Curse of the Weak Orange Spark

[Desert Patina]

Hello,

Its been like wrestling an Octupus, nailing down arm after arm.

So now I have everything together, Everything electrical is off-the-shelf (not necessarily new because its been sitting for a while, but straight off the shelf) from ECU to engine harness (modified from an '89), to distributor, PIP, TFI, COIL, battery and ignition switch. Oh, and a 3G alternator.

Its been almost two years since it ran, and now its up and going on about 1-2 cylinders.

I've checked voltages, and checked the spark. I think the only thing I've seen that is at all suspicious is that it has an orange spark about 90% of the time.

The first cylinder is really the only one that fires when it starts, and then when the revs get to the point the alternator kicks in another cylinder (I'm assuming its #4 because it starts to feel balanced) kicks in and starts revving more freely but still missing.

Each cylinder is getting gas, I smell it when the spark plug is out. Each fuel injector lights up with a NOID, and the fuel pressure is almost 40 lb.. Each cylinder gets spark, but they all get the mostly orange spark. Spark plugs are gapped to around ~.32-.33.

I tested the resistance and voltage at the coil (at standstill). All of those look fine as well.

Brand new rotor and cap on the distributor as well and wires.

[Raven855]

Are the terminals in the cap aluminum or brass? I have had issues with missfiring with the aluminum terminals. What shape are the plug wires in? What kind are they? What is the voltage that you are seeing at the coil? Check the coil grounding, especially with reference to the battery.

[Desert Patina]

Thanks for helping.

The rotor and cap were selected because they had brass terminals. The plug wires were right off the shelf, a 8mm Car-Quest brand.

The voltage at the coil is about 90% of what it is at the battery itself, and over 12V (its analog 50V is the closest range I can get, and that is the best I can do for precision). The resistance between the coil ground and the negative battery connector is zero.

[MikeFleming]

My first thought is the plug wires are instelled in the incorrect order.

Second thought was moisture inside the cap but you probably wouid have seen that already..

[svono50]

Have you tried firing up the engine in a dark lighting scenario? This would help you see any spark plug/coil wire leakage, where you will find a 'glow' or spark coming off the wires rather than putting all the power to the plug. One other thing, make sure the tang on the rotor is in contact with the coil terminal pin in the cap.

[Desert Patina]

Yeah, no water in the inside of the cap, and no light show in the dark.

However, there is plastic spread over the cap where the coil terminal comes in at the center, the place where the tang of the rotor would touch. It looks much like a rivet spreads at the bottom of a hole. Its probable 1/16th to 2/16ths at some places. I'll get a pic in the morning.

[Raven855]

Many parts are shipped with a light coating of cosmoline, usually a waxy type of substance, on them. Be Sure and wipe down those parts, with an electrical cleaner, as it can act as an insulator.

[svono50]

Yeah, no water in the inside of the cap, and no light show in the dark.

However, there is plastic spread over the cap where the coil terminal comes in at the center, the place where the tang of the rotor would touch. It looks much like a rivet spreads at the bottom of a hole. Its probable 1/16th to 2/16ths at some places. I'll get a pic in the morning.

Interesting, would like to see a pic of that to see what you have. I have seen that center pin be both fixed and spring loaded, depending on the brand of cap. I prefer the models with the fixed pin and let the tang on the rotor take up any gap/movement.

Glad to hear no light show, but that may be due to very low energy being sent out from the dizzy cap. Have you checked your coil's spark capability? Just be careful how you hold that wire, it can give a pretty good kick.

[MikeFleming]

However, there is plastic spread over the cap where the coil terminal comes in at the center, the place where the tang of the rotor would touch.

I think I read somewhere that plastic is an insulator.

Maybe switch to your backup dist cap?

[Desert Patina]

Here's the pic of the inside of the distributor cap. At the top, where the coil terminal is, there is a plastic hemisphere that is the friction point for the top of the rotor. I'm going to shape the rotor cap tang so that it angles more and gets closer to the brass ring and try again. (Before it was probably angled away from the ring by the time it was compressed down, I'm opening the angle up more so that it angles up and into that ring).

[MikeFleming]

Very hard to tell from your pics . In my spare cap, there is a small, round, radiused graphite-colored thingie in the center hole. That is the conductor that the spring portion in the center of the rotor presses against to make electrical contact. Make sure the spring thingie in the center of the rotor contacts that black thing.


Img_1954.jpgImg_1955.jpgImg_1956.jpgImg_1957.jpg

[Desert Patina]

Yes, that is what mine looks like, and I have wear marks on both the rotor and that graphite ball.

I also tried switching the firing order (just in case) and switching out the cables. The long and short of it is that no matter what cable I try, only the first cylinder really fires enough to start when that is in the right position, (sometimes a second one kicks in from I don't know where if I can rev it high enough).

I'm going to change out the cap and rotor.

Thanks again for y'alls help.

[TheSVOTrust]

You are going to make me come out there again AREN'T YOU !! Really mad we didn't get to together in Jan (again) now. You would be driving!

Mark

P.S. Is the ground on the driverside inner fender from the negative cable?????

[Desert Patina]

The ground is there, I even replaced the bolt with something bigger and shinier just to be sure.

I replaced the cap and rotor on the distributor.

Unfortunately no change. Still just the first cylinder is firing.

[svopony]

just thinking out loud........... I know it could be dangerous but have you looked at the pip or the ignition module on the dissy????????
Bar

[Desert Patina]

Well, I do see the noid light working on all of the injectors, I'm told that validates the PIP.

We also checked at the coil wire terminals with a test light, which I'm told verifies the TFI?

Update:

It roars occasionally now, revving freely and as far as I can tell on all cylinders. And even when it doesn't (about 80% of the time) instead of just the first cylinder firing I get a more traditional random missing. I reseated the injector wire connectors (my mechanic friend noted the 4th had come loose). I also replaced the ignition coil.

The spark from the coil is clearly orange and weak (maybe some sparkly white at the edges of the spark) when gapped at 3/8ths of an inch.

When I did the 3g upgrade, I might have used the red-lightgreen wire from the coil to splice as the 12v ignition/start into the voltage regulator on the new alternator. That wouldn't affect this would it?

[MikeFleming]

When I did the 3g upgrade, I might have used the red-light-green wire from the coil to splice as the 12v ignition/start into the voltage regulator on the new alternator. That wouldn't affect this would it?

It certainly won't help. If i understand correctly which wire you used (has two wires into the coil?) then that's the TFI side of the coil and NOT the power side.

In any case you want the reference wire to the alternator voltage regulator to go *directly* to battery - not through assorted voltage drop thingies like the ignition switch and small gauge wires.

[Desert Patina]

Well, the good news is that I didn't splice the voltage regulator on that wire. I actually spliced it into the green-red wire that turns into a thicker white wire at the old voltage regulator.

So 1 & 4 are firing well. After running it, 1 & 4 exhaust ports were very hot, and 2 & 3 were only mildly hot.

I'm still wondering what I can do to get a better spark at this point, and what might make the inner 2 so intermittent. Perhaps their Fuel Injector circuit is sketchy? I'm not even sure how they share the same circuit and work to be honest, but my instinct says that is a red herring anyway.

I've ruled out the spark plug wires, distributor cap and rotor simply by changing them out and by testing the spark at the ignition coil right before the cylinder.

I still have codes 23, & 82, 83 (even after building a new EGR solenoid vacuum system for it). I have a better multimeter now to re-calibrate the TPS with, so I can do that again no problem. The solenoid itself was from a junkyard, so I could imagine I simply need to buy a new one.

Does the TFI cause a weak spark at all? I thought it was more of an off or on kind of thing.

Also I am driving it to produce a 3/8ths inch long spark, perhaps that is more gap than I should be using to test with.

Thanks again for the support and help.

[MikeFleming]

Testing spark beyond 0.100" can damage coils - the internal voltage is too high. So 3/8 is way overkill.

Work on fixing Code 23 - TPS out of Range. That does NOT mean it's mis-adjusted - most likely means there is an open spot in the sweep range.

Ignore 82/83 codes. This only shows you have an LA* EEC and didn't add the appropriate additional solenoids or resistance loads.

PIP, TFI, coil & associated wiring are the only things that make spark. In that order.

I recommend to always replace PIP and TFI at same time.

[Desert Patina]

Thanks. FWIW, I know the TCS needs re-adjusting because I put a new one on and tested it just a week or so ago. It swept cleanly.

However, I was never very confident in the low-voltage setting because it was done on an old analog multimeter which didn't have the calibration or precision to work in the 100ths of a volt with much confidence.

Do you happen to know how the injectors fire individually while being on the same circuit? I'm just curious.

thanks again,