I need some help from some people smarter than me. I'm having a hard time figuring out my problem. This is my sons only mode of transportation and I'm at a loss. It's a 2002 Disco II


A couple of weeks ago his check engine light came on so I checked the code it was a P0153, cleared the code and told him to only use 93 octane in the truck and haven't seen it since. This week he said he was driving down the road the SES light came on and was flashing so he immediately pulled over and cut the truck off and called me because he couldn't get it to start back. Finally it started and he came home. Pulled the codes and this is what I found : p1300, P0300, P0304, P0305, P0307, p0308 p0307 P0308.


I thought after reading on here plugs and plug wires were in order so I replaced them. All plugs looked a little lean but pretty much normal. Check the number 4 5 7 and 8 cylinder for moisture and nothing was found. Water level is fine. I know these cylinders are on different coils so I don't believe the coils are the problem...maybe I have another if recommended I need to replace it I will. After a couple of days of driving it he gets all the same codes. He told me he had a code for all cylinders misfiring....but I don't know of one maybe he means the P0300 code.


Obviously this problem is coming and going. When the codes are thrown the truck runs really rough but runs fine any other time. He did mention for the past couple months he would be at a red light and the engine RPM would raise up to about 1200 1300 rpm once and may happen in a couple times in one trip. I bought a O2 sensor if that's suggested to replace I will. What other kind of problems could I be looking at here? Could the rear O2 sensors be faulty? the O2 sensor test came back normal for all 4 on the code reader. Im thinking something with the computer, fuel injection, or something else really complicated....as you know it take a special person to troubleshoot these landy's so that's why Im here.

 

When my truck was acting like this it was the Crankshaft Positioning Sensor, but it also threw a code for that.

 

It's either spark, fuel, or air.

Spark- it's possible you have bad coil packs, you could test with inline spark tester. Or maybe your coil packs are not bolted down and causing the wires to intermittently connect.

Fuel- maybe clogged injectors, you could try an aggressive fuel additive or a cleaner that is hooked up to the fuel rail.

Air- might have an air leak.

i would start the car and grab a fresh can of brake cleaner. Start spraying around all vacuum and intake hoses, maybe flex or wiggle intake hoses while doing to replicate movement or rev the motor at the same time. Especially spray under the upper intake looking for fuel injector o ring leaks. I would start here as it's the easiest.

But, Im guessing you have a spark issue.

 

I guess I forgot to mention the CPS was replaced a month ago because it was giving a code and some lights were on on the dash but the CPS did fix that problem. Today a whole different problem.


Could the o2 sensor be causing this problem? I will try the break cleaner today as that seems plausible.


Can anyone explain how the coils not being bolted down be causing the problem? I will say the coil pack is missing a bolt but the other bolt is tight and the coil pack isn't loose. Ill put a bolt in it but really curious how it could be causing the problem.


Keep in mind this is a intermittent problem and not continuous....right now it runs great and no problems but I expect the codes any minute.

 

Can anyone recommend a aggressive fuel injector cleaner?

 

if it was loose it could be bouncing around causing connection issues. I've also seen damaged coil packs with intermittent connection issues, internal cracks.

BG petrospecs 44K is good, but not readily available. Maybe try royal purple brand, I know they sell it at Autozone.

Being intermittent is why i suggested tweaking hoses while spraying cleaner. Could be a crack in a hose or connection that opens up when flexing.

 

Today I will clean the MAF, IAC, and Throttle body, spray break cleaner on intake, hoses, injectors and look for vacuum leaks, tweaking hoses. Ill put 3 bottles of techtron in with 93 octane. I will get a fuel pressure gauge and see if I can check fuel pressure. If I cant recreate the problem what do I do next?


Thinking of changing the bank 2 sensor 1 O2 since it threw a code a month ago. bank 1 sensor 1 was replaced a couple months back.


I read somewhere a fuse box could be the problem intermittent like this? Any clue what fuse and which box? Since its intermittent then maybe wiggle the fuse box will throw the code? The thing that's got me puzzled is the small rev in RPM's he's been having for months now. I cant help but think they are related. What Im not sure is why it only revs once.

 

Ok replaced the IAC and MAF, cleaned the throttle body, sprayed break cleaner and no results, made sure the coil was bolted down, thing runs great in the driveway but i have noticed sometimes is really hard too start. Took it for a drive does great 30 minutes into the drive i get the flashing cel light and same exact codes. Get home and put in fuel injector cleaner. Everytime i get this code is always around 40-45 miles an hour.... can't imagine that had anything to do with it. No performance difference when i get the codes. Idles very nicely. Please help i dont wasn't to hurt the truck by driving it but i don't know what to check. Could the cats be causing the problem?

 

All the diagnostics thus far have not worked.

if I were you I would:

1- remove upper intake
2- replace coil pack with new and make sure all wires are seated at coils and plugs.
3- replace fuel injector o rings
4- replace upper intake manifold gasket

button back up and see what you got. Assuming you did the wires and plugs correctly, i think it's your coil packs, but it's hard to say hearing your steps second hand.

good luck.

 

Any changes in the weather when this occured? Deep water on road and splash? My guess is the coil pack as well. Plugs may not be seated properly at the back or coil pack need replacement. Climbimg a slope and suddenly the ses light start blinking? A good complete tuneup including coil packs is a must. About my question with water on road. When engine is hot and you hit water, spash and steam will rise behind where coils are located and often wet the contacts when not sealed properly.