Car Down On Power Over Entire Rev Range, Causes?

[Rolls]

My R32 is down on power over the entire rev range but mainly down low, it feels very doughy and laggy even though it builds boost very quickly, perhaps even quicker than normal like it is running on the cold start map (retarded timing)

My car is an r32 skyline with rb25det neo with r33 intake and ancilleries, highflow (gt2871r spec), 740cc injectors, r32 rb20det ECU with nistune, z32 AFM and upgraded fuel pump making 260rwkw, it still feels fast on full boost but not as fast as it should be, down low it feels like an rb20, laggy and gutless. Overall it still runs well, eg idle feels fine and it doesn't miss or run rough, it doesn't have flat spots or feel like I've blown a headgasket or rings, it generally feels like it just has had heaps of timing taken out of it.

I first thought it was the knock sensors so I checked ECU talk and it said no error codes, to be 100% I unplugged the knock sensor and it ran much slower again proving it wasn't the knock maps.

The next thing I thought was the VCT solenoid was stuck even though I could still hear it clicking in the engine bay, so I unplugged my boost controller (controls the VCT) and it got even slower again ruling this out.

One thing I can think of is the fuel pump isn't giving enough fuel (still on stock wiring with 8/14v switchover) however it is still down on power when on full boost which imo makes me think it isn't this and it has been fine for the last 2 years.

One other is perhaps the coolant temp sender is shagged, what would this show as in ECU talk, is it the analog temp sender eg I would see 0c from this sensor, or is it a digital on off sender that shows as something else?

Finally the only other thing I can think of is there is a boost leak, though my vac looks healthy at idle and there aren't clouds of black smoke behind the car.

Other than taking it to my tuner and sticking a probe up its ass to see if it is running excessive rich or down on timing what else could cause these problems?

Cheers

Edited October 24, 2013 by Rolls

[scotty nm35]

It's an extensive list Rolls, it could be so many parts causing power to drop. I would start with checking the cat isn't blocked, and pressure testing the intake for leaks. Work your way through the free diagnosis and only replace parts once you know they are faulty, or it will cost you plenty. Check the condition of the plugs too.

One thing that does come to mind, the wastegate may need some more preload, usually 5mm is perfect. You can simply stick a few washers under the actuator.

[ARTZ]

fuel filter

[Rolls]

Scotty it feels slow even on full boost at 3k so I doubt the wastegate is the issue. Things that I think are next on the list are fuel filter, pressure test intake, drop exhaust.

It isn't pinging though so fuel filter/pump I feel are unlikely.

Edited October 24, 2013 by Rolls

[ARTZ]

if it feels like its had heaps of timing out, could it be a CAS issue...

[Rolls]

if it feels like its had heaps of timing out, could it be a CAS issue...

I thought about this but does it ever actually happen in the way I am seeing? I thought if it was an issue it would cause pinging (advanced timing) / loss of power (retarded timing) in the high revs where its effect is worse, not the opposite which I am seeing eg low power down low but up top ok.

Edited October 24, 2013 by Rolls

[GTSBoy]

What fuel are you using Rolls? I ask because I've been generally a bit disatisifed with my Neo too the last couple of weeks. I would suggest that the mix coming from the refinery has changed lately (winter into summer)and would be tempted to put down some or all of my car's lack of sparkle to that. I'm not trying to tell you that there's nothing wrong with your car, but given that we both driving around the same place in basically the same car....it's a possibility.

[hy_rpm]

Have you even checked the base timing?

That's the exact same issue I had before and it was base timing out on cas had to have it retuned after setting the cas otherwise it will ping

Edited October 24, 2013 by hy_rpm

[GTScotT]

Definitely check ECU coolant temp sensor (the 2 wire one) and definitely check fuel system (despite lack of ping).

I have had cars drop a pump or reg and not ping, but lost lots of power everywhere. Like you noted, with a blocked filter I encountered mega ping/hesitation, but I still wouldn't rule it out entirely.

These are definitely your first point of call.

[Dave.TAS]

Air filter or exhaust blocked

[Rolls]

With the temp sender what does it do when at temp, ground the voltage coming to it? Or is it a resistive element giving an analog temperature? What would be the best way to check it? I'll check all of my filters tomorrow and also fill up with a full tank of fuel.

edit: I guess the CAS could have just shifted, I'll see if it is tight.

Edited October 25, 2013 by Rolls

[GTSBoy]

Rolls, the coolant temp sensor is a resistor. Varies with temperature.

Easy to check. The temp vs resistance relationship is google-able. Then all you have to do is measure the resistance when the sensor is at a known cold temperature and at a known hot temperature (take it out and put it in hot water with a thermometer) to see if it is on spec or not.

[Rolls]

I'll just check ECU talk is reporting the right temperatures in that case, I knew there was an analog sensor just wasn't sure if there was another digital one that the ECU used.

[Missileman]

go for a run and log the data, then check to see if timing is matching up the main map

[Rolls]

go for a run and log the data, then check to see if timing is matching up the main map

I would but I don't have a nistune license.

[ARTZ]

With the temp sender what does it do when at temp, ground the voltage coming to it? Or is it a resistive element giving an analog temperature? What would be the best way to check it? I'll check all of my filters tomorrow and also fill up with a full tank of fuel.

edit: I guess the CAS could have just shifted, I'll see if it is tight.

mine broke the bracket...no idea how, but it was very sluggish coming onto boost..pretty rare thing to happen i imagine..

[Rolls]

https://dl.dropboxusercontent.com/u/1428435/revs.xlsx

here is a datalog I did, runnign around 35 degrees timing at ~2000 rpm full throttle about to come on boost. at 3-4.5k full boost running about 27 degrees then drops to 19-20 when on full torque.

Do these numbers sound abotu right? Full boost isn't until around 4k in 2nd gear.

Coolant temp sensor seems right reading about 60 degrees as I only just warmed the car up.

My speedo cable is broken so speed was wrong

Edited October 25, 2013 by Rolls

[Missileman]

it looks a little low to me, I would have thought it should be around 25 degs, but without knowing what the timing map looks like I can't be sure.

One of the tuner around here will have more insight than my noob opinion.

[Rolls]

Just put some new fuel in it and checked the cas, feels nice and tight. Will replace filters and drop exhaust tomorrow

[hy_rpm]

Just try advancing the cas abit if you don't have a timing light and go for a test drive if it fixes it you found you problem if not just return it back to same spot