1993 RX7 R1 - Check Engine Light (CEL)

Here are the symptoms:

„h CEL (05 = knock sensor) comes on after driving for a while and the goes out (most of the time) after driving at highway speed in 5th gear for awhile.
„h With engine cool, reset computer by removing battery cable and press break pedal; CEL (05 = knock sensor) goes out as it should.
„h Drive 7-10 miles; engine is strong. CEL is out until start to drive at slower speeds and engine warms up (?).
„h Reset computer again while engine is still at normal operating temperature (fan is running); CEL (05 = knock sensor) will not reset.
„h Engine cools for several hours; resetting CEL will now work and light stay out until engine warms up(?).

Any suggestions? What is next step?

Thanks, Lee Steelman

 

So, if I read you right, you've resetted the check engine code twice or so and the same code kept coming back. If so, your knock sensor needs to be replaced.

 

Thanks for the lead and other help on this forum.

The problem I had was an open wire. The knock sensor wire was broken at the connector; hidden under the connector. After locating the knock sensor, and pulling lightly on the wire to trace it back to the connector, it came loose. I resodiered it to the connector and the check engine light went out for good!

 

Is there any way to pull codes from the computer without a scanner or dealer tool?

 

Here is another good source to check engine codes:
http://www.rx7city.com/ecucodes.htm

 

If the knock sensor is not working, what are the sypmtoms? Does it cause major problems? Where is the damn thing? the shop manual doesn't show it very well?

 

the knock sensor is located (screwed into the block) directly above the top front spark plug with a single wire comming out. there is a very good gen3 shop manual online (www.iluvmyrx7.com). This is sometimes very helpful.

I think it listens for "pinging" in the engine and lets the computer know so it can compensate to help prevent damage to the engine via "detonation". this is what i have guessed after running down a problem when my check engine light would come on. This will occure when the knock sensor is either open or shorted, based on what i could find out on internet.

One machanic told me that when the check engine light (knock sensor) comes on, the first thing he does is clear the code to see if it will return; if it does, then replace the knock sensor. i don't know how to check to see if one is bad, but there may be a way. anyhow, when i started to remove my sensor, the wire was broken at the connector. I soldiered it and have had no problem since.

this is the extent of my knowledge; hope it helps!

good luck