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914World.com _ 914World Garage _ Spark Plugs Almost instantly Get Fouled Up W/Carbon
Posted by: JohnWayne Aug 19 2012, 06:43 PM
I can't figure out why the spark plugs are getting fouled up with carbon within 2 minutes of idling.
Thanks in adnvance
Posted by: Vacca Rabite Aug 19 2012, 06:58 PM
What engine? Old and tired? fresh rebuild?
What fuel system? Djet? Ljet? Carbs? EFI?
What kind of gas?
What kind of plugs?
Tell us more and we will help.
Posted by: JohnWayne Aug 19 2012, 07:04 PM
it's a 73 1.7L fuel injection djet. It has premium gas in now and has the OE Bosch Plugs. The engine has new rings and that's about it.
Posted by: tim_nd Aug 19 2012, 07:04 PM
Can you post some pics of your setup and your fouled plugs?
Posted by: JohnWayne Aug 19 2012, 07:15 PM
I Also have brand new Bosch Wires
Attached image(s)
Posted by: brant Aug 19 2012, 08:17 PM
are the rings seated?
perhaps the CHT or MPS is out and its runing uber rich?
its got to be fuel or oil.
Posted by: tim_nd Aug 20 2012, 12:29 PM
Are all the plugs the same way? When was the last time you did a valve adjustment? The first thing in order would be a compression test (engine warm)
Posted by: McMark Aug 20 2012, 02:20 PM
A wideband O2 sensor would really help diagnose this. 
Posted by: SLITS Aug 20 2012, 03:16 PM
1.) is the black wet? = oil fouled
2.) is the black just sooty? = way rich
Posted by: Rand Aug 20 2012, 03:22 PM
If it gets that bad in two minutes, I would think it's got to be oil. If it was just uber rich (rich enough to do THAT) it would be tough getting it to idle well at all, and you'd have to smell it in the exhaust.
What kind of smoke are you getting out the exhaust pipe?
Posted by: JohnWayne Aug 20 2012, 03:40 PM
I figured out the timing was off, so now it's not smoking anymore. It drives really smooth now, but the plugs still get fouled up enough that it won't start after about 20 min of driving. The idle stays around 1000 rpm.
I was also wondering about the ECU. My dad got it from this porsche mechanic and i don't know if it's for a 2.0L or 1.7L. I don't know if that would make a difference in richness or not.
I got a Manifold Pressure Sensor from the same guy and also don't know if that is for a 1.7L.
If the ECU and MPS is not for the 1.7L would it cause the richness i'm getting?
Posted by: SLITS Aug 20 2012, 04:16 PM
I figured out the timing was off, so now it's not smoking anymore. It drives really smooth now, but the plugs still get fouled up enough that it won't start after about 20 min of driving. The idle stays around 1000 rpm.
I was also wondering about the ECU. My dad got it from this porsche mechanic and i don't know if it's for a 2.0L or 1.7L. I don't know if that would make a difference in richness or not.
I got a Manifold Pressure Sensor from the same guy and also don't know if that is for a 1.7L.
If the ECU and MPS is not for the 1.7L would it cause the richness i'm getting?
Read this: http://members.rennlist.com/pbanders/djetparts.htm
Posted by: JohnWayne Aug 20 2012, 07:18 PM
I put a different MPS in and I think that was the problem because the spark plugs aren't that bad anymore. I just need to break in the new rings now.
Thanks for all the answers
Posted by: Rockaria Aug 21 2012, 11:52 AM
I put a different MPS in and I think that was the problem because the spark plugs aren't that bad anymore. I just need to break in the new rings now.
Thanks for all the answers
Quick question? Before your fixes, Did it get so bad that the car died while running and would not restart untill the plugs were cleaned?
Posted by: JohnWayne Aug 21 2012, 12:36 PM
yeah
Posted by: messix Aug 21 2012, 12:37 PM
pull the dip stick and smell the oil to see if it smells like gas, if it does change the oil and filter now!
running rich can wash the oil off the cylinders and gall the rings and cylinders and then the rings will never break in.
Posted by: Rockaria Aug 21 2012, 01:40 PM
yeah
Well Howdy Doody! I bet that is my exact problem as well. My MPS no longer has the epoxy on it and when I put back the 270 Ohm resistor I bet the combination was way too rich. Who knows what the PO has it set to.
Thanks!
Oil Change is on the schedule! ( I have new rings as well.)
Posted by: Cap'n Krusty Aug 21 2012, 03:29 PM
Two issues jump right out. Premium fuel. It's pretty likely you don't need it, and it's less volatile than the lower grades, meaning it burns more slowly. Bosch wires: There's a reason Porsche has never used them as a factory part. They're junk. Granted, you have other issues, but these need to be fixed.
The Cap'n
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