Ignition/spark related issues. Not plugs though (I believe)

[tt335ci03cobra]

Any suggestions?

Symptoms:
•all that bad spark plugs would suggest
-trouble starting. Temps are in the 20-40° range most days, 15-25° at night. I have to hold the gas pedal in half way, sometimes pump it, sometimes hold it down to bypass injectors.
-slight hesitation/rowing sensation (like on a boat) while gently accelerating.
-8.xmpg the last tank.
-cuts out on wot pulls sometimes, not every time
-sometimes the engine gets very quite as if it's almost off, and barely combustingmuch like if the plugs weren't sparking. More things as well like dying sometimes coming to a stop, aggressive bucking while coasting without throttle sometimes, a sensation of inability to accelerate or resistance to accelerate sometimes. All of this goes away for the most part if I clutch in and rev the engine a few times. Also, much like fowler plugs, if I drive around at 4-5000 rpms for a few miles on the freeway, it dramatically helps.

This all sounds plug related. So we put fresh tr6's with a healthy .028~ gap. Car runs on 9-10psi right now.

Most all issues still persist. Ok, bypasses the boost-a-spark. Still persists. Check the coil packs, very healthy, 1 year old ford units. No reason these should be an issue.

I'm wondering if a frayed ignition wire somewhere along the harness could be causing these issues. My xcal shows battery voltage is being read at 14.3-13.6V depending on driving conditions.

Only thing I can think is frayed wire shorting out slightly. Any thoughts? I've also heard that iridium plugs aren't the best choice for boosted modular mills, but I've also seen that br7's and so forth have even more choppiness and poorer street manners.

Coolant temps never cross 185-190, iat's swing between 30-75° depending on outside time, stop and go or highway, etc, load isn't too high but touches .29-.40 depending on road grade, gear, etc. Tuning is done by the best tuner in the state so it's not a mistake in any of the tables or perimeters. Sct xcal, factory ecu. MAF's read great.

Car has does not have iirc' or mill, and the fuel system is custom without pprv if I recall correctly.

 

[nxhappy]

did you ohm out all of the Coils?

 

[tt335ci03cobra]

All of them read fine :-/

It's intermittent and irregular. It isn't very spontaneous when the symptoms creep up almost like when you have a loose electrical connect on a phone charging cable or so forth. Sometimes it's flawless, sometimes it's a bastard and acts up

 

[nxhappy]

no codes huh? From your description is sounds like fuel cutting out. Especially if you know coils/plugs are good. Have you checked fuel pressure?

 

[tt335ci03cobra]

No codes, and the only thing that has come up was an eVap code 2 weeks ago but it turned off on its own.

Fuel pressure varies from 39-55~60 depending on throttle position, etc. sometimes it's as high as 70psi but it idles at 38-40. Never dips below that, even when the spark is acting up.

I thought at first it was alternator or battery related but that stuffs all new, and my actual voltage never drops below 13.6. It's as if the ignition system chooses to take a break sometimes.

Something seems to be going out, failing, or being impacted/shorting out.

I have solid engine mounts and a stiff/bumpy enough chassis that if something is frayed, the vibrations are likes to shake it against metal somewhere is all I can think of.

 

[MG0h3]

My old turbo fox left the tuners with a lean at cruise/lean tip in condition. Didn't show up on the dyno for some reason. Sounds very similar to your condition. If I kept applying throttle it would clear up right away and pull hard.

If you really aren't igniting you should be rich or maybe cooked the wide band by now. Probably even smell fuel out the back. You should also have a cel.


Sent from my iPhone using the svtperformance.com mobile app

 

[tt335ci03cobra]

Problem found!

Now as tech savvy as I claim to be, this one is in the weeds and almost over my head.

Soooo.... Don't shoot at me too much if this sounds impossible as I don't remember the names of certain parts but here goes.

We had pulled the ac condenser from between the radiator and intercooler for spacing.

The ac pump was still connected and kept trying to complete a loop/signal. It started to fail but unbeknownst to us.

Slight weird symptoms krept in but we very rare.

Fast forward 2 months and 1500 miles, the car has the spark plug like issues daily.

After checking coils, plugs etc with testers, swapping, etc nothing.

So Heath thinks back and remembers the last time he's ever seen anything like this.

**This is where it's over my pay grade so I don't know the components or parts as well**

Something had stressed a component in the timing assembly which operates on a "ring gear" iirc and a slot style groove which had worn those parts out from excessive movement.

This lead to a system pulling/retarding timing to 5-6°...

Intermittently...

Additionally, because it was almost stalling/dying, it was cause slight clutch engagement signals which further mucked things and created worse drivability. (I'm sure I've butchered the diagnosed by now, use your knowledge to decipher my lack there of)

So... Heath's ordering some billet pieces that can't fail as easy (it's 14 years old stuff anyways) and pulling the turbos off to get the timing cover off and fix it.

Please comment and let me know if you have an odd issue, I'll run the symptoms by Heath and see if he has any ideas.

Heres the best part... Heath puts the car on the dyno to test his theory. It baselines like 520whp when it had made 720whp before. Timing was 5-6°. He sets it for 20-24°. It goes to a realized 12° and runs perfectly, makes 700whp again...

The guys insanely talented... I would never have found this.

 

[MG0h3]

Sounds like hes talking about the crank or cam signals but not sure how that has anything to do with the AC system or modifying it. Or how it would play into hard parts being warn. Either way sounds like he found the problem if he forced extra timing in and fixed the problem.

And by clutch are you talking about the AC compressor clutch? If the system was evacuated with no condenser it should never try and turn on---but who knows depending on what else was unhooked.

Hope yall got it!!

 

[tt335ci03cobra]

Ya in complete honesty at this time, I'm incapable of accurately restating what he found, but I was stoked he found it so quickly.

Clutch wise I was under the impression the ac clutch was semi engaging, which puts additional strain to accessories and crank. Minor, but (I'm assuming) detrimental when the computer isn't actually informed that it's engaging.

Something about the minor engagement taking excess draw, some component then creating movement of the inner ring gear, and so forth.

I need to have him explain it to me step by step. We had a 30-60 second conversation about it while I grabbed a tool set I had left in the trunk.

 

[badcobra]

So he's pulling the timing cover off to replace what? The cam gears? Why wouldn't he just replace the cam/crank sensors first? Cam gears don't go 'bad' unless they break/crack so doubt this is gonna fix anything.

 

[01yellercobra]

Sounds like he's replacing the reluctor wheel on the crank. My guess is something wasn't torqued correctly allowing the reluctor wheel to bounce back and forth. The slot keeps getting wider causing some wide changes in timing. If the dampner isn't torqued down enough it can cause this to happen.

This happened on my last engine and caused some weird issues like yours. I never had the ignition cut out, but it would stall randomly and not want to idle.

 

[tt335ci03cobra]

I'll have to get the names from him. He knows his stuff. What he told me made sense at the time.

It's like a smaller pin like thing that he described, not a physical clock like gear...

 

[tt335ci03cobra]

It's called the exciter ring. Or reluctor wheel. Crank trigger. Kept moving and wore out.

 

[Juiced46]

So he's pulling the timing cover off to replace what? The cam gears? Why wouldn't he just replace the cam/crank sensors first? Cam gears don't go 'bad' unless they break/crack so doubt this is gonna fix anything.

We have seen this before. Obviously it did not go bad for no reason. What happened was, the crank balancer bolt was not TQ'd properly causing the trigger wheel on the crank to rock back and forth on the keyway. Over time, it opens the keyway up larger and larger which then throws off the timing signal. I have a trigger wheel at my shop I think still that this happened to because the bolt was not TQ'd right.

 

[tt335ci03cobra]

Exactly. The balancer bolt led to the failure. I don't know that the ring itself is damaged on mine, but the bolt simply isn't doing anything productive.

When he threw 24° of timing at it, it came back to life which confirmed the suspicion.

Something about the ac pump constantly engaging it's clutch mechanism and the difference that makes to the rotating assemblies strain excasserbated the wear on the bolt.

Additionally, we had a tensioner assembly literally bend from heat related issues, leading the serpentine belt to slip off. I wonder if the 3-4 weeks that the tensioner assembly kept bending more and more had anything to do with exacerbating stress to the crank and balancer bolt.

It's interesting but very frustrating how little things lead to bigger problems...

One thing I am a little worried about is compression. The mill showed 130psi of compression in each cylinder, very uniformly, but that just seems low. My previous 4.6 and 5.4 builds have had 160-180psi. Those had stock c heads/cams/valvetrain though.

I have heavily ported stage 3 for heads flowing 370cfm, and 9.3/1 compression right now from a 3.8s/3.7b so that is going to lead to lower numbers but if I had had to guess, I'd have assumed healthy was into the 145-150 range.

Is 130psi healthy for compression on this mill?

 

[tt335ci03cobra]

Additionally I am running stage 3 cams from mmr so the duration and lobe separation isn't close to stock. It's probably fine the more I think about it. If the stock head/cam and 8.5:1 is yielding 170-180, 130-135 that I had is probably right about on point.

 

[Juiced46]

Additionally I am running stage 3 cams from mmr so the duration and lobe separation isn't close to stock. It's probably fine the more I think about it. If the stock head/cam and 8.5:1 is yielding 170-180, 130-135 that I had is probably right about on point.

Cranking compression is going to depend on how you have your cams degreed.

Have you done a leakdown test at all?

Also, I found the trigger wheel with the oblonged keyway hole due to a loose balancer bolt. You can clearly see how it was banging around on the key opening up the keyway hole because it was loose.

 

[nxhappy]

glad you found the issue !

 

[tt335ci03cobra]

Leak wasn't performed because my builder/tuner felt the comp test was very healthy.

It is an aggressive hci set up, low compression assembly, and 4500ft of altitude. They were all within 5pts of each other so it probably is fine.

That wheel is definitely worn, wow.

Thanks for finding the wheel and posting those pics