Catalytic converter and smell

[TimpanogosSlim]

It appears that the o2 sensor for an EFI spider is a Bosch 11051, which costs about $23.

At that price, i might install a new one on principle, unless i knew that it had recently been replaced.

The o2 sensor kit for my land cruiser cost me $240 for two upstream sensors. I spent $70 on an aftermarket NTK sensor for the downstream position on my GTI, while the upstream costs somewhere around $190.

So $23 is a deal.

[micbrody]

Is oxygen sensor (while car hot and running was fluctuating between 0.1-0.7. I had read that they are suppose to oscillate. If true, then maybe it is working. Also, I only tested it when at idle; and if my understanding of throttle position switch is correct, the oxygen sensor is only used by ECU during throttle switch activation; so maybe the oscillation at idle is insignificant.
Also in my readings (and this thread), it seems that O2 sensor probably does not make great contribution that could explain very rich fuel mixture.
So I am retracing other diagnostic things I have done. I test CSI and it definitely sprays fuel; I tested the temp timer switch connected to CSI, and it goes on and off (by voltmeter). But I don't think I ever actually checked to see if function of CSI actually turns off.....maybe it is stuck open. Maybe that would explain everything

[micbrody]

I just finished checking CSI. It is not stuck open. I had a tiny squirt; but nothing with the engine running.

My differential diagnosis of what is left:
1) Fuel pressure regulator not functioning correctly in that it is letting fuel into fuel rail at a much higher pressure than it's suppose to. I had read it is supposed to be in 36 mmhg? range. Is that correct? I don't have a fuel pressure gauge. Don't really want to mess with it yet.

2) AFM. Previous owner had bypassed the fuel pump switch in AFM and had it energized at "run position", even when engine not going. I reversed that; and cleaned up the double relay.....which was the source of the initial problem. During this exercise, I did open up AFM. I had to cut through some 3rd party gasket to open (meaning somebody else had gone into it). Everything looked normal. But, I really did not carefully look at it. I just cleaned up the fuel pump contacts.

Could a previous owner have changed the "spring" setting to cause it to run rich? How would I check that?

[micbrody]

I forgot to mention I had also checked the auxiliary air valve. I removed it placed it in freezer and mildly heated. The opening seemed to change appropriately.

[bradartigue]

You can check on the correct position of things:

With the AFM top off and the engine off. If you are very lucky the PO will have marked the original position, or the silver mark from Bosch will still be there...maybe.

The armature (the two copper loops that sweep) has a tiny dot on the end. It needs to post precisely at a little shaded rectangle when at rest. If it does not you can adjust it by loosening the screw at the back of the armature.

Each tooth in the wheel represents about 1% of carbon monoxide adjustment (e.g. more fuel). The problem is this: you can't adjust this thing without an exhaust gas analyzer. When POs mess with them they usually only move it a few teeth, if I were you I'd mark it then adjust it two teeth at a time, and if two is too much, go back one, and so on.

More tension = lean; less tension = rich

For those of you who think messing with this will add performance - stop, take a deep breath, and move on. A notch or two and you're going to be washing your bores with an over-rich mix of fuel, burning up O2 sensors, and destroying catalytic convertors. L-Jetronic doesn't like you fiddling with it - buy a nice set of HP pistons instead, it actually likes those.

[micbrody]

Brad, thanks for your input. These discussion boards are a life saver.
I will open up AFM in next day or two.
In the mean time, I did change spark plugs. Their tips were whitish; all equally; and though I did not measure, the gap looked larger than they should be (compared to the new, properly gapped Bosch plugs.)When I went to start car, it started right away; not sure if it made a difference, as car sometimes starts beautifully. I will need a few more cold and hot starts to see if new plugs solved some of the issues

[bradartigue]

Brad, thanks for your input. These discussion boards are a life saver.
I will open up AFM in next day or two.
In the mean time, I did change spark plugs. Their tips were whitish; all equally; and though I did not measure, the gap looked larger than they should be (compared to the new, properly gapped Bosch plugs.)When I went to start car, it started right away; not sure if it made a difference, as car sometimes starts beautifully. I will need a few more cold and hot starts to see if new plugs solved some of the issues

If they are all white-ish then don't open the AFM, they are supposed to be like that.

[micbrody]

Well, I have started car four times from cold start (and a hot start), and........... it works greats! Car starts right away, and the first few seconds of low RPM are now about a half a second of slow RPM at most. AND , the exhaust has much less smell.
Even though the car seemed to running great on old plugs, it now runs even better.

Thanks for the board help. The old saying of "If it walks like a duck, talks like a duck, looks like a duck, then its probably a duck" rings true with my issues. I probably should have first changed/inspected the plugs. The secondary gain of my "brain fart" is that I learned so much about how the ignition system works, because I had to test all the components involved (coil, wires, Ignition control module (which did fail when hot; replaced), CSI, Thermo time switch, t-piece temp probe, double relay (fixed), AFM, ignition switch(reversed PO electrical bypasses), fuel pump, etc.......)

The only thing left I think I have to inspect is the distributor cap/brush; and I know my vacuum advance does not work. I have the replacement parts from Autoricambi); I just have not gotten to it, yet.