I think you may have broken part of the vent system to take battery fumes away from under the seat. See my previous post of March 6.

Have you checked your air and fuel filters?

 

See I Dont thinks the fuel & air filters are the problem...
Whats your battery rated at?

What do you know about the ignition module?

 

The coils mount on top of the ignition module but when you look at the coils you think it is all one assembly. Each of the 4 coils comes off and the ignition module is there. It can't be serviced, just replaced.

 

I found the following while searching the web:

"I had a customer's '96 Cadillac Deville with a 4.6 Northstar engine with one of the less common but difficult to find problems I run across. It is a coolant sensor circuit that went askew intermittently. This problem usually results in hard starting because of over-fueling cold; however, as the engine warms up, the sensor begins reading normally. Connection issues and corrosion problems have a tendency to become worse as the cold affects them."

 

Thanks for you help....
but I might have to rule out the cold thing, because it happened when it was 70 degrees....
Anyhow... I think I might try the ignition module.... those are probably pricy huh?

 

Any ideas ?

 

IMO, Katz has it right. connections, voltage and fuel.

this may sound silly, but after reading 4 pages of back and forth posts,
i be changing fuel filter ($5 parts + 12 minutes) TONIGHT.
it only takes one bad batch of fuel to shut you down.
i highly suggest you just replace it, dont even bother checking it.

if that does not fix it,
i be checking the fuel pressure on the fuel rail.
next i be checking the grounds and applying dielectric grease to
every connection you touch.

if that doesnt fix it,
let us know if you have FIRE on the plugs when it wont start.
REAL IMPORTANT to know that. WHEN IT WONT START ...

i know jack about the N*, but an engine is an engine and
a fuel delivery system is .... ditto ....

also, i cant figure out if you changed or tested the coils, but unless all
four coils failed at the same time, the engine should start and stay running.

lastly, IMHO, i would lose that DELCO ASAP and get a GEL.
i will NOT use anything but a GEL when the battery goes in the passenger
compartment. someday i may start a BATTERY THREAD and you
will understand more, but not now. if that DELCO releases fumes under the seat,
or leaks, not only your seat belts will fail, but the upholstery will crumble. if you
think a battery is expensive, compare that to the cost of those items.



.

 

i suggest you go and read what may be the best thread in this site.

https://www.cadillacforum.com/m_6068/tm.htm

the impact of the subject there shuts down thousands
upon thousands of cars .. and it may be affecting your car ...