Printable Version of Topic

Posted by: Porschef Feb 23 2012, 11:00 AM

Got about 800 miles on these, pulled em out to open the gap with the Pertronix
install.

How do these look to you? All four are essentially the same.

Nevermind the tea leaves.


Attached thumbnail(s)


Attached image(s)

Posted by: jmill Feb 23 2012, 11:12 AM

Looks lean or plug is too hot.

Check this thread and compare your plugs to the pictures.

http://www.914world.com/bbs2/index.php?showtopic=167481&hl=plug

Posted by: struckn Feb 23 2012, 07:09 PM

They look Good, almost perfect.

Posted by: whatabout1 Feb 23 2012, 07:32 PM

Very lean or hot. I don't like that little chip on the ceramic in the close up pic.

So lean you may be getting knock (chip). Next you will have to worry about
the exhaust valves.

Posted by: ConeDodger Feb 23 2012, 08:22 PM

Reading plugs supposedly became inaccurate with the use of unleaded fuels.

Posted by: Cap'n Krusty Feb 23 2012, 08:48 PM

You beat me to it. The Cap'n

Posted by: Porschef Feb 23 2012, 08:58 PM

I'm running Ljet. I haven't read the A/F ratio. I do get some light pinging under load. And I don't know how to enrich the mixture.

What now?

Posted by: ConeDodger Feb 23 2012, 09:14 PM

You don't necessarily need to enrich the mixture. (please understand, I am not saying you are or are not running lean. You don't know, and plug reading is an obsolete black art with the advent of unleaded fuel). Light pinging under load can be taken care of with a bit of timing change.
If you really want to know what your A:F ratio is, you have to check it. I would guess though, that with all things running correctly, you have a pretty good A:F ratio. Properly operating LJet is taking care of that for you without adjustment. IIRC, there is only one 'adjustment' and it is on the AFM and is only intended to adjust for idle conditions.
LJet uses TPS, CHT, and Air Flow to meter fuel. People have fooled with the spring tension in the AFM, put resistors in line with the CHT, etc. to try and get more 'performance' out of their LJet engine. Instead, I think they have gotten less driveability.
Adjust your valves, check your timing, then go through the procedure outlined in the Bosch manual or it might even be in the FSM to check your LJet. Make sure your wiring is in good shape as the CHT uses a resistance signal, and the AFM and TPS use a position signal. If your wiring is bad your signal to the ECU will be garbage.

Frankly though, if all you have is light pinging under load you are worlds ahead of the jackstand brigade around here.

Posted by: Porschef Feb 23 2012, 09:30 PM

Rob, thanks for the reply. The car runs good, and I may have discovered a slight vacuum leak this afternoon, I'll have to see this weekend.

The only thing that was bugging me was the idle.

Joe

Posted by: ConeDodger Feb 23 2012, 10:11 PM

LJet (most all EFI systems) HATES vacuum leaks. Unmetered air will cause a high idle and can cause a lean condition.

Posted by: Valy Feb 24 2012, 01:15 AM

What's the problem with the IDLE?

Posted by: Porschef Feb 24 2012, 05:34 AM

It would start ok and then idle way too low until warm, then be pretty good when fully warmed. Never truly consistent though.

I had to wait for it to fully cool to see if it improves with the possible vacuum leak found.