I just noticed that both my fans are running constantly. Datalogging is reporting a coolant temp of 240+, but the dash gauge is pretty much maxes out at about 160.

Seems like I may have an issue with my Coolant Sensor that feeds the ECM?

anyone know off hand where exactly that sensor is? 88 TPI Vin F Motor.

AC is not on btw. Its broken, the clutch doesnt engage at all anyway.

I did just update my ECM to an 89 BIN. But now that I think about it, I think the fans were going all the time pre update. I never notice them coming on and the sound has always been consistent once I started it. The car has been hard to start when cold. seems to me that if the ECM is getting a 200+ temp reading all the time, I'm probably not getting any cold start enrichment.

 

sensor should be on the intake under the t-stat. if the computer is sayin 240+ then that sensor is either dead or grounded out.

 

from everything i can find on the 88 305 tpi, its only supposed to have 1 fan, is the dual fan set up original? the 350 got the dual fans. im basing all this on the autstin 3rd gen wiring diagrams

 

Certainly looks stock. I bought the car a couple months ago and found absolutely no signs anything was touched on the vehicle except for some sporadic routine maintenance. Just checked my service manual and I see a reference to a Secondary fan relay.. and "Primary cooling fan" but it doesnt seem to mention a second fan...

odd....

I did pull codes and got nothing. But I noticed that after checking codes, when I started the car up, the fans stayed idle for about 2 minutes before firing up.. No where near the 185 I have them set to come on at.

 

the ecm runs the main fan on the dual fan set up, and the secondary fan is run off a second relay with a fan switch in the head.

 

if the dual fans arent original, someone could have wired them both to the ecm, or both to a fan switch.

 

what temp is the ecm seeing with the engine cold and not running?

 

I was seeing 240.8 on my TunerPro RT Datalog. I think I saw it go a bit higher after it ran a while, but the engine didnt seem to be anywhere near that. I was getting false TPS sensor reading in my log as well, so figured it was another bug... But now, I'm pretty sure the sensor is shot.

 

easy to replace, and only like $5 at the local auto parts store. just be sure to tell them coolant temp sensor

 

Replaced, Fans still kicking on early... Did find a hack though. Seems someone jumped the Primary and secondary relays together with a piece of wire and some scotch locks...... looks like its the ECM trigger wire for the fans.. Green/White

Gonna get the logger back on after lunch.

 

the secondary fan is run off a switch on the passanger side head, looks like the knock sensor. it should be on the ground side of the relay. possible the fan switch went out and the PO just wired it into the primary relay to kick both fans on. or the dual fan was added and rigged in.

 

Next time I'm in the engine I'll check that out.

thanks