1983 caddy coupe sputtering while driving

Hello Friends,

I am not a mechanic but not totally in the dark either, my problem is
my 1983 caddy coupe de ville 102,000 miles and the worst engine by caddy corp. 4100 .

Here's the problem, while I'm driving all of a sudden (mostly when I come to a stop light) the motor drops in rpms and will start to sputter, when I take off it has no power although the motoris revved up high but only reaches about 25 - 30 mph .

then the car will cough and will run fine again, this is what I'm thinking

1. cat. converter is clogged
2. fuel filter is dirty and clogged
3. fuel pump going out

am I on theright track , or did I leave anythig out any info will be GREATLY
appreciated.

thank you , carleton

well if you had a clogged cat you would see it have a harder time the higher up your speed got and you woul'nt really be able to get up over around 50 MPH depending on how clogged it was.

If the fuel filter was that clogged you would be lucky to see the car get going. No matter what the throttle is at the fuel pump is always pushing at the same strength. It is the regulator and the injectors that determine the fuel flow.

If Your fuel pump was going out you would see problems at other times as well not just in this one condition.

I can't help but wonder if you have a bad Thottle position senso a bad coolant temp sensor or a bad vacuume line on your car. Do you have an engie light on.
Any other info you can give us is greatly appriciated. Last tune up. Any recent parts replacement. Have you checked for codes? I though you could access them on the older Caddies by pressing the off and warmer buttons on the HVAC control. joe allen wrote:well if you had a clogged cat you would see it have a harder time the higher up your speed got and you woul'nt really be able to get up over around 50 MPH depending on how clogged it was.

If the fuel filter was that clogged you would be lucky to see the car get going. No matter what the throttle is at the fuel pump is always pushing at the same strength. It is the regulator and the injectors that determine the fuel flow.

If Your fuel pump was going out you would see problems at other times as well not just in this one condition.

I can't help but wonder if you have a bad Thottle position senso a bad coolant temp sensor or a bad vacuume line on your car. Do you have an engie light on.
Any other info you can give us is greatly appriciated. Last tune up. Any recent parts replacement.




Joe, there are no engine lights on at all it will all of a sudden start sputtering, very hard to drive as of today 3 / 30 /05 .

Top speed was about 45 mph replaced alternator ,roundlast october well what i would do as a quick test is climb under the car undue the two bolts holding the exhaust on th the exhaust manifold pull it away and take the car around the block. See what you get at top speed.


This is a quick test that will tell us alot. Let me know what happens. Since your last post i have more reason to suspect the cat is your problem. Guru1 wrote:Have you checked for codes? I though you could access them on the older Caddies by pressing the off and warmer buttons on the HVAC control.


Thanks I found how to find codes but can't find out if it is pvc,egr,tps or what NOT EVEN CADILLAC DEALER isn't that some crap.
well for some reason i got a code 7.3 H E L P

THANKS carleton Hi carleton, I just read your post and being a Caddy tech wanted to say that you may have activated the switch tests because there isn't a code 7.3
As for the fuel injector firing one side what I do is is switch the connectors on the injectors and if the other one now works then test the wireing and ecm for a problem. If it still doesn't spray then the injector may have shorted out. There is an old service bulletin on that condition. If you need more help then repost and I'll try to help. Bill Sounds to me like you may have water in the fuel tank. When a spot of water goes into the intake it will cause it to spit, sputter, then cough...then run ok until another spot get into the system. You said:
"then the car will cough and will run fine again"
I'd at least remove the fuel filter, hold the fuel in, then empty it into a clear container and see what comes out...might surprise ye.

Have you disconnected the battery cables recently or changed the battery?

If so you may need somthing as small as a crank relearn or an IAC relearn.

Reply on the batery part please. Hey thank you for responding, my battery have not been disconnected or changed, shortly after i e mailed you i went to library to find a book ( chilton 28260 ) to try to get an idea of the self diagnostic funtion this car has, found out i was just doing switch tests, book suggested i might have a vacum , or egr problem , and now as i read it might be more. well i changed the vacum lines that i could BUT , there is one port i can't identify. there is a triangular shape connection thats is missing its hose.
I followed the one line that leads to the front of car to a large canister on passenger side, 2nd line went to small skinny metal tube I can not for the life of me find out where that 3rd line goes to. I also replaced the lines on the breather (both of em ) I also read that the diaphragm on the egr should be able to be pushed up , well it is solid not budge, and the vacum signal tube is clogged solid tried to unclog with paperclip, no penetration at all.... and now car only goes about 35 40 mph and back fires , just started back firing day b4 yesterday... thats whats going

GM_Mech_319 wrote:Have you disconnected the battery cables recently or changed the battery?

If so you may need somthing as small as a crank relearn or an IAC relearn.

Reply on the batery part please.
thank you for responding I will check out the filter also found out there was a recall on gas filters on my model car so that will be looked into... do you think cadillac dealer will honor the recall ... i was gonna e mail and ask.... all they can say is NO

also thanks for the link to you site ... you will have a new member

Tommy Sessions wrote:Sounds to me like you may have water in the fuel tank. When a spot of water goes into the intake it will cause it to spit, sputter, then cough...then run ok until another spot get into the system. You said:
"then the car will cough and will run fine again"
I'd at least remove the fuel filter, hold the fuel in, then empty it into a clear container and see what comes out...might surprise ye.

Hi carleton, With the vacuum hoses 1 short hose goes to the metal tube behind the plug. The second goes to the air management valve near the RH valve cover and the third continues to the front of the engine.
Recalls are a safety issue that the dealer is required to inspect and replace parts as necessary without regard to time or mileage unless it is specified in the recall. For example in '85 we had to install a recall carb part on a '76 caddy carb. that was creating higher than normal emmissions.
Sounds to me like you will be replaceing the egr valve because it should push up with finger pressure. Caddy has problems where the 2 egr tubes in the intake manifold below the throttlebody carbon up and the repair is to remove the throttlebody and drill them out.
As for the backfiring are both your injectors firing now and what is your fuel pressure. The spec says 9-12 psi but if it isn't 12 then running problems will start to happen. They have a pressure tap on the fuel line behind the throttlebody to screw a gage onto. Did you get any codes after pressing off and warmer? Keep us posted. Bill Hi carleton, With the vacuum hoses 1 short hose goes to the metal tube behind the plug. The second goes to the air management valve near the RH valve cover and the third continues to the front of the engine.
Recalls are a safety issue that the dealer is required to inspect and replace parts as necessary without regard to time or mileage unless it is specified in the recall. For example in '85 we had to install a recall carb part on a '76 caddy carb. that was creating higher than normal emmissions.
Sounds to me like you will be replaceing the egr valve because it should push up with finger pressure. Caddy has problems where the 2 egr tubes in the intake manifold below the throttlebody carbon up and the repair is to remove the throttlebody and drill them out.
As for the backfiring are both your injectors firing now and what is your fuel pressure. The spec says 9-12 psi but if it isn't 12 then running problems will start to happen. They have a pressure tap on the fuel line behind the throttlebody to screw a gage onto. Did you get any codes after pressing off and warmer? Keep us posted. Bill friday 15th, today i looked at the book and tried to go according to diagram and it was all bad... any way i'm changing to how you are describing here... cause it won't stay started... NOW about injector wires I switched em over and the one the one that was working ... now is not and vice versa... will keep you posted on progress ,any more ideas let me know

thanks again i SINCERELY appreciate your help

carl




willnick wrote:Hi carleton, With the vacuum hoses 1 short hose goes to the metal tube behind the plug. The second goes to the air management valve near the RH valve cover and the third continues to the front of the engine.
Recalls are a safety issue that the dealer is required to inspect and replace parts as necessary without regard to time or mileage unless it is specified in the recall. For example in '85 we had to install a recall carb part on a '76 caddy carb. that was creating higher than normal emmissions.
Sounds to me like you will be replaceing the egr valve because it should push up with finger pressure. Caddy has problems where the 2 egr tubes in the intake manifold below the throttlebody carbon up and the repair is to remove the throttlebody and drill them out.
As for the backfiring are both your injectors firing now and what is your fuel pressure. The spec says 9-12 psi but if it isn't 12 then running problems will start to happen. They have a pressure tap on the fuel line behind the throttlebody to screw a gage onto. Did you get any codes after pressing off and warmer? Keep us posted. Bill
Hi, Sounds like you need a wiring diagram to tell where the wires go at the engine computor module connector to determine if the wire is open or the ECM is bad. Disconnecting the ecm connector with the key off and then useing an ohmeter at each end of the wire...you will need a jumper wire to extend a meter lead...make sure they aren't open. There are times that at the bulkhead connector at the firewall that you loose the connection because they put alot of anti-corrosion stuff in there and after awhile it causes a poor connection. If it is determined that the ECM is bad then you will need to test the injectors resistance to make sure they are ok and not shorting out. Keep us posted. Bill