My 1989 Firebird formula 350 TPI is misfiring and i'm trying to find out why? Anyone know the firing order for the distributer cap? Anything else it may be? I have just put new plugs, wires, wires and distributer cap and rotor. The timing has also been done. Any help would be much appriciated.....

 

Firing order is cast into the intake manifold.... 18436572

 

And it's clockwise if you're looking DOWN at the cap.

If you use the firewall as 12 o'clock...... the #1 terminal is in the area of 4-5 o'clock (more around 5).

 

Okay, I just did this yesterday, maybe we should write some tech articles for newbies like me. I did it wrong the first time and here's how to do it right (or at least, how I did it this time).

cylinder numbering

cylinder numbers from steering-wheel (firewall) to front of the car:

driver side:
7,5,3,1

passenger side:
8,6,4,2

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wires

buying

Get an ohmmeter with you. While you're in the store, open the box. The resistance you measure end-to-end for each plug wire should not be more than 650 ohms/foot. They often come in bad batches so this is a good precaution.

Get 8mm, bigger is usually an overkill.

Except for Accel Extreme 9000, every other plug wire from Accel is no better than a stock plug wire, if not worse.

MSD, Taylor and Jacobs are okay. Magnecor is the best and probably an overkill.

Basically what you want is normal resistance (under 650ohms/foot), temperature-resistance and RFI resistance so it doesn't fudge up your TPI ECM.

Get some wire looms (wire guides) when you are at it ($5) and some silicone grease ($3).

installation pt. 1

When you buy new plug wires, they will be in different lengths. To fit them properly on exhaust manifolds (routing under the manifolds, not over) install them in this order:

shortest wires go to:
7,8,6
longer:
5
longer:
4
longest:
1,2,3

On a stock thirdgen with all emissions stuff and A/C, you'll probably be able to comfortably reach only #1 from the top. The rest you'll reach from under the car. If the old wires have been there for a while it will be a pain to take them off. You'll have to tug on them (grab the boot, not the wire itself!) until they come off. Patience is necessary.Watch out not to damage the spark plug.

new spark plugs

If you are putting new spark plugs, torque them at around 24 ft/lbs using a torque wrench (if possible). Apply a little of anti-seize compound ($2) on the plugs before putting them in, it will make your life much easier when you need to take them off. The new spark plug gap with unmodified ignition should be .035 (+/- .003).. someone correct me if I am wrong.

If possible, use AC Delcos, they are the cheapest and safest bet and they work just fine, especially if you are going to install aftermarket ignition later, use a blower or whatnot.

Do not use Splitfires (they simply suck on our cars) and do not use Accel Shorty U-Groove's (the plug wire boot comes off by itself after some vibration no matter what you do).

wire installation pt.2

Before putting the plug wire boot on the spark plug, apply a thin coat of silicone grease on the inside of the boot (use a screwdriver or something) -- try not to put grease on the metal contact inside the boot. This makes removing the plug boot less of a nightmare and prevents arcing, RFI and moisture from entering.

Make sure to press the plug wire boot hard against a spark plug (press the top of the boot if it's a 90* or the whole end of a boot if it's a straight boot) until you hear a click.

Same goes with connections to the distributor cap. They have to be pressed all the way in, hard and firm until you hear a click.

If the plug wire didn't make a click, chances are it's not making proper contact and it's responsible for missing.

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wire routing

If you still have stock exhaust (manifolds), route the plug wires around and under the exhaust manifolds. Remember, if the wire touches the manifold it will burn through and become worthless. Use wire looms ($5 a set) and zip-locks to prevent this from happening.

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cap

any aftermarket cap should do (brass endings).

To install, uninstall unscrew the two screws holding the cap in place. Either use a thick #2 or (better) use a thin hex-socket. The back screw will be hard to reach because of the firewall. Use a short screwdriver or combine some adapters to reach with a hex-socket. In the latter case, tape your adapters because you don't want things to fall into hard-to-reach places in your engine compartment.

You should apply a little silicone grease to the inside center tip of the new cap, to prevent corrosion. Tighten the cap down firmly, you don't want moisture entering.

#1 should be around 5 o'clock (as AJ mentioned)

The firing order is 18436572, in clockwise direction, so this should be enough to install the plug wire boots (don't forget to make them click!).
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rotor

any aftermarket rotor should do (brass endings)

The rotor will fit only one way, because the distributor shaft has a groove that points toward the cylinder that needs to fire.

Did you push the rotor all the way down?
They are somewhat tight when new and usually you need to press them down hard. After pressing down really hard, I put a screwdriver handle on it and hit it a couple of times with a ratchet just to make sure it's down all the way. It should have no more than a 1/10th of an inch clearance.

Apply some silicone grease around the rotor tip and wait a little bit (a minute) until it dries off. This prevents RFI trouble and makes it hard for spark to arc somewhere where it's not needed. It also slows down corrosion.

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Okay that should be it. Comments, suggestions?

 

 

Sweeeeet this diagram is exactly what I was looking for when i did the distributer cap........

 

Excellent write up Marin.

Just a few things to add.

Instead of silicone grease, make sure it's "die-electric" grease. My major is not chemistry, so they could be the same thing. It's cheap and it's not effected by heat or electricity at all (although silicone may not be either... I don't know.)

The little hex heads on the cap are 5.5mm. Buy a 5.5mm socket and put it away in a secret spot. I've got mine in the same drawer as my mics and dial guage. That way I know where the little "one use" tool is.

Besides totally agreeing with what you said about Sh*tfire and "U" groove spark plugs, that's all. :lala:

 

Thanks AJ!

I am thinking of sending a PDF of this (and maybe HTML later on) containing all this info, together with Vader's diagram. Almost everything I wrote I learned from other www.thirdgen.org posts. Maybe we should have a newbie section in Tech Articles. I bet you we could avoid plenty of long posts.

Silicone is a dielectric grease. Dielectrics are non-conductors (prevent current from flowing), but they don't interupt the flux and are nice concentrators of electric field. Air is also a dielectric, but its dielectric property breaks down after certain voltages, which is why you have arcing -- air starts conducting current all of a sudden.

Silicone grease has a 2 to 3 times higher breakdown point than air, which means it will take a lot more voltage to get it to flow current. (Click here to get the exact definition of a dielectric.. and here to see how they work)

By putting some silicone grease on/near contacts, we actually make a small capacitor. Capacitors are, among other things, great noise reducers -- they absorb all the voltage spikes and stuff and then predictably discharge. That is why applying some silicone grease on certain areas dampens RFI (radio frequency interference)...

We also prevent air and other stuff (moisture, dirt) from entering and causing all sorts of problems. (corrosion, wear, etc.)

 

Here's what I use for spark plug wire boots, among other things. It's a Dow-Corning product, part # is {get ready for a long one} 4

http://www.dowcorning.com/applicatio...3128&type=PROD

Alot of the spark plug wire people seem to supply the very same stuff.

 

Yeah definitly a good write up for doing plugs and distributer.....wish I had it the first time I did them.......bah oh well at least now I have them and so will anyone else that needs it....Thanks a ton Marin.

 

Thanks for clearing that silicone thing up for me. It gets confusing since silicone is used for sooo many things (like bewbies).

There's one more thing I thought of to add to the write up.

Crawling under the car will shave about 1/2 - 1 hour off your time. :sillylol:

 

My car was misfiring after tune up, I just had the #4 and #8 wire mixed up on the distributor