I just bought my Z about 3 months ago and have had problems with it folling out the # 4 plug. It has good wires and is getting spark. We thought it was a valve seal so the intake and valve covers are off. The valves in bith heads are clean( I always thought that when your seals go you get a build up on that valve. Correct?) Any ways I am stumped The only other problem i can think of from doing alittle searching on here is that it may be a injector? Is there anyway I can check them off the car? On other question the cars an 86 Z28 305 car with a 350 from a pickup in it, could there be any computer prob??
thanks


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Ryan
1986 Z28 Tune Port 350
Alpine, PPI, Eclipse

 

My first thought was the injector.

I dont know how to check them off the car.

John

 

Some places how injector testers that pulse the injector a certain number of pulses to see if its malfunctioning. I used them in school, but I don't know if there are any places that test them.

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1990 Pontiac Formula 350
Rebuilt 355
COMPCAMS 212/212 .440/.440 cam
Flowmasters 80 series.

 

Not sure what you can see of the valves, other than the stems, with the heads still on the car.

Yes, excessive oil through the guides can cause the valves to coke, but it would take a lot of oil and some high temps I'd think.

While the covers are off, go ahead and replace the stem seals, it's not too difficult, just a little time consuming.

What's the plug look like (color, etc)?

 

Many places will test and flow injectors. Try <A HREF="http://www.cruzinperformance.com/">Cruzin' Performance</A>

 

is it gas fouled or oil fouled? thanks, tom

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86 iroc 305tpi auto. mild cam

 

I have a similar problem on my number 6 cylinder. As questioned before, make sure it is either gas or oil. If its oil be sure to do a compression test, and if at all possible a leakdown test will tell the rest.

If its gas and all of your ignition components are good then yes, it is probly an injector.

Brendan

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1987 IROC-Z L98,SR,EB 6085's,LPE 219/219 SR Cam, Crane 1.6RR, EB TPI Base, 58mm TB, Stock T5, 30lb SVO, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, Aluminum DS, 94 Disk Rear, Adjustable Prop Valve, Precision 3.73 Gears, Weld in Sub-Frame Connectors, Hotchkis LCA's, KYB Shocks/Struts, Poly Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm, Big stereo, 730SD Conversion.

To see the ROC, Check out the webpage Here

 

Hello guys,
Sorry i have been busy. About the plug i am not sure I have to check in the morning I thought oil but my dad says gas so I will get back to yas.
If its an injector form what i have read the ohms whould be different correct? I am getting 13.2 13.5.
Thanks agian


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Ryan
1986 Z28 Tune Port 350
Alpine, PPI, Eclipse

[This message has been edited by Tite86Z28 (edited September 06, 2001).]

 

Damn, I just deleted that email from Rich where he told me the tolerances. I think they should be around 14ohms.

 

Alex,
13.5 should be fine then correct? Every one is right arounf the same. I thought if it was a stuck injector then the number 4 one whould be off more. But I am testing them off the car. From what I read you need to warm up the car before testing??
Anyways another day I dont put miles on it!!

------------------
Ryan
1986 Z28 Tune Port 350
Alpine, PPI, Eclipse

 

Well there's the GM way and then again there's the way you have to resort to when you don't have all the time or equipment that GM has.

You can check them for leaks, by pulling the plenum and runners. Then disconnect the fuel lines, raise the fuel rails enough to allow the injectors to come out of the manifold.

Now you can re-attach the fuel lines, put a piece of 2x4 under the fuel rails to hold them up and turn on the pump.

If one of them is leaking it'll show up. You may even see it dripping, but in any event, the tips will always be wet even after wiping them all off with a clean paper towel.

Of course, there is an official Service Manual procedure for doing it, but many times I find a "work-around" is easier.

If you have a fuel pressure gauge installed and the pressure drops almost immediately after shutting down the engine you can bet it's either an injector(s) or the pump itself. Then you've got to figure out which it is by squeezing off the rubber fuel lines with a pair of pliars and watching what the gauge does.

The procedure I used on my injectors not only showed that I had a leaking injector but also which one it was.

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

Hay,
I just talked to my mechanic and he said that our cars have a problem with intake leaks, which would explain why when I step on it, it smokes bad. The plug is oil fouled. The valve seals are fine. Is there any other posibilities that I should check?
Thanks

------------------
Ryan
1986 Z28 Tune Port 350
Alpine, PPI, Eclipse

 

There are only a few ways that oil can get into the cylinder.

1. Rings, including excessive blow-by being sucked in via the PCV system.

2. Guides/Valve Stem Seals

3. Intake Manifold Gasket

4. A piston(s) ring installed upside down or in the wrong groove or gapped incorrectly. Too wide a gap allows excessive blow-by to enter the engine and too tight a gap causes the rings ends to butt, twisting (the correct word which begins with "c" followed by an "o", then another "c" and lastly a "k" then the "ing" keeps getting changed by this site's word checker - wonder why?) the ring and killing the ring seal.

5. There are other much more drastic causes, like a hole in he piston deck, but I don't think your engine's suffering from any of those.

A compression test and (better) a leak down test will show up worn rings (and a leaking valve)

Worn guides or bad seals usually show up as loys of blow-by and a buildup on the backside of the valve which calls for removal of the intake manifold to see.

Oil can get sucked into the intake port from the underside of the intake manifold due to a leaking intake manifold gasket. This condition can many times show up as a vacuum leak using a vacuum gauge when the guage reading won't hold steady.

Can't think of any other possible causes right now.

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9



[This message has been edited by JakeJr (edited September 14, 2001).]