[Peter]

Misfiring problem comes back like boomerang. I have put NGK BCPR7ES (3330) and still have misfiring!

I used to drive using NGK BKR6EP-11. After making my car BPU I have noticed misfiring (not only at high boost of 20 psi but also at 0 boost at high rpm). After some discussion on the forum, I have decided to check coils connections and to change spark plugs to 3330. I have done it yesterday and made some tests. Car is powerful but sometimes especially at high rpm (5000-6000) it is misfiring. Strange think I have noticed is that: on full boost it is accelerating pretty well, but while driving after that at high rpm about 5000-6000 with no boost it is misfiring.

Coils looks OK, but never been changed – you can not see any signs of high Voltage on them (misfiring) rubber parts looks fresh, connections are perfect. I am stupid – I do not know what to do. I do not want to spend fortune on new 6 coils because I would prefer to spend it for new modifications.

Please help

 

[Josh S]

What gap did you set them at? Seems that some cars need a smaller gap than others to prevent the misfire. You may need to take them out and gap them down a bit then try again. You generally want to run the largest gap that will prevent misfiring.

 

[Peter]

I HAVE NOT TOUCH GAP. It is set as NGK has set it. But that is strange to me because it has nothing to come with BPU. I have misfiring at low boost, at 20 psi I do not have misfiring!

 

[Ranger498]

i think you need to check the gaping ..even the stock plugs need to be checked!

 

[Zerosoul]

coil "looks" good? you should check it according to repair manual for its resistance. I'm gonna tell you what I tell everyone else cuz I went thru all the plugs, testing, misfiring, detonating hesitating period. from my experiecne, you will find a new set of coil packs the solution to your problem. It works for all the BPU supras that I know of. it should work on you. those copper plug is a quick fix to problem, not ideal.

 

[Peter]

Thank you for all ideas. Yesterday I have found out what caused my misfiring problem. I have noticed that my A/F gauge is showing very rich while driving high rpm without boost. I started thinking that engine has too much of gasoline and that causes misfiring. I could not figure out what is the real reason. I was thinking and thinking and suddenly I screamed EURECA !!!! I’ve got it. BOV. I started to drive with open windows (-10 Celsius degrees) and I could hear psssssss almost all the time. I tightened BOV spring to max and now everything is OK. I am genius...

Thanx once again, I will come back to Supra stock gap and put platinium spark plugs. Hope my coils are good if not than I will listen to Zerosoul. Zerosoul - now on new coils do you drive 1.1 mm gap like in stock Supras?

 

[Zerosoul]

glad you found the problem. good job!
yeh, after putting new set of coil packs in, I've switched to Denso Iradium plugs, 1 degree colder, but stock gap. been running like this for over 10,000miles with 91octan without missing. I'm never going back to those NGK copper plugs, they make car idle rough and drives rough too IMO.

 

[DevilChrist]

zerosoul

do you get those at sparkplugs.com?

what's the item number??
part number??

 

[StSupDog]

Peter Poland

Is this right?? you said that your problem was your "BOV" (blow off valve)??and that you tighten the spring and the problem was gone.

 

[Zerosoul]

Re: zerosoul

do you get those at sparkplugs.com?

what's the item number??
part number??

yeh I got them there. check with them again, but I believe its Denso IK22. they are not cheap, $12 each.

 

[Peter]

Re: Peter Poland

Is this right?? you said that your problem was your "BOV" (blow off valve)??and that you tighten the spring and the problem was gone.

Right I have APEX'i BOV and now it is tightened to the maximum - you can not see the screw.

 

[supra178]

Thank you for all ideas. Yesterday I have found out what caused my misfiring problem. I have noticed that my A/F gauge is showing very rich while driving high rpm without boost. I started thinking that engine has too much of gasoline and that causes misfiring. I could not figure out what is the real reason. I was thinking and thinking and suddenly I screamed EURECA !!!! I’ve got it. BOV. I started to drive with open windows (-10 Celsius degrees) and I could hear psssssss almost all the time. I tightened BOV spring to max and now everything is OK. I am genius...

Thanx once again, I will come back to Supra stock gap and put platinium spark plugs. Hope my coils are good if not than I will listen to Zerosoul. Zerosoul - now on new coils do you drive 1.1 mm gap like in stock Supras?

how did your screw on the BOV became loose????

 

[Peter]

I am not sure if I understand your question. From the begining my BOV was screw soft - minimum

 

[mac]

@peter poland
have you both bov`s? (stock `n`apexi)
when you have only apexi, you couldn`t set it too hard...
cu
mac

 

[Peter]

I have only APEX'i but now when I have set it to maximum, I can hear psssssh even with low boost like 7psi

 

[supra178]

so Peter, the ever since you installed your BOV your car is running rich? I'm glad you've found the problem.:bthumb: :bthumb:

 

[Peter]

Correct, I am happy too...

 

[chester]

Isn't that more of a boost leak? Excyuse my ignorance but can someone explain this to me!

 

[Peter]

Yes, it was a boost leak thrue BOV, now when it is set to maximum boost leak is finished = no boost leak anymore

 

[chester]

What I am trying to say is that I do not understand how it was causing you to misfire? Also if your BOV is at its tightest, meaning (I think, excuse my ignorance) it takes alot more pressure to release it right? Can this hurt you in the long run, say if I tightened my HKS SS BOV all the way up, will it not release the air correctly? I have the HKS SS BOV and I don't have the stock BOV with it.