jjcobm

iTrader: (18)

Hi,

I am wondering if someone can give me a hand with this. My 91 vert (all stock besides header and cold air intake, no emmissions removed) currently has a CEL code 13 and 17.

Let me start by saying I started to diagnose all these codes due to an rough idle I have. It sounds as if it is "pulsing" around 750rpm the rpm needle bounces up and down slightly. My engine was running fine until the past 2 days, before that I didn't have my rough Idle. All my vacuum lines are fine, I have double checked and triple checked. I have adjusted my TPS also and idle screw, and still, nothing. Anyway:

I have check my boost sensor per the FSM, applied the 3.9 inHG and it read 2.9v. So according to the FSM this is working properly. Now why I am still getting the Code 13? Is there any other methods I can check to really make sure this is working as it should? If you can point me out in the right direction I would appreciate it.

As for the Code 17. I checked out my O2 sensor output by backprobing the O2 Sensor wire at the connector near the 5&6 port actuators. At Idle I am reading .8V. This sounds too rich to me, but besides this, when I blip the throttle, the voltage increases and on release, the voltage drops. It is reading fine.

Now I am stumped with this. Why is my car throwing these codes at me, and most importantly, why I am getting this rough Idle with the O2 sensor reading rich? What am I missing here....

Thanks for your helps......

jjcobm

iTrader: (18)

I rechecked my tps again, reads fine as the range increases. Then I decided to play with the idle screw on the top of the throttle body, I turned it all the way in, and voila, my idle is back to normal.

So I rechecked my voltage at the O2 Sensor, with my multimeter it now bounces around .6-.1, but I am guessing I will need a scope really make sure its working properly. This is good enough for me, at least it isn't stuck at .8. This is a new O2 sensor by the way.

Ok so now, why am I getting the two CEL codes when both of those components are functioning properly? I will reset the codes, and go for a drive, waiting to hear some suggestions....

barnett87rx7

iTrader: (1)

for the idle issue your throttle may have come loose. kinda sounds like it because you had to tighten the idle screw all the way and its meant for a more fine tuning.

jjcobm

iTrader: (18)

I got the codes to clear by setting the TPS via the voltage method and replacing my O2 with the O.E style one instead of the universal it had. I still have a funky idle, I am thinking it is my fuel injectors or just a tired engine (140k at the moment) since I have pretty much at this point replaced and checked everything besides the injectors. My idle will fluctuate from 600-850 (sounds like it is misfiring alittle), it will stay steady with the A/C for some odd reason though, and yes I replaced the BAC. Runs fine when accelerating. When setting the timing, the mark will jump around once in a while, even though my idle is around 750ish (probably due to the funky idle...), yes the initial set connector is grounded. Will do this even with the BAC removed.

For now I am driving it as it is, I just assume it is a tired engine......

RotaryRocket88

iTrader: (7)

The reason idle smooths out with the A/C on must be because the ECU triggers the BAC to increase airflow while it runs. What happens if you increase overall idle speed, either via the air adjust screw or the throttle stop screw? I've had some TPS that test ok, but still give some bouncing when the throttle is at a particular position. I'd normally saw it as the thermowax expanded, and idle speed slowly dropped. Adjusting the final resting position of the throttle plates w/ the throttle stop might have an effect. Just keep in mind that around a quarter turn can change idle by a few hundred RPM.

Also, 0.8V on the O2 sensor is actually normal sounding. If you ignore the temperature changes, 0.8V corresponds to about 11.8 to 13.2 AFR. This is a very crude estimate, but it gives you an idea. To put it in perspective, my car idles the smoothest when set to between 12 and 13 AFR.

jjcobm

iTrader: (18)

It's really odd, as I increase the throttle speed via the air adjustment screw you can hear the car idling funky-er as the rpm increases. I thought it might be a dirty TB so I cleaned it and still the same. Though with the a/c, once in a while it will still give me the funky idle, not as much as without it. Also, same thing with driving normally. Sometimes if I sit at a stop light the idle smooths out, but still stutters a bit once in a while, other times if I am sitting at a light or parked you can hear it idling a little wierd. It just sounds like it stutters (misses a pulse) once in a while. So this can really be seen when adjusting timing, the mark will bounce around once in a while but stays pretty consistent the rest of the time. RPM gauge is seen as stutters a bit from 600-850, it is more like a sweep from those ranges as you hear the car idling rough... I also replaced my good working tps, with another one and I still have the same symptom.

The only things I haven't checked are the thermowax, water thermosensor, p/s switch, and CAS. I will measure those out today and see if they are within spec. I will give it another shot today by playing with the throttle cable a bit and let you know, but I am sure it will just idle funky as the rpm increases. Would be really nice if I can get the idle to smooth out....

On the side note, one thing that really makes me think my engine is just tired is that a new cat would start to smoke really bad as soon as the engine got started. I decided to take it out, but it just really seems like the car idles/runs excessively rich. No smoke out the exhaust unless I get it up to 8500ish, then I believe my bad oil control rings start to show....

Thanks for the tips....

RotaryRocket88

iTrader: (7)

Sounding more like dirty fuel injectors may be at fault for the roughness part of it. You might try running some fuel injectors cleaner through the system until you can get them a sonic cleaning. It's not too expensive, and it's never a bad idea, even if it doesn't turn out to be the cause.

Oil control rings can cause some smoke under hard acceleration sometimes. On my 180k NA engine, it would only do it while the engine was below full operating temp. Not sure why a new cat started smoking on you. It could be that it's overly rich, and leaky injectors would do that. Or it could be the airpump/ACV aren't getting air to the cat properly. But that's not too likely unless there's a problem with the relief solenoid. Most of the air going to the cat is injected at the exhaust ports, rather than through the split air pipe.

jjcobm

iTrader: (18)

Yeah, the injectors is what I was looking at. I am going to get them professionally cleaned with RC engineering. It's the only thing I can think of.

I played with the TB and cable today, it did like i said. It just runs a bit funky the higher I set the idle, runs a bit shaky but while driving it's fine.... I'll keep you guys posted on this when I get time to do that. Thanks for the suggestions.