76 280Z turbo takes too long to warm up

[HadesOmega]

I have a 1976 280Z with an 82 turbo engine in it with the stock ecu and all. I also have a electric cooling fan with thermostatic switch that I can adjust. The engine came with these teal injectors that are obviously not the stock turbo injectors but the car ran at 12:1-14.7:1 AFR when warming up. Now I installed the brown injectors and it idles and cruises at 10:1-11:1 AFR. I notice when I'm driving the water temp needle never goes past half-way, it always a tad below it. Not enough to take it out of cold start mode unless I let the car sit in one place. I know its not the fan also because I adjust the temp higher and it doesn't do anything unless I'm sitting and the temp goes high enough to kick it on.

 

I like the brown injectors because they're better for when I boost, the teal ones have this problem after a while it just goes lean under boost and I have to reset the ecu.

 

anyway how can I get my car to warm up faster so it doesn't eat up so much gas. Should I get a hotter thermostat? What thermostat are the turbo guys running? Its summer and its still overcooling O_o. Why is the ecu so picky about the CHT temp when warming up garghh...

[nscason]

i dont have a turbo yet but, the injectors i have are the black ones which are for the zxt. what temp tstat do you have? 185? when is the last time you looked under the housing? maybe it is stuck closed? just figured i would throw some ideas out there. hope i helped some.

[Tony D]

Skew the reading the ECU sees manually with a pot or variable resistor in parallell with the sensor. You can put enough bias so it comes out of cold-start virtually any place you want, but you will have to experiment...

The best way is to rig it up, and then do the resistance check at the pin-out at the ECU. Basically run it up till your temperature stabilizes, then shut down, disconnect the ECU Connector, put your multimeter on the two pins relating to coolant temperature, and twist the variable resistor till the resistance reads equivalent to 180+ degrees F. That will make it out of cold-start mode at normal operating temperature.

 

Also, for trimming fuel under boost, you can can by adding one in series tweak and put the engine into cold-start mode while under boost to add more fuel...

 

Also, the stock gauge in the dash is very unreliable, verify your temperature with something like a Wal-Mart Meat Thermometer stuck in the radiator while you're warming up.

[HadesOmega]

hmm that sounds very interesting, trick the ecu.

 

Just wondering but for the turbo engines is the only thing that the ecu reads is cylinder head temp and not the coolant temp? If I remember correctly its the CHT that the ECU bases how hot the engine is.

[Tony D]

CHT and CLT is interchangable. They both have the same response curve.

I have a CHT as CLT on my Megasquirt. Like you can interchange the 82/83 CAS as a plug in replacement for an 81CAS unit, you can swap in the CHT sensor and plug the CLT sensor pigtail in it and it will work just fine.

 

Only the US Cars used Cylinder Head Temp, everywhere else used the Thermostat-Housing Located Sensor.

 

They both send the same sort of signal, and their response curves are identical, so from the ECU's point of view, either input will work.

 

In the bad old days, you would rig Hobbs Pressure Switches with resistors on them wired into the circuit to progressively move the thermostatic reading to the ECU "colder" maps---ultimately if you look to the FSM you will see that something like X ohms = -50F, and that's about all the enrichment you can get that way. Good enough for some decent boost as long as the pump doesn't deadhead....

 

Just have to have been around when we did this crap al the time to rememer it---it's nothing new! For sure I'm no electric genius, either! LOL