Project Comanche Posted May 5, 2014 Share Posted May 5, 2014 What sensor/sensors are responsible for fuel delivery/injection while cranking? 1987 comanche 4.0 I have spark and starts %100 of the time with the smallest shot of starter fluid. I have checked fuel system and I have perfect pressure at fuel rail. I have checked and cleaned all connections/grounds as recommended by cruiser's renix tips. Link to comment Share on other sites More sharing options...
Oddmodman Posted May 5, 2014 Share Posted May 5, 2014 I'm not an expert, but my first thoughts are IAC and TPS. I just replaced my roommate's '93 4.3 Chevy's TPS and now he doesn't have to start it with his foot in the pedal. Just a thought. Other people will know more I'm sure. Link to comment Share on other sites More sharing options...
MuddFoot Posted May 5, 2014 Share Posted May 5, 2014 starter relay send fulls power to starting system while starting Link to comment Share on other sites More sharing options...
Eagle Posted May 5, 2014 Share Posted May 5, 2014 I don't think any sensors are involved, if we're talking about a cold start. The Renix ECU ignores most (or all) sensor inputs and operates on a hard-programmed fuel-air map until the block coolant temperature sensor sees a temperature of 165 degrees or higher, after which it switches to operating in closed loop mode and responds to sensor inputs. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 5, 2014 Share Posted May 5, 2014 Have you ever refreshed the relay bank relays and receptacles? The Relay is triggered by the ECU to fire the pump. See if you have a fuel pump ballast resistor on the driver's side inner fender near the air cleaner. Link to comment Share on other sites More sharing options...
Blue XJ Posted May 5, 2014 Share Posted May 5, 2014 Isn't the cam sensor in the distributor responsible for controlling when the injectors fire? Link to comment Share on other sites More sharing options...
nitroxsteve Posted May 5, 2014 Share Posted May 5, 2014 Isn't the cam sensor in the distributor responsible for controlling when the injectors fire? I can't figure out what the sensor in my distributor does. I can't tell any difference with the distributor plugged in or unplugged. Link to comment Share on other sites More sharing options...
Blue XJ Posted May 5, 2014 Share Posted May 5, 2014 I wasn't too sure, I always thought the crank sensor controlled the spark and the cam sensor controlled the fuel. Maybe that's only on the newer vehicles, or like mentioned above, only when the Renix is in closed loop mode? Link to comment Share on other sites More sharing options...
cruiser54 Posted May 5, 2014 Share Posted May 5, 2014 Kinda sorta but not really. ECU fires the injectors sequentially with the engine firing order based on info from the "sync generator" inside the distributor. If it gets a crappy signal, it just guesses. I have never fixed a driveability issue with a sync generator replacement. Only way we ever knew they were bad was when we spotted it while testing for something using the factory tester. Go unplug yours and see how it runs. Link to comment Share on other sites More sharing options...
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