fans come on before a cold start
 

Hey,

Long time no post. Car has been working that good.

Yesterday I put the key in (stone cold engine) and turned to the on position and hear the usual click click and then the fans came on. First time ever. went to start the engine and it didn't want to run then slowly came around. Went to run some errands and several in and outs and the fans came on each time with the turn of the key (engine is not hot enough to warrant them coming on) and it started like crap. I thought the engine had low compression and that was the new reality. well, i redlined it a couple times on the way home pulled in the drive let her cool down for a couple minutes cut it off waited 20 secs and turned the key to on , no fans came on and it started up fine.


Did some diagnosing today I have 100 psi compression 7 bars, 17.5 inHG, and new plugs. fans come on and starts like crap, I leave the key in on position disconnect the neg on battery and hook back up to stop the fans and it cranks and idles fine.


Whats wrong


Thanks...Scott

Is your AC on? I know the fans run when the AC compressor is on (at least in my FD) so as to draw air over the condenser. While not probable, the extra load on the engine could be making it start funny. Should start no matter if the AC is on or not though....

Is your batteey fully charged and alternator working properly?

AC off, fully charged battery good alternator nothing else wrong that i know of.

Google search about other cars have led to possible coolant temp switch faulty, fan motor switch, or fan relay bad, so ill have to check all that tomorrow.

I know that the fan come on when the ecu is not plug so maybe a bad ground on the ecu will do the same!

One of the fan relays is kicking on when it shouldn't. Could be the relay is stuck, or one of the inputs is grounding out when it shouldn't.

Dale

Normally these kind of electrical gremlins happen after a build or they are the result of modifications to the electrical system. You are implying that you haven't installed anything recently--have you messed with the electrical system at all for anything? I do wonder if your ignition switch is flaking out though. Some circuit isn't getting power.

isnt the AC fan relay supposed to turn on aslong as the AC is on regardless of Temps ? or maybe its set up via the Power FC to do that ( I've never driven a car on OEM ECU )

It has been a while since i posted a problem, so apologies for lack of pertinent info.

Way back in 2001 I installed a new off the boat from Japan engine. Along with the install I put a fluidine radiator, an HKS downpipe, replaced all the vac lines with viton, the fan switch mod, and a defi boost gauge. The rest is completely untouched stock everything. Since 2001 all i have done is replaced the alternator, oil changes, sparkplugs, plug wires, and fuel filters as regular maintenance.

So a couple days ago I get in and turn the key on and for the first time ever my fans come on. I looked to see if my ac was on and it was not. They would run for around 5 or 10 secs and then cut off. Sometimes it seems longer and sometime not. When they come on and i crank the engine it runs horrible, when they stop running it starts normal like it did for the past 13 years.

I talked to Dave yesterday, he said flip the yellow and green relays by the battery and see if it stops, indicating a bad relay. I did it did not. He said to check the grounds. ECU ground good. Plenum ground to fire wall good. He said there were some grounds behind the passenger side bumper. I am still trying to find them(does the bumper need to come off or is there a simpler way). It has been so long since i worked on them are there any more I am missing. I even have an extra ground to the battery.

I have cleaned some corrosion off the battery with baking soda and water and noticed yesterday some of the mixture over time has spilled onto the fan motor. Could this be the culprit?

That's all I have for now.....Thanks

Do you have the fan control module/fan recall?

I've never heard about it. Is it too late?