Possible injector or HPFP?

[tommyb13662]

Howdy guys.

So unhappy news for me. Been tuned since 29kish miles. Modded since 30k to FBO and outlets. Now the trouble. Im at almost 45k miles on the clock. This morning headed home from work was running 140+ so the guy in a new lexus couldnt keep up noticed some hickups in power never felt before. Got off at my exit and low load low rpm had some very noticable shudder/missfire. Pulled into nearest station. Read the codes missfire cylinder 4. Pulled all the plugs put coil from 4 onto cylinder one. All plugs looked great(replaced@35k). Flashed to safe stage one 91 octane cookie cutter tune. Drove rest of the way home nothing... this was like 5AM ish. Around 7AM brother needed a ride to work so i took him. Shudder/missfire came back after a while (within 5 miles) pulled into first gass station pulled plugs again and read codes still cylinder 4 missfire but also a multiple cylinder code :-( so any other DIY guys out there have trouble shooting tips to help me figure out wich one it is? Thanks.

Tom

[rocksarntpeople]

Sounds like injectors, but based on the original event (140 plus pull and FBO) I wouldnt rule out a vacuum leak either...Ive had my hot-side intercooler pipe coupling come off and cause very similar symptoms on stock tuning...just some thought...check your intake track and make sure everything is nice and tight.

[infinitekidM2C]

Does it happen only at WOT?

[tommyb13662]

Ok sigh of relief. Its changed to cylinder one misfire then cylinder 3 missfire following that coil. Only need a coil it looks like for now but will keep you posted.

[Tecmo89]

So I was having the same problem. Make sure you have colder plugs with the proper gap for higher boost. I also found out my JB4 was a big contributor to it. Since I switched to the MHD flash I haven't seen that problem.

[infinitekidM2C]

which plugs are u using tecmo?

[Tecmo89]

Think they are NGK 95770 ILZKBR7B8DG Laser Iridium Plug. Used to be old part number 5992. Gapped at .022 I believe, just google it, plenty of threads on it.

[tommyb13662]

Im also gonna get Autolite XP 5682 they are about 1.5 cooler since i am over 100HP more than stock. Run em like mentioned .022"

[tommyb13662]

https://www.amazon.com/gp/aw/d/B01MT...yaL&ref=plSrch

Damn these are almost too good to be true... anyone order these?

[Sam_M]

If it seems too good to be true, it probably is.

We can get Bosch coils in the UK for £23 a pop which is by no means breaking the bank.

[tommyb13662]

Got the Advance auto store brand injector looks just like a bosch. First fire up it doesnt even work. Try reconnecting it and its ran good on a short test. Will try a good run on it in the morning aster i get off work.

Just a bandaid until the denso set arrives.

[tommyb13662]

Ewww guys in the US DONT EVEN BOTHER with the Advance Auto store brand coil. It is the only one they carry in stock... but out of the box was dead. Returned swapped for another new one it lasted 15 min then was misfiring like a bitch... the original bosch one as long as I keep it under 4k rpm I do not get any misfire issues... weird

uggg.... gotta wait until monday-weds for my set of Denso coils :-( so im stuck having to drive like a granny until next week...

[AntonioZ]

In for update!

[tommyb13662]

So odly enough the cheap set from amazon I linked earlier came first. I bought them just to see the quality. Ill post pics up later. So far just testing them around town. My car is back to normal. Im going to compare them to the name brand ones i ordered as well. ;-) first impressions though. They lock in and fit very snug both to the plug and the electrical connector. They seem to weigh a bit more than the stock bosch coil. They have a plastic body and the insulator rubber feels similar to the bosch. The only part that felt slightly cheaper was the soft rubber that seals the top of the spark plug hole. No missfire, timing seems to be running same as before. I also installed the autolite iridium plugs i mentioned. Old plugs came out light tan as expected only about 10k miles on them since i changed those. Very surprised that i had issues with the advance auto knockoff bosch coils... But these have been tearing it up for a few hours no issues. They even come with a one year warranty! I say so far worth the $83!!!

[tommyb13662]

Welp... so installed the plugs and finally got to do some 1/4 mile power pulls... multiple missfires& 1,5,6. Sooo thought i was back to stage 1 until i looked at the brand new feeler gauge set i bought. WTF?? The guages are way way off. The .025" is thinner than the .024"&.022" is thicker than the .026"so i disassembled the feeler guage and measured them all. None of them are close. The .022" is close to .028" so ill have to regap them all and try again. Damn el cheapo autoparts feeler guage!!!

[tommyb13662]

Cant really complain though this car has been up until now bulletproof layin the power down since its tunes 29k-45k and this is the first issue. I used a friends camera scope through the intake and gotta say without a walnut blast at all in its 45k miles the back of my valves are mostly clean. A bit of gum on the very upper part of the stem but the backs of the valves are clean. I did try the 20 min@3500-4500 rpm highway run. But did not check them it before that so not sure if it removed anything. I think ill check it every 5k or so with the scope to see when it gets dirty.

[tommyb13662]

So with stock plugs back in im no longer getting misfires but i do have timing pulls.