hi ive a 84 rwd deville in england and just out a new 4.1 engine in it it was running fine till it snaped its new rotor arm and sort gone down hill snice then fitted a new 1 started and ran great for about a week

then went to the car and no spark again ive now checked everything inc fitting new leads cap coil rotor arm and the things inside the dissy its self

now the only thing i have found is if i unplug the 4 stud plug from the dissy it will start but not rev up ? or tick over for long

any help please cause im :banghead: now and its starting to get me down lol :suspense:

thank you if you can

Maybe it's the ignition module in the distributor, which not only supplies ignition pulses, but pulses for the injectors via the ECM, by the rotor shaft pickup wheel.

thats what sits inside the dissy cap right ? if so ive brand new one of them i did the fault codes today and got 52 and 33 if i unplug the 1 plugs when it will start but cut out

i also took the ecm out today and it looks like it may of been getting damp so im thinking maybe this is nackerd if so are they hard to get / cost alot ?

If you think you may need one, call around to auto parts places for a price. My last ECM was from Advance Auto, for around 100 bucks exchange.

my big prop is i live in england and parts for a cadillac are hard to get i have to oreder from the usa so is there any way of testing 1 ?

thanks for help everyone

A great place to buy online is RockAuto. Very good pricing and will ship anywhere. They have a website. All is new or reman, so they are reliable parts. RA will stand behind their stuff....great customer relations! Lotsa Cadillac parts there.........

First thing to buy is the factory service manual. It will keep you from replacing un needed parts. WHY DID THE ROTOR BREAK, WAS THE CAP NOT FULLY ON? ARE ALL THE ENGINE GROUNDS CONNECTED? THE MAIN ONES ABOVE THE STARTER, THE ONES ON THE ALTERNATOR BRACKET?

carnut is right, grounds can be tricky if they are loose or not torqued good. These cars have grounds all over the car, and a factory manual shows their locations.

i will double check all the grounds over the weekend as for the rotor arm we aint sure why it was fitted right was new 1 that came with car and snaped at the end all can think of was a cheap part so i fitted the old 1 back on that is fine ive checked it aint snaped again

all grounds seam to right was talking to bloke today that reckons its not the ecm

can any give me any other idea what could be wrong with it

Spark plug wires out of order? :hmm:

right ive got it running to guy that put the engine in put a earth lead in the wrong place but it wont run right at all running on about 6 and pops and farts from the carb/ fuel injector i did the fault code's and got 52 thats ecm so think its that ?

All 52 usually means is that either the ECM or distributor at one time were disconnected. If it only displays twice, its a history code and needs erased. Popping thru the throttle body means timing off or a flat camshaft. Hope for the 1st one!!

thats not good at all it was running fine till few weeks ago so dont think the cam is flat had lots power etc when fitted and done no more than 2 miles in the car snice had the new engine put in i am starting to get sick of the this car though

We need to approach this logically. "Ran fine for a week then the rotor broke" You need to determine why it broke. I think the dissy cap was not fully on. Yes I doubt the cam is flat given the new engine.
Everything I read points to timing or weak spark or low fuel pressure. Was the coil ground lead swapped over to the new cap? easy to miss. Is the basic timing at 10 degrees, green connector behind dissy disconnected? Whats the fuel pressure? If fuel pressure is low, it will run lean and pop back thru the throttle body or not rev up. Report back with fuel pressure reading and verified ground strap under the coil is there.