Badly fouled spark plugs Options

[andreic]

Hello,

I have a problem on my newly rebuilt 1.8L engine, with L-Jet.

Yesterday as I was driving home the car simply quit about 5 blocks away from home. Until this point it was running very well. I had to have it towed home and now I started trying to diagnose it.

So far I've checked that the fuel pump operates when opening the flap in the AFM, so I suspect I got fuel pressure right. The starter spins the engine well.

I have strong spark on the main distributor cap wire (coming from the coil), and putting a brand new spark plug into one of the spark plug wires I have spark at that too. (Originally I was too lazy to pull an actual plug from the engine.) But this morning I tried pulling a spark plug from the engine, and it is completely black and covered in carbon. Not wet, just covered in a thick layer of solid black material.

I can't check right now whether the spark plug from the engine is fouled badly enough to not give a spark at all, or if it still is OK. (I need to wait for my son to come back in the afternoon to help me, this is a 2-person job.) But assuming the spark plugs are the problem, can somebody offer a guess as to what could have caused the engine to foul the spark plugs so badly and so quickly as to stop the engine while driving? Before that there was no indication something was wrong.

Other slightly strange things.

a) I've noticed the car burns a lot of gas. I barely get 20 mpg in mixed city/highway driving.

b) I have about 600 miles since the rebuild, engine ran well all along.

c) The only other issue with the car is that I can not get the idle right: it seems to idle at 1800 rpm most of the time, but if the engine is well warmed up (after about 1/2 hour of driving) or if I hold off the clutch as I come to a stop until the rpm's come down to 900, it'll idle at 900. I've tried two different throttle bodies, thinking it may be the throttle that sticks, but it behaves the same way with both. I started to suspect that the distributor is sticky and does not retard the idle sometimes.

Any suggestions, highly appreciated.

Thanks,
Andrei.

[timothy_nd28]

Sounds like you may have one or more leaky injectors. Pull out all spark plugs and post some pictures.

[andreic]

OK, will do that this afternoon.

[Dave_Darling]

As I said over on the Bird Board, you're running pig-rich. Check the oil; if it smells like gas change it.

Check that everything is plugged in, especially the CHT sensor near the #3 spark plug.

Verify the fuel pressure, don't guess. It's not that hard to hook things up backwards and get super-high fuel pressure.

--DD

[injunmort]

newly rebuilt, check compression, you rings may not have seated

[andreic]

Here are 4 photos of the spark plugs that I pulled out. They are all 4 equally black and sooty.

I checked that the CHT sensor wire is connected. (It is.) But maybe I'll check tomorrow again the resistance between the pin at the computer plug and the ground, that should be fairly easy to check.

What else could it be making it run rich? I understand that a leaky injector could be a problem, but is it likely that I have 4 leaky injectors? All 4 spark plugs look the same.

What would be an indication that the rings have not seated properly? I can run a compression check sometime next week, **if** I get the engine running well enough to get it to warm up. But if it is coming from the rings, wouldn't it foul the plugs with oil, so they would be covered in oily, liquid stuff? And wouldn't I be smoking through the tailpipe? My exhaust is perfectly clear.

Finally, how do I check if I have gasoline in my oil? I don't want to dump all the oil; is it enough to smell it on the dipstick? My problem is that my garage anyway kinda smells like gasoline, so I worry I may not be able to distinguish it... My original plan had been to change the oil after the first 1000 miles, when I would also have done a valve adjustment, right before putting the car in storage for the winter.

Thanks,
Andrei.

[andreic]

One more thing, before I launch into the fairly complicated task of testing fuel pressure. After letting the car sit overnight, if I turn the fuel pump on (by activating the flap in the AFM) I can hear the pump running, and after a few seconds I can hear the pressure valve opening and letting fuel through back into the tank. Does this not indicate that I have it plumbed correctly? Otherwise I assume it would never let anything through.

[andreic]

OK, I went now and checked the CHT sensor. I measure 2000 Ohms (2K Ohms) between pin 13 of the ECU plug and ground, with the engine completely cold. I think that is OK, from what I remember.

Also I tried smelling the oil I wiped off the dipstick (I dipped it 4-5 times to get a good sample). Something strange is happening. The oil looks very good, and does not smell of gasoline to me (but I may be off; my wife says she thinks it does). But what is strange is that I remember clearly that when I put oil in I had it below the high mark on the dipstick, and now it is about 1/8" above the high mark. Could it be that so much gasoline has seeped past the rings that it made the oil level rise? Wouldn't then the oil smell of gasoline very strongly?

[andreic]

Bump. Anyone else with a suggestion why the L-jet may be running super rich? (If that's what my spark plugs seems to indicate.)

[timothy_nd28]

I wouldn't take a chance with a newly rebuilt engine, drain the oil. Gasoline is a good solvent, if gasoline and oil are traveling through the journals, bad things could happen.

The 5th injector could be leaking, which would cause all spark plugs to foul up. It would be nice to test all injectors not only if they are leaking but for spray patterns. It's also good to know the fuel pressure.

Lastly, this is only a theory. Perhaps before the rebuild, you had leaky seals that caused a vacuum leak, at that point, someone made adjustments to the AFM to compensate the vacuum leaks. Now with a newly rebuilt engine (maybe all new seals), the AFM is still adjusted from it's last rich running condition even though you have a now tight system.

Go over the basics first. Fuel pressure, FI spray patterns, timing (could be adjusted too far retard) and then we can look at the AFM.

Don't adjust anything on the AFM till the very last, you will need a A/F ratio meter to aid

[Localboy808]

Sounds like you really need to do that compression check. Doesn't have to be fully warm to give you an idea. If there is a problem you are goi g to see it.

[andreic]

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.

[andreic]

I should have said that I'll do a fuel pressure check too, though that's bound to be messy (anyone have any suggestions on how to remove the pressure from the fuel system, so that when I remove the bolt that covers the pressure checking port I don't get fuel spraying all over the engine compartment?).

[Dave_Darling]

More oil in the sump than you put in is a classic symptom of gas getting into the oil. Gasoline does not lubricate your bearings very well...

If you can hear the pressure regulator opening, it is probably hooked in correctly--but it is still worth checking the pressure.

Make sure the vane in the AFM moves smoothly. Double-check all wires and hose connections.

--DD

[andreic]

OK, let's go with the assumption that it is some of the injectors that are leaking. I can't imagine all four being messed up at the same time, so with all four plugs being fouled this would clearly point towards the cold start valve (CSV) being the culprit.

I think I can pull it out and check if it is leaking. But could it be the case that the CSV is actually fine, but the thermo-time switch is messed up and keeps the CSV open all the time? I assume I could test this by pulling the plug off the CSV and measuring with an ohm-meter how long the thermo-time switch stays open after starting the engine, right?

I would like to not have to worry about changing the oil, then doing diagnostics, only to find that I've been leaking again fuel into the oil so I need to change the oil yet again... So I'd like to isolate the fault as much as I can before changing the oil, i.e., I'd like to test as much as possible without running the engine. But some of the tests (like checking the thermo-time switch, and checking oil pressure) require the engine to run, and from what I've heard I should not run it now until I haven't changed the oil.

[clarkcou]

I had a similar issue after rebuilding a BMW engine with L-jet, the plugs fouled like yours and I had poor power and fuel mileage. It was due to a weak spark instead of high fuel pressure or leaky injector. I would rule out spark issues before assuming fuel issues. They are easier and cheaper to fix.

I ultimately traced this to the speed switch - a pin on the board inside the switch was barely making contact with the metal case thru an insulating sleeve.

I found that a gas soaked plug will not fire well again. Cleaning did not return proper performance even after fixing the weak spark issue.

WhIle a weak spark due to multiple possible causes will result in fouled plugs I would change the oil and monitor closely for a leaky injector.

[Dave_Darling]

I think I can pull it out and check if it is leaking. But could it be the case that the CSV is actually fine, but the thermo-time switch is messed up and keeps the CSV open all the time?

The thermo-time switch provides the ground to the CSV. The power to the CSV is supplied by the yellow starter wire. Therefore, the CSV will only open while the starter is cranking.

It is possible for the CSV to be leaking, but a shorted TTS is only of concern while you are trying to start the car.

You can remove the CSV from the manifold and run the fuel pump to pressurize the system. If the CSV sprays or dribbles, it is bad and is at least one cause of your trouble. If not, then it is not the cause.

--DD

[forrestkhaag]

When I received my 2.2 (built by others), it exhibited the same thing / badly fouled plugs and soot in the tail pipe coupled with black oil in 200 or less miles....

It was unseated rings. The problem went away after running a few hundred miles and I agree with DD as to needing to change the oil along the way.... several times.Gas and Oil may mix but the two tether are a poor lubricant.

[andreic]

OK, did more work on the car today, and I am completely puzzled. Things I did:

a) Cleaned up all four spark plugs as best I could with a wire brush, and reinstalled them.

b) Checked that all 4 injectors "click" when grounding the corresponding pin of the ECU wiring harness.

c) Tried to start it -- started with great difficulty, ran very unevenly (as if firing only on 2-3 cylinders) and got to 2-3000 RPM only with great coaxing and pressing a lot on the throttle. Lots of foul smelling smoke came out of the tailpipe, looking like a haze (smells like burning oil).

d) Pulled a plug immediately after running it, and it was again black, but the sooty thing on it seemed a bit more like oil than like dried carbon deposit (what I had before).

e) Pushed car onto ramps, and drained the oil. Oil looks good to my uninformed opinion, no metal observed in the oil. (But I did not run it through a strainer.) There was more oil than I remember draining out at other times -- almost exactly a full gallon. Smelling it there is somewhat a smell of gasoline, but not sure. I have not yet pulled the oil filter, but will do that later this afternoon (after I buy new oil and a new filter).

Several questions:

a) I assume the oil smoke I see from the tailpipe suggests that oil is getting into the cylinders. How could this be happening? Could it be that having a higher oil level than the high mark on the gauge could somehow be allowing oil to slowly leak into the cylinders while the car is stopped?

b) If I do a compression check with the engine stone cold, will it tell me anything useful? I can't see how I could warm the engine enough to do a proper compression check with the engine running so badly. I don't dare run it more than 30 seconds, what with all the bad smoke coming out and the uneven way it runs.

c) Could the timing be terribly off and cause it to behave the way it does? Should I try to fiddle with the timing, or at this point I should leave it as it is?

At this point (or at least after I put the new oil in and change the filter), I am at a loss which way to go forward. If someone could tell me what would be the best steps forward it would be very helpful. Thanks.

[andreic]

I forgot to say what I was planning myself to do this afternoon:

a) Change the oil filter and add new oil.
b) Do a compression check with the car cold.
c) Check fuel pressure when fuel pump runs; also see how long the system holds pressure after fuel pump is stopped, under the assumption that if there is a leaky injector this would show up in a rapidly dropping pressure in the fuel system. Is this correct?

I don't really want to remove the CSV immediately since it seems to be a bear to take out and put back in.