Engine cutting out.

[Chopd65]

I finally got my clutch installed and the car back on the road. The clutch has a much different feel now than it ever had. I guess all new components from the master down will do that. Now I experiencing something that wasn’t happening before. The car starts fine, normally on second try sometimes third, and settles into a nice idle. The throttle is properly responsive and on the road everything seems to be in order, until I hit 4500 rpms, then it cuts out. Every time, regardless of load. I had it running in the garage and slowly brought it up to speed while watching the gauges, nothing notable was happening when it cut out. Fuel was constant at mid 50 psi, no jumps in any other gauges. Oil pressure was steady, I think around 70 psi.

I’ve gone over looking for something missing and can’t find anything.

 

This is a 2002 SV, Zetec.

 

Any help would be appreciated.

 

[sltous]

My old Crossflow would do this, there was enough vibration for the crankshaft position sensor I installed for a distributorless ignition to shake out of position and lose track of the trigger wheel.  I made a much sturdier mount and it fixed the problem.

[Chopd65]

Thanks sltous, I’ll check that out.

[coffee break]

FWIW recheck the electrical connections involved in the clutch replacement and ground connections.

[Chopd65]

I plan on going back over all the connections and grounds when I go poking at the crankshaft position sensor.

Seems like I’ve done it a dozen times already but I’m clearly missing something.

[sltous]

Without knowing all the details of the Zetec, I found that using a cheap oscilloscope and measured across the crankshaft position sensor.  What I expected to see was a waveform such as this one

and instead got a waveform such as

While you may be able to analyze this dropout with a multimeter, I found that being able to see the CPS dropout made my debugging much easier.

where my yellow trace is the RPM signal and my blue trace is the output form my crankshaft position sensor.  You can see that the missed tooth signal is not coming through at exactly the same time that the RPM signal drops out and this really didn't leave me with any alternative explanation.

 

 

[Chopd65]

Thanks sltous, I think that would be jumping in at the deep end for me. No O scope and certainly no idea how to use it.

[ashyers]

Watch the tach carefully when the engine cuts out. See if it drops slowly with the crankshaft speed when it cuts out or if it dives for 0 instantly. That may give a hit to if you're loosing your RPM signal. When the old Ford TFI modules used to die this was a quick diagnosis.

[Chopd65]

ashyers,

Thanks, I'll add that to the list to check. As soon as it cuts out I let off the throttle and didn't observe what happened afterward.

Bill

[924s]

I found this when researching Ford Zetec and Duratech. Maybe it might be related to your problem.  Intake manifold valve can cause the Check Engine light. If your car doesn't accelerate after 3000 rpm, maybe your problem is in that valve.

[JohnCh]

When the engine cuts out, does power to the rest of the car remain on or flicker?  

 

-John

[Chopd65]

924s, thanks I'll look at that.

 

John, everything else seemed to stay steady but I was focused on gauges, I'll run it again and watch the lights.

 

Thanks,

Bill

[JohnCh]

My guess is there is no power interruption, but it's good to rule out things that are dead simple to check.  Assuming power remains steady, I'd be inclined to focus on what's been mentioned by others and add some related things:

• When checking the CPS for tightness, make sure the gap is within spec
• Examine the trigger wheel and make sure no teeth were damaged when removing/installing the engine
• With the engine running, jiggle the connectors on the CPS loom to mirror vibration. It's possible a wire or connector was damaged when removing the engine.  It won't hurt to jiggle other parts of the engine loom for the same reason.
• If none of that works, and it's easy to get to your ECU, you might want to detach it from the car while it's running, hold it in your hand and see if it still cuts out.  With an old ECU there is always the possibility of a micro break within the circuit board that opens from heat and/or severe vibration.  Given the sudden onset of this after an engine removal, this does seem a stretch unless you somehow managed to damage it during that process, but..well, Murphy's Law.

-John

[Chopd65]

Thanks again John. I’ll run through these and the other suggestions.

It seems that Mr. Murphy is renting a room here this year.

Bill

[Chopd65]

Thanks to all for the help.

 

@JohnCh for the win! We went back through all of the connections, shook all of the wires while it was running, including the ECU and nothing.

Went to remove the CPS and the screw was kind of loose. Tightened it back up and no change. Finally decided to check the gap on the sensor and while I couldn’t find a definitive gap measurement what I found seemed excessive. It had two washers on it, I removed one and it was like magic.

Ran it up well past 4500 rpms with no issues.

Went on a test run that turned into the first blat of the year, ran great the whole time. Stoked to be on the road.

 

Thanks again John.

[JohnCh]

After nearly 15 years on this forum, I guess I was bound to guess correctly eventually   Glad you got it sorted and hope Murphy gives you a wide berth going forward.  

 

-John