OK, really losing a lot of power(timing related?) when at operating temp..

[goofynick6]

Ok, I thought I'd cured my problems when I found a boost leak, but no.

WHen I first start the car for the first time of the day, let it warm up for a few minutes, and then drive it, it is incredibly fast. Like, it'll hit 4-5 psi with very little throttle load, and when that 4-5 psi hits, you REALLY feel it.

However, after it's up to operating temp and you've driven it for about 10 minutes, it feels totally different. It will take more throttle to hit that 4-5 psi, and when you do, it's barely noticeable. It no longer breaks the tires loose in 1st or 2nd gear and it feels like it has lost about 40 hp..no exaggeration.

So, I don't get it...watching my wideband, it runs the same air/fuel and the boost gauge says it is the same, so the only thing I can gather is that I am somehow losing the timing; something is retarding it. My question is, what would do that?

My timing is at 15 deg at idle, but something is pulling a LOT of timing once the car gets up to temp. Coolant temp sensor doing this? Or what?

ANy opinions welcome! Thanks guys,

Nick
Modified by goofynick6 at 8:06 PM 9/15/2004

[gani]

that coolant temp sensor is a big culprit to doing that. check the resistance of the sensor according to factory spec and change it if necessary. i think a 300zx twinturbo coolant temp sensor is the same but you ahve to use the plug from the 300zx.

[Wulfgang]

Based on the R vs. T profiles, I would guess that the KA sensor has an identical thermistor in it. However, I do not know if it has the same thread. Instead of pulling that thermistor to test it, you can measure voltage across it in situ. There is a page in the FSM on this.

[Imissmyturbo]

Is it possable that your intercooler is getting heat soaked? If you are using the stock sidemout it will do that and make a big difference.

[goofynick6]

OK, I'll go check this..I think the rb25 manual says 3volts at 20c and 1 volt at 78c. I would think it would throw a code if it was bad? I'll check it out though, any other ideas?

Thanks,NIck

[gani]

i should throw a code on the ecu

[BoostFab]

Is it possable that your intercooler is getting heat soaked?

i was thinking about that

[goofynick6]

I have a 24x12x3 hybrid front mount and it's always pretty cool to the touch

[goofynick6]

Well, just checked and the coolant temp sensor is proper voltage and has good ground and connection all the way to the ecu.

Would a tps that reads .55volts idle and 4.05 wot be causing this? I just don't understand, but it's definitely only fast when the car is all nice and cool..

[goofynick6]

Ordered an Apexi Multichecker tonight...at least I'll be able to monitor my timing and adjust my tach to match it..heh.

NIck

[Wulfgang]

Nick, you've got a laptop and do a bit of EPROM burning, don't you? Then you should probably also get the PLMS Consult interface so you can monitor ECU functions directly:

http://www.plmsdevelopments.com/consult_if.htm

[goofynick6]

I don't know why I didn't know this worked for RB20's! Grr...a day late. I bought that multichecker last night, and this basically does the same thing....hehe. I guess if this wideband I'm soldering together myself comes out ok, then I'll order one of these and build it and then sell the multichecker.

Thanks for the heads up

Nick

[DSMs_Suck]

Nick you may want to try just throwing in a resistor instead of a temp sensor for testing purposes.

Wulfgang, do you have that R vs. T chart? Or can you give us a safe resistance value to go off?

Murray

[Wulfgang]

The chart is in the R32 GT-R manual and looks the same as the S14 chart. Should be right around 1V dropped across the thermistor at 80ºC (right after your thermostat begins to open). That's also 300 Ohms, so you could just put a 300 Ohm resistor in like Murray said.

Btw, I am fairly certain the ECU will NOT throw a code for a faulty engine temp sensor. On the other hand, why would a thermistor fail?