I have a weird misfire issue.

It started when my son had a random misfire issue P0300.

Bought him a new wire set (7mm NGKs from Rock Auto for $25 -- they suck, more on that later).

He replaced the wires only back in October, and it ran fine.

Car then developed a manifold leak (traced to the rear rubber manifold valley seal using a smoke test)

Since the upper manifold was coming off anyhow, decided to use the opportunity to replace the coils (not Bosch, bought from Lucky 8) and wires since a couple of the plug caps had pulled off the wires -- the NGKs fit really tight -- too tight.

After a lot of work, everything was back together. Used dielectric on the caps/plugs on both ends of the wires.

It ran fine for about two months, then started running rough and threw two P0305s -- cylinder 5 misfire codes -- and a P0300 random misfire code.

Inspected the wiring and found that the 5 wire popped out of the rocker cover clip and the insulation on the wire had gotten burned on the SAI plumbing.

Patched the cable with some asbestos tape and crossed my fingers.

Engine then ran rough again and threw two P0304s (cylinder 4 misfire) and a P0300 code. Inspected the 4 wire and found that the cap was loose and not seated to the plug (so either these NGKs fit too tight or too loose?).

With 2 wires "bad", I decided to buy new wires (NGKs again from Rock Auto -- stupid me), pulled the SAI pipe and upper manifold and replaced the 4, 5, 6, 7, 8 wires (6 because I had to pull it off the coil anyway to get to the 4 wire below on the coil and 7 and 8 because they were very easy, right on top and at the end of the coil packs).

Now I have two P0301s -- cylinder 1 misfire -- and a P0300 code.

Anyone have any idea/theory as to what is going on here?

Are these lousy wires failing one-by-one?

Are the fresh coil packs bad?

Do I really have an injector issue and just think I have an ignition issue?

Could it be that I use 87 octane gas?

FYI, if I have to change wires again, I am relocating the coils to the front of the engine (where they should have been designed in the first place).

Any/all advice would be appreciated.

 

Using cheap low octane gas will certainly foul your injectors and gum up the fuel rail. That can and does lead to misfires.

If you have not done so, clean the injectors with Seafoam or similar and run some through the gas tank after you filled it half full of top tier premium.

I think you know about the wires so I'll refrain from comment on that issue.

 

I've used 87 octane in the past with no bad effects, but I prefer to stick with what the engine was tuned for aka Supreme 93 octane.

NGK wire wise I've used them in the past with no issues, but the D2/P38 Bosch setup is very picky and the heat under the hood puts a lot of stress on the wires. They turn brittle & break. It seems to me like the SAI D2/P38's are even worse.

 

Ok, I am officially sick of sticking my hand in that tiny space between the firewall and coils, so as step one I have ordered the coil relocation kit from this forum.

The fellow selling them has a new wire provider so we'll see how that goes.

Re. wires and the SAI D@/P38 engines, I was surprised that the SAI pipes could get hot enough to burn the insulation off of a plug wire, but they did.

BTW, in my cheapness/stupidity, not only did I buy the NGKs twice, but both times only 7mm wires (maybe that's why the 5 wire fell out of the clip on the rocker cover and onto the SAI pipe). The new ones will be 8mm.

The relocation project

 

I did clean the injectors thru the brake vacuum line using seafoam and will pour Seafoam or Berryman (stronger) into the tank at the next fill-up.

How can you test the injectors. I know the "noids" but that's just electrical signal. What about pattern?

Again, I find it funny/weird that I have this moving misfire issue: first 5, then 4, now 1.

 

You've probably seen STI, Kingsbourne and Magnacore wires all recommended here. I can't speak to the last two but the STIs on my truck have performed well for probably nine years and probably 70,000 miles (I don't have my maintenance file here to validate those numbers but I believe them to be close).

 

I'm with you 100% on STI wires! I've used these for many years (RRC, DI,& DII) with zero issues. And I've hade too many failures with Kingsbourne (& not just on Rovers). Not a fan of that junk!

STI> https://www.fcpeuro.com/products/lan...e-rover-hls103

 

Ouch. Just bought Kingsbornes that are custom-made for the coil relocation kit available on this forum. Hopefully, by being custom/made-to-order they may be better.

In any case, no more scraped, bruised and cut-up hands behind the Upper Intake.

Will let you know how it goes and whether the coil relocation and new wires (3rd set) solve my non-stationary (cylinder 5 to 4 to 1) misfire code or not.

 

Ouch too! I'm scared. I guess you are closer to Kingsbourne and you get yours this week. Mine will be tuesday according to tracking. But, I got the Yellow cables coming. I am hoping that somehow you get yours working. I just got a Westminster, drove home great and 5 days after, KABAM! SES! misfires all over. Well, so I just power wash engine bay yesterday really good so I get more codes and start from there. I got the new cheap coil packs again from ebay like the one I purchased 5mos ago. I wish I could get Karlyn coil packs by STI, but next time, they are very expensive.
Read your misfires. Did you check in total darkness if the cables are arching? I am hoping the 8mm Kingbourne will run well, many people here like using them as well and its less than $182.00 than Magnecor. Though Magnecor wires are the ones you get from AB and yes, they are expensive.
Cheers and good luck.