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Discussion Starter · #1 ·
I have a 90 CRX all Stock that is throwing a code 4 on the ECU. So far I have reset the ECU, replaced the Distributor, replaced spark plugs and wires, tried a known working ECU same model and a known working relay. Timing appears right although the marks are hard to see. I'm getting 12v when running and spark across all four wires and wires to battery look okay and terminals are clean. Checked all connections and wires to the distributor. Starts fine and idles good but once I take off I get the check engine light and the rev limit kicks in. Any ideas would be greatly appreciated as I'm at a loss what else to try.
 

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Code 4 is an issue with the crank angle sensor in the distributor. Since you have tried a different distributor and ECU I would focus on the wiring.

Does this car have pretty much stock wiring or has it been tucked or otherwise hacked up?

Is it a HF, DX, or Si?

Mike
 

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Discussion Starter · #3 ·
DX stock but the motor was replaced. Wiring looks clean no cuts, modifications or anything to indicate an issue but I'm starting to think it's a wiring issue as well. Had an issue with the ground wire at the battery being corroded that I cleaned up but I might try replacing it first. Thanks for the reply.
 

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If the car is cranking over the battery ground must be good enough.

There is a ground connection on the thermostat housing for the ECU and it's sensors. Problems with this ground can produce a wide range of strange problems. It's worth taking a look at this ground point but don't obsess over it. The thermostat housing is on the back side of the motor, just follow the radiator hose to it.

Disconnect the ECU. On the smaller of the two black connectors there should be a white wire and an orange wire at one end of the connector. With a good crank sensor and wiring there should be between 350 and 550 ohms between the these two wires and an open circuit between both wires and ground.

If it fails this test disconnect the connector at the distributor and repeat the test on the distributor(the wire colors are the same).

Mike
 

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If the car is cranking over the battery ground must be good enough.

There is a ground connection on the thermostat housing for the ECU and it's sensors. Problems with this ground can produce a wide range of strange problems. It's worth taking a look at this ground point but don't obsess over it. The thermostat housing is on the back side of the motor, just follow the radiator hose to it.

Disconnect the ECU. On the smaller of the two black connectors there should be a white wire and an orange wire at one end of the connector. With a good crank sensor and wiring there should be between 350 and 550 ohms between the these two wires and an open circuit between both wires and ground.

If it fails this test disconnect the connector at the distributor and repeat the test on the distributor(the wire colors are the same).

Mike
Found your discussion helpful. My son and I are having same exact issue, same version of stock 90 CRX. Done all the same things and the ohm reading on the new distributor is 380 ohms. No issues with a grounding of either the Orange or Yellow wires. At this point I'm lost. Going to call tech support at All Computer Resources where we purchased the replacement ECU and see if they have any ideas of what to check next.
 

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Thread is from 2009.
I doubt you get him to answer back.
Was anything done to the car before the code ?
If you have a base model DX you need to match the distributor code. The Si uses crank sensor I'm not sure the DX does.
That is one of the cables that needs to be rewired when going multiple injectors instead if the dpfi.
 
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