I have a 2.8 mpfi in an 87 camaro. it has been parked all winter, since early october. when i parked it it ran excellant. now it won't start. no spark. battery was dead so i charged it and the charger slightly overloaded, (@18v i believe). when i tried cranking it it would start to kick but would never completely run. like maybe the spark is intermittent. any ideas? this car ran fine when it was parked, i think due to sitting something went out. i have voltage to my coil. in order what should i check from spark plug back? i have a ****ty haynes manual that isn't descriptive enough. please help! i need to get this thing running tonight!

 

well do you know your getting spark?
confirm things before going at it in the dark.
pull plug and crank with someone holding it.
Did you put "Fuel Stabil" in it before parking?
Did you put in "Fuel Anifreeze" in it before parking?

Either of those will most definately cause probs.

 

no spark, already checked. yes to stabil, no antifreeze, but fuel is not the problem, it's getting adequate fuel. i basically need to know what values i should get on my fluke meter on various points in the ignition system, so i can begin tracing the problem

 

ok if this helps, i have 12 volts at one of the four wires going to the coil. (the four wires i am refering to go into the pickup in 2 plugs, side by side, each with 2 wires .

 

is power coming out of the coil?
Is power reaching the madulator?
If so, but not raching the wires, bad module.

 

modulator? are you refering to the ignition module? i quit working on it for the evening casue it's outside in the dark and FREEZING out, but i want to make sure im not missing anything. is there a modulator too somewhere?

 

<i>I've</i> never heard of a "modulator"... I have posted a few times already though on how to check voltage at the coil. The pink/black wire on the gray coil connector should have +12 when you turn the key from "off" to "on".

 

Funny, there is an ignition module(and GM has just about ALWAYS had one, at least since the invention of HEI). Guess ya missed that?

But yes, if that is bad, nothing can get through. Most say a continuity test will confirm one way or the other. I say, if your not getting spark, thats a very likely bandit. It either works, or doesn't. You can take it out and have it tested though.

 

no such thing as an ignition moulator, it's an ignition module.....

i have checked resistances, continuity, and voltages..........

pickup coil good
module good
coils...getting 12 volts hot but not sure about teh negative signal yet......workin on that right now

 

I have heard them called by both names, but they are the same part. Thats what I get for living all over the country.

 

Funny how you'd think that I've never heard of an ignition module.

What's strange is, when a module dies, it usually won't work when it's hot. As in, the car runs great when cold, and then dies when it's hot. Car cools down, and runs great again. When you charged the battery, did you leave the key to "on"? Leaving the key "on" for an extended period of time can overheat the module, and burn it out.

Have you checked for spark right at the ignition coil, before the distributor cap?

The +12 to the coil (via the pink/black) powers up the whole ignition system. The gray/black coil connectors use the coil as a "bridge" to each other. If you check out the connectors closely, you'll see a small "A" and small "B" on each one. The gray connector's A wire connects (inside the coil) to the black connector's A wire... and same for "B".

Try disconnecting the two-wire connector from the module, and testing for +12 and ground at the module's side of the black 2-wire pigtail from the coil. You might have an intermittant on this wire that's preventing the module from getting power.

Do you have any way of borrowing a spark coil from someone? If you have a two-wire spark coil, you can wire it up to your 4-wire connections. Wire it as "gray A to black A to coil negative", and "gray B to black B to coil positive".

Does your fuel pump kick in? If not, the fuel pump/ECM fuse could be blown. This is located on the passenger side upper frame rail, near the radiator support, with an orange and red wire. If the ECM doesn't get power, the car won't turn over. Although, you wouldn't be seeing the SES light when the key's on and the engine's off.

 

whent he module dies, its gone. does not work under any condition.
It's like a switch, on or off. No in between

 

I've tested modules that would fail on the first couple tests, then pass on the next three and vise-versa. some modules start to fail when they heat up. Depends on the module itself. Take the module in to parts store & have them test it. at least FIVE times in a row. If it fails once, get a new one.

 

That's not true. I had an 89 Vette the other week where the motor ran OK under 1500 rpms but above it ran like $hit. When the engine hits about 1500-1800 rpms, the module alters timing depending on load and MAP readings. This one wasn't doing it right. The 'scope pattern was perfect until 1500, then it went haywire.

Cliff Notes: Module bad, car still ran.

 

Well to put it another way, everyfailure I have found, it either worked or did'nt. No in between. When it failed on one of my 2nd gens, it took me forever to find out what was wrong(then I also was not that into cars at the time). I had a freind pull it and do a continuity test, and it failed. He said replace it, I did, and ran great for 3 years till I sold it(the car).

 

OK FYI, DID MY RESEARCH......MODULE CAN ACT UP AT SOME POINTS AND NOT AT OTHERS, SO IT'S NOT LIKE A FUSE THAT EITHER WORKS OR DOESN'T, IT'S NOT CALLED A MADULATER OR ANYTHING ELSE ANYWHERE, IT IS AN IGNITION MODULE IN OHIO AND AN IGNITION MODULE IN CALIFORNIA, IT DOESN'T CHANGE, AND JUST BECAUSE POWER IS GOING TO THE MODULE AND NOT THE COIL, DOESN'T MEAN THE MODULE NECESSARILY IS BAD. FOR EXAMPLE...MODULE IS GETTING POWER, WHICH IT DOES ANYTIME THE IGNITION IS ON, BUT NOT THE SIGNAL FROM THE PICKUP COIL, WHICH IS ON THE DISTRIBUTOR, THEN THE PROBLEM WOULD NOT BE IN THE MODULE, EVEN THOUGH IT'S GETTING POWER BUT THE PRIMARY COIL ISN'T.....

 

Ok FYOURI, I could care less. As I said, I have never came accross one that, "choose" to work sometimes, but not others.
Everyone that I have come accross that was questionable,(when engine refused to start) the module was bad.
On the ocassions that the car ran like crap sometimes but not others, the module was fine, and it was something else.