Poor idling 89 Excel

Hi, I'm a newbie here and have a query about my daughter's 89 Excel which I bought as an abandoned car last year - it won't idle smoothly and gas consumption is poor. It is quite low mileage (88,000kms) and was parked up unused for about a year or possibly longer. The mechanics say the compression ratios are very high and suggest the rings are gunked up. I have added 2 lots of oil treatment to disolve the sludge and done 2 oil changes and changed to 98 octane fuel at their suggestion also but to no avail - it still runs on (diesels) when it is swithed off and still won't idle smoothly. I have exchanged the carb for another "fresh" one off a recently running Excel and no difference. Has anyone any other suggestions? It doesn't appear to be burning oil and runs okay at highway speeds but is a nightmare to drive at slow speeds. It is an auto. Hope someone can help.
Cheers.

I have an 89 Excell with about 75,000 miles on it and it idles extremely smooth. Poor idle can be a vacuum leak, a bad or burned valve, an EGR valve that doesn't close, a bad spark plug, bad wires, a bad distributor cap, a bad rotor, or a million other things. First, if a vacuum hose is broken or disconnected the idle can be poor. You need to listen closely to see if you can locate such a problem. Try and get a diagram of the vacuum lines to be sure they are all in place first. Sometimes a vacuum leak can be heard, sometimes not due to the fact that the engine is misfiring. Next, one by one remove a wire from each of the spark plugs to see which one is missing. If you remove a wire from a spark plug and there is no difference, chances are that this is a failing cylinder. Now, check the wire, the plug and the connection at the distributor cap to make sure they ae connected good. Remove the spark plug and inspect it to see if it looks alright. You can swap it with another known good spark plug to make sure it is firing. Replacing the wires, plugs, distributor cap, and rotor would not be a bad idea and not a big expense which will eliminate a lot of time troubleshooting as well. Before you run out and get your vacuum guage to check and see if the valves are working properly, make sure the EGR valve is closed at idle. You can just about see the diaphragm of the EGR valve by looking at through the holes in the front of the EGR valve. Goose the engine while you or someone else checks to see if the diaphragm moves at all. You can remove the EGR valve with two screws and lock it temporarily to see if the idel improves. If it does, either the EGR valve is stuck in the open position or ther is vacuum going to the EGR valve at idle when it shouldn't be. This is enough to get you started. Hope this helps. Good luck!
Frank
Hi, I'm a newbie here and have a query about my daughter's 89 Excel which I bought as an abandoned car last year - it won't idle smoothly and gas consumption is poor. It is quite low mileage (88,000kms) and was parked up unused for about a year or possibly longer. The mechanics say the compression ratios are very high and suggest the rings are gunked up. I have added 2 lots of oil treatment to disolve the sludge and done 2 oil changes and changed to 98 octane fuel at their suggestion also but to no avail - it still runs on (diesels) when it is swithed off and still won't idle smoothly. I have exchanged the carb for another "fresh" one off a recently running Excel and no difference. Has anyone any other suggestions? It doesn't appear to be burning oil and runs okay at highway speeds but is a nightmare to drive at slow speeds. It is an auto. Hope someone can help.
Cheers.