Feels like a bad plug wire. Coilpack?

[Silverbullet91]

I'm having a problem with my redtop s13. Pretty much stock sr20det redtop except for upgraded exhaust and IC.

Sometimes after I've driven for about 45 mins, give or take, the car starts to feel like a motor with a bad plug wire. Its fine when idling and under a light load, but if I get on throttle some, it almost feels like a cylinder cuts out. Noticable loss of power and the exhaust note changes. I had cars do this because of a bad plug wire so I thought maybe it was a coilpack playing games with me. Only other thing I could think of was maybe there is a tiny boost leak somewhere, but there is no "bucking" like of that associated with a boost leak. Any thoughts?

[da40]

have u checked ur spark plugs ?could be time for new ones colder ones wouldnt hurt

[Hijacker]

I would check your spark plugs first like da40 suggested. It's possible one may have some carbon built up on it making it spark weaker, which would be noticable at greater loads.

After that the only other course is to go coil pack hunting. Borrow one from a friend and start swapping it out for your packs. There's only 4 options at least.

[da40]

I'm having a problem with my redtop s13. Pretty much stock sr20det redtop except for upgraded exhaust and IC.

Sometimes after I've driven for about 45 mins, give or take, the car starts to feel like a motor with a bad plug wire. Its fine when idling and under a light load, but if I get on throttle some, it almost feels like a cylinder cuts out. Noticable loss of power and the exhaust note changes. I had cars do this because of a bad plug wire so I thought maybe it was a coilpack playing games with me. Only other thing I could think of was maybe there is a tiny boost leak somewhere, but there is no "bucking" like of that associated with a boost leak. Any thoughts?

how much boost are u pushin?

[Silverbullet91]

Sorry, I meant to mention in my original post I changed the plugs just to rule them out. The old ones looked fine though.

I'm running about 12.5 psi of boost.

I wonder if the coolant temperture sensor is guilty...

[Silverbullet91]

Oh yeah, I don't have any friends with sr's like me so I can't swap coilpacks with anybody.

[da40]

what gap are u running ur plugs at???

[da40]

Oh yeah, I don't have any friends with sr's like me so I can't swap coilpacks with anybody.

check the oltage on all ur coilpacks witha voltmeter u might have to gather some coilpacks to see if thats what the problems are at courtsey nissan they go for 60.48$each part# is 22448-sr20

[Silverbullet91]

You guys are quick with the replys. I appreciate the input!

The gap is whatever the plugs are pre-gapped to. About .030 I think. I'm using NGK Iridium IX BKR6EIX. I've been using this kind of plug in my motor for about a year so I really don't think they are the problem.

Not really sure what you mean by checking the voltage on the coilpacks. As I understand it they just have a 12V, ground, and signal wire to them. I would think since all four cyclinders are firing I wouldn't find much by checking the voltage on them but its worth a shot. I have already measured the resistance of each of them. They all have about 0.8 ohms.

I've already thought about just replacing all of the coilpacks with new ones, but its kind of hard to commit to that without knowing for sure thats whats wrong.

[Silverbullet91]

Well, its not the engine coolant temperature sensor. I checked it cold and hot. It was completely within specs.

[Ramius83]

Well, is it constantly misfiring when you go WOT, or is it doing it ocassionally? What is your base timing set at? What fuel pump, regulator, and pressure are you running? Are you sure the plugs are gapped correctly? Have you tried regapping them? Does the engine "misfire" when you are at idle and rev it up to a certain RPM and hold it?

As you know, a misfire can be a multitude of things. I am not meaning that all of the above is your problem, but any one of those can contribute to a misfire. The more information you can give us on top of what you already have will help us to help you.

[Silverbullet91]

This is only an occasional thing, but it is very noticeable when it does happen. I'm running a Walbro 255 lph fuel pump. Plugs are new and gap is good. 12.5 lbs. of boost. I've have never checked or adjusted the base timing since I got the motor so I can't gurantee its at 15 degrees, but I really don't think the base timing is off "occasionally".

If you read the 4th sentence in my original post you'll see that it is fine at idle and light load. This only happens, when it does happen, at around a quarter throttle or more.

I've ruled out the engine coolant temperature sensor and plugs. Voltage at MAFS seems good.

Resistance of all coilpacks is about 0.8 ohms, but I still dont' trust them. I haven't thought about a fuel problem but thats definitely a possiblity. I'm going to check for boost leaks and re-wire the MAFS where I had to extend the wiring harness during engine installation.

[jrb92se]

sorry to thread jack but i think im having the same problem with my rb25. under hard acceleration it cuts out for a second usaully in second or third gear you can hear it in the exhaust it sounds like its choking or something. but it will go away imediatley and then it runs fine. should i check my coils and plugs also? i posted a thread earlier tonight in the rb forum but none replied. if its misfiring will it blow up? should i park it?