Hi thank you for looking in to help me. I will get to the point.


Trouble Codes

Codes:
P0300
P0302
P0304
P1590
I got a secondary air bank system fault code (cleared it has not re-appeared)

Symptoms

Intermittent miss at idle. Ranging from not that bad to bad enough to activate check engine light

Chronology

Est. 2 months ago put in a can of BG44k. Truck ran smooth then started to miss, and miss hard. It would miss at idle, it would miss on acceleration over 2.5k on the tach.

Est. 3 weeks ago found leaky HG's. Started leaking 3-4 days (after I switched for DEX to PEAK) or the leak could have been there all along. Got the good HG kit from British Atlantic with some new good stretch bolts replaced gaskets. Found a stripped screw in the lower intake manifold. Replaced the lower intake manifold. Had the Heads machined while they were off the truck. Replaced STI wires with 8mm Magnacor. Replaced NGK plugs with Bosh +4 plats. Replaced the Coil Packs (I will admit I only mounted them with one bolt to the engine, the only bubba and not "attempting perfection" thing I did. At least that I know of).

Truck ran great est. 2 days, later my *** detected a small miss at idle. Has progressed. Now has thrown codes.

As a side note. My dad said he has never seen any cleaner work as good as the Bg 44k. He was really surprised. When we took off the heads he was shocked at how it was eating at the carbon on the cylinders.

We put in new Peak coolant - Rotella T6 Oil - & a bottle of purple ice.

I have not lost any coolant in the last 200+ miles. *right after HG job the bleed screw failed. Replaced it and it holds its coolant level now*

Parts Repaired on the truck w/in the last 5k

Expansion tank cap
Radiator
all hose clamps
hosing as needed
fan clutch (hayden)
Fan (01')
thermostat (soft spring 180)
bleed screw
Head Gaskets and all other necessary gaskets included w/the kit
Valve Job
Machined Heads
Plugs (bosh +4 plat)
Wires (magnacor 8mm)
Coil Packs
put in 1 can of bg 44k est 400 mi ago
Coolant change to PEAK 50/50
Oil was using Amalee switched to Rotella T6
lower intake manifold

Current Plan

Check spark plug wires
another can of Bg44k or seafoam

???

 

Might be easy to check the only screw thats grounding the packs. Also check the idle air control valve. Do some search within the forum about the p1590.

 

Honestly I'd swap out the Bosch 4x Spark Plugs as step #1. I ran a set way back in the day in my 97 RR Vitesse & they caused misfires very quickly (before 3k). When I removed them some of the plugs had completly covered center electrodes. Swapped em out with some NGK plugs and I never had another misfire issue on that LR.

On a LR I personally have had flawless results with NGK. Swap em out first and see how that works for ya before diving into it to deep.

 

You can look up codes with
http://enginecodemaster.com

Was built to show rover codes from the get go

 

To the OP: Great, concise, informative post.

Something else odd and free to check... check the GROUNDING STRAP at the back of the driver side head. Another electrical fault that it could be (especially with the P0300) is the MAF. Whenever I get a P0300, I swap in a different MAF (I'm lucky to have some) and most of the time, that is the issue.

Otherwise, it sounds like a vac leak to me. I am very weak on SAI because I have never had it, but the recurring SAI code, recent HG repair, and the specific misfires on one side point to some sort of vac leak on that side only. That makes me wonder whether the SAI connections are sound. You could spray brake cleaner on the connections with it running and listen for a change in the engine, but use good judgment because the spark plugs wires are right there.

Also, what side did the original HG leak happen on? Passenger? If so, I'd suspect that your passenger catalytic converter is gummed up. A good way to find out (if your neighbors are deaf or you are trying to run them off) is to drop the passenger exhaust just below the header and, idling a couple of minutes, see if you feel a miss. If not, that is probably the issue.

 

P1590 is an ABS rough road fault. Which means you probably have the 3 amigos, or a problem within the ABS system.

With the SAI systems I had on all my 03-04 D2's it was the little valve that is mounted directly above the purge control valve on the driver side just behind the throttle body. It could also very well be a vacuum leak, but you can buy new little vacuum 90 nipples at any Auto Part store usually on the misc HELP isle. I never had a problem with the little hard lines themselves.

I would still pull those Bosch plugs and replace them with an Iriduim or Platinum from NGK, Denso, Champion, AC Delco, or even Autolite. All of those spark plugs have an exposed center electrode and they do not foul nearly as easy as the flush mounted center electrodes found on the Bosch Platinum, Iriduim, 2x, or 4x plugs. Our LR's already run on the rich side and are picky with setting mis-fire faults. So I'd truly avoid anything from Bosch unless it's an old fashioned copper core spark plug.

 

A preliminary thank you to all who posted. Once I am back at the house I will take all of the above advice and report back in more detail.

 

Double check the connections to the coils. After doing my head gaskets I had the same codes and it was because one side of the coil packs was not plugged in properly. Causing the car to run on 4 cylinders and get errors.

 

I was just checking about the coil pack grounding which I said earlier since I have been reading a lot of posts, that most of the bolts had to be used for better grounding. I'm not even sure about that now coz I have another set of coils I tested where that metal bracket base does not even do anything just to hold the coils in place. I hope I'm wrong but I used only one bolt on mine as well that is why its also enclosed in ceramic to isolate the internal components.

 

I know the conventional wisdom on the coils being grounded but I have to toss out that though mine are bolted at all four corners, I have just set them in there for an extended period (a year) with no bolts and had no issues. I have also run my engine with the coils just sitting on top of the intake for testing (loom separated) with no issues. Maybe I was just lucky.