Hesitation

[satan_srv]

Re: Secondary O2 Sensor?

I’m not familiar with a secondary O2 sensor on the ’92 NSX. To be honest, I’m not totally sure what a secondary 02 sensor really is? I assume that the ’92 O2 sensors were equal and that the ECU can adjust injector pulse with individually to get good front bank and rear bank stoichiometric readings individually.

Note: I have RM (B&B) headers which have the O2 bung in one of the header tubes before they join—I think, ill have to lift up my car to verify this. If this is the case, then the O2 sensor is just reading the #2 (rear) and #5 (front) cylinder. Hmmm.

DanO

Doh, nevermind...NSX doesn't have a 'secondary' it's one for each bank like you mentioned, that makes it clear now. I was thinking of OBDII cars that actually had a secondary O2 added. you can tell I haven't starting ripping apart the motor yet on the project car heh..

 

[DanO]

Update

Update

During last track event, the car started misbehaving again—same symptom as above. I disconnected the EGR vacuum line and plugged it and the hesitation disappeared or subsided significantly. I ordered a new EGR and installed it (needs a low-profile universal 12mm socket wrench for this…another story). Now I am getting an immediate and persistent CEL: #41 (Oxygen Sensor Heater circuit) and the car still runs with the hesitation. I will go down the flowchart with this error when I get a chance. I’m wondering if I have a loose wire or connection in the front oxygen sensor connector or related wires since I’ve had a #1 and a #41 (both front oxygen sensor related circuit problems) and the problem seems to be intermittent.

One of these days I’ll break down and order 6 new coil packs and it will probably fix the problem.

-DanO

 

[DanO]

Update 2

After testing for the CEL #41 (O2 Sensor Heater Circuit) it was obvious that the front O2 sensor needed to be replaced. I replaced the O2 sensor and the CEL #41 went away and so did the hesitation for about 5 miles, then another CEL, #2 (Rear O2 sensor) with the same hesitation problem.

I guess I’ll try switching around coil packs and injectors to see if this has any impact. Interesting note: since I have the RM headers, the O2 bungs only read one cylinder per head. If I incrementally switch coil packs and injectors around then I should be able to find if one of these are causing the problem. If none of this works then I’ll order up a rear 02 sensor and go from there.

Ideas, Comments?

DanO

 

[matteni]

Hey DanO!

It is strange that the problem seems to come and go. Since you were able to get it to clear with the new front O2 senser temporarily - my money is now on one of the coil packs or the ECU itself.

Did you pull the clock fuse and reset after the first O2 swap?

Have you replaced with a known good set of coil packs? Maybe we can swap ours Sunday night or some time Monday and test?

Long shot: I asked but didn't see if you responded to the fuel filter / fuel problem possibility. Replaced your fuel filter lately? Chance of bad gas? Only other time I have seen something weird like this was debris in the fuel line at the fuel filter and it would bounce around and "clear" for a little while but get stuck at the filter eventually starting the hesitation problem all over again.

 

[DanO]

Hi Nick

Thanks for the reply! I can rule out bad gas b/c I’ve gone through at least 2 tanks now. I reset the ECU after every CEL. Fuel filter is a possibility but I don’t think it’s it because the car runs great at WOT or even 50% throttle. The hesitation feels like the engine is actively hunting around for the proper mixture and there is an occasional misfire at idle. I’ve switched my coil packs front/back with no discernable difference. At this point I think it could be a number of things and I might as well start going down the list replacing things. This could get expensive (I guess it already has).

See you Monday!

DanO

 

[Larry Bastanza]

Hi DanO,

As I read throught the post and looked at the time line, do I understand it correctly that the rear 02 sensor was once in the front giving you trouble?? Did I miss something? The way I piece this together you had an original #1 code, swapped sensors and it cleared up, did not swap back and now have a #2 code?? If so it is moving with the sensor. I re-read this:

I don’t think it was a connection issue altogether; I was getting the hesitation before and after I did a valve adjustment, which entails disconnecting and connection the O2 sensor wires. It could have been a short in the O2 wire in which case it will probably manifest itself again in a code #2 at some point in time, and that would be alright with me.

Did you answer your own question??

Maybe confused!!
LarryB

 

[DanO]

DOH! I think the main beam might have fallen on my head one too many times when I replaced the front O2 sensor for the second time! That’s right. I swapped the O2 sensors to see if I could get an error on the rear one and that’s exactly what I’m getting. Seems like the next logical step is to replace the rear O2 sensor—a piece of cake!

Thanks LarryB for keeping this DIY project on track.

DanO

 

[DanO]

Update 3

Installed rear 02 sensor today. Car runs great.

Hopefully this fix ends this particular thread.

DanO