1987 Mercury Cougar XR7 5.0

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1987 Mercury Cougar XR7 5.0

May 20, 2014, 08:28:40 PM

I am getting codes 12, 41, and 91, I know what they mean but what could cause this? I have replaced a lot of parts except ECT and neutral safety switch. I do get a bang some times when trans shifts in to overdrive and when she goes in reverse. All vacuum lines are good, looks like I have volts to TPs, egrps. When warmed up she will stay running today was 70s and she would not stay running. I smell gas, and no smoke out exhaust. Any ideas? Thank you...

1987 Mercury Cougar XR7 5.0

Reply #1 – May 20, 2014, 10:54:12 PM

Your iac is either not working or your idle is adjusted improperly.

both codes 41 and 91 says system lean. what's your fuel pressure?

1987 Mercury Cougar XR7 5.0

Reply #2 – May 21, 2014, 12:38:45 AM

better said is.....
how is your fuel presure while driving the car.
you need an extender hose attached with the gauge duct taped to the windshield.

fuel pump pres will cycle down and up in between gears.
if between first and second the fuel pres goes lower than 25psi, start questioning the pump.

check your spark is nearly white/blue and if not, the ign or pick up module is going out.

1987 Mercury Cougar XR7 5.0

Reply #3 – May 22, 2014, 07:07:23 PM

Code 12 could be IAC right? Do not know fuel pressure, replaced fuel pump about 2 years ago. Pump sounds good and shuts off and then comes on when car does run. When running down the road I will push pedal down with a little hesitation and then she will go with no problems. Its when she is cold and warming up she doesn't want to stay running. It said in book that code 91 is o2lean and ss1 shift solenoid, (neutral safety switch) I am guessing. Just replace dizy pip and control mod, plugs wire cap and button, ignition coil. I will check spark to see what color and to look at plugs and see whats going on. Funny thing is I just remember when I had a cd player, amp and subs installed shortly after the car didn't want to run right. The factory amp had to be unplug because it would mess up the new amp and radio because of the common ground. I wonder if a ground to the factory amp being open is to blame? Don't think so but I seen some weird things over the years. Car does have cold air intake and flowmaster true duals but been on car for 10 plus years with no problems. thank you

1987 Mercury Cougar XR7 5.0

Reply #4 – May 22, 2014, 08:38:26 PM

My tbird when my buddy owned it drove fine with no miss and 12psi of pressure. didn't figure out anything was bad until he couldn't pass emissions.

don't worry about a "nss". If the car starts, its not your problem.

fuel is controled based on input esentially from three sensors. your map sensor (which should throw a code), o2 sensors (which IS throwing a code), or ect (which isn't throwing a code.

you also have not one, but two lean codes, and without a map sensor code more likely than not your either missing injector pulses (which would also throw a code) or you have fuel problems, possibly spark, but if you had a spark problem, it would probably be reading rich not lean.

i forgot to tighten two spark plug wires on my old 88 crown vic (same motor, eec, ect) and never noticed a problem till i did plugs before emissions the next year and found one plug touching the exhaust. i got comments constantly about how much power and how smoothly the engine ran, before i fixed it.

id try an engine cylinder test as that is cheap/free and will tell you if you have an actual problem. if the results are incosistant or highly variable, id he willing to bet on a fuel problem.

anyone can throw money at junk and swap parts. to do a good job you need to know what's wrong, and the computer is trying to tell you!

1987 Mercury Cougar XR7 5.0

Reply #5 – May 23, 2014, 06:24:07 AM

Andy codes 91 Left bank lean and code 41 right bank lean tells you that your engine is lean. This can be caused by low fuel pressure a vacuum leak or bad injectors. Or anything that controls the mixture. And low compression is another issue on small ford engines. Low compression can alse cause it in some extream conditions. I had one last year and posted it on here. So always check compression on a small ford engine it is important. I would check the fuel pressure as low pressure will cause that and also a bad fuel filter or split in tank connector hose. Anytime the fuel pressure drops off you will get a lean code and if it drops lower than lets say 20 Lbs it might not even start. When the in tank hose splits and fuel pressure falls below app 20 Lbs you will most likely have a no start and if it starts the car most likely will not drive but may run like if it can run at all. I have seen this many many times in my career and split hoses are very common on these cars. So concentrate on a lean mixture and a vacuum leak. The IAC issue is most likely a miss adjusted min idle setting. And dont forget to check the TPS voltage and it should be at somewhere around .6 VOLTS. I never run any TPS higher than .6 volts in my builds. have a good day Guys.

1987 Mercury Cougar XR7 5.0

Reply #6 – May 23, 2014, 08:03:48 AM

the hesitation mentioned.
the injectors have tiny tear drop fuel entry screens.
start a small screw in the top of each injector
with pliers pull real hard and out comes the injector filter.
replace with new ones or dont put any in at all.~i dont put them back , i just replace my fuel filter more often like 3 or more times a year duing random oil changes.
99% of our members disagree with me not putting injector screens back but after the 1% try it, they never forget to say thanks for the suggestion.

above, tom is talking about the small 2'' long oem supplied / installed fuel pump hose. you may remember the in tank pump has a small section of rubber hose that transitions its output up to the exterior fuel supply fitting. Nearly half of the people here have learned this hose cracks and the fuel pump is dumping fuel back into the tank rather than providing 100% flow/presure up to the regulator.

oh yeah,, pluck the vac line off the regulator and look inside and see if it has moisture (which is fuel), and if you see this then the regulator rubber diaphram has a pin hole.
if you have a hand held vac pump, with the car off, just remove the regulator vac line and pump your hand held unit up and verify the regulator *holds* suction.
while your at it, perform the same test on your EGR vac line fitting.

Above tom also mentions the TPS...
with key on only, prob the green wire with a stick pin and with your red meter lead attched to the green wire and your black attached to battery ground, verify you have .6 to about or lower than 1v dc.
now repeat the test by grounding your meter to the chassis and repeat attaching your meter lead to the TPS black wire.
while connected in any or all of the three tests i describe, you can **VERY SLOWLY** open the throttle by hand and watch the TPS voltage increase ***SMOOTHLY***. The only real way to see the *smooth* part is with an buttstuffog multimeter such as those cheaper ones you can find whch have needles. If you have a simpson 260/360 or something like it, this is ideal for testing potentiometers because thats all the TPS is.

the same test can be performed on the egr sensor (evp sensor) and to check its sensor you simply slowly add vacuum presure and watch the voltage go up/down slowly and smoothly.

any odd ball deflecton in you buttstuffog meter display indicates a momentary open circuit in the potentiometer.

1987 Mercury Cougar XR7 5.0

Reply #7 – May 23, 2014, 08:10:20 AM

oh yeah, and to what haystack says,,,,,,,, i remember a discussion here about a year ago and i believe the person postng the problem said he was running pig rich or what he percieved as very rich based on whats coming out the tail pipe.
the end result what his engine was running *lean* and the sensors were working hard to compensate.
after that thread i started to dismiss lean/rich code authentication, rather focus on the other things that could influence lean/rich conditions.
sometimes this stuff can get confussing.

1987 Mercury Cougar XR7 5.0

Reply #8 – May 23, 2014, 06:55:12 PM

Check fuel pressure. I'm betting it will be off.

too many variables that point to the exact same thing.

1987 Mercury Cougar XR7 5.0

Reply #9 – May 23, 2014, 08:02:51 PM

Got car to stay running and check some things out. I did not check fuel pressure don't have gauge yet, but I check top dead center again on dizy check OK, tps OK, IAC OK Throttle body really seams too be sucking a lot more air then normal sometimes she chokes out with to much air (with not enough fuel). When driving around town the pedal push down from a stop to pick up speed all she would do is sputter and then open up but like . I with you guys I think fuel pump problem. Don't drive car but maybe 800 miles a year now and the pump in the tank is only 2 years old, but I know things go bad. When I replaced pump I did notice that the strainer kept falling off I got it to stay on but I wondering if that could be something? Got a friend at Ford he's a diesel tech I am going to see if he has a gauge kit so I can check fuel.

1987 Mercury Cougar XR7 5.0

Reply #10 – May 23, 2014, 10:17:24 PM

Do you guys know what Fuel Trim is? I sure wish the older vehicles had them in there data. The modern ECM/PCM is a awesome thing. Id check your fuel pressure, some else mentioned taping the gauge to the windshield while test driving, I can't tell you how many times Ive done that exact trick. Good Luck.

1987 Mercury Cougar XR7 5.0

Reply #11 – May 23, 2014, 10:58:22 PM

I put anairtek pump in my tbird wheny buddy owned it. 15 minutes later it died completely. $10 more got us a 130ish lph pump. i have personally put over 50k miles on it since then in the last two years.

1987 Mercury Cougar XR7 5.0

Reply #12 – June 01, 2014, 09:56:14 PM

I could be WAY off here but I see you only drive the car 800 miles a year , my 1st thought is old,bad gas. just a thought.

1987 Mercury Cougar XR7 5.0

Reply #13 – June 02, 2014, 04:26:27 PM

Its 93 gas with stabilizer and I never fill up. Just did fuel pressure and its 37psi at idle, never drove down road but did drive back and forward about 20 yards or so play with gas pedal and put car in different gears and pressure never drop below 28. I took off vacuum line to fuel pressure regulator and psi went to 40, 42, and cars idle smoothed out and sound better. When I put vacuum line back on car start to run rough again. I replace fpr a couple years ago but could that be my problem?

1987 Mercury Cougar XR7 5.0

Reply #14 – June 02, 2014, 07:37:32 PM

Unplug the o2's and see if it goes away.

at this point, id double check timing (dist is in correctly), and grounds for ecu if you rule out the o2's. you may also want to try uplugging the spout connector to see if it makes any differance as well.

why run 93 octane? Have you bumped up compression or done some engine work?