HT4100 4.1, 4.5, 4.9 Discussion, Fuel Injectors 94 Deville 4.9L in Cadillac Engine Technical Discussion; holy crap...ok at first there was not a spark but after about 3 or 4 secs of holding it there ...
holy crap...ok at first there was not a spark but after about 3 or 4 secs of holding it there it started i dont know what happened but it did. So i looked at both ends of the wire and made sure it was ok so it could snap on....and the end of the plug that hooked to the spark plug was bent a little so i straightened it out. To make a long story short through the climate controls i shut off #5 and it did it.....but only a little compared to the others. The other 7 make a pretty big difference in the rpms and #5 does about half as much? Thanks everybody who helped me get this far. But what now....lol
also about the high idle.....i disconnected the isc and the rpms went down to like 850 or so...they were up next to 1000 or 1050. Does this tell me its bad or needs adjusted? Gonna take it for a test drive around the block and see how shes running!
the car ran great....thanks dfbonnet whatever you told me to do did something...i dont know what but i love the basics! LOL. I washed it while i was out there i have been neglecting it a little since it hasnt been running the greatest. i think im gonna replace the plug wires again just to make sure.
Should I try adjusting the idle speed control or should I just replace it? The idle was high and I unhooked the ISC and the idle dropped to normal. Is it bad to leave it unhooked?LOL
Here's what I've done based on my recollection of posts by him who's name may not be spoken. Remove the air horn and open the throttle and look down the bores. Dirty? Spray bores and throttle plates with carb cleaner and brush with old tooth brush. Do not use a metal brush. Spray again to rinse. Do you see those two tubes down in the bores? Are they clogged up? If they are, rod them out with a piece of coat hanger wire or such. No need to be immaculate, just mostly open. Those tubes are part of the EGR system. Not germane here but a good time to check them out. Don't worry about any crud falling into the manifold. It causes no problems.
Start the car. How is the idle? Still high? While still running, find where the wiring from the ISC motor plugs into the wiring harness and separate the connection just enough so the ISC still works but the retaining clip is not latched. This is so you can get it apart with one hand. With one hand, or with a helper, advance the throttle a bit while pressing in on the ISC plunger with your finger. It should retract fully under pressure. Now finish disconnecting the ISC wiring from the main harness with your third hand. That will freeze the ISC in the fully retracted position. Let the throttle return to closed and turn off the car. With the throttle closed and the ISC fully retracted you should have about .030" +/- clearance between the plunger and the throttle. If there is no clearance screw the ISC plunger in until there is about .030". Doesn't have to be exact. Sometimes they are tight and require a bit of force. Reconnect the ISC to the harness. Disconnect the negative battery terminal to reset the ISC settings to default. Reconnect the battery and start up. If the ISC is still advancing the throttle too much it is probably defective.
I have found that GM X-66A works best for cleaning the throttle bores. It is a carbon dissolver that GM developed for top cyl cleaning. Works well, very well. See your local GM dealer... They have X66P also, it is the POUR can, the X66A is Aerosol spray.
Automobile(s): 1992 Seville STS & 1991 Sedan Deville
Re: Fuel Injectors 94 Deville 4.9L
Originally Posted by devilleman1024
hey caddy scout.....did you ever get around to changing the injectors. I have to replace one in my 94 deville 4.9 and wanted to know how hard it was? i recently found out how and did the fuel injector test and cut each injector off for 2 secs and found that the #5 injector was not firing. well i just wanted some info before i got into it. Thanks
How do you test the injectors seems I have read you can make them work by the heater controls. I dont own a fsm but I need to test mine asap.
Procedure is a bit complicated. PM me with your email and I will forward scans of the pages from the FSM. In order to get into the diagnostics, hold down OFF and WARMER on the climate control until you see it come up on the dash. Then follow the instructions in the pages sent.