low spark?
 

So I've been working on this car for months on end I broke down and put a rebuilt motor in it and now I'm a very weak spark from my coil packs. This making my car not start timing is good spark plugs and plugs wire are good brand new I sanded down where the coil packs go for a better ground still nothing anyone got any ideas?

The coil packs don't ground through the mounting bracket. You need to make sure your ecu grounds are good. The main ground is bolted directly to the engine below the intake. Also check for battery voltage on the B/Y wire on the leading coil pack when the ignition switch is on. Are you sure it's getting fuel?

The engine harness bolts to the engine for your ground that's correct but your chassis harness is the one that runs your coils and it has a bad ground somewhere hopefully not under the dash

Bump grounds are good checked them yesterday the CAS and coils have continuity to the ecu but still have low spark I have the spin the CAS 3 times in order to get 1 spark has anyone else had this problem?

im woundering if the ecu could be in limp mode, im not sure exactly but the problems your describing have happend to me before and i re-did all of my grounds. got rid of hesitations but i still had my flooding issue.

anyone have a pic of a 87 NA engine wiring harness. i dont know if ive looked hard enough but i cant seem to find it..

thanks

Desperate bump no mods or any wiring gurus ever had this problem? 1 spark for every turn of the crank angle sensor? I'm desperate I need my car up and running for deals gap any help would he greatly appreciated

Every 3 turns of the CAS 1 spark

Sounds like the ECU is loosing sync with the CAS. What condition is the wiring? Has it been modified? Anything not stock?

I'd suggest trying a new CAS first...

Just a guess but check the cas. where it plugs in sometimes the pins push back making a poor connection . Just a thought .:)

I've tried several CAS and same thing is happening also swapped out the leading coils twice same thing also changed out the plug on the to the CAS and no difference the wiring is all stock no mods or cuts in it and I've tried 3 different ecu's and the same thing is happening

No one on this forum has ever had this problem? What are the odds it happens to me

Maybe you need new plugs and wires?

Haha I have brand new Denso plugs and brand new street thunder plug wires

Let's start from the beginning...How do you know you have a weak spark? FC coils are quite robust, almost never fail, and are not weak. :)

Because I took out the plug and turned the key and its not sparking like it should then turned the key to the on position and took out the CAS and spun it manually I get 1 spark for every 3 full rotations of the cas Idk if you would call it weak spark but definitely irregular

In what condition is the wiring from the CAS to the ECU? The CAS wiring meets up with the front harness near the starter. Plugs clean, wires in good shape?

The CAS runs at half engine speed.

It sounds like you've tried replacing everything but the coil pack itself. Since the ignitor is also in the coil pack, and they are available used for around 20 bucks, might be worth a shot.



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I have tried 3 different sets of coils the odds of them being bad are slim

Well you have tried pretty much everything but were the parts being swapped in ever checked to make sure they are good ? I still think you have a poor ground or poor connection in the ignition system . maybe a broken wire inside the insulation check them for continuity with a meter .

I might get a blast for this but does the cas have or did it have a condenser screwed to the side and is it or was it hooked up or not to a live with ignition on wire . ( there should be a connector at the cas for it if it has one )

When I built my direct fire ignition iI found the hard way that if the pickup wires in the cas are reversed it will make a very weak and off timed spark . Just a thought :)

Do you have a picture of what your talking about because I don't know what you mean

Ok forget what I said about condensers it doesn't apply and wouldn't stop it from running anyway ..

You said you changed the cas and the plug if you changed the plug you either changed the harness or you removed the wires from one plug and plug into another . the cas plug and the harness plug have a different color code I was just thinking maybe you mixed them hooking them up . I'm surprised you can hold the cas in your hand and make it work I thought they needed to be grounded .:)

Bump update so I spent all day ecu OS good CAS is good changed out the engine harness for the third time only problem is my signal from the CAS and ecu to the coils is slow Idk anyone got any ideas