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Discussion Starter · #1 ·
I've been working on a neighbor's car recently. It's a 85/86 gli with a lot of ghetto rigging. It's got the stock ke3, but at some point, someone changed in a vac adv dizzy. Whatever. It's the least of the car's problems.
She's trying to pass smog at the moment, and it's running pig rich. So I watched the DPR from a cold start. Everything is normal, slowly dropping down to 10ma. Then it oscillates around 10ma for few seconds, and then climbs up to 20ma, where it holds.
If I unplug the o2 sensor, it'll drop back down to a stable 10ma. Plug it back in, and it slowly goes up to 20ma again.
So I set the mixture based on o2 readings (via voltmeter). The best I could do was around 0.7v at idle. The smallest turn lean will result in the reading going to 0.1v.
Revving it in neutral, I'll see the o2 sensor lean out, showing 0.1-0.3v. Exhaust smells real lean as well.
For the time being, I've unplugged the o2 sensor for her. Obviously, it won't pass smog as is.
Basically, with the o2 sensor plugged is, the ecu responds the same as if the lambda wire was grounded out. I'm getting about 0.55v from the ecu lambda wire to ground.
Bad o2 sensor?
She's not interested in really spending any money at all in the car. As is, she needs a new battery. It's losing coolant and oil out of everywhere. Lifters clacking something fierce, even topped off with 20w50. If she can get it to pass smog on the cheap, she'll keep it. Otherwise, it's probably back to GM for her.
 

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Re: ke3 not going into closed loop properly (ziddey)

you are on the right track thinking its o2 sensor related. and probably a few vacuum leaks. my car ran so much better with a good o2 sensor. it still falls into test mode sometimes at a stop light. also, put a good air filter in it. a K&N filter made my car idle better even.
 

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Re: ke3 not going into closed loop properly (ziddey)

Quote, originally posted by ziddey »

If I unplug the o2 sensor, it'll drop back down to a stable 10ma. Plug it back in, and it slowly goes up to 20ma again.

This is the clue. It's adapting more fuel in. This could be for a couple of reasons. If there really was too little fuel then it's trying to add more to reach stoich. If there is too much air, from say a vacuum leak or exhaust leak, then it would also try to add too much fuel. It almost sounds like the O2 sensor is not switching rich/lean. In closed loop the KE-Jet brain will deliberately march the DPR current up until it sees a switch rich, then march the current down until it switches lean. In this manner stoich is maintained. This cycle should take about 3s or so at idle. So it sounds like the O2 sensor might not be switching to rich, so the brain keeps adding more and more fuel until it reaches what sounds like a max value of 20mA.
 

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Re: ke3 not going into closed loop properly (GTIspirit)

I should have tapped the o2 sensor with it connected to the ECU. While adjusting the mixture manually, the o2 sensor did respond unlike what I've seen in other cars. It'd hang at around 0.7-0.8v, and then the tiniest crank lean would result in 0.1v or so.
She definitely would refuse to buy a new o2 sensor. I wonder if any of the neighbors has a spare.
Cheers. Hope it's the o2 sensor. It looked to be original. Still had the original zip ties
 

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Re: ke3 not going into closed loop properly (ziddey)

O2 sensors are cheap if you get the generic three-wire one that is the suggested replacement for our cars. I forget the Bosch number, but I think it was around $30. Only catch is that you have to splice it into the old connectors, not hard, and worthwhile to save about $50. A quick search around the 16V forum, maybe in the FAQ's, should yield the part number.
 

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Re: ke3 not going into closed loop properly (GTIspirit)

you don't need to tell me they're cheap. hell, i went with a bosch universal unheated unit for my fox. $15. but i don't think she'd even go for that.
she's running ghetto rigged saturn 16v spark plug wires and who knows whatever else handmedown parts to keep her car going.
not a vw enthusiast. the car is just a ****box that needs to hang on
 
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