Contour Enthusiasts Group Archives Forums General Troubleshooting Rough Idle, Backfire, Missfire, No Power, Hiccups

98 Contour V6 Duratec 24v 2.5L Auto

1. I bought the car not running so I have no history on it.
2. The engine was turning and kinda trying to start
3. Replaced the cam position sensor with a known working one, reset the ECU, turned the key 3 times to build fuel pressure (I could hear the fuel pump building it up)
4. Turned the key and the car started. It runs but it is idling rough, misfires and backfires in the intake tubes. Has no power, hard to rev and more pops come when trying to step on the gas.
5. Replaced the crank position sensor with a known working one - Runs as described in # 4.
6. Replaced spark plugs, wires and coil. Cleaned the MAF, new air filter and PCV valve. No obvious vacuum leak, at least nothing visible on the plastic and rubber hoses. Fuel valve sprays strong. Runs as described in # 4.
7. Took it for an OBD II check although there was no CEL. 2 codes came up
P0171 - System Too Lean - Bank No. 1
P1152 - Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Rich - Bank No. 2.
8. Replaced the fuel filter - Runs as described in # 4.
9. Replaced the fuel pump - Runs as described in # 4.
10. The spark plugs on the front side of the car were black with carbon. The ones by the firewall were clean like washed from the gas. All of 6 of them smelled like fuel.
11. Rebuilt the UIM & LIM, as described in the MODS section in this site and installed new spark plugs - Runs as described in # 4.

Any suggestion guys as my partner and me are running out of ideas?
I really Hope that you can help me solve this puzzle...

confirm plugs wires and coilpack are good, verify they're wired for proper firing order, plugs must be double platinums. many people have messed up on plug firing order. learn to use the search feature of this site, tons of info available about these subjects. poor power could be clogged cats also.

If it says your running lean, check your pre-cat o2 sensors as well...make sure they are getting the propper voltage...sadly im not sure waht the voltage is off the top of my head.


Lupe

I have been reserching this site for the last 4 months, but i couldn't get an exact description of my symptoms. the closest that i could get was rebuilding the UIM & LIM. that's why running out of ideas i have this post looking for help.
Plugs and wires are brand new. the plugs are the second set. coil pack is known to be working off of my other contour. all of them make spark - checked. plugs are connected to the coil in the order indicated in the manual. However i am using the chilton manual and my partner just said that for his supercoupe the chilton's firing order is incorrect. could that cause all my troubles? is there a hidden post here that i cannot find showing the right order?
i personaly think that the lost power comes from the improper functioning of the motor that i am trying to figure out - the same one that gives me the rough idle and the backfire in the UIM.
and let's say that the pre-cat O2 are cousing it to be lean, what is causing the richness in the other bank? and if it is the O2 wouldn't that just trigger a CEL? Anyways i will swap those with my other ones from my other car to see what happens.
I am just freaking out because all that i know and i have done doesn't help me and the car still runs bad...

well, bad hego does not cause it to run lean, perhaps some leak does. you wouldn't happen to hear any hissing or somep'n? what was the condition of the o-rings? did you change fuel pressure regulator during the rebuild?


firing diagram according to Haynes
465 <--coil pack
321
1-2-3 <--engine
4-5-6

front of the car

i can't doublecheck right now cause it's dark outside

but I'm sure you have the same. kinda hard to get this one wrong...

did you try to run a compression test? shouldnot be hard to do.

I would also suspect cat, as others indicated.

your CEL did not come up b/c you just reset the ECU. it needs to accumulate several fault codes before it lights CEL up.

hth

Check the three harnesses on the passenger head to make sure they are COMPLETELY clicked together.

Use a scanner or multimeter to check mass air voltage. Should read about .08 at idle on a stock sensor.

Swap fuel injectors from back to front and see if the fuel soaking follows. Could be stuck open. Check fuel pressure at the rail also. Should be about 46psi at idle.

Nothing hisses, but i might not be able to hear it. when it runs, it is so loud that i have the feeling that it is a diesel. i will check the firing order tomorrow. the o rings were like brand new. i did not changed the fuel pressure regulator. do you think that will isolate the front and rear banks and cause my problem? because i think that's exactly what is happening - it is running on only the front cylinders. will do a compression test. about the cats - it is smoking from the exhaust tip. how do i chack if thet's the problem? can i just disconect the Y pipe? i know it's gonna be loud but...
i will also check everything as advised by Keyser... but if i swap the injectors as Keyser sayes, could i use the same UIM gascet since it is brand new?...

IM gaskets are reusable more or less even if not new

clogged cats are normally an issue at 3K rpm and above. you indicated that it gets worse when you step on it -- hence the question.

fuel pressure regulator question was just my shooting in the dark, I doublt it's relevant, but def do what Keyser says:
Key off.
Release the fuel pressure.
Install fuel pressure tester.
Scan Tool connected.
Key on, engine off.
Run the fuel pump to obtain maximum fuel pressure.
Is fuel pressure between 35 and 40 psi (240-280 kPa)?

it will not affect front and rear different though, afaik.

now, since the injectors are behaving differently front and rear, inspect very carefully injector harness (i'm sure u did already though) insulation is known to crack, although on older engines, and it is known to rub too. doesn't look like an intemittent short, but who knows.

is it really smoking out of the exhaust pipe?


Actually let me copy from Ford manual:
Runs Rough/Misses/Buck/Jerk/Backfires/Hesitation

• Air/Vacuum
  
  
• Check vacuum lines for leaks, blockage or wear.
  
• Check air intake system.
  
• TP, IAT, MAF, IAC
  

Fuel

• Check for correct fuel pressure
  
• Check for fuel contamination/quality.
  
• Check fuel filter.
  
• Check for restricted fuel lines
  

Ignition

• Check for correct base timing
  
• Inspect spark plugs and plug wires.
  
• Inspect EI system for damage.
  

Power and Grounds

• Check for generator/regulator noise interference.
  
• Inspect electrical connections, wires, and harnesses.
  

Other

• Check engine coolant level.
  
• Check thermostat operation.
  
• Check EGR valve sticking.
  
• Check PCV valve for correct operation.
  
• Check for exhaust.
  
• Check for partially binding brakes.
  
• Check camshaft timing and cylinder compression.
  
• Check for weak or broken valve springs.
  

You pretty much covered 99% of it by now...

If you got good fuel pressure and sparks I think there is a good chance your computer is shot.

Since you checked for air leaks & did a rebuild on the UIM/LIM, I would next think the MAF could cause the described problems. You cleaned it, so try unplugging it the next time you try to start the car. If the MAF is fubar, unplugging it will allow your car to run.

Next, since you have a donor car, remove the ECU from the problem 98 & put it in your car to see if the ECU is at fault. That way you don't risk your good ECU, it'll be sitting safely on the seat next to you.

I'll think some more on this ...