Please comment on my spark plug pic
 

If you have read my previous posts, my 3.2L engine has been running like crap from lack of use. I changed the battery, fuel, fuel filter, oil, oil filter, and now spark plugs. It has a hard time maintaining idle and dies. If you look at these spark plugs, can one deduce that I have clogged injectors? Some are completely coated and the others look like they just came out of the box. If so, what is the easiest way of test my injectors?

Jon

do you know what cylinders each plug was pulled from?

i wouldn't discount the ignition system. you might have bad plug wires, or need a new cap or rotor.

i would say to check your wires for equal resistance, however the 3 "dark" looking ones look as if they're soaked in oil, but it may just be the pic. does your 911 smoke at all?

The top of the picture would be the front of the car so the plugs are placed at their cylinder location. The dark ones smell like gas and the clean ones do not have a smell. The car does not smoke at all.

Jon

Also, the cap and rotor are new (C2 distributor). If a plug wire was bad, wouldn't the plug still be covered with crap? If I did not have fuel spraying in the cyclinder, would the plug remain clean and free of gas smell?

I left one piece of info out. My engine is twin plugged and the second set of plugs look exactly like the set I posted in the same configuration. Even if I had bad wires, What are the chances that the same wires to a specific plug from two separate distributors are bad?

Jon

It looks like you could have three injectors not opening at all... I suppose that the way the engine would (barely) run in that case could fit your description - and cause the other three to look as they do..
How long has the fuel been sitting in the unused car?? Clean your injectors, and see if you can get more cylinders to kick in. They may need to be removed to clean properly at this point...:(

Jon,
There was a thread here a few weeks back about pulling injectors and testing by running fuel into a jar....might be worth a search to see if you want to try that, or switch some injectors around to see if the problem moves from cyl to cyl...:cool:

I can think of 3 ways the motor could go really rich.

1. Head temp sensor. You can unplug this and substitute a resistor of the right value in order to rule that sensor out.
2. Air flow meter, or more specifically, the signal from the air flow meter. If the DME "thinks" the engine is getting more air than it really is, it would richen the mixture.
3. Fuel injectors not opening on one side/bank. The average gas mixture that the O2 sensor would be leaned out and the DME would richen the mixture too much.

I'm going to go with Door #3 cause its more exciting. :D
The injectors are all fired at the same time but the left and right banks have their own circuit. If it was my car, I would reseat the connector on the top of the firewall.
-Chris

lack of use will do that to an engine.

you say you changed the plugs, but how long ago? did you swap them and the engine ran like crap straight away, and then you pulled the plugs and they looked like that???

the black ones are definitely "rich" (fouling could be caused by lack of use), and two "white" ones on the right look very lean.

if you put all new plugs in now, how'd it run???

since you got fuel going in (hence sooty appearance) i would say you got an ignition problem if anything. even if it was running rich, if you put new plugs in it would run fine until the plugs fouled up.

The plugs in the picture were installed 3 months ago. I drove around the block twice (actually there was some puching involved after stalling). I have been trying to get it started and running the entire 3 months so the engine has been turned over ~40 times. I still want to believe that I have blocked injectors. Remember I have the engine twin plugged so I have 2 coils feeding 2 distributors feeding 2 spark plugs. I pulled all 12 spark plugs and each cylinder had the signature for each spark plug. If I had a issue with wires or a coil, I would expect one of the two plugs to be dirty from the problem cylinders.

Jon

jon

ok, the white look normal then if they're that old (young).

the black one on the right looks slightly diff. to the other two on the left or is that the lighting?

the reason i say its probably spark, is because you've got fuel going in there (hence its black and sooty), but its quite obviously not getting burnt.

usually with "rich" conditions it takes some time for build up to make an engine run rough becuase of fouling.

have you checked that you've got strong sparks on those plugs??

i hear what your saying, but if the injectors are blocked it would stop the flow of fuel?? (lean)

have you had it running properly since twin plugging??

how did it run the first time, with new plugs?

if it was something fuel related other than injectors, idle control valve for instance, i would expect the plugs to be the same.

The engine ran great. I am restoring a '72 and the engine was completely rebuilt with new heads, new valves and guides, new Mahle euro P&C's, all new sensors, big bore throttle body, boat tailed crankcase, shot peened rods and balanced, raceware parts, modified cylinders for breathing, mass flow, Andial splitter, C2 distributor, SSI heat exchangers, and a custom Autothority chip. I basically did avery mod Bruce Anderson suggested. I add a Carrera fuel tank, fuel pump, F&R suspension, oil tank, and cooler. I rebuilt all the brakes, petals, and it has a fresh '83 transmission. The axels, CV's, and motor mounts are new. Externally, the only thing that looks different are the steel Carrera flares with 8x16 Fuchs. I have replaced every piece of rubber and every rusty/dirty bolt with SS replacements. It also has a new bare metal body Silver paint job.

I have not put the glass or interior in yet (which is all new). This said, I have never driven it on the street since I bought it 6 years ago. I put the engine in 2.5 years ago. My problem started this year due to my neglegence starting the car. I killed 2 new Porsche batteries by letting them discharge too many times. The fuel pump was replaced 3 months ago because the other new one locked up.

This has been very frustrating. I guess I could change the plug wires since they are the original wires that came with the C2 distributor. To answer your question about the plugs, The car runs the same with the Bosch plugs pictured vs. the new NGK plugs.

Jon

what 2.5 years ago??

i'd test each plug and see what sort of spark you get - if its strong look at fuel.

i beleive you can test injectors by removing them and letting them squirt into a jar - but i've no experience so try a search.

could be that the fuel system is gummed up, but it'd have to be pretty bad.

good luck and let us know how you go.

Jon,

I assume you've first checked that the plugs are getting spark?

After that, check that your injectors are running. There's a bunch of excellent posts on fuel injectors and fuel pressure on this board. They're really easy to pull out and somewhere there's a post by John Walker showing a device he built using 6 graduated cylinders. You pull all your injectors, put one in each of the cylinders, depress your air flow sensor and see if they're running at equal rates.

Here's an old post where I got some good advice:

http://forums.pelicanparts.com/newreply.php?action=newreply&threadid=84765

Yeah but.....this is a 3.2, so it's not CIS (I assume), it's Motronic. Still, there must be a way to ask the injectors to squirt into jars as though the engine were running. I wouldn't be surprized if three of those injectors are not spraying. That's about the only way I can explain the appearance of those spark plugs. Three are getting too much gas, or perhaps even too much oil, while the other three are getting nothing, or next to nothing. If they were igniting any gasoline, they would have some film on them, white at least if not tan or black. But they look new. They're operating in fresh air.

Yup. Motronic's different isn't it.

Could you pull the electrical leads to one of the injectors and check it for voltage while the engine is running? If it's getting pulses of voltage it should be opening. You can also check resistance across the injector to see if it's shot. Pulling them and cleaning them may free them up if it's getting voltage and isn't burned out. I've heard you can soak them in Techtron or have them professionally cleaned. If the injector isn't getting voltage then the electrical hunt is on.

O.k...here's the straight scoop...not a guess...

If the injectors are black/sooty carbon when you run your finger off of them, you have a run rich condition. If the black is oily/greasy, you have internal engine problems.

"since you got fuel going in (hence sooty appearance) i would say you got an ignition problem if anything"

Not necessarily true. You could have dirty injectors, with a pintel valve that is totally jammed and not allowing the injector to close or function within parameters, allowing too much fuel into the cylinder. Perhaps the corresponding plug wires are toast, but doubtful if the wires are factory Beru (high quality stuff.)

What is odd is that some plugs look good while others do not. This pretty much rules out cap/rotor/cylinder head temp sensor/etc for me. If any of those were bad, all the plugs should be equally messed up IMO.

"usually with "rich" conditions it takes some time for build up to make an engine run rough becuase of fouling. "

Again, not true. I bought an '84 3.2 with a fouled #3 plug. Ran lousy. Plug was black sooty like unburned fuel. Changed plugs... good improvement, but preformance dropped right back to where it was again after only 100 miles. Same plug was fouled again, replaced #3 injector 750 miles ago...running tippy top now. Obviously, injector was bunk.

What I would do is put the plugs back in, pop off the fuel rails and shuffle the injectors around. A little bit of work, but if different plugs are now screwed up after some running of the engine, I'd say its time for a set of injectors...

Now, to go a step further if you determine that injectors are/are not the cause, I would proceed to some of ChrisBennet's suggestions, as it is also possible if this has been running rich for some time that the O2 sensor, etc. may have been damaged.

Good luck-
BG

And also FWIW,

"The injectors are all fired at the same time but the left and right banks have their own circuit. "

I believe this is true with the CIS cars, but not with Motronic equipped 3.2's. One of the reasons Motronic is better than CIS is that the fuel can be precisely metered to *each* cylinder at the appropriate time for intake, creating more precison fuel delivery.

This is some great info! I am considering pulling the injectors and having them cleaned/analyzed. Since everything else on the engine is new, it would make sense to buy all new injectors. Who has the best price on new injectors? Vertex has them for $70. A non Porsche friend needed new Bosch injectors and he was quoted $100 each, but he cross referenced them to another car and got them for $45.

BTW. The car ran great until I went to Singapore for a month in March of this year.

Jon

Best price is Pelican Parts, as they host this BBS, and that's where the info is coming from...

BGCarrera32

granted but........the 02 sensor only works once warmed up;)

if its only happening on three cylinders its got to be injectors or ignition??

dickster...

Right...my point is only that if the car has been running for some period of time in this condition (I don't know based on the info given) that there may have been more problems created downstream by the rich condition. Hence he could change the injectors and still find problems caused by a messed up O2 sensor or a plugged catalytic convertor.

When does the O2 start sending signal? Does it work when the engine or cyl head temp has reached a certain temp?

BGCarrera32

yeah, as i understand it.

it seems that the engine was fine until stored 2.5 years ago, so it would be related to the little use its had??

the trouble wouldn't be further upstream would it?? you'd expect all the cylinders to be the same??

gummed up injectors then:D :D :D

Here is my reasoning for thinking it might be the fuel injector circuit. I'd want to check it for this reason.
If the picture indicates that 3 cylinders on one side are effected..
Then it is likely something that all 3 cylinder share.
Three cylinders share a cam and an injector circuit.
I doubt it is the cam. :D
I doubt 6 plugs on one side coming from 2 different distributors all failed to fire.
I doubt 3 injectors plugged at the same tiime, all on the same side.
That leaves one injector circuit. The connection or the driver in the DME may have failed.

You really need an oscillocope to check the injector signal I think.
-Chris

Thanks for the info...

I guess I missed that it had been stored 2.5 years. Definetly fouled injectors would be my take on it...probably never saw sta-bil in the gas tank...not that it would have done any good after that long anyway:D

Chris,


I think that your "IF" statement evaluates to False because when I look at the picture I see two plugs on the left side are fouled with carbon and one on the right side is fouled with carbon while the others are all clean so I don't think it's valid to diagnoes the cause of the problem to something that affctes the while bank.





Doug

Yes, I looked again and I think you are right Doug.
-Chris

New development
 

I talked with a mechanic friend of mine and he brought up an interesting point. I have been through 3 fuel pumps because the check valve kept sticking. He suggested that I have too high a pressure in the fuel line. He suggested that I check the fuel pressure regulator. But be that, he suggested that I test the return line to make sure it is not blocked. I pulled the hose off the regulator and I could not force any air into it. I removed the hose at the front of the car and verified that the line through the body was clear. I blew into the last bit of hose connected to the tank and I finally managed to create bubbles. After the dizziness subsided, I tested the tube again and it was passing air. What could possibly be in my tank that would block air passage through this connection? Sometimes it was clear and sometimes it was clogged. I looked inside the tank with a flashlight but I could not see that far over. Could this blocked return line have broken 3 of my injectors?

Jon

There is a tool that some shops use.. think it's called an injector driver.
Basically the pressure gauge is hooked up to the rail to test residual pressure (if the check valve in the pump is not holding), key turned on to check "deadhead(?)" operating pressure, and then turned off.
This little device is connected to a solenoid. It fires for .5 seconds and the drop in rail pressure is noted. All the injectors are then checked for an even drop in rail pressure.

Considering its happening on one side, it might be a good idea to blow out the lines as well.