Another Random Misfire

[edthediscoman]

Hello all, its been a while.

1994 D1.

Runs strong, then all of a sudden very rich and misfires. Shut off car for 10 sec, restart and back to normal.

Replaced while chasing this:
Rotor, Cap, wires, plugs are good, removed cats (they were clogged per pressure test - which started this mess I think), one O2 sensor pass side, removed cleaned and tightened every ground wire, checked and replaced vacuum hoses, new IAC valve, replaced position sending unit on dizzy (Yes I need to relocate that to the coil), changed coil, checked wiring for tightness to coil/dizzy.

Seems to happen once while driving, usually about 10 min after starting, then it will run fine for hours. I have not changed but might have to: Fuel pump, TPS (although I now have one), MAF, and the list goes on.... Incidentally, mine has no schraeder valve on the fuel rail. I have two others in the part bin that do. Found that strange so will be replacing the rail when the intake etc gets powdercoated.

Almost like you are driving and then remove foot from pedal - but it reeks of gas at that point. I have done extensive reading and replacing, but so far no luck. Also - no codes on the OBDI.

Thoughts from the gurus?
Thanks
Ed

 

[AfiRover]

death to dizzy

 

[edthediscoman]

death to dizzy

Specifically? Do you think it might be a bad magnetic pickup signal? I have a spare but the one currently on it is the only one with the mechanical advance working. Made the old yank the rotor mistake on the other.

 

[AfiRover]

NO the problem with the truck is the fact that is has one

but your issue is in the feed back loop
start looking at 02 sensors and wiring harness

 

[edthediscoman]

I don't usually have a problem with the dizzy. I replaced the amplifier and plan on moving it to the front, along with the upgrade from australian land rovers. They use a higher powered amplifier off other vehicles.

OK, I'll pretend I haven't been messing with them for 30yrs and will double check the magnetic pick up, already checked the wiring and have signal both ways.

I am thinking it might be other O2 sensor, or possibly ECU and TPS/MAF not lining up to the ECU. Just have never seen this problem, or heard of anyone with a D1 having the same.

 

[edthediscoman]

Changed TPS now as well. Problem still exists.

 

[olyller]

Changed TPS now as well. Problem still exists.

Watching

 

[XCELLER8]

I wonder if you are having some issues with the injectors....if a couple of them were to suddenly stick open for a spell it would puke gas really bad and runlike crap, shutting it off obviously cuts the power to them....as to why it will run fine for "hours"after the restart >>>well,....this IS a Rover...

fwiw...I just had a rough running spell with my '95.....turned out to be the coil wire to the dist shorting out to the connections on top of the coil....coudnt see it, but sure could hear it snapping

 

[discostew]

Could be exhaust valves sticking. If its a valve you might be able to see it make a vacuum guage bounce a little bit. If you do see something on a vacuum gauge then you could take off a valve spring and open close the suspected exhaust valve while rotating it in the guide. If its sticking you will feel it.

 

[edthediscoman]

Since last post - Bought Magnecor wires and installed, no change - but definitely more power when running. O2 sensors arrive today and will install them tonight along with fuel relay and other goodies.

Also added lucas to oil to see if this might unstick any valves and also to give it a little more lubricity on starting.

I have spare injectors and can swap them when I do the fuel rail/valve cover/throttle body change. I feel this has to have something to do with the Y pipe issue initially.

Strangest thing. This morning - no problems at all driving for 20-30 min. Last night on the way home though, had the same problem. Shut off for 10 sec and all is well again. Basically I think an ECU reset is happening and all back to good.

I bet its a timed item with the feedback being off. Then it needs a reset and all is well again.

Will keep everyone in the loop, but as the car is in awesome shape (135K miles), paint looks brand new, interior is spotless - this car is along term keeper and therefore no expense will be spared! (And its my DD - although I have other cars to drive)

 

[jims95]

The 14CUX engine management system, requires the gap inside the distributor to be in specification. Many years ago my 1995 RRC, which also has 14CUX engine management system, would suddenly go rich and misfire. I replaced the cap and rotor, as I thought that I might have a cracked cap. I tried to diagnose the reason with no luck. I handed my truck over to Inland Rovers, in Riverside, California. They checked my fuel pressure to make sure that I did not have leaking injector(s). With their computerized equipment they were able to check the function of the oxygen sensors, and the injector pulse width (which would suddenly pulse for longer, and you could smell the rich condition). The coil was checked with a known good one, the MAF was checked with a known good one, and they even reset the base idle. They checked the air gap inside the distributor, and found that it was not to specification, adjusted it, and the problem went away.

Good luck.

 

[edthediscoman]

I am almost at the point Gordon gets it as well!!!

This weekend I will check the gap. Strange that it goes out and back every once in a while.

Also, I have bought LR rotors and the new ones are crap. Had one fail within a week. Now I am back to my old (2007ish) Lucas rotor.

 

[jims95]

Many years ago after installing a new cap and rotor, I had that new cap crack within 250 miles, and cause the engine to miss very badly. Sprayed with water mist, and the arcing was epic. I always check that there is no continuity from the tip of the rotor to retaining spring inside the rotor, before installation. Quality control is spotty at best

 

[edthediscoman]

Good to note, just received another rotor from AB and will check that one as well. (Now I have 4 - 2 brand new ones - 1 has failed already and 2 older Lucas logo embossed ones)

 

[edthediscoman]

New O2 sensors installed and still the same problem.

I have to admit that with each new part the engine runs better, just still has that random misfire that kicks in about 10-20 min after starting. Then I shut it off for 10 sec and its back to normal.

Have not checked gap on dizzy yet as it rained most of the weekend.

 

[edthediscoman]

Is it possible this is the VSS? I have a slight exhaust leak at the seam (after cats/before resonator). (Cats are gone)

mmmmm....new parts to order.

I assume my D1 has one, will go look when I have a minute.

 

[Grenade]

Is it possible this is the VSS? I have a slight exhaust leak at the seam (after cats/before resonator). (Cats are gone)

mmmmm....new parts to order.

I assume my D1 has one, will go look when I have a minute.

Yes it has a VSS, its located on the Left Drivers side by the parking brake hub near the driveshaft.

Check to see that the bolt has not come loose. Its an Allen 5MM. I know my 95 would exibit misfire problems and stumbling and a hard to start condition when this was loose.

You may want to suspect the fuel pump as well and if its the stock one then you may be on borrowed time.

 

[edthediscoman]

Its there, doesn't feel loose.

Will get a spare and change tomorrow. Probably used.

 

[Grenade]

Its there, doesn't feel loose.

Will get a spare and change tomorrow. Probably used.

From what I've read if its not falling apart and it seems as tho the shaft is not binding up your original should be good to go.

FWIW I just installed a new Bosch Fuel pump and Fuel Filter on my 95 and the idle and throttle response has improved a considerable amount. There is a quick throttle response and a very smooth idle that was not there before hand. Since you can not check pressure I would look into trying a to find a way to eliminate the fuel delivery system as a contributor.

HTH

 

[edthediscoman]

I have changed the fuel filter during this fun party as well - fuel rail is on the list.

Well: Disconnected the VSS. No misfire!! (Yeaaaahhhh) but it does cut out when coming to a stop (boooh). Probably the IAC valve (Also brand new) but would not know exactly where to go and probably gets in the wrong spot.

So: New VSS it is. Didn't manage to get one on Sat and Sun was honeydo day.

Will get one and report back to see if the stall goes away when slowing down also.
But this is better news!