1988 Honda CRX Won't start after turned off

KRIMSYKRIM

MEMBER
1988 HONDA CRX
4 CYL
FWD
MANUAL
17,500 MILES

My 88 crx will start up and run great, untill turned off. It does not matter what length of time -2 seconds to an hour- the car was running, it will not start back up UNLESS I unplug injectors (2 or all 4). When the car is started without any number of injectors it will not, no mater what, go over 4,000 rpm and will run a little rough between 3 and 4 thousand. When the car starts up on its own it fires up with no problem and runs perfectly for however long I am driving it. It has full power and full rpms.I have already replaced all spark plugs(new platinum series), injectors, distributor (factory new), fuel filter (factory new), and main relay(factory new). The only error code I have left on my ecu is code 6 (coolant temp). The car has an aftermarket fan and radiator that I blame that error code on. For the injectors, I purchased 4 from a junkyard, took the ones on my car off, soaked them all in chemtool (fuelsystem cleaner) and picked out the four best and put them back on the car (made sure the check all gaskets on them) The car's performance greatly increased. However, still will not start after turned off. The engine is a jdm d15b (not the American version aka d15b1-7, it is a flat d15b) When unplugging injectors, after a failed start, the engine will fire with NO injectors (will die out 1 or 2 seconds later), so I am getting fuel into the cylinder and have spark. I have checked for spark and I have spark every time. The car always turns over, just does not start, so I doubt it is the starter. As far as when it will start on its own- for sure every 2 hours, not sure about less. I was, at some point, able to start the vehicle by turning it over, removing the old main relay, turning it over again, and putting the main relay back on. After that, it would turn over, sound like it was starving for fuel (id rev it up), it would burn some oil out the tailpipe, and run great. (It stopped working and I replaced the main relay). I do live in phx, AZ, and it does get over 100 degrees. Also, a few weeks ago (before injectors and main relay, the car would not start AT ALL during the hot parts of the day. When I bought the car a month ago it had problems going over 3,000 rpms (the seller had a distributor line off) but would start every time no problem. I did not start replacing parts untill it started to not start after being driven.

1 Reply

KHLOW2008

MECHANIC
41,815 POSTS

Hi krimsykrim,

Thank you for the donation.

You have a Code 6, a fault with the Engine coolant Temperature ( TW) sensor. This circuit is NOT related to the cooling fans or radiator. The sensor is exclusively for sending the cooant temperature readings to the ECU.

The wrong signals are being sent to the ECU which is in turn keeping the injectors opened for longer periods than required and thus flooding the cylinders.

Here are the diagnostics.

Coolant Temperature (TW) Sensor
The TW sensor uses a temperature sensitive resistor (thermistor) to measure coolant temperature. Resistance of thermistor decreases with a rise in coolant temperature.

CODE 6: COOLANT (TW) SENSOR

1. Turn off ignition. Remove hazard fuse in main fuse box for 10 seconds to reset ECU. Start engine and observe Check Engine light. If light is off, problem is intermittent. Test drive and check again.

2. IF light is on, warm engine to normal operating temperature (cooling fan on). Disconnect C101 (1.5L and standard) or C151 (HF and Si) connector from C210 connector. See Fig. 6. Measure resistance between Red/White wire terminal and Green/White wire terminal of C101 or C151 connector, on sensor side of harness. If resistance value is not 200-400 ohms, inspect for short or open in Red/White or Green/White wire between connector and coolant sensor. If wires are okay, replace coolant sensor.

3. If resistance values are within specification, reconnect connectors. Disconnect 2-wire connector directly from coolant sensor. Measure voltage between ground and Red/White wire on sensor harness. If voltage is not about 5 volts, go to step 5). If voltage reads about 5 volts, measure voltage between Red/White (pos.) and Green/white (neg.) wires. If about 5 volts is not present, repair open in Green/-White wire between ECU and coolant sensor.

4. If voltage reading from Green/White wire to Red/White wire of coolant sensor harness was about 5 volts, substitute a known good ECU. If about 5 volts is now read, replace original ECU.

5. If voltage reading from ground to Red/White wire of coolant sensor harness was not about 5 volts in step 3), turn ignition off. Connect system checker harness between ECU and ECU connector. Turn ignition on. Measure voltage between terminals C6 (pos.) and C12 (neg.). If about 5 volts is present, repair open in Red/White wire between ECU terminal C6 and coolant sensor.

6. If voltage reading is not about 5 volts, disconnect "C" connector from main wiring harness only, not at ECU. Measure voltage between terminals C6 (pos.) and C12 (neg.). If about 5 volts is now indicated, repair short in Red/White wire between ECU terminal C6 and sensor.

7. If about 5 volts is not indicated, substitute a known good ECU. If condition is rectified, replace original ECU.