I am talking about a 91 Trans Am with a 305 TPI 100% stock (only a throttle body by pass made)

Well, all come from thre weeks ago. One day it was very hard to start in a very cold night, but after 3 or 4 times start, and not happen again.......

until this thursday. It crank but not start at all. Only spin the engine.
First check out, put new distributor cover and rotor and voilá..... start, I warm up it, all sound ok, shut of, close the hood, and not start again. This was yesterday.
Today between 10:00 AM and 17:00, I crank it a lot of times and start normaly..... well, I went to the city, park it in the street about hour and half, and not start again . Now I had the coil, and the spark timming module ( this one inside the distributor) from a running car of a friend, but the problem persist. I had to call the assistance to carry it to home.

Now in home, I check it with scanner. All sensors work right........ TPS, IAC, MAT, MAP........ I only find one thing that I don't know if it is normal or not.
When I crank, with engine spinning, the scanner says 0 ms to the injectors. I don't know if this is normal when cranking or not,

After this I check the coil input, right, 12,2V with ignition on, 0V when ingnition is off. Put a new spark plug in the coil wire, at the distributor side, cranking, and there are not spark.

Now are the questions,
What can cause the coil dont give spark ocassionaly?
Are there any relay that can cause this fault, with a good know coil and spark timing module what could be?, ecm?, prom?

I forgot to tell that there aren't any error code at all, and the scanner also says that the VATS system is OK.

Thanks for read all this . and double thanks for any idea

 

'asturYou may have a reluctor coil going bad on you. This coil is inside dizzy and tells ignition module when to fire. Bad reluctor coil will cause both spark and injectors not to fire. You can check it with DVM - very easy.//RF

 

Thanks, I was thinking that those coil only was the "mecanical" advance by ecm orders.
Only a few months ago I had problems with a 87 Iroc-Z advance, and this coil was the culprit, but those time problem was with the idle only.

I will replace the coil and tell

 

I was thinking about.......
You are talking about this, isn't it?

 

fran

Yep that's the coil - just get a DVM, set to measure resistance and measure coil resistance. Most of the time they fail open. On very rare occasions magnet gets demagnetized. But measure coil resistance first - it should be around 500 to 1500 Ohms depending on application.

To replace this coil you'll have to remove dizzy from engine, remove dizzy gear by punching out cotter pin, remove shaft, pull the shaft out to get access to this coil.

//RF

 

Well, this is what ready the coil, as I think it is good, but, yes, this is an ocassional fail, perhaps this time the engine could start......... . Anyway, I bought the coil, and hope arrive in two days. I will put it, and see what happen.

I seen when just conect the ohmeter terminals that the value don't was fix, move up and down between 1,35 and 0.65 k ohm.(aprox.) during about 15-20 seconds until stay in this 0.93 k ohm. Could this be any symptom?

 

Hmmm - let me check readings on my spare distributor, but generally readings should be steady unless rotor is turning. When rotor is turning - rotor magnet rotation will induce current in reluctor coil which will affect measured resistance readings.

//RF

 

Well, problem is partialy fixed. As you said, was the coil pick up, but I had an extra problem when I was replacing it.
The distributor axle between the bushings had a lot of rust,and was very hard pull it out. I had to knock with a hammer, and the magnet on it loosse and broken for one side, from the hole to out. I didn't make any pic becouse I didn't have my digital camera with me. I mount all with the new coil anyway, and crank the engine. This time run without problem, but the spark advance is crazy, and the rpm was up and down like a old farmer diesel engine with only one cylinder
Now, I am waiting for a new distributor from Ebay, I didn't find replacement for this part, so, I this I will waiting about other week and half to can drive the car another time. This is the bad part of live in Spain

 

Fran

Ouch!!! Distributors do not like being hit with a hammer, but what is done is done. Lesson learned! I have seen distributors get stuck to the intake manifold like you described.

Before pulling your dizzy out for the last time make sure that you mark location of rotor tip on the body of the dizzy. As you pull dizzy up the rotor will rotate counter clockwise. Mark final location also. By marking these two locations it will make easier job for you when inserting new (ebay) dizzy. This way your initial timing is going to be very close to what you had originally. While dizzy is out do NOT turn your engine!

Life in Spain is not that bad, but traffic is hideous in Madrid - that I know first hand.

//RF

 

If I want to pull out the axle I only could make this. Rust on the axle didn't want to pass throught the upper bearing. I know that I could broke anything, but had take the risk...... and anything broken.
About instructions to pull out dizzy, thanks so much, that is just like I make it, but I only mark firs location.

I live in north of Spain, here traffic is not than hard than in Madrid, but here, american car fans like us, are crazy to the rest of the people they prefer to pay about $300+ for any issue with the european cars becouse his cars have a good gas mileage (most of them diesel), also when most of people here only make less than 10.000 milles at year.

 

Fran

Let me post couple of pictures. I have short block and intake manifold sitting on an engine stand in my garage. These photos will make your life a lot easier.

You can NOT remove rotor shaft without removing distributor from the engine. Once you see photos it will be self explanatory.

//RF

 

of course, I removed the distributor to change the coil, My problem was when I pull out the axle of distributor after dissasemble the distributor gear, that pic was taken before remove the distributor.

 

Aghhh - OK ---> Good show.

I took some pictures just in case, but since you are getting a whole new distributor my pictures are somewhat redundant. Having rotor position marked will make setting initial timing a lot easier once new distributor arrives.

I have experienced difficulties removing distributors before. There are couple of tricks to make this job easier and less frustrating. If you look at distributor - there is a square pedestal just below main plate. In the past I've used adjustable wrench to crab a hold of distributor body at that point. Here in USA we have a plethora of such wrenches - Channel-Locks, Wise-Grip, Robogrip and many others. Some of them have positive lock and hold capability. Once locked - give couple gentle taps with small hammer - rust, crud and etc will break loose almost immediately.

//RF

 

Remove the distributor itself was not a problem, the problem was pull out the rotor shaft off of the distributor body, after remove the botton gear. There was a lot of rust and dirty between the bearings of this shaft, and I am hiting to pull out the shaft when the magnet loose and broke. Once the magnet broke, it gone out of the shaft, and them, I pull the shaft to botton (gear side), and come out with the botton bearing, Then,I clean all very good,and mount again, but with the broken magnet engine run, but very very bad.

 

problem finally fixed. Past Tuesday arrived the new distributor, mount it, set timing at 6º and run........

Thanks for the replys