1987 Mercury Cougar XR7 5.0

Topic: 1987 Mercury Cougar XR7 5.0 (Read 5916 times) previous topic - next topic

1987 Mercury Cougar XR7 5.0

Reply #15 – June 02, 2014, 07:38:39 PM

Oh, and by the way, I've put 893 miles on my car since you started this thread. .

1987 Mercury Cougar XR7 5.0

Reply #16 – June 02, 2014, 08:31:40 PM

State Trooper had car before us, bought it new and we have bill of sale and sticker and it says 93 so that's what we put in . Just cold air intake and true dual flowmaster exhaust. Check Dist timing and its right on, will check ecu ground and the other things. When I unplug FPR psi went up to 40 and she smoothed out like the FPR is bad maybe or is that normal? Is there two ports to test fuel psi? I didn't look much seen the one front right by number one cylinder. Don't know if yours is the same.

1987 Mercury Cougar XR7 5.0

Reply #17 – June 09, 2014, 04:48:53 PM

I unplug O2s and nothing, unplug spout and motor idle went up and down like it was going to cut off. Unplug intake air temp sensor motor idled up, unplug coolant temp sensor same thing. Could it be the O2s?

1987 Mercury Cougar XR7 5.0

Reply #18 – June 09, 2014, 08:20:16 PM

Unplugging the spout shouldn't effect the way the car runs much. the fuel pressure sounds like its doing what it should.

if you unplug o2's and nothing changes, that would point to o2's. if the computer has a problem with a needed sensor it will put itself into limp mode and ignore more sensors and run off of a set table. sounds like what it might be doing.now.

i have a hard time beleiving both o2's are bad though. out of the 7 or 8 cougarbirds I've owned and put over 500k miles on, i have only replaced one o2 sensor. ill see if i can find a link for testing resistances to see if the sensors are bad.

1987 Mercury Cougar XR7 5.0

Reply #19 – June 09, 2014, 08:24:35 PM

http://sbftech.com/index.php?topic=29771.0

as promised.

1987 Mercury Cougar XR7 5.0

Reply #20 – June 09, 2014, 09:34:08 PM

Removing the vacuum source from the regulator points to a lean engine. When the fuel pressure rises the fuel delivery increases. Is your TPS set at ,6 volts at idle. You can monitor the O2 switching or cross counts by back probing the signal leads. This will tell you your fuel trim in a sense. If the o2 sensors are running lean the voltage will be high. The cross counts are what you need to know. The ECM processes fault codes correctly and should not be transposed. When the O2 voltage is low the ecm knows the mixture is rich and vice versa. Do not ignore the codes as they are accurate and deliberate. Have a good night guys.

1987 Mercury Cougar XR7 5.0

Reply #21 – June 09, 2014, 09:44:58 PM

Reading that link, a broken wire on pin 49 will make the car always run lean.

sounds like you could just have a bad ground.

1987 Mercury Cougar XR7 5.0

Reply #22 – June 09, 2014, 09:47:04 PM

Drivers side rear head, look for the ground to block orange wire. check for breaks and check pin 49 and check back in. you've got me thinking now.

1987 Mercury Cougar XR7 5.0

Reply #23 – June 09, 2014, 09:48:09 PM

That is why he needs the cross counts. That ground should be near the Dizzy if memory serves me. Or at the back of the cylinder head on some models. Cross counts are patterned at a mean voltage of 450 MV. have a great evening guys.

1987 Mercury Cougar XR7 5.0

Reply #24 – June 11, 2014, 01:19:10 AM

at night, visually verify your spark is blueish white.
just undo a plug wire and stuff a spare plug in the boot then ground the threads of the spark plug to chassis.

to keep fuel from being delivered, unplug the fuel pump relay at the passanger side of the trunk near the trunk lid hinge.

now you can crank all you want with no fuel coming up front.

a spark check like this is the next simplest thing to test.............

1987 Mercury Cougar XR7 5.0

Reply #25 – June 11, 2014, 01:24:35 AM

oh,, and a rather expensive but likely required simple tune up.
i had totally forgotten my plug wires all these years while owning my 20th since 2007,, dont know why but now at 263kmiles.. i have had a constant bucking in an unpredictable manner,, had me tricked to think it was always around 45mph.. did a tune up and sure enough, pulled a plug wire off and for some reason this time the spark plug connector stayed on cyl 3... even though i dumped $ at the oil, filter, fuel filter, rotor, cap, wires, plugs,, problem went away.

now my highway mpg is back up to 25.5 (level ground up around pittsburgh) and local in town driving is at 22 mpg

1987 Mercury Cougar XR7 5.0

Reply #26 – June 11, 2014, 01:29:16 AM

also, with a can of wd40, start filling up about ever vac line you can.
those vac lines go everywhere, electrical signals are sent to solenoid actuated vacuum doors or paths so to speak.
those solenoids with vac lines have a lot of rubber pieces parts inside them and with a car sitting and drove very little, these little parts may just need some lubrication.

1987 Mercury Cougar XR7 5.0

Reply #27 – June 12, 2014, 05:42:12 PM

TPS volt are good, spark is good. I have a wire that has been cut open for years but car ran great so I didn't worry about. Now looking at the drawing diagram where the 2 10 pin connectors are the wire come out of the wire loom and I can not figure out what that wire was until I seen the diagram. It looks like wire # 19 hego sensor ground and its come out of the wire loom about 5 to 6 inches back from the 10 pin connectors and about middle of car below ac line. Talked to my friend who works for ford, said without looking at the car said vac leak at intake because of both O2s saying lean. I will do the cross counts, broke wire, ground and check back . Thank you