Black51

It's gotta be the coil then.

If the rotor is not lined up but the car runs, it will just run like crap.

So I guess the next question is how does the car run?

joker2cv

The primary resistance of the coil (6 months old) is 1,2ohms instead of 0,4-0,6 ohms: could this difference justify a waek spark?

P.S. : the secondary resistance is about 6,5 kohms (ok).

joker2cv

Disconnect the ignition coil output wire at the distributor cap.
Connect a spark plug to the end of the ignition coil output wire which you just disconnected.
Connect a ground wire to the threaded portion of the spark plug.
Disconnect the ignition coil ground wire from the negative terminal on the coil (Green Wire).
Connect one end of a ground wire to the ignition coil negative terminal.
Turn the ignition switch to the ON position.
Tap the other end of the ignition coil ground wire jumper on an good grounding point (for example the battery negative terminal) and look for sparks at the spark plug that correspond to the frequency of your tapping of the ground wire.
If you have a good spark at the spark plug, the ignition coil is good.
If you don't get a good spark, check for approximately 12 VDC from the coil positive terminal (black wire) to ground with the ignition switch in the ON position. You should also get approximately 12 VDC from the coil negative terminal (Green wire) to ground



I have done the coil (i tried 2 coils) test like clark's garage suggest: i have i very weak spark at plug, while i have a big one on the jumper wire when i tap it to ground.
I have not the 12VDC on the green wire (ignition turn 0n), but 5,5KOhm to ground: what's the matter??
Please help me

Turbo17

It sounds like you do not have a good spark at step 8:
"8. If you have a good spark at the spark plug, the ignition coil is good. "
Since you tried 2 different coils, the coil is probably good.
You say you have 5.5 Kohm to ground (secondary), which is within the normal range of 5 to 7.2 Kohm. This helps confirm the coil is good.

You also say you "have not the 12VDC on the green wire (ignition turn 0n), " If it's not 12 volts, what is it? It must have some voltage on it to get any spark. If it's close to 12 volts, it's fine. If it's way off 12 volts, you need to find out why. If it's anywhere close to 12 V, I would check the wire from the coil to the distributor.

You may also want to run the engine with the lights off. You can sometimes see spark leaking from the coil, coil wire, distributor, etc. in the dark that you can't see in the light. (but be careful not to touch anything under the hood in the dark)

lee101315

Just a quick question, what is mainly wrong with the car?

I noticed once that faulty speed sensor connectors will give a weak and erratic spark.

Turbo17

I'd like to know what's wrong with the car, too. A weak spark might need to be fixed, but it's sometimes hard to judge just by looking at the color of the spark. The Clarks Garage test was a direct test of the coil, which should have ruled out a speed sensor problem, but perhaps whatever the problem is that started all this has nothing to do with the spark voltage???

joker2cv

The car is stock, and i have some hesitation when the boost starts to build up at approx 0,4bar in 3-4-5th gear. At wot it's fine

blown 944

Based on this statement I would look at the afm or tps.

joker2cv

The AFM has been tested and refurbished, TPS is new and well adjusted.
Injectors cleaned, Lambda new.....

Tom M'Guinn

Is your car actually missing and running poorly, or is your concern based solely on the color of the spark?

Your written English is better than many native speakers who post here, so no worries on that front.

joker2cv

Hello Tom, thanks for your answer. The engine has little hesitation during acceleration at part throttle when boost starts to build up: i see that is better if i disconnect The oxygen sensor plug

Tom M'Guinn

Normally, on these cars, a weak spark is more noticeable under full boost in higher gears. Does the motor smooth out and pull hard on full boost after the hestition?

joker2cv

At full boost is ok

Paulyy

100% sure i assure you the spark isn't weak

joker2cv

According to you why The engine hesitates?