Backfire makes me think ignition system (coils are part of it) or timing.

 

I wonder how do you test the coils?

 

I think the mechanic needs to isolate the cylinder(s) that are missing. He should have an engine analyser to plug into the computer. Once that is done then I would just replace that coil because the plugs and wires are new. Of course he should look at the plug again once he knows which one it is.

 

One of the issue's we have had is it doesn't do it all of the time. Oops, two things, It only does it under load.....one of those where you wish it would just break......

 

Coils usually fail under load.

 

when facing ignition issues, i usually dont bother with diagnostics since
such is time consuming and if you are paying someone, EXPENSIVE.

my approach is to replace all the standard stuff AND THEN see what i got:
plugs, wires, coils, ignition module, distributor cap & rotor, fuel filter, air filter,
(easy for me to say, i only have ONE coil .... )

and i also disconnect each injector and dielectric grease connectors,
clean the intake trottle, set timing, new drive belt, etc ...

also, my '88 has the capability to TEST each injector by way of the
dash D.I.C., so i do that also.

all that is really faster than testing at $90 / hour.
it is even cheaper.

 

[quote]ORIGINAL: Stealth


also, my '88 has the capability to TEST each injector by way of the
dash D.I.C., so i do that also.

all that is really faster than testing at $90 / hour.
it is even cheaper.

[quote]

The 94 should have this capability as well, my 98 does. Good suggestion Stealth.

 

What bothers me about this issue is when you remove the EGR valve the problem dissappears. The problem points in this direction as if it is vacuum related. I cant fathom that I cant find a mechanic in Dallas that hasn't had experience with this problem on a Cadillac. I am getting real close to selling the car.....cheap.

 

OK, I spoke to a couple of Cadillac service people that said they had no experience with that particular problem. But, for $121.00 an hour they would take a shot at it......
Another thing that I have noticed is depending on the level of fuel in the gas tank the problem is worse. Also, Three times now the car has died when I have been stopped for a traffic light, light turns green, accelerate and turn left....No codes and no indication of a problem...It drives me crazy to, that you have to stop the car, put it in park before it will restart....
I really like this old car and hate to get rid of it....

 

you dont give us much to go on.
we dont know what has been done,
low tank or full tank makes worse? which one?

insufficient data ...
however, lets see .. the posibilties.

EGR ?
low fuel / full tank? emissions fuel tank line?
M.A.P. ?
vacuum lines?
fuel filter?
coke buildup in throtle intake?
ISC ?
primary wires ? you did check engine compartment in the dark .. right?
distributor ? capacitor unit within?
u did check the firing order .. right?
cracked spark plug ?
whatever the case, its gonne be a $20 part ... bet on it!

coils rarely if at all, show failure at idle. under load or cold start, yes.




.