I did some searching but I still have some questions about replacing one or more injectors on a 94 Cadillac Deville with 4.9L engine and 140K miles. We want to get around 30-40K more miles out of this car and we only use it for road trips so this means about 10 years.
I recently replaced the head gaskets and also removed the fuel rails and cleaned the intake before reassembly. (PS thanks to everyone here who helped me, the suggestions from this website helped alot). The car runs great except I now notice that the fuel used is about 20% more than what the computer indicates. I kept careful records over a recent 1000 mile trip. It used to get 24-25 highway mpg's but on this trip it only got around 21. These mpg's are from my own calculations not the computer.
I checked the regulator with engine running and it does not leak. I will check the injectors this weekend by pulling the fuel rails up and energizing the pump. I suspect that one or more injectors will be dripping. So here are my questions:
1. Is it best to replace all injectors if one or more is leaking?
2. Do I need any special tools to take the injector off the rail? And to replace.
3. Do I need any other parts besides the injectors? I put new o-rings on when I did the head gasket job, can I reuse these?
4. What is the best price I can hope for and where do I get injectors at this best price!
If you start hearing any tapping at all, that is a good sign that they are pretty bad. You can take them off and look, but find out the proper torque to torque them back, do not guess!! Use a torque wrench!
In my opinion, any car over 100K is worn enough to replace. Probably the only way to check is to get a new one and measure it compared to an old one. They are aluminum with steel arms rubbing on them with lots of force. It wears fast...
devilleman1024 said:
to check just take off the vave cover? How will i know if its worn?
I didnt get a chance to get back on here yesterday to get your advice on checking the plug after 5 sec. I will be sure to do it in the morning. I did get a chance to check the compression and it was around 195 in #5.... no burnt valve thank god! Im going to change the cap and rotor in the morning and if that dont do it...maybe I got a bad injector its possible since I did put a used 1 in....should have spent the $90 for a new 1. The guy I got it off of guaranteed it would work so he will replace it. I should have known the 1 that was in my car looked better then the 1 he gave me. Is it possible its a computer problem? Could the comp just shut down just 1 cylinder if it was bad or would it do it to all? Thanks for all the help guys.
I didnt get a chance to get back on here yesterday to get your advice on checking the plug after 5 sec. I will be sure to do it in the morning. I did get a chance to check the compression and it was around 195 in #5.... no burnt valve thank god! Im going to change the cap and rotor in the morning and if that dont do it...maybe I got a bad injector its possible since I did put a used 1 in....should have spent the $90 for a new 1. The guy I got it off of guaranteed it would work so he will replace it. I should have known the 1 that was in my car looked better then the 1 he gave me. Is it possible its a computer problem? Could the comp just shut down just 1 cylinder if it was bad or would it do it to all? Thanks for all the help guys.
First, you can not go by appearances alone, the injector will either work, leak, or remain dormant. A brief start of the engine, then stop, pull the plug inspecting for wetness. Wetness is a good indication of misfire.
The computer will not shut off only one cylinder. There is no program for that.
195 compression from a single cylinder test tells you nothing. The proper way to run a compression test is with all plugs out, and test all cylinders. The difference between the highest and lowest reading should be less than 20%. 10% is very good for an engine with over 100K miles.
Getting the engine to fire on all cylinders should be your goal for now. You can purchase a set of NEW injectors later from eBay or Five-O. There is nothing wrong with keeping a good used part, especially if it fixes the problem.
So if I have a problem in that cylinder testing that one wont tell me anything...doesnt make sense...but what does. All I did is what I was told check the compression in that cylinder. Getting this thing running on all cylinders in definatly my goal I wouldnt be doing all this if it wasnt. By the way what is a normal compression for each cylinder with around 130,000 miles on it. Do you think im on the right track with the cap and rotor and also checking that plug after a short run? Any other advice? Thanks.
Testing a single cylinder for compression is like brushing one tooth. If that is all you have, then it is adequate.
It would be wise for you to also clean the throttle body and EGR tubes while the engine is down for maintenance. Be sure your negative battery cable is disconnected.
If you have a factory service manual (FSM)
It would be wise for you to check the calibration of your throttle position sensor (TPS) and idle speed control (ISC). They work hand in hand together and should be checked for proper calibration (within tolerances). This procedure can be done without running the engine.
I was told if I have a burnt or stuck valve that I would have low or no pressure in that cylinder and that why I tested that one since that is the only giving me trouble. I will be getting a manual soon so I can do some other repairs. I already cleaned the throttle body and egr tubes
I was told if I have a burnt or stuck valve that I would have low or no pressure in that cylinder and that why I tested that one since that is the only giving me trouble. I will be getting a manual soon so I can do some other repairs. I already cleaned the throttle body and egr tubes
If the injector is the issue just go to a junkyard and get a set of orange topped, injectors from a 91-up Town Car, Crown Victoria or Grand Marquis. They fit right in and work perfectly. Then you never have to worry about another one failing. The ones that are in your car now are the Denso injectors, the orange top ones that the ford 4.6 uses are the Bosch equivelent. I just recently tried this on a car I bought to resell and they work perfect.
See thats my problem I dont know if it is the injector. Like I said before I know its getting juice because I unplugged the #7 injector and plugged the #5 into it and it fired so I know theres power. Whenever I get motivated enough ill go out there and pull the plug to check for fuel on it to know if the injectors firing. I better do it before football starts or ill never get to it. lol. Thanks for the advice next time im out at the junkyard ill pull a set and put em in.
See thats my problem I dont know if it is the injector. Like I said before I know its getting juice because I unplugged the #7 injector and plugged the #5 into it and it fired so I know theres power. Whenever I get motivated enough ill go out there and pull the plug to check for fuel on it to know if the injectors firing. I better do it before football starts or ill never get to it. lol. Thanks for the advice next time im out at the junkyard ill pull a set and put em in.
Have you tried holding the spark plug wire next to the exhaust or another ground while its running and see if it will shoot a spark out. Compare it to another wire that is firing.
sorry guys just got done mowing the grass im pulling the caddy in the garage right now and trying some things that you have suggested ill get back to ya in a sec....keep em coming. Thanks for the help
Ok I pulled the spark plug and yes it does smell of gas and looks wet. I also put the plug wire right up next to a solid ground and no spark. I even switched 5 wire with 7 just to see if I got a bad wire and still no spark. I think im gonna run to the auto parts store and pick up a dist, cap and rotor.
Ok I pulled the spark plug and yes it does smell of gas and looks wet. I also put the plug wire right up next to a solid ground and no spark. I even switched 5 wire with 7 just to see if I got a bad wire and still no spark. I think im gonna run to the auto parts store and pick up a dist, cap and rotor.
After you get the situation retified, you might want to change the oil and filter even if it has been 100 miles ago. All that fuel going into the cylinder is ending up in the oil.
Yeah I just got the cap and rotor yesterday and it is still not working....i dont know what else to do. Are you serious about the fuel into the oil....I really hope not because its been like this for a while now and I hope it aint gonna mess nothing else up.
Yeah I just got the cap and rotor yesterday and it is still not working....i dont know what else to do. Are you serious about the fuel into the oil....I really hope not because its been like this for a while now and I hope it aint gonna mess nothing else up.
You know, you can check the injector operation somewhat with a stethescope. You can hear it. Listen for the ticking.
Do you have a timing light? Connect it to #5 and see if it is triggering the light.
Are you missing a tooth on the pickup coil in the base of the HEI? If so, it will miss forever and you will never be able to fix. Look for the 8 poles on the dist shaft inside the distributor. Make sure all 8 are there.
Since that cylinder is on the front bank I would do a compression check if you havent done one. I would do one even if you have done one just to make sure. Your beating a dead horse if a a valve isnt working properly. The one directly next to it is cylinder 7, do one on it and then one on five.
If you start hearing any tapping at all, that is a good sign that they are pretty bad. You can take them off and look, but find out the proper torque to torque them back, do not guess!! Use a torque wrench!
In my opinion, any car over 100K is worn enough to replace. Probably the only way to check is to get a new one and measure it compared to an old one. They are aluminum with steel arms rubbing on them with lots of force. It wears fast...
Can you connect a volt meter across the injector connector contacts?
You should see readings on the AC scale. DC will be erratic, AC should be smoother, and a decent reading, around 1-2 volts. The dwell meter might read better yet. Put on the 6 cyl scale.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Cadillac Owners Forum
4.8M posts
369.7K members
Since 2002
Cadillac Forums is the perfect place to go to talk about your favorite Caddys including the ATS, CTS, SRX, Escalade, LYRIQ, Vistiq, concept and future Cadillac models.