maps.... could be something as simple as bad fuel.

[Spencer87]

Hey Thanks,

Still am running stock setup. Without a load, runs fine(turbo spooling, engine sounds good). I've been using 91 Oct from Shell but just filled up with 94 from Petro. I may do the upgrade anyways, as I hear it is a common issue in Skylines.

It's been at the shop since yesterday (Im waiting on the update still) but I'm sure they're going over the basics. I'll make sure to check no air-leaks and I'll mention the stuff about the loose coupler. Is MAF main airflow? Still new to the game but I really appreciate all the insight.

[DreadedFist]

Replace the pump with a Walbro 255. They're pretty cheap. A used GTR pump is still going to be used, so you might as well buy new. I don't think I'd trust used fuel system parts. Maybe injectors depending on how old they are/how long they were used for.

If you can't go over 3000rpm at all, probably MAF related.

[Spencer87]

I was looking at either the Walbro 255 or a new GTR pump. Without a load, runs fine (minus the fact if you don't watch her, she can stall).It's when she's in gear the trouble starts.

I'm still waiting to hear back from the shop but I might go with the GTR pump anyways.

[Skym]

At higher loads (when engine transistions to boost), R33 25T knock ignition map can go to 0 degrees (engine stops reving) and dump alot of fuel in via knock fuelmap. But at lower loads (reving at idle) it's normal ignition timing, fuel. I would think engine is knocking, going by what your saying. It could be something is loose on engine that's setting off knock sensor on engine, fuel pump related, fuel octane, CAS not adjusted properly, just to name a few area's to look at.

[Spencer87]

Thanks, I'll make sure I bring it up!

[Spencer87]

UPDATE:
Was the fuel pump.

Thanks again for everyone's insight.

On the plus side, I have a better fuel pump now which means..... Next: Boost controller. Party.

[RSi]

What pump did you get?

[Spencer87]

Walbro 255 lph High Flow Fuel Pump