1995 Misfiring

[crown14]

OK I hate for it to come to this but a little input from others might help at this point. Plus, so many of these threads get started and never seem to be resolved, I will keep this one updated as much as I can for posterity.


So my 14CUX 1995 Range Rover started misfiring the other day. She starts up fine and will idle like normal for a while when cold, but as she warms up idle deteroriates to a dead skip situation. Driving it quickens this situation. Once it gets bad enough it will throw code 44 (bank one O2 sensor). Not sure of other codes as I cant get the 44 to clear.
If I am driving and it starts to act up, it can almost stall, pop back through the intake, and wont run over 45mph.
Now the day before I had both been through a carwash with an undercarriage sprayer AND had been low enough on fuel to trip the low fuel lamp. Has either of those got anything to do with whats going on now, I dunno, kinda doubt it but my first thought was ignition system. Maybe some moisture from that stupid car wash had gotten in somewhere it shouldnt have.
FIRST step, replace plug wires. The wires werent old but I could see a little corrosion in a couple and the boots just starting to look like they were starting to split. Installed a new set of wires- no change. Swapped Dist. cap and rotor from my other 95- no change (and no misfires developed on the other 95 with the parts from this one). Brand new set of Champion plugs, no change.
SO I start thinking trash in the fuel filter maybe. Brand new fuel filter, no change. :(
Back to ignition, swapped coil wires, nope. Swapped entire distributors, nope. Little resistors in harness? Nope.
Scratch head for a while, ponder the reason I bought these old ass trucks, stare at the ground, kick a few rocks. Nope.
Swapped out alternators, no change.
Swap MAF, nope. Swap ECU, nope.

Now I have heard of trash in the fuel rail/injectors before but never ran into it myself. I have another good fuel rail and what should be a good set of injectors, but somehow, I am all out of the o rings.
Other than that, I am pretty well lost. I mean, I havent messed with the ignition module but they usually cause it to stall when they fail. I suppose it could be a coil, getting hot and losing its ability to squeeze out a hot spark...

Any ideas fellas?

Follow-up Post:

I think I will go back out and try to get it to do the dead skip at idle, then I should be able to check the spark intensity and maybe even nail it down to a certian cylinder or two.

[madcowdungbeetle]

I had something similar happen, and what it ended up being was one of my cat's had blocked up, and was causing it to build pressure and pop back through the intake.

[crown14]

HMM

I actually had to put new downpipe gaskets on this truck the day before all this started happening. The Y pipe/cats have been replaced but I will certianly explore this possibility- thanks.

Follow-up Post:

Had to put new gaskets cause the bank one side had a little leak but when I got the old gaskets off it was not blown out....
Maybe excess pressure from blocked cat was venting at the old downpipe gasket and the new one is sealed too tight and pressure is backing up into the head

Follow-up Post:

also bank 1 is the code being thrown

i will create a leak on that side and test drive

[cellulararrest]

Maybe something strange with the O2 sensors? I think the computer ignores them until it warms up, correct? Possibly related to undercarriage wash?

I don't know why it wouldn't go away once dry, however.

Are you clearing the codes properly to see if there are multiple?

[crown14]

Tried clearing the codes only way I know how without an autologic, unplug the connector, wait 5 secs, plug the connector, switch ign off wait for main relay to drop out, switch ign back on??

I think it probably has the bank 2 code as well if it sits long enough running poorly, but my clearing procedure might not be working. I can disconnect the battery and clear them that way of course.


I forgot to mention I did remove the bank one O2 and check it out, no visible issues. Anyhow a bad O2 should not cause misfires, maybe an excessive rich condition with black smoke and what not but I am getting none of that.




I created an exhaust leak and tried that, no dice. I also pulled individual wires off the cap while it sat and idled like shit, every wire makes a difference but not much. Spark is purple and STRONG.
I think its shit clogging the fuel rail/injectors and leaning it out

[130Tdi]

on my classic when it started missing like that there was no bridge left in the head gasket between two cylinders. Compression check ?

[madcowdungbeetle]

Definitely compression check time.

I've also seen this with the early onset of a hole in a piston.

[crown14]

Its not that, I have seen enough of those that I can see them coming. This truck ran fine till I ran it low on gas taking pics to so I could put it up for sale.

I think its a fuel problem, when I pulled the 'old' fuel filter inlet fuel was dirty outlet fuel was clean. I love to guess, so lets make a bet.



how about this- if it is a fuel problem- doug and the carter the dirty hippie each buy me a 12pk. If its a bad cam lobe or head gasket I buy them each a 12'er of their choice.

[rover4x4]

I had something similar happen, and what it ended up being was one of my cat's had blocked up, and was causing it to build pressure and pop back through the intake.


x2. I also have an injector thats not 100%. Ive done all the little ignition trouble shooting, module move, O2 sensors. When I unplug the #3 injector it acts the same, if I unplug all the others its clearly the issue. I did run 3 containers of Techron through about 25 gallons of fuel, that helped a little.

[crown14]

Want me to grab you some injector orings Phil?

[rover4x4]

Ive got a set of Ford injectors waiting for when I tear into the top end. I might go ahead and do heads cam etc on the 90. I have been holding out on the Classic as I think there is something going on in the bottom end. I hope to start "building" a 4.2.

[evilfij]

When you say you swapped distributors, did you swap ignition modules?

If you have a plugged cat, you can remove the 02 sensor and let the exhaust out that way and it should improve.

Also, since you are getting a code 44, did you swap that 02 sensor? They don't do anything until the truck warms up IIRC. "Anyhow a bad O2 should not cause misfires" -- untrue, they will cause misfires.

[130Tdi]

if it is a fuel problem- doug and the carter the dirty hippie each buy me a 12pk. If its a bad cam lobe or head gasket I buy them each a 12'er of their choice.
ROFLMAO ! You are a better mechanic than I but ok-deal.

[crown14]

When you say you swapped distributors, did you swap ignition modules?

If you have a plugged cat, you can remove the 02 sensor and let the exhaust out that way and it should improve.

Also, since you are getting a code 44, did you swap that 02 sensor? They don't do anything until the truck warms up IIRC. "Anyhow a bad O2 should not cause misfires" -- untrue, they will cause misfires.This does not feel like an ign. module failure to me. I did suspect cross firing within the dist. but swapping distributors from another good running truck eliminated that. Also the other truck developed no misfires with the dist. from this truck. I would welcome a correction to this but as far as I can see- on a vehicle with no computer controlled timing there is no reason to suspect the ign. module with these symptoms. Like I said spark is good, difribulator type purple lightning bolts. I have chased a similar issue on another 95 RRC before and it was purely ignition, spark seemed OK but in the end wasnt good enough, long story, this time thats the wrong tree to bark up.

Tried creating an exhaust leak, made no difference (although I liked the idea a lot). Have not swapped O2 sensors, give me an idea how an 02 will cause a misfire, I am curious. You mean if its showing a rich value to the computer and the computer leans that bank maybe? I am used to 02s wigging out and giving false lean signals, causing excess fuelling and black smoke, etc but you may be onto something. In that case I should get a serious improvement just unplugging the sensor(s) wouldnt you think? I will give it a shot this morning.

Surely this will throw the 44 code again right off the bat but should go to a baseline fuel map.

Rover Diagnostic ("Fault") Codes 12 Mass airflow (MAF) sensor or MAF sensor circuit 14 Coolant temperature sensor (CTS) 15 Fuel temperature sensor (FTS) 17 Throttle position sensor (TPS) 18 Throttle position sensor (TPS) 19 Throttle position sensor (TPS) 21 Tune resistor (open circuit) 23 Fuel system pressure 25 Ignition misfire 28 Air leak 29 Electronic control module (ECM) memory check 34 Injector (or its wiring) - cylinder bank "A" 36 Injector (or its wiring) - cylinder bank "B" 40 Misfire - cylinder bank "A" 44 Oxygen sensor - cylinder bank "A" 45 Oxygen sensor - cylinder bank "B" 48 Idle air control valve (also check the idle speed and road speed sensor) 50 Misfire - cylinder bank "B" 59 "group fault" (it's either an air leak or a fuel supply problem) 68 Vehicle speed sensor (VSS) 69 Gear selector switch 88 Carbon filter solenoid valve ("purge valve") leak

Follow-up Post:

Tried unplugging the sensors, I could tell on startup somethign is still wrong, after 3 trips around the block it was back to the same behavior- would barely idle in gear.


Surprised noone has asked about fuel pressure yet, as that is something I should have checked first. Trouble is my fuel pressure tester is nowhere to be found ( I thought I had one ? lol ) so I had to skip that step. There is a possibility that something is wrong in the tank, hopefully I will get my hands on the tester kit today and have that information.

[crown14]

Son of a bitch, after reviewing the replay, Ron you may be the winner

[evilfij]

Son of a bitch, after reviewing the replay, Ron you may be the winner

What was it? Where is my free beer?

Ron

[crown14]

looks like it may be the 02 after all, I will report back soon

Follow-up Post:

IT APPEARS THE MYSTERY HAS BEEN SOLVED

Just when I gave up all faith in the self diagnostics of the 14CUX system I am proven wrong. Trouble all along was the Bank 1 O2 sensor. Must have had a break in the wire somewhere or something and gotten wet in the undercarriage wash, leading to the catastrophic malfunction of the sensor- which in turn told the ECU the fuel mixture was way too rich on that bank. ECU leans out fuel trim to its maximum which is enough to cause misfires.
Remember yesterday when I guessed that if this was the case, unplugging the sensors would go to a baseline fuel map and should show some improvement? Then I did that and drove it and no good? Well turns out I missed the fact that two wires were falling off the distributor cap at the same time. I reconnected them and drove it with the 02s unplugged and it was back to its old smooth running self. So in the past 5 days I have put who knows how many hours and at least another $300? in this sucker but boy does she run great now.

[cellulararrest]

Maybe something strange with the O2 sensors? I think the computer ignores them until it warms up, correct? Possibly related to undercarriage wash?

:cool:

[crown14]

OK you and Ron can split the victory beer images/smilies/happy.gif

[cellulararrest]

I'm just glad you tracked it down before getting too frustrated. It happening right as it came up to temperature really gave it away though.

[rover4x4]

maybe I need to unplug my O2's on the Classic, I just got a code 45 yesterday....... My new used O2 sensor failed me..

[cellulararrest]

it's probably not your O2 sensors...

[rover4x4]

I am sure, that would be way to easy.