Running rich? Try checking the knock sensor!

[dhen]

I realize that this may be obvious to some, but I thought I'd try to give something back to those of us in the CA community who are still learning.

To make an extremely long story short, my CA was running extremely rich. I got a different ECU which helped, but I was still running very rich. Those who care can read about it here:

zer...00969

Then I came across this thread about wiring up the knock sensor:

zer...00969

The CA swap I bought came with the knock sensor, the knock sensor wire, but no plug, so I ran the car without the knock sensor connected. In the above mentioned thread I read that a 1 meg ohm resistor will trick the ECU into thinking it has a knock sensor. I hooked up one end of the resistor to the sender wire and the other to the firewall, and sure enough it started to idle at about 14.7:1 (stoich).

So my problems appear to be solved. I took the car for a drive and it's about 14.7:1 on the highway and 12-13:1 when I'm boosting. (I'm running 10 psi.) One issue I'm having is that after I came home it was idling at about 12-13:1, but since this is only at idle, I'm not too worried.

Anyway, I've very happy today.

Thanks to everyone who tried to help!

PS If you don't have a pigtail, you can use shielded wire and a splice connector as a plug. I know it's ghetto, but it worked for me:

[zmannz]

This should be added as a step with the swap guide, that is a good pic! I have a write up on extending the wires and adding the knock sensor to the harness correctly.

[progman]

I thought the knock sensor had nothing to do with the general running of the engine. I had problems running rich the whole time I had the factory computer. I think I had the knock sensor hooked up when I first got my engine but then I broke the plug and never ran with it after that.

I would like to see if other people have the same experience after hooking up the knock sensor... If we find this to be the case then this should be added to Float's build thread.

I can't confirm or deny this claim but I did have rich problems the entire time I used the factory computer and I did not run the knock sensor but I tried many things to fix this problem. I used to have a SAFC II and no matter what I set that for I could never get the idle to lean out (I think the factory computer is closed loop in idle though...).

Dhen: on a side note, I like how you got rid of the hard line for the pcv but why didn't you have just one long line up to the cam cover? why the connector?

Also what is up with that starter connector? my ground barely stays on my starter and your setup looks so clean. How did you manage that? I really like that.

I'm going to try that splice connector things as a plug. I have been wanting to figure something out for that. I wonder if megasquirt can read this sensor.. time for research
Modified by progman at 1:47 PM 10/8/2009

[RS12Turbo]

Dhen: on a side note, I like how you got rid of the hard line for the pcv but why didn't you have just one long line up to the cam cover? why the connector?

Modified by progman at 1:47 PM 10/8/2009

I can answer this one.....

Because the nipple is larger on the oil separator than it is on the valve cover. I did the same thing when I pulled my head. Don't remember the sizes, but seems like on the oil separator side it's 3/4" dia. and on the valve cover side it's 5/8" dia.

[progman]

Yep, that's right. I just ripped that hard line out and now my setup is actually the same. I was about to wrestle that hard line in there because I had it off. But this way is sooo much easier. That hard line makes two really pita hose connections when it could be super easy that out that junk... everyone should do it like this....

funny thing too. the ground on my starter just fell off like 30 minutes ago after doing this. lol.

[dhen]

Dhen: on a side note, I like how you got rid of the hard line for the pcv but why didn't you have just one long line up to the cam cover? why the connector?

Also what is up with that starter connector? my ground barely stays on my starter and your setup looks so clean. How did you manage that? I really like that.

Glad you like the setup. I wish I could answer your questions, but I didn't swap the engine into the car. Also, with the exception of the engine and transmission, my car isn't a Nissan, it's an MG.

http://www.britishv8.org/MG/DarianHenderson.htm

I'm going to try that splice connector things as a plug. I have been wanting to figure something out for that. I wonder if megasquirt can read this sensor.. time for research

I was surprised how well the splice connector fit. I used the pink ones they sell at Auto Zone, and it wasn't too tight or too loose. I've got a real pigtail on the way, but I wonder if this would work fine for years...

Besides the fact that it solved my richness issue, a knock sensor is a nice bit of insurance to have.

On another note, I really recommend a wideband O2 sensor. I know they're not cheap, but it made it much easier for me to understand what was going on.

Darian

[progman]

Yes wide band is a good idea. I have two...