Was it *really* just the gas cap? (ECU code check-comments appreciated!)

[daeron]

I figured I would start a new thread, since my problem has changed its nature a bit.

 

old thread

 

I found a gas cap and put it on, the sputtering issue has decreased its severity, and its frequency of occurence DRASTICALLY.. but it isn't gone. I have elected to do what I can to eliminate all SPFI issues.. So I run the gamut of computer checks.

 

I am going through this independently of the thread, but i thought I would start it to get comments while I worked.

 

First, read memory mode. In my memory, i have only ever seen the CEL when I had triggered it through some odd change, or while I was replacing and calibrating the TPS. I am relatively certain the battery has been disconnected since then.

 

Read memory mode indicates a code 24, Idle Air control valve. This is one of the ones that is as likely to be a wiring issue as it is an actual valve issue, but if I am not mistaken all I need to do to rectify valve issues is remove, soak overnight, clean and replace, right? the IAC is the longish cylinder-shaped bit on the front of my TB, correct? It looks like the wire runs straight up into it, and I am running out of daylight to find the connector back from it. It also looks less than easy to remove, that bottom screw might pose a challenge to my limited supply of philips head screwdrivers here at my house. I tried to clear the memory (both plugs connected, engine ran until the CEL came on... ) and it didnt clear squat.. so I have to deal with that. thats the only code in read memory mode.

 

Okay, D-check puts out a 32, a 33, a 51, and a 61.

All code readouts are taken directly from the '89 FSM "chunk"

 

32-O2 sensor (abnormal sensor signal)-my dad has a couple O2 sensors I think will fit the bung.. they are old narrow bands from his RX-7, but if the shoe fits, wear it right? I am going to try swapping one of those in tomorrow, hopefully.

 

33-car speed sensor (no signal is present during operation) Clueless how to proceed, will read the FSM on this.

 

51-neutral switch (continuously in on position)

 

61- parking switch (continuously in on position)

 

these last two are simple switches in the shifter mechanism are they not?? I may hit the JY and nab them outta the 89 DL that was there, it had a 3AT too.

 

Daylight fading, I intend on reading the FSM procedures on all codes.. but haven't as of this typing.

 

Thoughts and comments are appreciated, I got stumped and distracted before I fixed these D-check issues about eight months ago.. and this is the first time I have come back to it.

 

Also, no MAF codes whatsoever. I have a spare MAF now, should I just grab the IAC off the car in the boneyard tomorrow while I am there, just in case?

 

allright, daylight fading, time to read. post your knowledge, USMB! thanks in advance (no pun intended)

[GeneralDisorder]

Okay, D-check puts out a 32, a 33, a 51, and a 61.

All code readouts are taken directly from the '89 FSM "chunk"

 

32-O2 sensor (abnormal sensor signal)-my dad has a couple O2 sensors I think will fit the bung.. they are old narrow bands from his RX-7, but if the shoe fits, wear it right? I am going to try swapping one of those in tomorrow, hopefully.

 

Any single wire narrow band should work as long as it fits.

 

33-car speed sensor (no signal is present during operation) Clueless how to proceed, will read the FSM on this.

 

Speed sensor is in the speedometer. It's either wireing, or a problem with the guage cluster itself. Being a digi it shouldn't be too complicated inside. Probably just a wheel with a magnet or something.

 

51-neutral switch (continuously in on position)

 

61- parking switch (continuously in on position)

 

Both are in the shifter mechanism.... actually they ARE the shifter mechanism if you get my meaning. They are built right into it, and if they are shot, you'll have to replace the whole unit likely.

 

Your hessitation is probably the O2 sensor. I'm not sure exactly what you changed with the fuel cap, but *if* everything else is normal, it really shouldn't matter. The only possible explanation I could see for it would be a vacuum leak created through the vent line to the tank.... but that would probably require some other components to be bad as well, or the vacuum lines hooked up wrong.

 

GD

[daeron]

 

Both are in the shifter mechanism.... actually they ARE the shifter mechanism if you get my meaning. They are built right into it, and if they are shot, you'll have to replace the whole unit likely.

 

Your hessitation is probably the O2 sensor. I'm not sure exactly what you changed with the fuel cap, but *if* everything else is normal, it really shouldn't matter. The only possible explanation I could see for it would be a vacuum leak created through the vent line to the tank.... but that would probably require some other components to be bad as well, or the vacuum lines hooked up wrong.

 

GD

 

 

You summed my thoughts up exactly, but I am still too much of a novice to take MY opinion all that seriously

 

Thanks for the quick response... People have asked me how the gas cap was causing my problem, and I havent had a good answer, either.

 

I am at a point where I know enough to figure out just about anything.. but where alot of people (read: men) would let their ego take control and blunder into things at my stage, Tim Allen-style, I choose to get hung up on doubts, as to whether or not I really DO know what I am talking about. In other words, thanks for reading between the lines and recognizing that I was fishing for you to confirm my suspicions.

 

O2 sensor has already been hit with Deep Creep, hopefully it shan't be too difficult to remove tomorrow. I really oughta just pick up a y-pipe assembly from the boneyard, as mine is riddled with leaks.. last time I ran a sea foam treatment, about 25% of the smoke was coming out from under the car, the rest out the tailpipe. They could market that stuff as an exhaust leak detector there are two or three issues in the pipes themselves, and a gutted cat that has rust-holes on the weld lines... I know this is going to effect the scavenging, and also the o2 sensor reading.. BUT while i know it could be enough to alter the way the car runs, could this be an issue that would either cause problems with my o2 sensor or (less likely) cause my ECU to READ problems into the o2 sensor? the ecu does a relatively "dumb" check of the o2 sensor that wouldnt find something like an exhaust leak in a million years, right?

 

as for the other three sensors.. I am definitely going to just go ahead and get the stuff outta de boneyard. its been a back-burner issue for long enough that I am fed up with it, and at this point, i want the ECU to give me the all-clear.

 

Providing that the o2 sensor swap makes that go away, it looks like my greatest hurdle between me and that all clear will be removing the IAC valve.. that doesnt look like fun, without removing the PS pump or some other components. Might it be easiest to just remove the TB first, or would that give rise to possible gasket issues? I have no disposable income right now (the ten bucks that I might have to spend on something before my next check is going to a badly needed oil change.. its just now 3K since I changed it, but I added seafoam last time I changed it and had no intention of going even 1000 miles before changing again... ) soi buying a new gasket is out of the question.

 

I spend a LOT of time on this forum.. but i have ahrdly done any actual work to this car. You folks have heard about it every time I have.. so draw your own conclusions. If I had a wrnech in my hand as often as I have a keyboard in my lap, I could probably have 8 cars by now. If only I could find a way to make this whole forum thing make me money....

 

Anyhow, Im going to the shop tomorrow and will bring along my camera. hopefully I can get some pics of the NOS soob stuff thats up there. I think its mostly OHV stuff, but i've no idea of what era. (speaking of making me money.. )

 

now I am off to print a hard copy of my FSM section... no PC at the shop.

[GeneralDisorder]

You can get at the IAC screws with needle nose vice-grips.

 

GD

[WoodsWagon]

On these old gen cars, there is no pressure sensor on the fuel tank, so having the cap off will not throw a code. having the cap off will create a small vacuum leak when the purge solenoid switches on, but it shoudn't be enough to cause drivability issues.