OBD II Codes P0300, P0305, P0306 on a '99 DII

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Hello,

I just picked up a '99 DII bone stock but loaded with everything, and I'm fairly new to Land Rovers (I owned a '95 DI for a short while), and I'm definately new to ODB II and reading/interpreting codes.

Anyway, the Service Engine Soon light was on when I bought this DII last weekend. I got the codes today after visiting Checker Auto Parts (they let you borrow their code reader and get the codes yourself). The first time I checked the codes, it was P0300, P0305, and PO306. I cleared the codes, restarted the engine and the SES light did not come back on. But after about a minute, the exhaust started clanking a bit back by the driver rear tire, I got out of the vehicle, put my foot on the tailpipe, the clank went away, and by the time I got back to the cab the clanking went away on its own but the SES light was on. I'm convinced the clanking had something to do with it, but I don't know if there is an exhaust leak/crack causing a clank or other problems possibly causing these codes, or if it's not even possible for an exhaust problem to cause these codes. So then I was thinking that the clanking was just another symptom of the engine running a little rough despite the fact I couldn't tell a difference in how it ran. This time I just left the codes and waited until later in the day to check them again at a second Checker on my way home. I got the same codes, cleared them, and after 10 miles of driving they didn't come back (nor did I hear any more clanking).

I know that P0300 means random misfire, P0305 means cylinder 5, and P306 means cylinder 6. What I don't know is what this actually translates into to pinpoint the problem. I read some previous threads and they basically said anything from plugs, wires, distributor packs, to slipped sleeves in the cylinder (I don't know what that is). The previous posts seemed to have a bunch of other codes at the same time, so my case seems to be a bit simpler.

The engine runs very smooth, has good power (more than my DI 3.9), I got 15MPG on my first tank of gas at 87 octane and combo city/highway driving, which surprised the heck out of me since my DI got 13.5 at best. Dealer service was done at all regular intervals by the previous owner up until 67,000 miles which was the last one. The previous owner said the only problems it's had were a couple leaks and a bad alternator. It now has 102,000 miles. I have no idea when the plugs/wires were replaced.

I was hoping to get more specific info on these 3 codes and how they could relate to my DII despite the lack of symptoms (besides a short-lived exhaust clanking).


Thanks!

mnwolftrack
 
C

campbell

Guest
Test your wires by running the engine in a dark area. If you wires, or a wire, are bad you will see a little light show. As some have suggested, you can use a spray bottle to mist a little water to accelerate the light show. I did not have to do that. I had the exact same thing going on with my 99 DII. I changed the plugs and still had the problem. Changed the wires and hadn't had the problem since.

Good luck.
 
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mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Thanks, I will try that as my first step. Any recommendations on plugs/wires? I'm not sure what brand the factory plugs were on these, nor the recommended interval for changing them. The dealer service interval records in the manual don't show what was done at each service up through the 60k mark.

The SES light did come back on, on my way to work this morning. I didn't actually notice any performance issues or clanking (I was already cruising down the road this time when the light came back on).
 

S Marks

Well-known member
Apr 20, 2004
373
0
As for wires, Magnecore. There are three sizes, with the 7mm and 7.5mm fitting into the factory looms. The 8mms are a tighter fit, but work. Do a search, has been discussed many times.

Plugs...many discussions as well. I opted for the cheaper Champions as recommended in the manual and have had no issues.
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Ok, so I've replaced the plugs with +4's and wires with 8mm Magnecors, and the codes still come back. The P0306 seems to come back the fastest and seems to come back at idle.

What should I do next? I don't have a repair manual (yet), but am planning to get one. I am going to check compression since it's easy and free, but I need to verify the proper procedure first (in another post I made).

Is there a chance this is the dreaded valve job needed? If so, how hard of a job can I expect? I've taken apart plenty of vehicles before (dismantled and parted out several Toyota pickups and 4Runners), but this is my first D2. I owned a D1 for a short while but I don't count that much because I didn't own it long and only had to do a couple small misc things.
 
B

barefoot

Guest
hmm...try running some 93 octane. some discos just dont like the cheap stuff...also run some seafoam through to help clean some of the carbon build up.

you did gap the plugs correctly? also, make sure the plug wires arent resting against anything metal...like the oil dipstick.

sounds like sticking valves...try the seafoam, one trough the plenum and one in the tank...it just might help..??
 

S Marks

Well-known member
Apr 20, 2004
373
0
I second the Seafoam idea...worked like a champ on my brother's DII w/ 110K miles. We only ran it through the brake booster line though, not through the gas tank. It will smoke like a b@stard, but it works.
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Thanks for the tips! I just happen to have a couple bottles of seafoam. How fast do I add it through the brake booster line?

We don't have 93 octane here, just 87, 89, and 91. I've tried 87 and 89 and haven't noticeed any difference between the two in performance or mpg. My '95 disco took 87 well.
 
M

mojowebcast

Guest
I had the same problem. Upgraded to bosch +4's, 8mm magnecore wires and replaced all 4 O2 sensors. Truck runs like new.

2000 DII with 116k miles.
 
B

barefoot

Guest
i dont know what a brake booster line is but add it through the oil pick up line that runs from the valve cover into the base of the plenum...youll know if your adding it too fast because the engine will stall. i usually run mine through until white smoke starts to surround me then cut it off and let it sit for 15-30 min. then start the car and hold the idle @ 2500 until clear (no more smoking). repeat above until very little or no more white smoke comes out!

try 91 octane for a while...you will notice a difference. although, maybe not at first.
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Well, she's idling right now after adding a 1/2 can of seafoam through the brake booster line port. It's been smoking for about 20 minutes. If I rev the engine and hold steady at 2k, it trips the service engine light which starts flashing. If I back off and let it idle, it stops flashing and stays steady. If I check the code, it brings up a, or, various P030x numbers that it wasn't pulling before. I'm assuming this is becuase of the seafoam being in there still.

I also put about a half can of seafoam in the crank case per the bottle instructions.

So far, it does seem to be running smoother, but it's still blowing white smoke so it's a bit hard tell yet. I'm guessing it was REALLY dirty.

I'm almost wondering if an injector is/was leaking. The engine light would normally come on with a cold engine, within a few minutes of starting, and often when idling. Perhaps fuel was leaking off into the cylinders when cold, and built up high enough to trigger the light? Yet, if I was running around doing errands getting in and out of the D2 and never letting it sit for more than a half hour, perhaps not enough fuel built up in a cylinder to trigger the light? If I cleared the light while the engine was hot, it seems to take a lot longer to come back. Just some abstract thinking on my part....

We'll see what happens once she stops smoking and I take it for a drive!
 
Oct 27, 2004
3,000
4
I got your IM, and wanted to share what I found.

I went into work this weekend and looked up reports from techs in the field for common fixes to this.

EVERY tech with these symptoms reported sticking valves.

2 Ways to confirm this.

1)Vacuum gauge. Vacuum should be steady at idle. If it's jumping,pulsing,etc.. Valves are sticking.
2) Leak down test. A sticking valve will hang up and leak pressure quickly.
3) Compression Test. Not as reliable for Sticking valves. It's not a sesitive so a valve stickign enough to cause a check engine light may not stick enough to show on a compression test.

The best,most reliable fix is a valve job. However, for some that may not be practical.

The seafoam may get it unstuck, and no harm in trying.

I would go to Sears and spend the $20 on vacuum gauge and see what it shows. I leakdown tester needs compressed air and it costly. Not sure if it its worth it as you may never use the tool again.
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Thanks Chris!

I ran seafoam, but I had to post a new thread on that as it has me a bit panicked! This post your looking at now continues on in that one. I ran 1/2 can in the crank case, 1/2 can via the brake booster port and the smoke just keeps coming (idled for an hour). Worse yet, now I get a flashing SES light, P1300, P0307 in addition to the others I mentioned. And I get all these codes almost instantly upon startup, and now regardless if I'm at idle, driving, etc... I've only driven it about 2 blocks. It now lacked power on this 2 block drive, and when I pulled back in the garage the exhaust smelled like eggs.

I waited 3 hours and let it cool down yesterday, then I moved it to a different garage on my property. It didn't smell like eggs that time, but it was only running for 2 minutes. The SES light did start flashing immediately.

Before I continue diagnosing, I'd like to ask these additional questions:

1. Am I safe to start it up and continue to let it idle with the seafoam in it, but with the SES light now flashing? Nothing in the exhaust has glowed, despite the P1300 error (misfire causing excess emissions damaging catalyst) and all the other errors that continue to happen. I'd LOVE to try and get seafoam to work for me, as it "does" seem to be smoothing out the idle despite all the issues mentioned thus far.

2. Regarding a vacuum test, I have a brake bleeder/vacuum gauge (mity-vac or mini-vac or something), that might suffice. What can I expect the vacuum to be at idle, and how much wander is too much (to indicate sticky valves)?

3. Regarding checking compression, what should it be? And, is simply pulling all the plugs then cranking the starter enough?

4. How is my case different than simply stuck or leaking injectors? I've read through many previous posts, and I figured I either had sticky valves or stuck/leaking injectors but short of doing a compression check, vacuum test, borescope, fuel pressure test, or some other test, I am not sure how to determine the difference.

I apologize for all the questions and too much info, but I'm trying to learn as much as I can. I really enjoy fixing things myself, and I have done my own maintenance on my Toyotas for the past 15 years. I'm new to Rovers and this feels like a whole new world!
 
Oct 27, 2004
3,000
4
mnwolftrack said:
Before I continue diagnosing, I'd like to ask these additional questions:

1. Am I safe to start it up and continue to let it idle with the seafoam in it, but with the SES light now flashing? Nothing in the exhaust has glowed, despite the P1300 error (misfire causing excess emissions damaging catalyst) and all the other errors that continue to happen. I'd LOVE to try and get seafoam to work for me, as it "does" seem to be smoothing out the idle despite all the issues mentioned thus far.

I think what maybe happening is the Seafoam is confusing the O2s??? WHo knows, but I wouldn't worry about it.
2. Regarding a vacuum test, I have a brake bleeder/vacuum gauge (mity-vac or mini-vac or something), that might suffice. What can I expect the vacuum to be at idle, and how much wander is too much (to indicate sticky valves)?

No, I'm talking about a gauge measureing the vacuum at the intake. It should rock steady. If it moves at all at idle (Remember, Higher engine load,lower vacuum) suspect sticking valves. Again, ANY movement at idle indictes something wrong.

3. Regarding checking compression, what should it be? And, is simply pulling all the plugs then cranking the starter enough?

Pull the plug and screw in your tester. If I remember it should be around 150, but your really looking to make sure all the cylinders are within 10% of each other. If one is %10 from the others, Thats a potential problem.
4. How is my case different than simply stuck or leaking injectors? I've read through many previous posts, and I figured I either had sticky valves or stuck/leaking injectors but short of doing a compression check, vacuum test, borescope, fuel pressure test, or some other test, I am not sure how to determine the difference.
D2 uses Bocsh injectors, instead of Lucas like d1s. Injector failure, while possible, doesn't happen as often. Your right though, the syptoms coudl be the same. Tests are needed to narrow your search.
I apologize for all the questions and too much info, but I'm trying to learn as much as I can. I really enjoy fixing things myself, and I have done my own maintenance on my Toyotas for the past 15 years. I'm new to Rovers and this feels like a whole new world!

It IS a whole different world. :) Rovers break. :)
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Thanks for all the help! At this point I plan to continue to just let it idle and get the seafoam out despite the SES light flashing because of it. I will watch it like a hawk though, especially for glowing cats. Once I'm past that and it's running w/o smoke, I'll change the oil (get rid of the seafoam and junk that cleaned off), check compression, get a pressure gauge, and possibly get a fuel pressure gauge if it's not too spendy. I like to get both of those anyway, as I've had a few times with my Toyotas when I could of used them.
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
Wonderful! Is there a preferred spot to hook a fuel pressure gauge and a vacuum gauge? I will be buying both of those gauges this week. I'm sure there are genenic instructions included with the tools, but I bet there are better spots and not-better spots to hook them up to.
 
Oct 27, 2004
3,000
4
The fuel pressure gauge screws into a tire type(Shroeder) valve in the fuel rail.

The vaccum gauge, connect to the manifold.

d2 Has a vacuum port toward the front of the engine,with a plastic cover on it.
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
I think I know what started this whole mess.....

I said to someone on this board a couple weeks ago when I bought it that it doesn't even leak oil! This is what I get for claiming the impossible.

I will take a gander for the schrader valve tonight, and the port for a vacuum line. It's nice that LR puts a connection on the fuel line. My other vehicles never had any such thing, part of why I hadn't gotten a fuel pressure gauge yet. On my other vehicles I'd of had to disconnect the fuel line around the fuel filter or similar area, buy a special banjo fitting straight from Toyota or make one by cross-drilling a bolt to put in-line.

I added seafoam to the Disco by hooking up a different hose to the brake booster port, but I gather there is a spare port on the manifold that I can hook up to.

I'm eager to get back into this! I HOPE the seafoam will work though.....
 

mnwolftrack

Well-known member
Oct 26, 2004
353
0
Minnesota
"

Well, this thread can offically end too as I started a new one called, "Low compression on #6--Seafoam won't fix this!"

Guess what bad news I found in addition to two wet plugs (6 and 7) likely causing my two lingering P030x codes, P0300, and P1300.