2000 Metro cold start problem: missing, backfiring, stalling
 

I'm getting an intermittent cold start problem, and am not sure how to proceed.

Circumstances:

- "Cold" start (ambient ~75 - 85F / 27 C), after not driving for several days.

Symptoms:

- It starts first try, but runs very rough, bucking and missing, and fairly quickly stalls out.

- Simply pushing the throttle causes it to bog and immediately stall out.

- However, pumping the throttle constantly, I can keep it running, but:

(A) the tach is bouncing wildly (much more than actual engine RPM),
(B) it's backfiring occasionally through the intake, and
(C) it's missing and bucking and not generating any power, even at high RPM -- ie. almost impossible to engage the clutch and move the car without stalling out.

- The last 2 times this happened, after multiple attempted starts (like 20+), pumping the throttle, etc., the idle eventually smooths out and everything goes back to normal.

Codes:

- First time it happened, I nursed the car along to where I needed to go (about 1.5 km, mostly downhill), and got a code for a cyl #3 misfire. Pulled the #3 plug wire, and the plug end connector FELL OFF. :D

What I've tried so far:

Replaced all 3 wires, cap & rotor with good parts from the Firefly. No problems for several more cold start cycles after that.

- But it's happened 2 times since then with NO codes.

Any suggestions on how to diagnose this or what parts to systematically change to find the culprit? I have the Firefly to pull good parts from to ID the problem.


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EDIT - Comparison to no spark on one cyl:

So the cold start problem happened today. After 20+ starts/stalls/playing the throttle, the engine eventually went back to normal, and I used the car for a short trip. It worked perfectly.

Just for fun, I pulled a plug wire when I got back to see how the cold start problem compares to missing spark on one cylinder. It's not the same. The car is MUCH more driveable with one spark wire disconnected than it is when it's doing this bucking/missing/backfiring routine.

Check the map sensor. Sound like an open loop problem. What does your scan gauge say about f.a ratio?

Good idea.

I once had a cracked vacuum line to the MAP sensor on the Firefly and it ran similarly badly (though I don't remember it backfiring, and it was still easier to drive down the road than this).

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EDIT -- just did this test:

1) Key on, engine off, OBD-II MAP value shows atmospheric ~14.7

2) Cold start (engine running poorly), MAP value drops to mid single-digits with throttle closed/pumping a bit.

So the sensor at least appears to registering manifold vacuum.

3) I went and got the MAP from the Firefly (same part #) and plugged it in.

4) Car started & ran normally. Yay!

5) Immediately plugged the original Metro MAP sensor back in... Car started and ran normally. Confused! Maybe just a bad electrical connection?

I'll keep the Firefly sensor in the car to see if it solves the problem again next time it won't start & run right.

I suspect your distributor is wearing out and the air gap is changing. Swap with the poor Blackfly and see if that helps.

Would either of these problems explain the occasional backfiring when I'm nursing the engine along by pumping the throttle?

Bad MAP / open loop could cause dumping excess fuel in the TB.

Bad distributor would mean no spark, accumulating unburnt fuel in the affected cylinder/s.

Intermittent ignition coil? Sometimes they'll develop small cracks in the housing which can cause spark to the frame. Usually you can see a spark jump in the dark.
JJ

2 good & 1 bad starts later...
 

Well, it's not the MAP sensor! After 2 trouble-free cold starts built up my confidence, today's cold start reverted to crap - and that was with the Firefly's MAP sensor in play.


So I immediately shut it down, fetched the Firefly's ignition coil and hooked that up.


And it fired up perfectly! So I immediately shut it down and reinstalled the Metro's coil. And it fired up perfectly again! So much for A-B-A testing... I hate intermittent problems. :D


I'll leave the Firefly's coil in play. If it turns out not to be the solution, next up will be the distributor or just the pickup sensor inside.

What is happening with fuel trim? If there was a spark problem from a worn dstributor the fuel would not gather in the combustion chamber so muchas blow throw the exhaust ports to the cat and O2 sensor. The sensor would detect less oxygen, the ECU would react. Is a Metro EFI? Does it have like one injector or something? I forget.

Wait... is this only in open loop?

Correct: one injector, throttle body ignition.

It's a cold start issue, so it must be open loop to begin with anyway. I'm not sure what coolant temp it needs to see to go to closed loop.

I had an intermittent coil fail a few years ago. Only when the car had been running for for about 10 miles did the problem present because the heat caused the coil to expand and fail. Otherwie it ran normally. You need a test procedure. Does the Metro have an FSM that is freely available?

Ha... I have the 3-volume FSM. You just reminded me. I should crack it open!

I have a hunch it's ignition-related due to the way the tach bounces crazily when it's not running right. If I'm not mistaken, the tach signal comes off the coil or the pick-up in the distributor.

We'll see what tomorrow morning's cold start brings.

Pick up coil under the distributor cap hasn’t turned to a mess?

Otherwise I’d check the cam and crank sensors/wiring. I suppose the one in the distributor might be the cam sensor...?

Oh and how’s your battery? Mine was giving issues when the battery was drained to the point of just barely starting the car. Was fine after the alt managed to finally kick in.

Tach bouncing indicates faulty Ignition Control Module.

Sometimes dying electronics will work better hot. You could try heating the ICM with a hot air gun and try a cold start.

^ Ignition control module = coil in the 1.0L Metros, from what I've read.


Stubby79: pick-up hasn't obviously self-destructed. And yes, that's the camshaft position sensor too. (First thing I did was bypass my engine kill switch, which is on that circuit.)


Today's report, so far: 1 cold start this AM on the Firefly coil = no problems.

2 for 2!
 

Two cold starts since changing the coil. No hiccups yet, touch wood.

Wooot wooot! [knocks on fake wood flooring] Come on bbig number three!

If it gives me 5 in a row, I'll put the original coil back in and see what happens. A-B-A, baby. (Think 5 is enough??)

Fyi, coils rarely fail on older systems. I have been doing this for a long time, and I have seen less than 10 regular oil filled coils fail in 40 years. Now the new coil on plug stuff and the air cooled GM crap from the 80s is another story. I change the Ford and Chrysler coil on plug crap all the time. Just to be fair I haven’t worked on any new GM stuff in 14 years.

I've been driving old $#!*boxes all my life (up to 30 or 35 by now?) and have never had an ignition coil fail before.

A-b ... A
 

5 times a charm! 5 cold starts with no probs, using the Firefly's coil.

I'm going to swap the Metro's coil back on tomorrow and see what happens for the next 5.


But I think that's got to be it (touching wood).

Cool. "Known good & free" parts make great diagnostic tools, haha! Looking forward to the return of bucking and stalling when the old coil returns to duty. :) Then we know!

It just wanted some love and attention. She'll be fine if you treat her right. ;)

I think Stubby might be right: I put the old coil back in and it fired right up. Just wanted some attention?

Intermittent problems are fun!

This is killing my tank average, too ... threatening my 70 MPG goal! SG said ~72 MPG when this nonsense started. Now it's 70.5

I should fill up now to lock it in. Put some of this silliness on the next tank. :D

Factory Ford troubleshooting has you install a known good part as one of their last steps on some of the diagnostic trees. This is great if you own a known good spare part.

But early in this thread I think you got the same results sometimes and then the problem returned a few starts down the line, no? with the "bad" coil, I would wait to see if it returns. Seems like it might.

Yes, definitely. Take that bummer off the list of bummers in trouble shooting.

Correct.

I'm hopeful.

One other thing I thought of: a simple run of cold starts might not be a valid test. I need to actually drive the car: heating the coil up might be part of the problem? I'll be using it again this weekend. (And I did have a couple of longer drives with the known good coil.)

For those still keeping track at home:

- Trouble-free cold starts on the Firefly's coil: 5/5
- Trouble-free cold starts since re-installing the Metro's coil: 2 (so far)

Done! :)

First kilotank (1k+ km = 620+ miles) in the beater Metro: 72 MPG US!

"We need a known good part."
"This is a Ford."

- Trouble-free cold starts since re-installing the Metro's coil: 3 (so far)


Have I mentioned yet how much I hate intermittent problems?

I’ve had two coils fail in my LSJ before I upgraded them, and I’ve had two coil packs fail on my L61, before swapping to the one I’m running now... the failures have always presented as a constant misfire though...

- Trouble-free cold starts on the Firefly's coil: 5/5
- Trouble-free cold starts since re-installing the Metro's coil: 5/5

It's healed!

(Have I mentioned yet that I hate intermittent problems?)


But seriously: now I'm wondering if it might have been a flaky connection to the coil that has been fixed by all the un/plugging.

Maybe. My intermittent starter motor failure healed itself five years ago when I disconnected it, swapped my transmission, and reinstalled the intermittently failing starter. Five years of never fail startup since. Go figure.

I had that happen on the old Ranger I drove, the coil contacts got corroded and it sometimes didn’t run right and the tach needle would jump around when it was missing... the cap ended up breaking and I converted to bolt on leads and an Accel coil...

I think the MAF on my car was bad. I disconnected it, car ran very poorly. Then i reconnected it. Next startup, I have my power back!

Has not manifested itself again in over a week.

I've experienced a vacuum leak on a MAF hose before, and it was similar, but not as bad as these symptoms.

I'm up to 8 cold starts with no probs since putting the Metro's coil back in.

However the car did throw a p0400 code on a 200 km trip this weekend. Intermittent EGR valve problem (I've seen it once before). I wonder how a stuck-open EGR valve would make it run.


I need to take it off & clean the valve &passages.

Cool. I think you have to consider that the stuck open EGR valve could be the entire problem right there. Or at least it and some other minor factors like connectors for your coil have been intermittently contributing to your rough idle and rough running. I mean, the symptoms of that code would be what you've been experiencing, correct?

Bad, very bad. Had an egr that was slow to close, would die everytime it came to a stop. Finally figured it out when I logged engine parameters on a drive. IAT shot to over 250° in mere seconds, only thing that gets that hot is.... exhaust.

It does make sense.


What doesn't make sense: the car ran completely normally on the weekend trip (400 km round trip), despite the EGR code coming up once on the way there and once on the way back. Not a hiccup from the engine: highway & city driving.

Yet when I was having all the cold start problems (now apparently cured), there were no codes at all.

Regardless, I'll be cleaning that EGR valve & passages.