car runs rough, rough idle, stumbles upon accelerration

abelincoln

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i own a 1989 lincoln mark vii lsc, maybe someone out there can help me or encountered a similiar problem. First of all car idles rough also stumbles upon acceleration, occasionally backfiring. At first i thought timing chain, but it checked out. i also pulled the spark plugs one of them the #5 was fouled, and i found fuel in the crankcase. obd 1 codes koeo 34, 31 koer 91, 34, 12 egr has been replaced, along with position sensor, also idle air control replaced, these variables have been removed seems like a leaking fuel injector to me, i never checked fuel pressure, dont have a gauge. oh by the way fuel pressure regulator seems ok (no fuel in vacuum line) Any help or input would be appreciated. i dont have much experience with computer cars, what would be the best way to go about solving this problem without throwing money at the problem. any similiar experiences out there ?
 
i own a 1989 lincoln mark vii lsc, maybe someone out there can help me or encountered a similiar problem. First of all car idles rough also stumbles upon acceleration, occasionally backfiring. At first i thought timing chain, but it checked out. i also pulled the spark plugs one of them the #5 was fouled, and i found fuel in the crankcase. obd 1 codes koeo 34, 31 koer 91, 34, 12 egr has been replaced, along with position sensor, also idle air control replaced, these variables have been removed seems like a leaking fuel injector to me, i never checked fuel pressure, dont have a gauge. oh by the way fuel pressure regulator seems ok (no fuel in vacuum line) Any help or input would be appreciated. i dont have much experience with computer cars, what would be the best way to go about solving this problem without throwing money at the problem. any similiar experiences out there ?


Abe,

Might try checking the spark where you had the fouled plug. If you have spark then try a different plug in that cylinder. Another thing you could try is to disconnect the injector wire to see if that makes any difference. Let us know what happens. Good luck
 
i own a 1989 lincoln mark vii lsc, maybe someone out there can help me or encountered a similiar problem.
...
Welcome.

Since you want to correct this without throwing parts at it, you're going to have to throw test equipment at it.

Digital voltage and continuity tester.
1172223410-63280200.jpg


Fuel pressure guage.
auto-tire-pressure-guage-dial-TP5KS.jpg


Timing light.
56-TimingLight.jpg


Non contact thermometer.
T490.jpg


With these four things, you can test almost any system in the car. When you get em, we'll walk you through testing and replacing needed items.
 
thanks everyone

just put about 6 fresh gallons of gas in it. i still have the problem of fouling out plug# 5 though. thank you!
 
thx

Abe,

Might try checking the spark where you had the fouled plug. If you have spark then try a different plug in that cylinder. Another thing you could try is to disconnect the injector wire to see if that makes any difference. Let us know what happens. Good luck

took spark plug out blew it out checked it out it gets spark when dry, but after a minute or so gets fouled out with fuel! thx any more suggestions let me know!
 
Welcome.

Since you want to correct this without throwing parts at it, you're going to have to throw test equipment at it.

Digital voltage and continuity tester.
1172223410-63280200.jpg


Fuel pressure guage.
auto-tire-pressure-guage-dial-TP5KS.jpg


Timing light.
56-TimingLight.jpg


Non contact thermometer.
T490.jpg


With these four things, you can test almost any system in the car. When you get em, we'll walk you through testing and replacing needed items.

cool thanx, i have a timing light and i used it, timing checks out. i also have a continuity/ voltage/ digital multimeter( i wouldn't know where to start with this though) I will buy a pressure gauge and thermometer this weekend. i will keep everyone posted. maybe you can let me know what to check for first. More history: I also did a compression test, good compression in all cylinders. Would my next test be to check fuel pressure? i keep scratching my head, is it an injector or something else? i really dont want to take apart the upper part of the engine if this could be something else. ha ha you guys are the pros anything you suggest i will try. im so used to the older carburated cars this is all new to me, but im trying! thx again!
 
took spark plug out blew it out checked it out it gets spark when dry, but after a minute or so gets fouled out with fuel! thx any more suggestions let me know!

sorry i forgot about disconnecting injector wire, i will try it this weekend i will tell you what happens thx again!
 
...
ha ha you guys are the pros anything you suggest i will try.
...
"Experience is the ability to recognize a mistake before you make it again."

I've only made more mistakes than you.

The only things left for you will be the fuel filter, voltage regulator, rotor and cap, wires, plugs (properly gapped to .050).

Search here for TUNE UP to get the operating parameters for these items.
 
looks like the previous owner replaced voltage regulator, but i will double check it. plug wires are good( tested them) cap and rotor already replaced, plugs are good except for #5 smells like gas and is fouling out. i will check fuel pressure this weekend. thx for the help! i will post test results sunday thx again!
 
I had the same problem with my 1990 mark vii lsc. it has 180,xxx miles on it and it would be very erratic with the idle, and sometimes stall. my problem was fixed when i changed the tps sensor (throttle position sensor) and set the timing. I also just changed my plugs and noticed that #5 was the only bad one. I am assuming mine is a piston ring since i also have oil coming through my throttle body. I am buying a rebuilt block, trans, and driveline from an f 150 for $250. Try a compression test to see if there in lies your problem about the plug. As i said for me the tps and 15 degrees timing fixed my idle problems.
 
i own a 1989 lincoln mark vii lsc, maybe someone out there can help me or encountered a similiar problem. First of all car idles rough also stumbles upon acceleration, occasionally backfiring. At first i thought timing chain, but it checked out. i also pulled the spark plugs one of them the #5 was fouled, and i found fuel in the crankcase. obd 1 codes koeo 34, 31 koer 91, 34, 12 egr has been replaced, along with position sensor, also idle air control replaced, these variables have been removed seems like a leaking fuel injector to me, i never checked fuel pressure, dont have a gauge. oh by the way fuel pressure regulator seems ok (no fuel in vacuum line) Any help or input would be appreciated. i dont have much experience with computer cars, what would be the best way to go about solving this problem without throwing money at the problem. any similiar experiences out there ?


I know excatcly what the issue is. There is a 2" hose in the gas tank that is connected to the fuel pump witch is located in the fuel tank.
 
sorry i forgot about disconnecting injector wire, i will try it this weekend i will tell you what happens thx again!

In addition to checking your timing, use the timing light to check EACH wire for spark. No need to point it anything in particular. Just use it to proove that juice is actually going to EACH plug.

Now would also be a good time to physically check your firing order. It might look right but it can still be two wires off and run.
 
I didn't see where you had resolved the issue, so I thought I would throw an idea out... Sounds like you have a leaky injector on that cylinder. Over time, the injectors can build up deposits on the nozzle, and be prevented from fully closing. Also, the seal in the nozzle could be bad.

I had the same problem, and swapped it out for a spare injector I had. It ran great afterwards.

This is a problem I've had on my Mustangs forever.
 
Have you resolved the problem?? Does car run any better after its warmed up and at correct operating temperature?? I have a simular problem but after my car warms up, it runs fine.
 
issue not resolved yet, put this project on the back burner thanks for all the ideas, when the weather breaks i will get back on it
 
try swapping the number 5 injector with another cylinder, if the new cylinder with that injector is fouling plugs then you found your problem. also check your ignition module i had this type of problem on a mustang, it kept fouling the number 7 plug only, i took a module out of another mustang and plugged it in and ran it for a week with no problems so i ended up buying a module and that solved it.
 
hey abe, i had the same problem with my lincoln. i threw plugs, wires, cap, rotor, timing adj. and everything else at the problem and nothing worked. my last ditch effort before an engine swap was a head swap. turns out my problem was a couple pushrods and a tweaked valve. it runs like a champ with the fresh heads on now.
 
As of this writing, Chicago is like 25 degrees F and Philly is like 30.

I think that doing it now wouldn't be a good idea for a Dude with no heated garage :)
 
Hey Abe, before you do anything too drastic, check your EGR valve. Sounds like it stuck open. Easy fix for about $85.
 

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