Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

6 Pages V < 1 2 3 4 > »   
Reply to this topicStart new topic
> Badly fouled spark plugs
timothy_nd28
post Sep 18 2016, 05:15 PM
Post #21


Advanced Member
****

Group: Members
Posts: 2,299
Joined: 25-September 07
From: IN
Member No.: 8,154
Region Association: Upper MidWest



Start the car again, unplug one fuel injector connector as its running. See if the engine stumbles. Do this for each cylinder.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 18 2016, 09:18 PM
Post #22


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



Thanks, Timothy, I'll try that tomorrow, after I do a cold compression check (I now have all the spark plugs out...)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
porschetub
post Sep 19 2016, 01:51 AM
Post #23


Advanced Member
****

Group: Members
Posts: 4,883
Joined: 25-July 15
From: New Zealand
Member No.: 18,995
Region Association: None



3 plugs are on the rich side but not real bad ,you still have a brown colour on the electrode centres,however the 4th plug has signs of unburnt oil on it ....not good,have you run this engine in properly,I personally don't like any "run in oils" ,you need to work the motor up and down to vary good gas pressure on the rings for about 500 miles or more.
As mentioned make sure your ignition system is totally up there,you need the best "fire in the hole" for running it in.
Change the oil regardless ok (IMG:style_emoticons/default/smile.gif) ,the rest has been mentioned,good luck (IMG:style_emoticons/default/beer.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mark Henry
post Sep 19 2016, 07:38 AM
Post #24


that's what I do!
***************

Group: Members
Posts: 20,065
Joined: 27-December 02
From: Port Hope, Ontario
Member No.: 26
Region Association: Canada



Ditch the Castrol oil, stuff is shit in a aircooled.

How are you driving it? are you babying it? Running below 3000rpm?
This is all bad at this point, you need to seat the rings...you need to drive it like you stole it.
Running below 3000rpm is bad at anytime.
You can actually ruin rings by babying the engine after a rebuild.

Goetze rings and a few others are hard as hell to seat and can take up to 1000 miles to seat proper.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 21 2016, 09:45 AM
Post #25


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



OK, I am now officially stumped. Here are the latest developments, and if someone could suggest where to go from here, I'd highly appreciate it.

a) I did a cold compression check on all 4 cylinders. (Throttle wide open, fuel injection disabled, all 4 plugs out, crank it with gauge tight in each hole in turn.) I have 125 PSI all around with very little variation from cylinder to cylinder.

b) Cleaned spark plugs again, this time with brake cleaner. As far as I can tell they are good to go. Changed timing slightly (advanced it). Tried starting it. Started almost right away, but again runs very rough, will not idle at all (dies if I take foot off throttle) and lots of blue-ish smoke billowing out of the tailpipe.

c) Took spark plugs out again. They seemed to have a fine layer of dusty soot, but also some wet spots, which I could not tell if they were gasoline or oil. The spark plugs looked roughly all the same, maybe the one on cylinder 1 was slightly dirtier but not much worse.

At this point I have two things I can think of that may have gone wrong: either I run way too rich, or I get oil somehow in the cylinders.

In favor of the oil contamination hypothesis is the fact that I blow out blue smoke. But if I had bad rings on one cylinder wouldn't I be seeing a loss of compression in that cylinder? I can't quite believe that all 4 have gone bad at the same time... Remember that the car had been running just fine before it stopped suddenly.

In favor of the "running too rich" hypothesis I guess I have the dusty residue on the spark plugs. But could running pig-rich cause me to smoke badly, with blue-ish smoke? I could certainly imagine some scenarios where some electrical connection for the L-Jet has gone bad and is causing it to put way too much fuel, but would that be causing rough running? I changed the throttle body about a week before this all started, and in the process I fiddled with the WOT switch and the AFM plug.

Please help... I feel like I'm losing my mind.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mrholland2
post Sep 21 2016, 09:51 AM
Post #26


Senior Member
***

Group: Members
Posts: 761
Joined: 7-September 11
From: Santa Maria,CA
Member No.: 13,531
Region Association: Central California



Are you using a zinc additive? I thought that was needed. . or one of the special oils with lots of old-timey zinc in it. Probably isn't causing this problem, but could cause others later?

QUOTE(andreic @ Sep 16 2016, 08:34 PM) *

OK, so this is the plan I have, let me know your thoughts about it.

a) Clean the spark plugs by brushing them with a wire brush; reinstall.
b) Attempt to start the engine to check if this was indeed what caused it to stop; only run it for a few seconds to check it.
c) Change oil and filter with Castrol 20W50 (what I've been using so far)
d) Start engine again, drive it for a bit, enough to get it hot.
e) Do a compression check.

After these items, which I know how to do, I should test the injectors, including the cold start valve (I assume that's what was meant by the 5th injector). But how does one test the injectors? Other than testing them that they "click" when one applies power, what else does one need to do? Should I try to take them out and pressurize the fuel system, to see if they leak? And how does one check the spray pattern?

Their history is this: I bought four injectors from someone here on the world, who said they had been rebuilt (seemed to be, came in sealed plastic bags with fresh rubber hoses, and looking nice and clean). Unfortunately two of them seemed to stick when I got them. One I managed to get unstuck, but the fourth one seemed to be badly enough stuck that I had to replace it with one of my old injectors.

Thanks a lot for all the suggestions.

User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 21 2016, 09:58 AM
Post #27


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



Well, for now my biggest challenge is figuring out why the car runs so badly. I'll worry about the long term things (like the zinc additive) later. For now I fear needing to replace the engine, frankly.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
injunmort
post Sep 21 2016, 10:18 AM
Post #28


Senior Member
***

Group: Members
Posts: 1,024
Joined: 12-April 10
From: sugarloaf ny
Member No.: 11,604
Region Association: North East States



blue smoke, 125 on each cylinder. still think rings, comp should be around 140. blue smoke is oil. as suggested previously, drive it to get the rings to seat.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 21 2016, 10:36 AM
Post #29


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



Remember the 125 is with the engine stone cold. It would probably be higher after warming up.

And how on earth could the rings not have seated after 600 miles of running well? Suddenly I get oil through?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
injunmort
post Sep 21 2016, 12:00 PM
Post #30


Senior Member
***

Group: Members
Posts: 1,024
Joined: 12-April 10
From: sugarloaf ny
Member No.: 11,604
Region Association: North East States



if they dont seat, cylinder walls glaze allowing blowby and oil consumption. if you drove it gently, they may not have seated. i know builders that immediately after rebuild will hammer the shit of the engine to seat the rings. i dont subscribe to that but the engine does need to revved to get the rings to seat properly.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
timothy_nd28
post Sep 21 2016, 01:56 PM
Post #31


Advanced Member
****

Group: Members
Posts: 2,299
Joined: 25-September 07
From: IN
Member No.: 8,154
Region Association: Upper MidWest



Try my test, might be harder now. With one hand on the accelerator linkage keeping the engine from stalling, and the other hand taking off one fuel injector connector. Listen for the engine to stumble, if it does, re-insert the FI connector. Repeat this for all 4 cylinders. I think you may find that one of the cylinders that you had removed the fuel injector connector, it may not cause the engine to stumble.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Localboy808
post Sep 21 2016, 02:18 PM
Post #32


Member
**

Group: Members
Posts: 185
Joined: 17-July 16
From: Palmdale, Ca
Member No.: 20,194
Region Association: None



I'm going to throw this out there. I just had almost the exact thing happen to me. Ran good. Then bad and fouled plugs. Ended up being the points or condenser. Changed both so unsure. I suspect the condenser which oddly enough was new. (Empi crap). As far as the compression. I only have 90psi on all four of my tired cylinders and I do not blow smoke.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Localboy808
post Sep 21 2016, 02:19 PM
Post #33


Member
**

Group: Members
Posts: 185
Joined: 17-July 16
From: Palmdale, Ca
Member No.: 20,194
Region Association: None



Also I've found in the past that once plugs foul? I can never get them to run right no matter how much I clean them.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 21 2016, 03:27 PM
Post #34


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



I am not ruling anything out yet, but I have a very strong spark on all 4 spark plugs, so I don't think somehow that the problem is with the points, condenser, or the plugs themselves. After I isolate the main problem I may try to improve on these items too, but I don't believe this to be the problem.

User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 21 2016, 03:40 PM
Post #35


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



Timothy, I did your test right now. All 4 injectors behaved exactly the same way: immediately after removing the injector connector the engine would speed up (quite a bit, 3-400 RPM I would guess) and run much better, then a couple of seconds later it would come back to almost exactly the same RPM as before. I had my son hold the throttle pedal steady while I was doing this test, at about 3000 RPM.

Two other strange things. At some point while doing this test I noticed that one of the main hoses had become disconnected from the main FI rubber body -- the hose that goes to the Auxiliary Air Regulator and to the Decel Valve. But even though I had this huge vacuum leak, the engine still ran mostly the same. In fact I reconnected the disconnected hose to the main FI rubber body while the engine was running, and the engine kept running almost the same.

Second, I decided to do a strange test: I pulled the AFM plug, and just shorted the two leftmost pins with a wire (so as to get the fuel pump to run). I tried running the engine this way, and again it ran just as before through quite a range of RPM's.

Do you think this might indicate that either something is wrong in the AFM or in the wiring harness (at the plug of the AFM?) so that the ECU does not read correctly the AFM signal and thinks the engine runs at full power and needs maximum fuel? (Hence the fouling of the plugs, perhaps running uber-rich?)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
injunmort
post Sep 21 2016, 03:52 PM
Post #36


Senior Member
***

Group: Members
Posts: 1,024
Joined: 12-April 10
From: sugarloaf ny
Member No.: 11,604
Region Association: North East States



blue smoke is not uber rich, its uber oil.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 21 2016, 04:21 PM
Post #37


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



I know that blue smoke is oil being burned. But I am trying to explain to myself how I could start all of a sudden to burn oil: truly from one moment to the next the engine was running good, with no smoke at all, and then it went dead. I would have thought that not having the rings seated properly would cause things to deteriorate slowly. And if it was a sudden problem with oil leaking in one cylinder, I would assume the other three would still work well (and when I disconnected the injector for that cylinder the smoke would stop, wouldn't it? and the test would show a loss of compression in that cylinder?).

My current explanation for the brief revving up of the engine when I disconnect one injector is that the engine is now putting in too much fuel, and when the injector is disconnected, for a short while the mixture goes down to what it should be.

Question: I am thinking that I can test for an injector or cold start valve leaking by pressurizing the fuel lines (by running the pump) and then seeing how long it takes for the pressure to go down. My thinking is that if the CSV is leaking fuel into the intake, then the pressure will go down pretty fast, in a matter of 30 seconds or so. Am I right?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Localboy808
post Sep 21 2016, 04:24 PM
Post #38


Member
**

Group: Members
Posts: 185
Joined: 17-July 16
From: Palmdale, Ca
Member No.: 20,194
Region Association: None



QUOTE(andreic @ Sep 21 2016, 04:27 PM) *

I am not ruling anything out yet, but I have a very strong spark on all 4 spark plugs, so I don't think somehow that the problem is with the points, condenser, or the plugs themselves. After I isolate the main problem I may try to improve on these items too, but I don't believe this to be the problem.

I had spark too. But it was intermittent as the engine ran! It was crazy. The condenser and points were new. I started replacing parts that I had spares of. I replaced the coil. Engine ran great! Thinking I fixed it. I started putting away tools and making an area to move the car so I could do my brakes and rotors. Went to move the car. Problem came back! I had spare points and condenser so I replaced them both. Problem went away permanently! I'm leaving out all the wiring repairs I did because I suspected it to be electrical. Fixing PO shoddy repairs. Best of luck to you! You will figure it out eventually!

Scott
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jcd914
post Sep 21 2016, 04:26 PM
Post #39


Advanced Member
****

Group: Members
Posts: 2,096
Joined: 7-February 08
From: Sacramento, CA
Member No.: 8,684
Region Association: Northern California



914 fuel system is not sealed like newer cars. When the pump shuts off fuel bleeds back to the tank through the pump and probably through the fuel pressure regulator.
You need to pull the injectors and watch for fuel leakage while the pump runs.

Have you checked fuel pressure?
High fuel pressure from a bad pressure regulator can cause overly rich running.

Jim
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
andreic
post Sep 21 2016, 04:53 PM
Post #40


Member
**

Group: Members
Posts: 172
Joined: 21-December 15
From: Madison, WI
Member No.: 19,479
Region Association: Upper MidWest



I will check the fuel pressure in the next few days, when I find some time. (Lately I've spent way too much time on the car, I need to do some work as well...) But since the car seems to behave exactly the same on all tests I've done on all four cylinders, I suspect I may have a CSV that's leaking (or something else I haven't found yet...)

What else could be causing the system to run super-rich? Bad ECU? I've checked now the AFM connections and everything seems to be fine -- 380 Ohms between pins 6 and 9, and 180 Ohms between 7 and 8. While there I also tested the TPS, and it appears to be fine. (Between pins 3 and 18 it is an open circuit until WOT, and then it is 0 ohms.) I had tested the CHT sensor before, and it's right on the nose.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post

6 Pages V < 1 2 3 4 > » 
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



- Lo-Fi Version Time is now: 13th July 2025 - 08:51 AM