I am dumbfounded car is running like sheetz

[phrogs]

Ok so I just moved to PA this weekend and my car is going to be my daily driver for at least a month or until the snow shows up.


I have had an issue with #6 cylinder not firing, I thought it was a coil pack or the injector or the plug wire. I tested the coil with my sisters pontiac grand prix it uses the same coil and the car ran great, problem is the coils are not
burried on the top of the engine like the LT5 my plug wire tested just fine as well so figured injector no problem I have extras.

So im on a time crunch because I had to get on the road swaped in a new accel injector and it was fine until the car heated up on the drive about 50 miles into the trip.

So after the car got hot I felt like I lost a coil pack but its hard to say I know what one cylinder not firing feels like but this was worse very sputtery The car can get up to speed but not like it should and I can not even use 6th gear the car will vibrate me right out of the seat.

I am so pissed at this car because I just had it apart the other day thinking my problem was the #6 injector now it seems the coil may be the problem, but I am getting spark at the wires..

I guess im venting its so hard to figure this out without a code being set!


So now I have to wait on my AC delco coils and spark plug wires to be mailed
from home because I forgot them! :-({|=

so is it
coils?
wires?
DIS module?
ECM?

If I lost spark to a cylinder wouldn't I get a rich code?


man where's my matches:icon_scra

[sammy]

i had a similar problem. one cylinder not firing when the car was warm . coils seem to show up bad when they get warm . thats what mine did i replaced the coil with just a autozone coil and all is now well . id be willing to bet that once that coil gets hot it starts not working . and yes you can have only one side of the coil go out . i got that info from jerry as it happened to him . hope this helps

[tccrab]

Johnny:

Any chance someone's been testing the resistance of the injector coils by back probing the ECM plug?
http://www.zr1.net/forum/showthread.php?t=10828

TomC
'Crabs

[phrogs]

man I do not want to find out I burnt a valve in this thing I checked compression this spring when I intitally started to work on it and it was within limits but not a bad idea to check it again.


And yes you are right the coils can go bad on one half!

but this feels like 2 cylinders are out.

[phrogs]

Johnny:

Any chance someone's been testing the resistance of the injector coils by back probing the ECM plug?
http://www.zr1.net/forum/showthread.php?t=10828

TomC
'Crabs


yes I did do that but I used pieces of safety wire wraped around my leads so I would not do that (learned that from my avionics mechs). Doesnt mean is wasn't done before me though.

[XfireZ51]

If it's 2 cylinders, can you identify and do they correspond to the pairing on coils? When you replaced coil, did you make sure there was only 1 gasket on the underside before plugging into ignition coil housing?

[Aurora40]

If I lost spark to a cylinder wouldn't I get a rich code?
It would show up as very lean, because no oxygen was consumed by combustion.

I think with the way the ECM averages stuff out, it would simply result in the car running richer on the other cylinders.

I could see the lean spike pretty clearly on my wideband O2 though when I had a coil pack crap out.

Like you, it was hard to diagnose. I saw spark at all cylinders when I was in the garage testing it, and it drove fine at very minor throttle. But then broke up terribly at speed and when giving it gas.

[Paul Workman]

Failure of coils/windings with heat is a classic symptom. If not an injector, then the coil comes under the microscope.

(From the FSM)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/LT5coils-2.jpg

NORMALLY (the operative word) the current flow in a lost spark configuration is constant - i.e., current in series (circuits) is common to all components in series. However, when the (lacquer) insulation on the windings begins to break down (in an ignition coil) arcing occurs, and we no longer have a series circuit anymore: suddenly there are other paths for current to take (to the iron core, for instance). This why we sometimes see only one plug not firing in a lost spark coil - the spark takes the path of least resistance, and can bypass a one of the two plugs.

There are other scenarios too, but my point is you don't have to have both plugs misfiring for it to be a bad coil. One plug MIGHT be a coil, and failing with heat is, as I said, a classic symptom of electrical coil breakdown.

One other note, in case anyone is still awake after reading this far, using standard digital volt-ohm meter to "ohm out" the coil windings often will not result in locating a failing coil. The reason is the standard volt-ohm meter operates at battery voltage levels, whereas the coil's shorting often only occurs when the voltage reaches a level sufficient to arc. A special volt-ohm meter called a MEGGER (http://dictionary.babylon.com/megger/) is used to test high (wire insulation) resistances - but not many of us have one of them in our tool boxes. But, IF you detect a fault with a standard volt-ohm meter(!), then there has been sufficient insulation breakdown to allow physical contact between the (coil) wires themselves.

If I may toss in one more ditty... Resistance across the spark gap of a plug increases with chamber "air" pressures. As deterioration of a coil winding's insulation progresses (with heat or whatever) arcing to ground can/often become the path of less resistance and the plug spark gap is bypassed (shorted). Hence the reason for a plethora of high-voltage (ignition) problems showing up only when under relatively higher levels of stress: at low throttle it is OK, but miss occurs at heavy throttle.

Sorry for the "Electricity 101" :blahblah::blahblah:

P.

[GrayZ]

JOHNNY.... I hope this helps.....:cheers:



http://i76.photobucket.com/albums/j9/kmoudy/20071001-002820.jpg

[phrogs]

you have more electrical knowlage in your big toe than I ever will

I just try to keep the smoke in the wires haha.


guess I may have lost more than one coil or with how bad this is running perhaps the DIS or the ECM or perhaps I have some pins bent or bad conections somewhere because it is deffinatly a problem that is electricly caused like I have a complete failure of something somewhere, on my drive here I could feel it and hear when the part stoped working and the car just became a bigger pile of dung.

I do not want to throw parts at this car..

Failure of coils/windings with heat is a classic symptom. If not an injector, then the coil comes under the microscope.

[phrogs]

If it's 2 cylinders, can you identify and do they correspond to the pairing on coils? When you replaced coil, did you make sure there was only 1 gasket on the underside before plugging into ignition coil housing?

Thats something I will have to check, I did not change these out yet they are old set that I checked the resistance on and they were good, they are original ones with the silk screen numbers on them or at least till they stoped making them, I replaced the cracked screamon deamon coils that were on this car.

[phrogs]

makes me thirsty! Women and their bugs!


JOHNNY.... I hope this helps.....:cheers:



http://i76.photobucket.com/albums/j9/kmoudy/20071001-002820.jpg

[phrogs]

I have no codes nothing!

I do have my spare ECM with me so I will throw it on as well and see what happens.


This may be of interest http://www.zr1.net/forum/showthread.php?t=12637

TFENT in San Diego has tomtom72's ECM at the moment which it turned out was the issue :cheers:

You have NO codes?

[TFENT]

I still have to conclude my ventures with my Z in my thread, but in short it was a combination of things but the main cause of my problems I believe was the PCM not firing some cylinders. It seems as though several parts failed all at once in my case...

My new PCM just showed up and after I install the starter relay and fix the no crank, due to me washing the motor, I will return Tom's PCM.