General Rough at times - Panda Farts?

[Auguste]

Ladies and Gentlemen,
I'm happy to state that my 93 Fire 1000 has gone shopping after I replaced the head gasket. Thanks to all who helped out during the work. Nice to have it working after all that! The smoke has cleared and doesn't seem to burn any oil nor consume coolant.

Now the fun begins, I think - this car has an ECU and you and Porter have told me that it will relearn the fuel mix and timing after driving a bit. I've driven about 50 km on local roads. The car does well except at that spot between 1st and 2nd gear, when it seems to need to be rev'ed up to prevent back firing or rough running. Out of that "spot" and it seems to hum along no problems. American's like me have a term called "lugging down" the engine, where the RPM's are very low due to bad gear selection and this is when the roughness is most noticed. Once into the higher RPM's it takes off.
I'm going to check the plugs for fouling but would like to see what this "auguste" forum thinks. I also plan to redo the timing belt just to be sure the alignment is correct between the cam shaft and the crank shaft.
thanks!
Auguste

 

[John H]

Back firing would suggest cam timing, ignition timing, or poor valve seating to me.

The ignition timing should be correct , given the limited understanding I have of your particular setup.
But, perhaps it is worth checking the gap/clearance for the timing sensor - if it is a bit wide it may be on the limit at low engine speeds.
I haven't found a figure for that gap in my books, but I'm sure somebody can find it and post here

One other point - I presume this condition is a change from the way it was before, or are we chasing an old fault?

If it's an old fault, it might be something as simple as poor plug leads, or even poorly connected good leads (surely not)

 

[Auguste]

Thanks John - I will check the gap tomorrow and see if it wants to move in closer, I was looking at it today and wondering.

It isn't an old problem, it is new and I think due to something I did during the rebuild.

Auguste

 

[Auguste]

[?] I checked the setup for the cam and crank, had both indictors pointing 90 degrees to the firewall per the instructions in Porter. [?] I reinstalled the belt, the housing, the alternator/crankshaft pulley, and tightened up the alternator.
[?] I reseated the ECU sensor and made sure it was clean, checked the plugs (nothing to note) and the cable seating.
The car starts right up but after running for 10 - 15 minutes (heating up?) it starts to cut out just when you try to accellerate. Once it gets up out of that zone it seems to do OK. Again, no smoke at all.
But, I think this cutting out is worse today. [?] I removed the air filter element, left the cowling on and pulled on the accelerator knob on the carb, but there didn't appear to be any difference with the filter in or out.
[?] I have not added any anti-freeze, am running it on just filtered water and there is some rust colored particles floating in the water in the expansion tank, but I'd guess that's OK. [?] I haven't driven it all that much and have not noticed any mayonaise.
Could it have blown the gasket again? [?]
Auguste

 

[John H]

It's possible you have a "lean misfire" once you are out of the initial warm up:
when the temperature sensors indicate it is cold the ECU gives a rich mixture to compensate for the cold - equivalent to pulling the choke out on an older car.

Thing is though, when warm, the mixture is finely adjusted according to the voltage from the lambda sensor in the exhaust pipe, but AFAIK there are limits to the range of adjustment which can be made.

Did you reconnect the leads to it?


Another option is that you have a significant inlet manifold air leak - it may be in the pipe work attached to the manifold, if not actually the manifold itself.
Does it tend to run rather warm when hot - unusually high readings on the gauge when driving, and fan tripping in a lot??

Earlier ECUd Pandas suffer this when the diaphragm in the vacuum advance unit pops...
Is your MAP sensor, and its pipework OK?
Is your brake servo and (new) pipework OK?
Are the valves and pipework for the carbon filter OK?

ISTR you can find leaks by spraying WD40* at the affected area - if the tick over speed increases, you've found a leak.

Best of luck


John H

*or something fairly volatile you can spray in small quantities.

 

[Auguste]

The problem was easily spotted once I removed the air cleaner cowling and turned off my work light - there were significant sparks jumping from the sparkplug leads to the cylinder head. It occured on two cylinders - putting them back on again turned around and pushed down very hard fixed one, I had to apply black tape to another. Looks like I need a new harness, yes?
Runs like it should now, no problems.
Thanks again for the advice and support,
Auguste

 

[John H]

Glad it's sorted now

Happy Panda driving.


John H

P.S. Don't forget the antifreeze!

 

[Auguste]

John - I did the antifreeze - thanks for the reminder. Auguste!