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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / December 20061989 Chevrolet Celebrity 2.5L cold starting issue, rich, flooding
This car drives great and gets good mileage when fully warmed up. When cold starting, you must hold the throttle to the floor and keep holding it until the engine revs up, then feather the throttle to keep it running. Lots of black smoke initially then it clears up. After the idle drops it tries to stall and if I am not feathering the throttle and it does stall, it is nearly impossible to restart. Smells very gassy when this happens. I'm assuming the throttle body injector is leaking. Or if this model (700) has a cold start injector, then IT is leaking. Once warmed up the car drives normally and starts easily. Check engine light goes off after 5-10mins of warm driving. Trouble code is 15, coolant temp sensor reads too low, yet engine runs at normal temperature and sensor is new along with radiator, water pump, all hoses, thermostat, etc... Does the model 700 TBI unit have a cold start injector, or just the one big one? > This car drives great and gets good mileage when fully warmed up. When > cold starting, you must hold the throttle to the floor and keep holding [quoted text clipped - 14 lines] > Does the model 700 TBI unit have a cold start injector, or just the one > big one? IIRC, you should have two temp sensors one for the dash and one for the computer. -jim No cold start injector. Some TBI injectors, it is easy to see the tip of the injector, not sure with your model. You can look. Prime the system by turning the key on, don't crank. The injector shouldn't spray or drip. You can clear the code, start the vehicle and see if the code comes back. If it does, clear the code again. Turn the key off. Unplug the CTS connector, by the way, are the wires yellow and black going to the connector? Put a jumper between the two terminals on the connector. Start the vehicle, let it run a bit, kill it, see if any codes return. What codes? Thank you, I'll check it tomorrow if it's still light out after work. That or it gives me a great excuse to go buy a Mag-Lite while I'm out and about. That little dollar store shake-it-up flashlight just doesn't cut it for mechanical work. The car runs beautifully once it's warmed up, and it only takes 2 miles to do that, from my house to the interstate entrance ramp. I'll bet the injector is leaking, because if I turn the key on and don't crank it, I can smell gas within 20-30 seconds if I'm sitting there adjusting mirrors and putting my belt on and organizing paperwork before the car is started. I also looked in the trunk for the first time today that I got 2 spare tires in the trunk! BONUS!!! Any little thing means a lot in a $300 car... > No cold start injector. > [quoted text clipped - 8 lines] > the vehicle, let it run a bit, kill it, see if any codes return. What > codes? > This car drives great and gets good mileage when fully warmed up. When > cold starting, you must hold the throttle to the floor and keep holding [quoted text clipped - 14 lines] > Does the model 700 TBI unit have a cold start injector, or just the one > big one? No cold start injector on your system. They are used on the Bosch type systems mostly on Japanese and Euro cars of the preOBDII era. Your code 15 is likely pointing you in the correct direction. If the coolant temp sensor (CTS) is in fact good (being a new part would suggest this) then you may have a bad ground wire at the sensor. I think the signal wire is yellow and the ground is black. Use a DVOM and measure the voltage at the connector with the key on and the connector attached to the CTS. Do this by backprobing the rubber grommets around where each wire goes into the connector with something like a paperclip. Ground your DVOM's ground lead to the engine block and then read voltage on the two wires with your DVOM's positive lead. With a fully warmed up engine the yellow wire should be in the ballpark of .5 volts. A cold engine would read around 4 volts. The black wire should always be as close to 0 volts as possible, preferably < .1 volt. If you see 5 volts on both wires then you have a loss of ground at the black wire. Trace it down and repair it or wire a new ground to the sensor*. If you have 5 volts on the yellow and 0 volts on the black then the sensor is bad (electrically open). Anyway, a code 15 means that CTS circuit voltage is close to or near 5 volts which is an illogical input value (this would indicate the coolant is -40F which is considered impossible in automotive logic terms). The ECM wants to see a range of about .5 to 4.5 volts. * It would be best to run the new wire back to the original ground source as indicated by the factory wiring diagram for purposes of controlling floating voltage accross multiple ECM sensors, but if you want a quick fix, running the CTS ground to a good engine ground should suffice. Don't overlook the possibility that a wire could be broken right at the base of the harness or that the terminals in the CTS or harness could be corroded or have weak tension. Toyota MDT in MO |
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