This may be a stupid question, but......

I've got a Code 13 on my '86 coupe. Going through the trouble shooting chart and it says to get the engine up to normal operating temp. and ground the diagnostic terminal. Then look for a "Flashing Open loop or Flashing Closed loop" condition. When I ground the diagnostic terminal, my SES light starts flashing and continues to flash. What is this telling me? Is it indicating Open loop or Closed loop?

TIA

 

Just for more information, I've got Headman long tube headers on this car with a single-wire O2 sensor which is mounted near the collector.

 

Generally speaking, an open loop would not send a signal, and a close loop would send the voltage signal. I would think there is a typo and you have a close loop flashing signal.

 

So now I'm a bit confused. I'm relatively new at shooting these trouble codes, so bear with me.

I thought that, once the O2 sensor warmed up, it went into a "closed loop" condition and thats what I should be running with. Am I right or wrong in my thinking?

Assuming my thinking is right, i.e., runs in "closed loop" what could be throwing this code? The O2 sensor is new.

 

Do you have cats? Did your headers come with emission testing....hmm

 

I only have the intermediate cat---got rid of the cats that were on the downpipes. Also have the EGR bunge in the passenger side header.

The reason I am going through all this is because the car has a hesitation when first starting out (not real bad once I going) and the engine seems to be holding back. This is my first Corvette and maybe I'm expecting more performance than I should. I've put new plugs, wires, rotor, cap, fuel line & fuel pump filters, checked the fuel pressure (39PSI), and adjusted the TPS to .54v.

It was also dropping a 33 code. Went over the MAF sensor, checked for continuity & voltages and found nothing. Sprayed the contacts with some cleaner and haven't seen the code come back.

 

MAF might just be wearing out....They do get old and die. Very exensive part which I hope it is not in your case. That 300 $$ can be put useful elsewhere.

 

Could be timing/vaccum advance trouble?

I just bought my vette, so I don't know how everything works yet, but on earlier HEI iginitions, when you accelerate, 2 thing's advance the timing to help with the extra fuel burn. Vaccum pressure advances timing (higher RPM's create more vacuum), and the knock sensor advances the timing.

Though I'd give you a few more thing's to add to you plate

 

I've been playing with the timing. Started at 6*BTDC and now have it about 10*BTDC. Helps a little.

If I didn't know any better, this thing is acting just like the advance mechanism isn't working correctly. On older cars, you have the advance weights/springs. I really haven't looked into this one yet. Thats another possibility. The car sat for 3yrs. before I bought it so I'm wondering if something doesn't need "exercise" to get it working properly.

 

Code 13 most likley means that your O2 has bitten the dust. Do you have a DMM(Digital Multimeter)? 86 has a 1 wire sensor and if it working properly on a warmed up engine, it should be cycling between .2 volts DC to .6 - .8 volts @ idle. You can unplug the sensor ( it may run a little sluggish) and test it with your voltmeter. If the voltage is staying sluggish and not actively switching, it is time to change the sensor. Also can test it by pulling vacuum hose loose from brake booster while idleing and watch the volt meter to see if it drop low quickly when you unplug the vacuum line. This tests the ability of the sensor to recognize low oxygen content in your exhaust. If it doesn't respond almost immediately, then time for a new one. Can likewise test the ability to go rich by spraying a touch of carb spray in a vacuum port to see if it will respond (voltage will go up to almost a volt), or by stabbing the throttle and it should do about the same thing. BTW, use a good quality O2, such as an A/C Delco, not an Autozone special, because good quality ones have quicker response times than the cheap ones. Good Luck. [8D]



Remember it's not leaking oil, it's leaking horsepower!!