hitmanpty

Hi every one.

after almost one year of learning and taking advice here at this forum. I find out that my problem is 2 dead cylinder. N0. 1 and N0. 5.

Because all the lerning here I was capable of determing what is the source of the problem.

I check the injectors. they are ok . Iam 100% sure about this becacuse. first they all was replace for good used one I get from Agent 86. and also I just preform a test on them and they work. I put voltage on the injectors and the fuel preasure drop the moment I did this.


Also I check the injector wires with a multimeter. and I get voltage at the wire when the car is running... so I know the wire are ok

also check for spark on every spark plug i get good solid volt. blue spark.
I did rebuild the distributor new rotor new cap, new pick up coil. I did not change the module, but in case I have a new one on my tool box.

New spark plug also. only I decide to check the spark plug this morning.

I find out that N0. 1 and N0. 5 spark plug have oil. the rest of the spark are ok. here are some pics to show you what iam taking about.

this is a normal spark plug pic

[IMG][/IMG]

here is a pic of number 1 and number 5 spark very oily

[IMG][/IMG]

So i guest I will have to look into the piston rings. or may the valve. any way I can see more test coming way to the terming the exact cause of my oily spark plug.

383vett

Do a leakdown test. It'll tell you the health of the cylinder. If there is leakage, you'll be able to tell if it is the rings or valves by listeneing for where the air escapes.

hitmanpty

I just saw a video on leak down test. I dont have the tools to doit.
I will go out and see if I can find the tools.

hope is not rings

hitmanpty

I went out and get my self a compreasion test gauge. i finish doing the test about 30 minutes ago. here is what i have.

cylinder No. 1= 115 psi
cylinder No. 2 = 130 psi
cylinder no. 3= 139 psi
cylinder No. 4= 139 psi
Cylinder No. 5 = 130 psi
cylinder No. 6 = 139 psi
Cylinder No. 7= 135 psi
cylinder No. 8= 135 psi

can someone tell me what is the specs for compresion. also if this is to far off from what is suposet to be

is ovius that is something wrong with cylinder number 1

also like to point out, regarding the spark test, i did check the plug for spark but did not check the spark plug it self. Is a farly new spark plug. but since is full of oil may be is damage so I will check that spark again.

mtwoolford

It's always a good idea to do a compression test. However, while compression pressure may be low due to worn rings, if over time, large crusty oil deposits have built up on top of the piston and in the combustion chamber, the compression ratio can increase and the compression pressure (what you measure doing the test) may not show a drop, or , may actually be higher.

I suspect that those two plugs were not firing.

I'm not saying that's not oil; but in my experience with a lot of oil burners, oil will carbon up and form black oily deposits which eventually encrust the whole sparkplug tip. The dark coating on your plugs looks more like unburnt gas...which would lead me to suspect a bad plug wire on at least those two cylinders.

plug wires don't have a real long lifespan, especially if they are the usual carbon core types (and not the more expensive spiral wound metallic core aftermarket variety). Long story short, while they may provide excellent service when new, over time the carbon core heats up, hardens and looses its flexibility, and once disturbed (as in doing a plug change), cracks into a zillion micro fractures which destroy the wires conductivity.

cv67

^^ could be any of the above..if it was oil it would practically short the plugs out.

They make plug extenders for oil fouled plugs they are a cheap band aid that usually work.

Try some fresh plugs/wires bet it runs much better. Gap them properly and use a touch of antiseize on the threads. Dont get them too tight!

mtwoolford

I've reread your threads;

first, the general rule is that cylinder compression is a relative thing, but should not vary more than 10 to 15 percent between the high and lows; seven cylinders clearly meet this test; only number one falls outside of it, and then only slightly.

replace the plug wires with new (especially if the ones on the car are over two years old)

If you're sure plugs one and five are oil fouled, I'd replace those two plugs with ones of a higher heat range (hotter) to burn off any oil deposits.

If you have the valve cover off on the number one cylinder side, see if the valve on that cylinder depress as much as the other valves do; if not, you may have a bad cam lobe, or the rocker could be bad or misadjusted.

start the car and see if the engine performs satisfactorily (I predict it will) and if so, enjoy driving your corvette.

leesvet

hmmmm
Those comp numbers seem a little low for my taste. 160 across the deck is a good street engine. 2 look fouled but not to the point of not running.

This engine is obviously tired but it can still run.
Those 2 plugs are not firing for some reason. Go back thru the wires and make/check each inj to see if its spraying. There is something basic wrong here. If it were just about bad rings why 2 cyl>? why not all???

Do the compression test with TB OPEN and run 4 puffs. Take the higest number. IF a cyl comes back LOW, squirt motor oil in the plug hole and try the test again. If it stays low, its valves if it comes up some, its rings.
I'd be focused on why those cyl were not firing...??? There is the mystery. That will solve all the problems too.

hitmanpty

I got my spark plug wires about a year ago. may be lest. not sure. any way they are the carbon type. but it was the only one I can get down here. dont know if this wires are good. any way to check them

hitmanpty

I just when down to the car . and check spark on the spark plug. i get good spark on number one plug. I also did some injectors test . looks ok. . I only have this car for a year or so. but i remeber not to long ago i had a chance to check all the spark plug and they all where ok. when i was doing the compression test i also discover spark plug No. 8 have oil also. but this one is working ok.

I wonder why will i have oil on some spark plug before was not like that. and I only have use the car may be for a few milles in all this time.

mcm95403

I agree that this looks like an ignition problem. Carbon wires don't last long with HEI. You say it has a "good" spark. The spark should be VERY strong.

You should check the cap and rotor too. Make sure they are OK. I think you should order a set of Taylor Spiral Core wires from Summit Racing. I'm sure they could ship to you. With those wires you know that you are getting a good spark to the plug.

hitmanpty

i will look into the spark wires. distributor is practicaly new. thanks

tunedport85inject

Those sparks look like flooded more than oiled, you actually have an ignition issue on these two cilinders in my opinion,i have had similar issue in the past the car runs flooded totally and not fired up at all,ended up been a sparks issue cured with 8 new sparks.I was thinking about bad or leaking injectors and ton of similar issue...sometimes the issue is at the really basic...wire and sparks first

aminnich

Any chance the plug wires are crossed between those two cylinders?

hitmanpty

nop

hitmanpty

Hi I just did some multimiter test to all my wires but dont really know what this meet.

set the mutimiter to 20K omhs
wire 1 = 13.00
wire 2 = 17.90
wire 3 = 15.00
wire 4 = 13.06
wire 5 = 19.00
wire 6 = 9.86
wire 7 = 9.56
wire 8 = 11.30

againg what this number are telling me regarding the spark plug wires

joe paco

GM spec is 30k max. look ok to me. if plug heat range is too cold, plugs may foul. a strong HEI should fire them. change the two out and go from there.

sailorsteve

If you can get hold of an induction-type timing light, you can use it on the plug wires for the two suspect cylinders. Attach the timing light and start the engine, the light should flash if that plug is firing. If a wire is weak, you could get a spark to ground when you test the wire while removed from the plug, but there might not be enough juice to fire the plug under compression.

Cliff Harris

Those plugs look like those cylinders are not firing. My thought was that the plug wires are crossed and then I saw aminnich's post.

The problem with swapped wires is that they will show a spark -- it just won't be at the correct time.

If the plugs were oil fouled they would have hard black deposits on them.

hitmanpty

is almost imposible foro those two wires to be cossed . because one of the wires is número one . i always install número one wires firm and use as referance foro install the rest of wires. for some reason número 1 and 2 aré not fireing . i Well get today 2new spark plugs and new wire set . and se what happend