Missfire comes and goes!?!?

[crazycoot80]

This is quite a wierd problem!! I have a 95 talon AWD with a JDM 6 bolt swap. Just replaced the head, timing belt and installed 272 cams, headder, timed it all up perfectly. Has big 16g turbo and stock injectors and im only running stock boost because i have yet to upgrade to DSM Link. When I replaced the head I installed Brian Crower cams and valve springs and retainers, new NGK plugs gapped to .28 and new plug wires. The cylinder that is missfiring is #1 and it comes and goes. I will be just driving down the road and then bam!! Engine starts running roughand the miss wont go away till i shut the car off and let it sit for a while. Then i start it up and its fine for a while then it happens again. When it is missing and i remove the #1 plug wire it arks to the plug tube like crazy so the spark is getting to the plug and when i pull the plug it does not look fouled. The only thing i can think is maby fuel issue?!? But when it is missing it will pop and bang like it is getting fuel and it is just being dumped into the exhaust and burning once it is expelled. Any feedback would be much appreciated!!! Thanks!

 

[eeeewidner]

If your fuel curve is too lean it may cause the same symptoms. Since #1 cyl is the last one to receive fuel. It sure does sound like a clogged fuel filter or weak pump....Ahhh. check your fpr also. And on another note. do a boost leak test and see if there are any leaks around the injector or intake gasket.

 

[No_Skillz]

Which NGK plugs? And I'm sure you mean 0.028"... Suggestions in last post are valid. You should also try pulling the actual plug instead of just the wire to make sure that it's not faulty. A compression test would also help, since something might have not sat right after your head work.

 

[Backinajiffy12]

+1 for running to lean.

 

[mikelv]

+2 (or is it plus 3)

The #1 is the leanest and hottest, so when you are running out of fuel it'll knock down there. Wait until you can get at least some 550cc injectors to boost the car at all.

 

[crazycoot80]

Ya i ment 0.028" and they are standard copper core -6 heat code. I have some 680cc injectors but i dont have DSM Link or anything to dial them in with, if i just install them will the car even run??? Also if it were running too lean in #1 wouldent that be something that would gome and go while driving?? My problem just happens and then it dosent go away at any RPM or load. It just continues to miss in cylinder #1 untill i shut it off and turn it back on. The leak i can see doing that so that is what i will check next. I also need to do a compression check but if it runs great one time and not great another time should i wait till the problem comes back and check it right as soon as i shut it off?? Thanks guys!!

 

[No_Skillz]

If you just plugged in your 680cc injectors, there's a decent chance it will run but you will be far worse off than where you started. You need something to tune for a change in injectors before you install them.

If you're fairly sure it's not a fuel delivery issue, the only two problems possible are compression and spark. I already suggested testing compression and the actual plug, but it probably wouldn't hurt to look at other electrical aspects such as the coil pack.

By the way, how do you know that it's cylinder #1 that is misfiring?

 

[crazycoot80]

I know it is cylinder #1 because i removed the plug wires one by one when it was missfireing and the only one that when removed did not produce an rpm drop and an even rougher idle was when i removed the #1 cylinder.

 

[No_Skillz]

So pull the plug and see if it's sparking. Or, if you don't like the idea of running the motor with a plug out, you can switch plugs with another cylinder and see if the misfire transfer to that cylinder.

If the plug isn't a problem, you can swap wires to see if it's the coilpack. Simply switch the wires on cylinders 1 and 4, and see if misfire transfers to that cylinder.

If it's still consistently cylinder #1, it's time for a compression test - when it's warm and symptomatic, just like you said.

 

[crazycoot80]

I bought a 255 fuel pump and regulator so im gona install that so i can be sure im getting fuel. Also gona replace my filter. This will also give me more fuel if i run higher than stock fuel pressure right?? By the way what is the stock fuel pressure and what pressure would anyone suggest i set the 255 pressure at?? Gona do a compression check this weekend.

 

[gsxAWDdsm692]

Spark plug electrode has fallen loose. Check the plugs. I've been there.

 

[No_Skillz]

I bought a 255 fuel pump and regulator so im gona install that so i can be sure im getting fuel. Also gona replace my filter. This will also give me more fuel if i run higher than stock fuel pressure right?? By the way what is the stock fuel pressure and what pressure would anyone suggest i set the 255 pressure at?? Gona do a compression check this weekend.

You don't want to run higher than stock fuel pressure. Stock tune is already rich, and getting going doesn't mean you'll get flow to a cylinder that wasn't getting it before.

Why not do as many have suggested and do the check on plugs and wires first? It's free and it's alot faster than swapping fuel pump and regulator.

If you still insist on installing the AFPR with pump, it needs to be set at 43.5psi with the vac hose off, ~35psi with it on.

 

[gsxAWDdsm692]

There's a rule, always start with the cheapest thing first...

 

[crazycoot80]

The plugs are new and I have checked them many times and they always look fine. The wires are new also. I will post the results of the compression check this weekend.

 

[gsxAWDdsm692]

Possibly the ignition coil.

 

[mikelv]

I bought a 255 fuel pump and regulator so im gona install that so i can be sure im getting fuel. Also gona replace my filter. This will also give me more fuel if i run higher than stock fuel pressure right?? By the way what is the stock fuel pressure and what pressure would anyone suggest i set the 255 pressure at?? Gona do a compression check this weekend.

Stock pressure is all you need, 43.5 psi. Don't worry about all that yet.

Just as No_Skillz said before, there is no need to install any larger injectors, AFPR, or fuel pump without any sort of engine management. For you, you wouldn't need more than an AFC.

To the root of your problem. You are running BPR6ES plugs, so you need to by all accounts go with a BPR7ES. Hell, they're probably messed up anyway like someone suggested before. That will suffice you for as long as you need. Get yourself a $12.00 set of good plugs at any auto parts store. The dude will tell ask you for make and model and all that, tell him: "NO, listen to me, I want BPR7ES"....he can look it up that way, don't let him tell you otherwise. If he looks it up by Mitsu or whatever, he'll just give you 6's.

Get the 7's, gap them and get things a little cooler in that cylinder. From there we can stop the back and forth about plugs. If you still have the problem, then you can at least eliminate spark. It's a pretty rare instance that'll be your coil pack, unless that car has heavy miles on it. We'll move on to fuel. If you're going to upgrade your fuel system anyway, invest in an AFC, too easy helping you out in that department.

 

[No_Skillz]

The plugs are new and I have checked them many times and they always look fine. The wires are new also. I will post the results of the compression check this weekend.

Now swap the plug wires like I said to test your coil pack.

 

[ArticNemesis]

What check engine code is being shown by the ECU when this happens? (Don't say it's not there, it is if you are getting a misfire)

2g. 6bolt swap. Random misfire anyone?

 

[mikelv]

Now swap the plug wires like I said to test your coil pack.

Forgot he said it was a swap! He's out somewhere. If he was 180 out, he wouldn't even run.

 

[crazycoot80]

It happened again today a block from my house while crusing at 45 mph. Stopped at a stop light, shut engine off and started it back up and miss was gone!?!? Checked plugs immediately when i got home and plugs were fine. Even tested spark of every plug by holding plug to ground an had a friend turn engine over. AS OF THIS POINT I HAVE DETERMINED THAT IT IS NOT A SPARK PROBLEM. Check engine light is not coming on but then again it might not even be hooked up. When I did the head job I did not replace the O-rings and gromets on the injectors so im thinking maby there may be an issue there. Its just so damn cold here in NW Ohio right now its hard for me to drag myself out in the cold to investigate these things and being a full time student and workin full time, time is also limited for me!! It sucks!!! All i want to do is build a beast of a talon but have no time to do it and no warm shop or garage to do it in. I could buy a DSM link tomorrow but have no time to install it. Im just tryin to get it running good till this weather warms up, then I'll get in there elbows deep!!

 

[No_Skillz]

Forgot he said it was a swap! He's out somewhere. If he was 180 out, he wouldn't even run.

What I mean is:

Take the wire out of cylinder 4
Take the wire out of cylinder 1
Plug original cylinder 4 wire into cylinder 1
Plug original cylinder 1 wire into cylinder 4

I won't matter if it's a swap since the firing order of the cylinders is still the same. The point is not to test if the motor is 180* out of time. If misfire occurs on cylinder 4 instead, we'll know it's a coilpack problem or maybe even something further upstream.

 

[mikelv]

What I mean is:

Take the wire out of cylinder 4
Take the wire out of cylinder 1
Plug original cylinder 4 wire into cylinder 1
Plug original cylinder 1 wire into cylinder 4

I won't matter if it's a swap since the firing order of the cylinders is still the same. The point is not to test if the motor is 180* out of time. If misfire occurs on cylinder 4 instead, we'll know it's a coilpack problem or maybe even something further upstream.

Yeah, I know I got ya now, I was kinda saying the same thing, just worded it wrong.
You're just taking a wire/plug that you know fires correctly and putting it on #1 (in this case) to ensure that the coil pack fires true either way. If it doesn't it's the coil pack, and if not further on up.

If it isn't a coil pack, then he would have to have problems in the ECU? Heck maybe even a bad transistor. (Hypothetical)

 

[No_Skillz]

Yeah, I know I got ya now, I was kinda saying the same thing, just worded it wrong.
You're just taking a wire/plug that you know fires correctly and putting it on #1 (in this case) to ensure that the coil pack fires true either way. If it doesn't it's the coil pack, and if not further on up.

If it isn't a coil pack, then he would have to have problems in the ECU? Heck maybe even a bad transistor. (Hypothetical)

Not sure, actually. I've been fortunate enough to have never had electrical malfunctions between my coil pack and ECU. (Yeah, I only bother learning if I'm upgrading or shit breaks) However, if this is the case I would try swapping either one if you have a DSM buddy.

 

[mikelv]

Not sure, actually. I've been fortunate enough to have never had electrical malfunctions between my coil pack and ECU. (Yeah, I only bother learning if I'm upgrading or shit breaks) However, if this is the case I would try swapping either one if you have a DSM buddy.

Or a DSM graveyard out back like I do.

Or if you drive multiple DSM's during the week, like I do.....one breaks and I'll tear shit off it, and/or hop in the other.

Let's not get on the might be a DSM'er gig.

On a serious note, I've had transistor problems before and they caused similar symptoms, BUT only under WOT conditions. Also, if you've ever improperly wired anything into your harness such as an AFC or MAFT, this can cause misfires. Basically you just splice things and it jars loose. Or someone can cut an ignition wire by mistake, ect...

But like I said before, they will usually only show their ugly head during WOT conditions.

 

[ArticNemesis]

It happened again today a block from my house while crusing at 45 mph.

Still sounds like the random misfire associated with utilizing a 1gCAS in a 2g for the 6bolt swap.

This is the criterion that must be met before the
ECU will start to look for misfires:
· 300+ seconds of steady state RPM less than 80% throttle position
· Engine coolant temperature -10C or higher
· Intake air temperature -10C or higher
· Barometric pressure greater than 76 kPa

http://www.magnusmotorsports.com/tech/1gina2g.pdf (Page 10)

I know you said you aren't getting a CEL. Does the check engine light illuminate on the dashboard when you first turn the key to the on position prior to starting the car?