I summon the SR tech gods to answer my prayer.

[ka24det-power]

Ok so I am having a little bit of an odd problem. My car runs like a champ for about 1 hour during mid day heat (Florida 96 Deg today). Then all of a sudden like a switch was hit I lose about 30hp. (kind of like when your crank angle timing is way off and the car makes no power)

It idles fine
Revs smooth
Temp guage has not moved
FMIC is warm on one side cold on the other
Makes a slighty diffrent tone during exceleration
I have a 14" and 10" fan on a stock SR radiator
Stock termostat

If I pull into work and let the car sit for 20 min and then take it for a drive it all goes back to normal. But this time the problem doesn't take an hour to resurface it takes like 10 min.

I am sure it is a heat problem because a couple of weeks ago my fan relay burned out and I got the exact same symptoms within 10 minutes of driving first thing in the morning. And in that case the temp guage as getting a little over normal heat.

I bought a nismo thermostat 149deg, I am going to put it in I am just afraid that it will just banaid the problem.

I have a DYNO tuning session on the 17th with my new GT25R so I am trying to get my swap to run perfect.

MY friend thought it might be the O2 since they run off of heat, but I am not sure. Apparently it is good practice to change the O2 when you swap the motor.
:hammer:

[Flybert]

It's not the O2. The O2 only operates at partial throttle.

My guess is that after your car starts to warm up, especially in that hot weather, your car starts knocking and the knock sensor picks up on it and retards the timing. It might not be an audible sound that you can hear. Have you checked your plugs for white specks? Do you have an SAFC2 or a power FC to monitor the knock? Who tuned your new setup? What are your oil temps and what viscosity are you using? Also, are you sure your base timing is set correctly? Are you throwing any codes?

[s14slide]

Definately check the plugs and their gaps, I just learned the hard way that SR's are really picky about plug gaps. Got any more info about your setup. Like how much boost ur running? etc, etc.....

[wutangben]

I agree, check plugs!

[ka24det-power]

Definately check the plugs and their gaps, I just learned the hard way that SR's are really picky about plug gaps. Got any more info about your setup. Like how much boost ur running? etc, etc.....

Motor and mods:
95 S13 Blacktop (good compression)
GReddy Intake Mani and BOV
3" Turbo Elbow, downpipe, and exhaust
GReddy FMIC pipes
24x11x3 Intercooler core 2.5" inlet
10-12 PSI
Walbro Fuel Pump
Denzo Factory Plugs, I checked the gap 2 weeks ago and I think it is .32 I will have to check.

[ka24det-power]

- 10w40 Red Line oil
- Factory Tune
- Timing 15deg

I was thinking about running a voltage meter into the car hooked to the knock sensor so I can monitor the voltage output. It ranges from 0 to 5v right?

[01SaturnL200]

check the coils....

[ultraDorksGarage]

who did ur wiring? if its a fresh swap and its coolant related, check to see if temperature probe is not hooked up to the ecu, only the temperature sensor is supposed to be hooked up, found this on a profesional swap once and had similar problems except car had harder time starting.

with my personal car, when the temp sensor blew up it did the same thing, but had a tendancy to miss at high rpm/high boost(albeit 555cc inj).

[ka24det-power]

who did ur wiring? if its a fresh swap and its coolant related, check to see if temperature probe is not hooked up to the ecu, only the temperature sensor is supposed to be hooked up, found this on a profesional swap once and had similar problems except car had harder time starting.

with my personal car, when the temp sensor blew up it did the same thing, but had a tendancy to miss at high rpm/high boost(albeit 555cc inj).


I did my own wiring, it is my second SR swap and I went by the heavythrottle.com wiring chart.

I retarded the timing a 1 or 2 deg at work today and the problem hasn't resurfaced yet. Then again it rained and the temp dropped quite a bit.

[withy]

are you running 70/30 water/coolant mixture? also are you using a fan shroud? both of these would help drop your normal operating temp.

[s14slide]

Denzo Factory Plugs, I checked the gap 2 weeks ago and I think it is .32 I will have to check.

Try a 28, I had my #4 out to 33 and it misfired in a certain range and really killed power until I dropped the gap and she runs like a champ now. It takes ten minutes to do. Unless your 100% sure about them, it only takes like ten minutes to check and gap. Best of luck to you with it though.

Lastly, I am forced to say; your screen name kinda throws me off. Being that you are definately not what you are saying you are.

[ka24det-power]

How can I change my user name? KAT was my old setup and it always confuses the crap out of people. :tweak:

[JDMs13]

its up in user CP.

[blu808]

Plug gap is not the factor. It would cut out and stumble if it was blowing out the spark, and it wouldnt be intermittent.


Anyways. Make sure your around 15deg timing when your motor is warmed up all the way.

Its most likely this.>

There are two temp sensors by the throttle body. One has 1 wire, that one is for the guage. The other has 2 wires, that is for the ecu. check the connection and the sender. Timing is retarded by the ecu when the motor is cold. If the sender or wiring looses signal it will make your motor think its running cold and pull all your timing and therefor power.

[JDMs13]

should the CA also be at 15deg when at operating temperature?

[420sx]

ok does it shake real bad and sound different ? it might just be problem with the harness, where the power to one of injectors is disconnected and it makes it run on 3 cylinders. this case, unplug/clean/check/replug everything.

[blu808]

ok does it shake real bad and sound different ? it might just be problem with the harness, where the power to one of injectors is disconnected and it makes it run on 3 cylinders. this case, unplug/clean/check/replug everything.


I would ask that too but he stated it runs fine for a little while.

[ka24det-power]

It runs smooth before and after the power loss, it just sounds ever so slightly different during hard acceleration when I am experiencing power loss.

I reset the timing to 14 deg just incase it is knock and the knock sensor is causing the power loss by retarding the timing. It seemed to help but it is hard to say because it doesn't happen all the time.

I just installed a Nismo Thermostat and a GT25R .64 AR today :D , so well see how it runs in the morning when I put the rest of it back together.


Oh, and I'll check those wires to make sure they are in good shape.

[sr240mike]

Im in a similar situtation. At times once warmed up I'll feel a loss of power just like you mentioned. I was think about the knock sensor too. I've asked this question before but nobody seemed able to answer. How long does the ecu read from the secondary("safety"/"low octane", whatever you want to call it) fuel and timing maps after detecting detonation?

[ka24det-power]

It seems like I have to park and let the motor cool down before it goes away.