Help please, RB25DET runs better on 1/2 throttle!

[Tonyr33gtst]

14 hours ago, GTSBoy said:

It was probably pinging its tits off.

It is probably still lean. You have been warned.

It wasn't at all. No pinging noise whatsoever which I would have expected to hear also. I think the ecu was stopping it by limiting the power and hence the sudden reduction in power when boost went over 5 psi. Thanks for the warning mate but it's not an expensive car so I'm not overly concerned, nor should you be ?. However I will definitely check the fueling when it is allowed to get out and on to a dyno. But I think it was just the timing issue tbh, 12 degrees wrong is a lot and the car now drives fine. Now if it was one of my more expensive cars I would be more worried. I appreciate people trying to help. On this occasion no one got the diagnosis right, no one said check the timing,  hey ho it's all a learning curve I guess. It might help someone else.

Stay safe.

Edited April 10, 2020 by Tonyr33gtst

[Dose Pipe Sutututu]

On 08/04/2020 at 7:06 PM, KiwiRS4T said:

Check the timing and the fuel pressure and then start looking for boost leaks  etc etc

 

[Dose Pipe Sutututu]

Solid post edit too ?

Didn't you say before something along the lines no-one said to check the base timing?

[Styles GTST]

I also have this ecu. Does your car have all the supporting mods for the chipped ECU? This is taken from bells:

RB Rebuild (Bells Auto Services) Stage 1 V2 ECU for Skyline R33 GTST.

 

New Stage 1 R33 GTST ECU V2 remap with improved fuel and ignition tables. Limiter increased to 7400 and a few other tweaks. Will give slightly more power and response over older versions.

Modifications required are:

- Front Mount Intercooler
- Full Exhaust System
- Decat
- Induction Kit
- Boost increase to 0.85bar
- Shell V-Power 98+ Octane fuel

Power can be expected upto 330bhp depending on engine condition and correct setup of ignition timing.

[silviaz]

On 4/7/2020 at 11:12 PM, GTSBoy said:

1 bar is 14.5 psi is 760 mm of mercury. The stock gauge is marked in hundreds of mm of mercury. So the 7 is 700/760 of a bar, which is 0.92 bar or 13.3 psi.

 

True. But your wastegate and/or actuator could be stuffed/sticky and not opening properly, hence giving you big boost until the exhaust manifold pressure rises into stupidland and blows it open a bit more, leading to spike then drop.

No, fuel is your first concern. Overboosting while it is lean as shit will KILL your engine. You have to stop doing it until you have diagnosed the lean issue.

No. Put a gauge on it. Don't f**k about with crazy secondhand ways of trying to work out what the fuel pressure situation is. Do it properly, measure it directly.

Another regulator will not magically make a failing fuel pump work any better anyway!!

Fuel pressure gauge gets teed into the fuel line, and you run it out of the bonnet and hold it in your hand/lap/passenger's hand/lap as you drive. If the pressure starts high and plummets on load, you know what's happening.

Even better, do it on a dyno.

Upstream means up stream, meaning in the direction from which the flow is coming. The fuel pressure is set by the regulator at the outlet of the rail. You can only measure the rail pressure at a position upstream of the reg, which means at the inlet end.

Can a jammed actuator cause black smoke on boost somehow? 

[GTSBoy]

14 minutes ago, silviaz said:

Can a jammed actuator cause black smoke on boost somehow? 

Not directly. I mean, there's nothing about what is happening at the wastegate itself that will generate smoke right there.

But....if the car is overboosting and the ECU is dumping in fuel (because that's what they do from factory) then, yes, black smoke will result.

It will also smoke if it is pinging its tits off too.