Caddy 4.9 missfire tips needed

[oilslick]

I looked at a 91 coupe deville briefly to check for miss. I pulled wires one at a time since we have no scope and found 3 and 6 not contributing much. The car had to go back but I can get it back tomorrow. I notice 2 things when I hold paper close to tailpipe it slapped against it almost pulling it in momentariley and I idles a little smoother when I hold the egr valve open, I am hoping to do a leakdown check to see if I have a valve held open or burnt and or bent. I realy have no interest in pulling heads on this motor due to hearing horror stories about corrosion and headbolt threads, any tips would be appreciated to inform me correct or otherwise. Also someone looks to have just replaced an injector on #8.

 

[Zeke]

Had a '90 CDV and went through all of that. Seems the EGR valve is a problem along with the injectors. So, it then sends wrong data to the ECM and the TPS and ICV go haywire.
Fooking things are way to interdependent.

http://www.cadillacforums.com/forums/cadillac-tech-tips/167181-tb-iac-idle-air-control-valve.html

 

[asemastertech]

almost guaranteed to have faulty injectors, just ohm out the ones that are misfiring, I bet they are out of range. should be in the neighborhood of 13 ohms. I recently had one in the shop for the same issues. Replaced all 8 injectors. Cost more than the car was worth but the customer said it hadn't ran that good in a long time. Just something to check. If it need \s the heads torn off of it its not worth repairing.

 

[Zeke]

http://www.injectors4u.com/

Motor Man Fuel Injection Supply. About 30 bucks ea. Some more, some less.