Please confirm my O2 Relay

[KKothand]

Hi everyone. I am going through trouble shooting my cold start problem (with much reading from this site), and as part of the process I ordered a O2 relay as a just in case. I ordered this from our host, but what I got is different based on the BOSH part no. and other info. I have attached pictures of both my existing relay and the one I purchased (on the yellow sticky note).
Can any of you good folks confirm which is correct. Based on my readings, the one I have currently seems to the the correct one. It also has an integral "flange" on the body with a clip to secure it next to the Lambda ECU. The one I bought from our host does not have this.

At this time all indication points to having to test the K-Jetronic system pressures methodically and go from there. I was hoping for a quick fix; my current relay looks pristine and shows 87.5 ohms between the 85-86 pins of the relay. I have no problem running warm once I coax the engine to over 950 RPM after cold start; which is terrible. This is the first time she is doing this, and I have had the car for 2 years. 1982 911SC.

Thanks in advance.

[gazzerr]

Hi, I think if you remove the relay when the car is warm and it starts to run like crap then you can confirm the relay is working fine. You can test the old one that way.

I'm going through cold start issues (low idle, grumpy) and it's air leaks around the injector seals and a WUR that's out of spec for cold control pressure because the WUR's heater element resistance is too low.

Basically you have to measure fuel pressures first, fix all the air leaks, check the ignition timing and go from there. Don't touch the mixture until you know everything is in spec and you have no air leaks.

Search on posts from tirwin, boyt911sc, Bob Kontak. Lots and lots to go on there.

Great place to start:

CIS Troubleshooting for Dummies

Here's a pic of my relay known to be good, seems to be the same one you bought. Note the diode in the circuit diagram on the side show. I know a lot of the relays supplied seem to be missing this diode and it's referenced in the 911 electrical diagram. The relay I had before is also the one you had and didn't have this diode but it doesn't *seem* to make a difference. I replaced it so it's the same as the factory spec. The Gurus here should be able to explain it's use.





Hope that helps.

[SCadaddle]

To test the relay:

1) Car in neutral, parking brake set to ON.
2) Right hand grabs relay under passengers seat with the fingers.
3) Left hand starts car.
4) During 3 above fingers in 2 above should feel relay make a single "click" if it is working, and after driving for a bit the relay will become warm to the touch.

With this warmer weather my 82SC was becoming more "cold natured" to start cold with no light accelerator help. So I remember what I did last summer, which was to disconnect the vacuum retard line (blue or black small rubber hose) from the distributor vacuum pod and plug it with a golf tee. Then I put a small rubber cap over the port on the pod from whence the line connected. Cold starts much better now.

[Bob Kontak]

The 019 019 relay is the one you want. It does not have the structural part that holds it to the Lambda box. I replaced the original with the 019 019.

Gazerr noted the diode. I never even saw the diagram embossed on the side. Does the original have a diode?

I know that there is a diode in the red fuel pump relay. The expensive one. The diode prevents current from going in the wrong direction. Where it would go is beyond me but it must have some importance. I have seen a later 80's 930 with all red relays vs. just red(s) and black.

If the original is without perhaps this is an upgrade. No functionality improvement, just higher integrity (built in traffic cop) so it works like it should.

[KKothand]

Thank you Gazzer, Scadddle and Bob. Yes, Bob and boyt911SC and others seem to be the SME's here (Sorry, my work is creeping in here. That stands for Subject Matter Experts) and have read their posts and advice on more than fuel injection.

Gazzer: I did your test and confirmed yes relay is fine. My car not only idled bad but it didn't start without the relay. My new Relay doesn't have the etched sketch on the side but right on top as seen in the picture, and it has a diode.

Thanks Bob for confirming that either relay will work (019 019). So the one with diode diagram is an "upgrade", but if my old one works I don't have to swap, right?

Now, on to more fun stuff that I was hoping I could avoid, but have to restrain from doing "while you are there" work while I address this cold start problem. Last year my clutch cable replacement ended up being a clutch pedal cluster upgrade, and left me with a sever crick in the neck.

NOTE: My 911SC does not have a CAT. Thought I should put it out there. The PO had put some nice headers and brought the HP to about 200, and removed the Cat-Converter.

[gazzerr]

Cool - I think your relay is good. I switched it out to satisfy my OCD that's about it.

No cat is fine if you are in a "too old to smog state" like me. The O2 sensor probe is before the cat anyway.

I have a new pedal cluster ready to go in. I just need the courage to try to install it .

Do a fuel pressure test and test the resistance on your WUR. That's a good start. Pressures will tell you what's going on.

[Bob Kontak]

Originally Posted by KKothand

Thanks Bob for confirming that either relay will work (019 019). So the one with diode diagram is an "upgrade", but if my old one works I don't have to swap, right?

gazzerr confirmed. I just backed him up.

The relays get tired. Contacts inside get a little crusty, a little corroded, etc. and it makes a difference with a new one.

However, I suggest getting your cold start issue nailed THEN drive your car with the old relay for a while. Stop and go around town after full warm up. Stop back at your garage and change to the new relay, get out there again and see if it makes a difference. I am certain you will notice.

This is not your cold start problem.

[KKothand]

If you need any tips on the pedal cluster let me know, I can share what I have learnt. I compiled a whole Powerpoint detailing my work, and saved it in case I need to get there again. I basically dismantled everything, sand blasted, painted, etc, etc..I think I do have some OCD tendencies ha ha ha.

[KKothand]

Originally Posted by Bob Kontak

gazzerr confirmed. I just backed him up.

The relays get tired. Contacts inside get a little crusty, a little corroded, etc. and it makes a difference with a new one.

However, I suggest getting your cold start issue nailed THEN drive your car with the old relay for a while. Stop and go around town after full warm up. Stop back at your garage and change to the new relay, get out there again and see if it makes a difference. I am certain you will notice.

This is not your cold start problem.

Bob, absolutely. I am meeting my friend who tinkers with 914's, and 911's tomorrow bright and early plus he has all the neat gizmos to test stuff with - lucky me. As you suggest I do want to test out the old and new relays once the cold start problem is fixed.

[Bob Kontak]

Originally Posted by KKothand

Bob, absolutely. I am meeting my friend who tinkers with 914's, and 911's tomorrow bright and early plus he has all the neat gizmos to test stuff with - lucky me. As you suggest I do want to test out the old and new relays once the cold start problem is fixed.

Good deal.

Gizmos are good.

Also, if you have an O2 bung in your exhaust and the O2 is in there and connected you are fine.

[gazzerr]

KKothand thanks! I have a rebuilt cluster ready to go in so it's really just a matter of R&R the old one but I'd love to hear your experience with that. I've heard it's a bit of a rabbit hole but not too nasty. I'm 1/6 of the way through my injector seals and seats now ... I'm slow.

[KKothand]

Gazzer,you are smart to do the way you are doing. It took me over a month, rebuilding it on my own, not to mention then PITA steps I had to do. Keep me posted on your fuel injection project.

As of now, my cold system pressure is low at 4.3 bar. Supposed to be 4.5 - 5.2 per Bentley Manual. My friend thought this is not too bad, and may be I should replace the fuel filter first. We checked for leaks around the hoses, and no issues. So I am starting with replacing the fuel filter. Any input or other ideas on next steps is much appreciated.

[Bob Kontak]

Originally Posted by KKothand

As of now, my cold system pressure is low at 4.3 bar. ................ We checked for leaks around the hoses, and no issues. So I am starting with replacing the fuel filter.

Tony needs to help here. Shims in fuel distributor allow tweaking of system pressure.

I seldom see filter changes alter pressure.

[KKothand]

Originally Posted by Bob Kontak

Tony needs to help here. Shims in fuel distributor allow tweaking of system pressure.

I seldom see filter changes alter pressure.

Bob, I am thinking the same thing since it seems related to the primary pressure regulator in distributor which is adjusted by shims. Means this would be above my capability and may have to take to a mechanic (?). I will also read up on Tony's posts.

I have to replace the fuel filter anyway, which at this time the fitting nuts on the fuel line are refusing to budge. The filter is over 3 yrs old.

[gazzerr]

Yep you'll need to talk to Tony there. Possible WUR issue too maybe.

I got my pedal cluster from Bruce Stone. Going slowly on the injectors. Working on #2 now.

Those fitting nuts are a b*tch. I've had the best success with a bit of PB Blaster (clean it up because you don't want that in your fuel system), then use 2 wrenches, one to hold the line on the lower fitting and one to turn on the top fitting that comes off then "squeeze" the wrenches toward each other in the right directions. Seems to work for me.

[KKothand]

Originally Posted by gazzerr

Those fitting nuts are a b*tch. I've had the best success with a bit of PB Blaster (clean it up because you don't want that in your fuel system), then use 2 wrenches, one to hold the line on the lower fitting and one to turn on the top fitting that comes off then "squeeze" the wrenches toward each other in the right directions. Seems to work for me.

I am trying the two wrench system,yes. I don't think there is another option there. Will try the PB blaster, if it remains stubborn. The nuts to be loosened are the ones on the fuel lines, as the others are "part" of the fuel filter, correct?

[gazzerr]

Yep - it's the nut around the line itself that you loosen. The nut on the adapter that's screwed into the "device" - in your case the accumulator is the one that you counter hold. Grab a set of flare nut wrenches for the top nut as it wraps right around the nut and gives you more torque on the nut. They don't seem to slip either.

WD40 doesn't seem to work anywhere as good as PB Blaster or Kroil. I don't think WD40 is really that good as a penetrating fluid.

[Bob Kontak]

Originally Posted by KKothand

Bob, I am thinking the same thing since it seems related to the primary pressure regulator in distributor which is adjusted by shims. Means this would be above my capability and may have to take to a mechanic (?).

Just drag your feet for a couple of days before taking to a pro. There is a recent post where Tony helped a guy put shims in.

If you did the pedal cluster there is little risk you cannot handle the shims.

Money saved will buy you two sets of pressure gauges.

[KKothand]

Thanks Bob, I think you make a solid case on both counts. Will keep you all posted...

[KKothand]

Hello all. Work has kept me busy but finally managed to do the pressure tests recommended. Here is what I am getting. Looks like fuel system side of things are good. Tests ran without engine running; jumpered 87A & 30 in relay in fuse box.

System pressure = 5.1 bar @ 73 F
Cold control pressure = 2.1 bar @ 73 F (WUR connection unplugged)
Warm control pressure (PEAK) = 3.7 bar; reached in a little over 2 mins, and stayed there past 4 mins. Ended test after 5 mins.

Residual pressures after shutting off ignition switch. Temp 73 F; all values in bar.
After 5 min 2.3 bar
10 min 2.0
20 min 1.75
30 min 1.65
60 min 1.60

Is my Control pr regulator aka WUR is the suspect now? I should note that I got no resistance value at the WUR electrical connection. Please let me know what next.
Thanks,