Stumped.

I have been trying to solve a very violent 3k hesitation on my new rebuild (1k miles on it) and have added a ground kit, cleaned all grounds, replaced engine wiring harness, replaced the ecu (stock), plug wires, and ignition coil harness with no success in solving the problem. I just pulled the coils and tested them per the FSM and all are within spec. Tonight I decided to slowly rev the engine in the garage and noticed that as soon as it hits 3K the engine starts missing and stays missing through higher RPM's. Did it every time I tried doing this.

No codes are reported by the ECU.

What can be causing this?

Steve

 

You did not mention spark plugs. Try replacing them and try again.


Later

 

It's been about 500 miles since they've been replaced, and I've been thinking that too, so tomorrow they will get changed again. I'll let you know.

Steve

 

Coil does this at around 3krpm, well it did for me at least..I replaced it and all was good.

 

Did you test the coils per the method in the FSM to find out one/all were bad? Mine were all within spec.

Steve

 

Not sure as it was done by a garage & not by me. The symptoms of mine were that above 3k rpm it was missfiring and had very little power, It happened at 3krpm regardless of speed or gear.

 

what spark plugs are they? arent they to cold for you car? i bough very nice denso iridium heat range 11,5 and guess what happened after less then 500 miles...

i would check the plugs

 

3k is where the secondary injectors come on - make sure the secondary injectors are happy. Also, check your fuel pressure.

Dale

 

I have a new Primary coil N3A3-18-100 in the box if your interested. They sell for $175.
IM asking $125 Shipped.

 

But Dale, would a problem with the secondaries cause missfiring with no load, i.e. just reving the engine?

Steve

 

I'm tossing ideas out .

First thought was the coil pack harness - I've seen the EXACT same problem on another FD, and the coil pack harness was the culprit.

Also, REAL dumb, but make sure the coil pack harness is plugged in properly (as in the trailing 1 connector goes to trailing 1, leading connector goes to leading, etc.) and the spark plug wires are all hooked up in the proper order.

In theory, the secondaries shouldn't come on with no load. But, it's the "test everything" phase here.

Your new coil pack harness - this is a NEW harness, the new style, without the ground connector on it, correct?

Do you have any ignition amps, like an HKS twin power or MSD/Crane box? If so, I'd disconnect them for testing purposes.

Are you running exotic plugs or regular NGK's?

Dale

 

Hey I had the same problem and i thought it was a fuel problem. Turned out to be the coil (leading coil) and degraded spark plug wires. I WAS SO DAME FUSTRATED i tested the coils and they were ok try them out anyway it will save you time and money later

 

Yes, the coil harness is new from Ray, no ground, and I installed it last week. And it is right with T1 to T1 etc.

No external amplifier is used for the ignition. Completely stock.

I'm running regular NGK's with brand new stock (from Ray) plug wires.

Can't remember though if the coil harness plugs into the engine harness or the harness on the drivers side. Hmmm. What do you think?

Steve

 

As I stated in a previous post, all tested within the ohm specs of the FSM. Your post is a little confusing. Are you saying all of your's tested ok? How did you determine it was the leading coil that was causing your problem? I'd love to isolate which one is giving me grief especially since Ray Crowe just quoted me $142 a piece for all three.

Thanks
Steve

 

Still no report back AFTER replacing the spark plugs.


Later

 

Iam telling you no lie they tested good but changed it out any way even a buddy of mine that works at mazmart had to the same problem with a car and coils tested fine they changed them a vuwala

 

i know this sounds stupid but listen, i had almost given up and my friend pointed me in the wriight direction

 

Badddrx7,
I've read that you are the electrical guru. Sorry for no update on plugs but life interrupted this weekend and I wasn't able to change the plugs. The current set only has approx 500 miles on them. I plan on changing them again this upcoming weekend but I'm not getting my hopes up.

Steve

 

No, it's not stupid. When bench testing components we are not actually testing them in their normal operating environment. There have been posts suggesting that we test engine components at "operating temp" which means put it in an oven at 180 degrees and then test it, which is good, because failures in materials can be amplified when exposed to heat. But you have to recognize that parts are subjected to dynamic forces as well, i.e. vibration, frequency, amplitude, etc., that we cannot replicate in our garage. So, if you tell me that you had a problem the same as mine and how you fixed it, I certainly take note and apprciate your input.

Steve

 

The engine will run pretty good with the trailing coils disconnected. If you remove the trailing spark plugs you will see the hole they thread into is smaller at the end inside the motor.

My ignition breakup was at 5k rpms & up.

I purchased a new Primary coil in hopes it would fix it.

Before it arrived further testing showed that my POS MSD plug wires were arcing from the cap connected to the coil to the block.

On the dyno you could see a bright light from under the throttle body at 5k rpms.

I purchased some OEM NGK wires & had no breakup to redline.

Well you can't return special order electrical parts so I now have a extra Primary coil.


So if your interested I can sell you a new Primary coil for $100 shipped ($50+ savings)