error codes
 

Hey dudes, quick question,

Is it possible for a particular component ( that the ECU displays codes for) to fail, and the ECU still display no error. If your test light says all is well, can you be assured that those components are OK?

Thanx, Gregg (old fart)

well, they are supposed to be working correctly at least

to really check that they are working right youve got to test them and reference their output to what they are supposed to be in the FSM.
haynes has got some refernces also
exe- to test the pressure sensor- read the voltage output of it at idle and other rpm ranges (or with a vacuum pump) and compare it to what it is supposed to be

Thanx man, what I needed to know.

Gregg

Personal opinion with no literature to back it up.......I don't think the 86 thru 88 will tell you a darn thing unless the plug is off. I firmly believe, and its nothing but predjudice. that if the boost sensor is giving a false reading, you get no code saying so. If the plug falls off, then yes it gives a code. As someone said a while back, the 86 thru 88 are as dumb as a rock. One more time with predjudice....if the plug falls off, yes a code. If the plug stays on, I doubt it very much that you would get a code even if the reading of that sensor was seriously off the correct reading. If you have an intermittent connection, probably get a code for a moment. Please, somebody with some knowledge of the ECU, tell me I'm all wet.

Hay HAILERS,

Hmmm, that's interesting. So all my dumb as a rock ECU is telling me is that there is electrical continuity, nothing about propper function. If this is true, the test light has been leading me astray!
Dude, you know the history of my car. After everything I've checked/done, it still raps like a one legged old lady on a bicycle.
Guess I go back to square one, get out the multitester, and check everything again, one by one.
I'm starting to think it's an apex seal. Did a compression check, but I don't have enough experience with rotaries to interpret the results. Everyone says equal needle bounces is the clue. No matter how much I used my imagination, I saw the first three needle bounces go up in stair-step fashion. Then again, with the trailing plugs out, I get that strong "whoosh" sound.
I'm about to tow the thing to my mechanic for a compression test to make sure I'm not whippin' a dead horse.


Gregg

Ahhhh! I covered my arse when I used the words *personal predjudice* and *personal opinion, no literature to back it up*. Lawyer talk. Saw it on TV. Can't sue me. On the compression test , yeah get a dealership to do it for piece of mind. You should have taken the *needle valve* (minds gone blank, can't remember the proper name) out and chunked it to the side, and then screwed the end of the hose in the plug hole. That way each time a side of the rotor comes around you'll see it bump up and then right back down, and then the next rotor side will come along and do the same. I put my thumb over the lower numbers while doing this and look for the needle to bounce past my thumb, and make sure all three bounces are the same, more or less. The same is better. If you leave the needle valve in the hose, then you see progressive increases which is really not the way to go. Needle out, The other rotors upper plug out. Crank the engine while observing the one bounce after the other, watching to make sure they are on the whole(lawyer term to protect the rearend) the same. And no, I am not a lawyer. I have a birth certificate showing I had father. Conclusive proof.

Hey HAILERS,

Hmmm. You seem to be pretty fluent in "legalese". You sure you're not in your car, wearing a cheap suit, following an ambulance right now?:D

Thanx for the info. I did the water " steam cleaning" trick tonight, as a last resort, haven't driven the car yet. Maybe I'll do a compression test one more time, just to make sure.

Gregg

My local rx7 mech. doesn't even bother checking the codes on 86-88 cars anymore. he doesn't trust the ecu at all, and would rather just check stuff himself. he's wasted hours tracking down what was causing codes to end up having it be something completaly unrelated to what the code was for.