Squrlsquash Posted April 7, 2015 Report Share Posted April 7, 2015 (edited) On cold start it barely stays idling, sometimes tach drops to just above zero and the engine tries to die Light throttle input makes it worse (revs drop considerably)More throttle input eventually gets the revs to come up, but it goes back to bad idle if released After 5 mins or so when its warmed up it runs perfectly fine (idle is strong and light throttle revs just fine) Which temp sensor tells ecu when to richen for cold start? one on intake mani right by the thermostat housing has always been an aftermarket cabin gauge looks like that's the bung where the factory one went (but i have an 85 fsm and 87 car- so not sure) Any insight helps,thanks Edited April 7, 2015 by Squrlsquash Link to comment Share on other sites More sharing options...
scott87star Posted April 7, 2015 Report Share Posted April 7, 2015 The ECU coolant sensor is the two-pronged one. Link to comment Share on other sites More sharing options...
StarquestRescue Posted April 7, 2015 Report Share Posted April 7, 2015 The ECU coolant sensor is the two-pronged one.It also has an oval base and the prongs are strait up. Link to comment Share on other sites More sharing options...
Squrlsquash Posted April 12, 2015 Author Report Share Posted April 12, 2015 Ecu temp sensor uses which bung in the manifold? Would its' absence cause this type of issue? Link to comment Share on other sites More sharing options...
Starfighterpilot Posted April 14, 2015 Report Share Posted April 14, 2015 Have you run a set of EFI error codes as per the Starquest FAQ yet? Let us know what you find. For What It's Worth. KEN Link to comment Share on other sites More sharing options...
Squrlsquash Posted April 15, 2015 Author Report Share Posted April 15, 2015 http://www.starquestclub.com/forum/index.php?showtopic=28043will post with what comes expecting a coolant temp code, since the two prong ecu one seems to be missing completely If that is in fact the case, does the 1 prong cluster sender have similar resistance readings?(suppose no need for 2 sensors if this is the case) Link to comment Share on other sites More sharing options...
Starfighterpilot Posted April 15, 2015 Report Share Posted April 15, 2015 http://www.starquest...showtopic=28043will post with what comes expecting a coolant temp code, since the two prong ecu one seems to be missing completely If that is in fact the case, does the 1 prong cluster sender have similar resistance readings?(suppose no need for 2 sensors if this is the case) NO, the single "prong" sensor is for the engine temp guage on the dash. You need the 2 "prong" oval sensor EFI ECU engine coolant temp sensor (known as the CTS) so the EFI ECU gets the correct signal for the engine temp. This sensor causes the EFI ECU to switch from Open loop (engine cold) to the Closed loop (engine coolant temp greater than 1760 F) fuel maps - or visa versa - depending upon the engine temp at the time. See '88 FSM pages 14-14 & 14-64. Here's a Link to the '88 FSM http://www.starquest...ervice_nav.html If the EFI ECU isn't getting a signal from the Engine Coolant temperature sensor (CTS), i believe that it automatically defaults to the Open loop maps and runs rich regardless of engine temp. Also see this link for more info: http://starquest.i-x...85f78e860a60024 For What It's Worth. KEN Link to comment Share on other sites More sharing options...
pcristquester Posted April 15, 2015 Report Share Posted April 15, 2015 Mine was doing the same thing out of the blue. Found a loose/bad crimp (original connector is gone) on one of the female connectors to the CTS. Put a new crimped connector on and back to normal. Link to comment Share on other sites More sharing options...
Squrlsquash Posted April 16, 2015 Author Report Share Posted April 16, 2015 Anyone have a spare 2 prong lying around? Link to comment Share on other sites More sharing options...
pcristquester Posted April 16, 2015 Report Share Posted April 16, 2015 Anyone have a spare 2 prong lying around?I'll check my extra intake manifold Link to comment Share on other sites More sharing options...
Squrlsquash Posted April 20, 2015 Author Report Share Posted April 20, 2015 (edited) found a 2 prong sensor on an extra mani in a pile of stuff from a parts buy anyone have the resistance readings handy?each pin had a different reading 1.5kohm and .5kohm if memory serves one pin is for ecu, and one for the dash gauge?anyone know the wire colors for each on an 87? Edited April 20, 2015 by Squrlsquash Link to comment Share on other sites More sharing options...
importwarrior Posted April 20, 2015 Report Share Posted April 20, 2015 www.starquestgarage.com has the answer. Cooling section page 7-5 Thermistor type16,200 at -20°C (-4°F) 2,450 at 20°C (68°F) 296 at 80°C (176°F) Link to comment Share on other sites More sharing options...
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