Miss on Startup Problem

R

Rich Thomson

Registered User
Since I put the Ford Reman engine back together with stock heads and 520 cam it has a Miss upon initial startup. Cold or Hot does not matter for the first few seconds the tach dies several times then runs fine. No other problems with the operation of the engine. I have checked the PCV and it is not the cause. I am going to do a compression test this weekend and check the plugs. I have already replaced the Cam sensor, Main Wiring Harness, Upper engine Wiring Harness, Injector Wiring harness, DIS Module, Coil Pack, MAF, Plugs, & Plug Wires. All the wiring harnesses were ohmed and none showed resistance or intermittent breaks. I have another EEC but have not swapped it out yet. My question is if someone has had this type of problem please post your experience. My gut feeling is oil is getting past the #2 compression ring (oiling ring) into the cylinder causing the initial startup miss. 90% of all my startups cause the miss.

Rich :mad: :mad: :mad: :mad: :mad: :mad: :mad: :mad:
 
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Hi Rich,
Could it be something as simple as not aligning the cam stator at tdc, so the eec is trying to find and send a spark to cylinder 1?
 
It's possible. When I took the engine apart I marked TDC and marked the Cam sensor position. I reinstalled it in the same position. I have a cam position sensor tool I'll verify it again later.

Rich
 
Rich,

Mine did something very similar when my fuel pressure regulator started leaking a little thru the vacuum/boost refrence hose. The fuel would leak into the intake manifold adaptor and run over to the nearest cylinders and flood it enough to make starting it hard and it would miss at initial start up.

David
 
Just had the blower off last week and did not see any fuel leaks. The FPR I will check and the Fuel press seems to be good 40 psi vacuum off and 33 psi at idle. Something is getting into the combustion chamber causing the miss. One idea I thought of is a leaky injector. Fuel Drips into the cylinder causing the spark to blow out. I could have a bad lifter? They were all new 5.0 lifters Still don't know if a bad lifter would cause the tach to die :confused:

Rich
 
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Rich Thomson said:
The FPR I will check and the Fuel press seems to be good 40 psi vacuum off and 33 psi at idle.
Rich
Click to expand...

Rich, is there a link on how to do the above? Thanks. Chris
 
Rich,

I don't really think it's a lifter because in order for it to be collapsed enough to cause a miss it would be very noisy (like a hammer tapping on the valve cover), but yes a dripping injector or even a bad valve stem seal can cause the problems your having. Are you getting any oil or fuel smoke at start up ?

An easy test for fuel leakage is to see if pressure drops off after the pump stops. It doesn't take much volume loss to drop the pressure 10-15 psi. When mine was leaking it would jump to 40 psi when the ignition was turned on then quickly drop to 20 psi when the pump stopped.

David
 
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Leaking injector would not cause the miss if I am running the motor then stop then restart. No time for the fuel to puddle in the cylinder. Engine oil in cylinder like a bad vale seal would not cause the miss after running the engine then stopping then starting the engine up again. No time for the oil to leak into the cylinder and pool. Compression test should verify.

Tonight I am going to pull the EEC and try the backup EEC I have. Since the problem does not seem to be ECT related I am forced to go back to a electrical problem. Since I have a EEC Tuner board installed I am thinking the Tuner board maybe causing the problem. I have another EEC Tuner Board to test with. Engine runs great and I have no other problems.

Just swapped the EEC and Tuner out and the Miss still happens but only about 50% of the starts. I am thinking the RF is causing the problem. I connect the laptop to the cable and the miss comes back disconnect the cable and roll it away inside the glove box and the miss does not happen. :eek: I am going to have to work on this problem more this weekend. I have a Superchip I am going to try later.

Rich
 
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I was able to finally reproduce the problem. The Fuel Pressure is low before startup. If I key the ignition 2 times it starts without any miss. If I start on the first try it has a 50% chance of a miss. My first thought is the fuel regulator. I also noticed I have to really richen the injector slopes to get the A/F right. I'll replace the fuel pump later if the FPR change does not fix the start problem. I already replace the fuel filter. When the fuel pressure gauge was connected the needle was jumping around it was hard to get a constant fuel pressure reading. After and overnight sit the fuel pressure in the rail was 0 psi. I do not smell gas so a leak cannot be the cause. Fuel Pressure and or Regulator is the cause.

Rich
 
The fuel rail around the front is very narrow and can collapse or get clogged. Is it lean just on the passenger side? Do you get fuel returning to the tank?

Maybe it's the fuel rail.
 
Rich I have the samething but I find I get it more with the tuner pluged in but will do it sometimes with it off. I wounder if something is not letting the pump run like it should or it's the rail.
 
Just finished setting the fuel pressure. I reset the fuel pressure to 43-44psi with the vacuum off. Rans the car until it warmed up and reconnected the vacuum hose. Waited 30 min as the fuel rail pressure of 40psi dropped to 32psi. Keyed the ignition and the pressure rose to 45psi. I get 35psi at idle 19in vacuum at 850rpm. Shut the car off and restarted it 3 times no miss. :) I did a test and after keying the ignition I blead some of the fuel pressure off until I had about 20psi. Started the car and the miss came back. Did same test and verified the LOW fuel rail pressure caused the miss. Will test again tomorrow after the car has sat overnight. Test drove the car with the fuel pressure gauge connected and saw 33 psi on full throttle decel with clutch in and max pressure of 59psi under WOT. The engine feels much better and tomorrow I will go back and change the injector slopes back to where they should be. 41.5 high and 50 low.

My suggestion is to verify the fuel pressure and adjust it to the proper psi. 38psi stock 30lb and 36lb injectors and 43.5psi for 42lb Lighting injectors (vacuum disconnected).

Rich
 
If the crank sensor was the fault it would die while driving or just not start. The engine never dies just misses on startup.

Yesterday replaced the FPR and it seemed to go away but the miss returned today. If I key the ignition twice to build fuel pressure it does not miss. Defently a fuel pressure problem. I am going to go back over all the fuel lines again looking for a pinch or kink. I am also going to verify the battery voltage at the pump. If that checks out OK then I will replace the fuel pump later next month.

Rich
 
I have finished a complete fuel pressure test and cannot find anything wrong. :(

I ran another code scan and found a code 522 which is Transmission Range (TR) sensor circuit open/vehicle in gear or Park/Neutral Position (PNP) or Clutch Pedal Position (CPP) circuit fault - Transmission MLP sensor out of range in park -

I am looking into the Clutch pedal switch now. I will let you know if I resolve the fault code and fix the startup miss.

Rich
 
nczimmerman2 said:
How do you adjust the fuel pressure with the vac line off?
Click to expand...

He's talking about changing the base or static fuel pressure, which is only possible if you have an aftermarket adjustable regulator.

David
 
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