Hey all, i have a problem that is similar to what roym was experiencing. at times my 97 sable 3.0L 12 valve vulcan engine 225,00 kms runs rough. for the most part if i let it run for 5 minutes before i take off it is ok. if i try to take off right away when i start it it has little power and bucks. if i hit the gas while it is doing this it will like backfire. at times when i am driving on the highway it will be running perfect and then it will start to buck a little. if i kick the gas peddle down to like passing gear it will kick in and then it will be ok. i took it in to the garage, being in canada i dont have the luxury of getting a free reading anywhere so i have to pay. anyhow, they hooked the computer up and it said that the cam sensor was the problem. you could see the top of the synchronizer was broke. so i picked up a synchronizer and sensor at the scrap yard. well imagine this, i still have the problem. i think the previous owner took out the check engine light bulb because it doesnt come on even when i start the car but if it were working i am sure it would be on. i have to take the cluster out to replace the bulb. i have changed the plugs, fuel filter, air filter. i did not change the plug wires. i was wondering if the oxygen sensor is bad if this could cause the problem? i had a 97 tauris wagon with the same engine and i had to change the o2 sensor but it did not cause the engine to run rough or anything when it was bad. i realize that no 2 exact engines perform the same. i am going to check all hoses and wires that i can to make sure they are ok. when i first got the car when i was sitting at a red light it would run very rought and act like it weas going to stall. someone told me to change the mass airflow sensor so i did and that solved that problem. now the rough running is mostly when the engine is cold but at times when it is hot. any ideas and info would be greatly appreciated.

 

O2 sensor can cause rough idle, but the cam sensor would cause the backfiring. If it's not backfiring any more, with as many km as is on the car, you may want to change the O2 sensors as well. If the garage gave you a list of the codes your car was giving, check it out for EGR codes as well. Fords like to clog up their recirculation pipes (as well as many other brands - it's kind of a generic thing on high mileage vehicles). Check the vacuum lines as well. Air getting into the engine other than through the intake can cause all kinds of headaches. You may need to change out the wires as well to complete the top-end tuneup you've already done so far.

 

hi slymer, i took the cluster out and replaced the check engine bulb, someone did remove it. i assume because the cam sensor was bad and the light was likely on. now when i start the car the engine light comes on and it goes out like it should so i guess thats the good news. on all my other fords, when the o2 sensors were bad the engine light came on so i will assume this one is the same so i guess the o2 sensors are ok. i checked the air and vaccum lines and i dont hear any air leaking anywhere, i almost wish there was. i am going to replace the pcv valve on tuesday. dont know if that could be the problem because its plugged up. whern i shake it i hear the rattle so not sure. i guess i'll replace the plug wires next week as you suggested to complete the top end tune up. if i take it in and have them run a diagnostic again will it show up if its a vaccum line or something like that? thanks for your reply to my post

 

vacuum lines won't show up on most diagnostics if it's a small leak. the only way to really tell is to get a propane tank (be very careful if you do this) and just open the valve a little and slowly move the end of the hose around the vacuum lines. if the engine speeds up (for no good reason) that's where the leak is. When you are done, leave the hood open and let everything breathe for a while so that the propane dissipates.

and yeah, since the check engine light isn't coming on, it's not the O2 or the EGR stuff.

With the way it's acting, I would almost think it was a loose connection somewhere or the ignition module, ignition coil, wires. It could also be fuel injectors. Try a bottle of fuel system cleaner if you haven't already with your next tank of gas. If the engine is stumbling due to misfire, it will store those codes and they can be read by anyone with an OBD-II code reader for Fords. I really would be surprised if all the parts shops don't read codes for free. but different countries have different means of getting customers into their stores I guess. Of course, the shop diagnostic should have picked up a faulty ignition module if that was the problem. so I'll stick with the wires as the next thing after the injector cleaner. (yes, injector cleaner or fuel system cleaner or seafoam motor treatment - directions on the bottle for fuel treatment... many folks I know have had very good luck with the stuff).

 

thanks slymer, i'll change the plug wires on tues when stores are open again. i put in a container of injector cleaner with my last fill up. i will try the fuel system cleaner also. and next time i fuel up i will try a higher octane fuel. i'll check what wiring i can again. i will let you know next week. thanks very much for your help

 

good luck. Hope it just some weak spark due to the old wires and new ones fixes it right up.

 

just out of curiosity, would a weak spark cause the engine to running perfect one minute while cruising along the highway and then all of a sudden start bucking. if i hit the throttle down it usually settles down and is ok till it does it again

 

it could because unburnt/slow-burn fuel may build up in the cylinder as carbon and revving the engine up some will help push the excess carbon out and allow better burn for a while.

 

coolfool,

I had exactly all the same problems you have with your Sable. I brought it in about 2 months ago to the shop, the computer code said 'cylinder 1 misfire'. They couldn't pinpoint the problem other than cleaning out the plug. The problem went away for about 3 or so weeks. Started acting up again and brought it in today. They went through every plug wire, checked the coils, wires, everything and still couldn't find the problem. But, he did recommend having the computer reprogrammed or replaced. I don't remember the exact term.

Would this have any help slymer? Since this was done at a private shop, he couldn't do the computer work. Have to take it into the dealer. Any ideas how much this would cost if it would even work?

 

not a clue how much it would cost. I've never heard of anyone having to reprogram the engine computer. replace sensors yeah. if the plugs are fouling then there's a reason for it. how was the plug fouled? if it's oil, you may need new piston rings (or just get some hotter plugs and burn the oil). it could also be a pinhole crack in the head gasket or very minor warp of the head causing oil to leak into the cylinder. if the plug was corroded, there's probably a coolant leak through the head gasket.

fixing any of these things is not cheap (labor intensive). If it's simply a sensor (like a cam sensor that flaking) then it's the cost of the sensor and usually minor labor. Definitely would need a dealer or other certified mechanic with the diag computer to check it out to help narrow it down. The only way to find out the cost of the diag would be to call the dealer/shop.