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Please help completly lost

1K views 15 replies 6 participants last post by  squekster 
#1 ·
I know this is a mustang forum but I don't know where else to go for help, I have a 87 ltd crown Vic with a stock non ho 5.0, recently going down the road the car started stumbling like someone was unplugging and plugging it back in really fast, on my way to the gas station I was on e so I figured I'm just low on gas, I fill up and it still continues to do it progressively worse and worse bogging and just loosing power like it's holding back the spark or fuel in a way. So I started from the basics and checked fuel pressure, it was around 25-29 so that's kinda low and my tank was leaking from old age so figured might as well do both now so I don't have too drop the tank twice and was hoping it was low fuel pressure, did all that still didn't change, I had my old coil which is still good swapped that out and tried a brand new tfi even tho the I had on was brand new two, dizzy is a month old from napa, still coudlnt get it to run right so pulled the fuel rail and injectors and went through everything and cleaned all 8 injectors, put a new fuel regulator on it with a new filter. Still, nothing changed, I tried a different map sensor that came off a running car and nothing changed, plugs were pretty rich imo so I went ahead and did 8 motorcraff plugs and still not a difference, car still idles failry good and the timing is spot on with no spout connector right at 10 degrees. I'm starting to think it's internal but the way it happened makes me think otherwise. If anyone has had this problem or has any opinion please help. I'm completely lost now. I know this is a stang forum but there's more people here then CV forums, thanks


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#3 ·
Have you scanned for codes that may be stored in the computer? Check for any vacuum leaks, you said you tried a map sensor, did you mean Mass Air Flow sensor? The MAF sensor is inline with the air intake tube from the air filter box. You could also unplug the Mass Air Sensor drive the car and see if it improves. The rebuilt NaPa dizzy even though not old can have a faulty P.I.P. sensor in it.
 
#13 ·
I agree remanufactured parts can be bad off the shelf or go bad in short order after being installed.Ford Motorcraft parts usually last from 50,000-100,000 miles.

He's working on a 87 Crown Vic,which uses the Speed Density setup,so he doesnt have a MAF sensor.
 
#4 ·
Did you check fuel pressure after replacing the pump to verify if it corrected the low pressure condition??
The specs for pressure are 35-45psi key on/engine off & 30-40psi key on/engine running.If pressure is still low,something is leaking.The short S (supply) hose,that you install between the fuel pump & the fuel pump sending unit,could be leaking.Did the pump come with a new S hose?? If you test fuel pressure again & its still low,you need to do a fuel leakdown test,to make sure the S hose & none of the injectors are leaking.Let the engine reach operating temp before doing the test.
Test- turn the key on/engine off,record fuel pressure,turn key off,wait 60 seconds,record pressure again.Did pressure drop more than 5psi in that 60 second time period?? If yes,the S hose,injector(s) or fpr is leaking.

I assume (because of you having an 87 model) youve still got the Speed Density eec-iv system,without a maf sensor,so that rules out a maf problem as being the cause.

Its definitely a good idea to check for vacuum leaks because they affect the fuel trim.In otherwords,if you have a leak,the extra air will get measured by the O2 sensors,causing them to read lean.When this occurs,the ecm (falsely) richens the fuel mixture in an attempt to bring the afr back to normal.An over rich condition occurs with the presence of a vacuum leak.

Im not sure what the wire colors are for your tps (throttle position sensor),but you need to test it because it sends throttle position to the ecm so it knows just how much fuel to supply.If it tells the ecm throttle is open 30% when the throttle is really open 60%,the engine wont get enough fuel to run correctly.If the tps says its open 60% when its really 30%,the engine will get too much fuel.
(TPS Test Link)
TPS Codes 23/53/63 Troubleshooting

You should also run a scan,like mentioned by my89foxbody,to look for codes.The following link details how its done.
DIY KOEO/KOER/Cylinder Balance Self-Test Procedure

If all of the tests above check out ok,disconnect the neg battery cable & remove the ecm from the passenger kick panel.Remove its panel & check the condition of the capacitors on the board.
http://sbftech.com/index.php/topic,37389.0.html
 
#5 ·
Well, there are some good answers posted here. I will recommend one simple test because it is so easy to do. If your plug wires are old they can be leaking voltage to ground. So when it is dark outside pop the hood, start the car, and look for arcing from the plug wires. You might be surprised at the fireworks show.


Randy
 
#6 ·
You can also put some water in a spray bottle and spray a fine mist of it over the plug wires at night.They'll arc even more with water.Plug wires should also measure 7k ohms or less for every foot of wire length.So if a plug wire is 1 1/2 ft (18") long,it should measure 10.5k ohms or less.
 
#8 ·
You can still run the koeo scan without the car running,you just cant run the koer scan.
If youve got a leak in one of the larger vacuum hoses connected to your intake,that'll make the car stumble and die after startup.You can also try removing the spout plug before startup to see if that allows it to run.If the egr valve is stuck open due to carbon buildup or a defective evr solenoid,it will also stumble & die or run really rough at idle.If its stuck open due to the evr,you can remove the vacuum hose at the egr valve & plug the hose then see if it will start & run.A pressure leakdown test can also be done (koeo) without the car running.If you start throwing money (parts) at it,without trouble shooting first,it could get very expensive.
 
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#11 ·
In that case,you might wanna check the ect sensor.The ect has a huge effect on fuel mixtures and when the engine is cold,the ecm richens the fuel mixture using the ect sensor readings as its guide.As the engine goes from cold to operating temp,the ecm leans the fuel mixture using the ect sensor readings.The fuel mixture wont be correct if the ect sensor is defective.The following link details the test procedures.
ECT Codes 21/51/61 Troubleshooting

Check the eec ground wire & its black harness plugs too.The eec ground runs alongside the neg battery cable & is bolted to the fender apron,to the right of the windshield washer fluid bottle.It forks off from there and turns into a black tubular connector plug then plugs into a matching plug at the main engine harness.If this ground is loose,corroded or disconnected,the engine will start up once you turn the key to the crank position,but it'll stumble & die as soon as you release the key to the run position.
 
#12 ·
87 Vics didn't have MAFS they had manifold pressure sensors. To Junk5.0: Check your throttle position sensor and egr valve. Had a similar problem on my '91 vic. Oh another item that causes that is the engine temp sensors... If the computer doesn't know hot hot the motor is it will make run rich/ like crap.
 
#15 ·
Dont feel bad,I sometimes get into answering numerous threads at the same time and I have to stop for a minute because :im confused: as to which car Im answering a question to and have to go several threads back when that member started a thread listing their year model in order to remind myself what the hell were working on.
 
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