Stacie

This issue started around August of 2011.

At first I thought the problem was the clutch as I badly needed a new one!

It finally lost all grip this July on the local bridge and I was towed home. I replaced the clutch and went through the 1000 mile break-in period with no issues, of course I never took the RPM's over 2000 because I wanted a smooth break-in.

The problem came back the first time I "got on it" on the highway. I went to pass someone going under the speed limit and the car sputtered and jerked and gave me serious grief.

Basically no matter how hard I mash the gas pedal, the car loses all power under load when it has these hick-ups. RPM's don't seem to dip, but there's a total power loss.

I thought perhaps it was a fuel pump or spark plug issue, I'm familiar with the rough idle of misfires but those also come with a code.

There's been no check engine light, no codes on the scanner, NADA.

Then, the icing on the cake: Friday I was driving to work and the car just completely lost power. Lost EVERYTHING. The engine died.

Stereo was still on, headlights on, but lost power steering, brakes, everything. I coasted to safety then tried to restart the car. No response. I tried several times over about 10 minutes. Finally it fired up.

I sat wondering if I should try and get to work or drive home (I live about 45 minutes from my office). about 45 seconds after firing it up, it flew the RPM's up to about 4000 then died. Then I waiting a few minutes and started it up again. "Limped" home.

Meanwhile, I'm driving my "backup" '99 that needs a ton of work and I need to fix my '05 asap or I'll soon be out of luck! Any ideas?

I have not gotten one single code and nothing is popping up on my scanner. However, the last time I tried to run it when I got home, the scanner now errored out as if the ECU fried my scanner. I'll be calling SCT next!

If it helps here are the aftermarket parts I'm running-I'm open to ANYTHING being the issue at this point...
BBK long-tube headers
BBK catted X-pipe
SLP loudmouth axle-back
Steeda CAI
Granitelli 60,000v coils
BBK fuel rails
SPEC Stage 3+ Clutch
SPEC Billet Steel Flywheel
Aluminum 1-Piece driveshaft (new w/ Clutch October 2013)
SCT X3 Tuner (Have tried to return to stock and reflash)
Optima Red-top (appears functional)
180 AMP Alternator (from local performance shop-appears functional)
Suspension items-shouldn't have any bearing on issue

Any ideas? Let me know!! I've cleaned the MAF sensor, recently replaces spark plugs (when I did the clutch) and cleaned fuel injectors. Still, that wouldn't explain the complete shut-off WHILE driving...that was too bizarre!

Oh, and I ALWAYS let her warm up in the morning for about 15 minutes or more while I get ready...problem was more pronounced on colder days but regardless I never drive it cold. I always let it warm up in the morning.

moosestang

The first thing I'd do is put the stock coils back on and try that. The aftermarket coils can fail completely and not throw a code. Mine actually idled pretty good, but power under load was crap.

Why did you put a spec stage 3+ in a car with no power adder? Seems like way to much clutch.

Stacie

I used that clutch because I have a ZEX Nitrous System, Comp ***** Tumpr cams, FR intake manifold and a ton of other parts I'm getting ready to throw at it that have been sitting in my closet for months.

But I'm not putting ANY more parts on this thing until I figure this out. My next purchase was going to be a Novi 2200 supercharger...but again I do the basics first and if I needed a new clutch I decided to get the one that would hold it because I don't have a lift and changing it out was a pain in the neck! It has more power than stock for sure, but it's not anything crazy yet.

I can't justify throwing parts at a car that's having issues...she has about 130,000 miles on her and I've had her since 10,000 miles.

I actually already swapped the coils to stock to see if that made a difference last month. There was no change except that gas mileage went down so I put the 60K back on. Replaced spark plugs. I only use Autolite, no Champion or NGK as I've seen a multitude of issues with those... (I've fixed friends' mustangs, done performance work on dozens of cars and have personally repaired and maintained all of my mustangs since 2002). I have simply never seen an issue that has stumped me like this before!

The way the car acts as far as the loss of power is beyond bizarre...then having it die on me on the highway totally threw me for a loop. It will literally lurch and balk, but it's not a drive-train problem.

It also has a cyclic behavior when it idles if that makes sense. The RPM's will go up a little, then come down a little, then go up a little, then come down a little. Bouncing between 740-900RPM at idle.

I also cleaned the MAF and CAI hoping that it was possibly a sensor issue...no change.

I know I need to throw the cams in sometime soon because I have the classic valve-train tick but I've had that since long before this issue which is why I started ordering the parts. I'm just waiting on rollers to dig into that, but again, I don't want to go throwing parts at a car that has an undiagnosed issue it's unwise!

Nuke

I agree with Moosestang about the coils. That was my first thought as I read your post. Aftermarket COPs have been almost nightmarish on these S197's. And if you hadn't mentioned that the car lost all power, I was hung up on it heitating/hiccuping on acceleration which is indicative of the TSB for the bad fuel pumps that plagued many 05, 06 and 07's.

JCON

It was unclear from your post but when you returned the tune to stock, did you also reinstall the stock air intake? Additionally, returning it to stock with the FRPP manifold will cause serious drive-ability issues. You have many variables that make it hard to return to stock easily. I would start with the air intake if you have a tune to run everything else with the stock box. I suffered for months with a very similar issue and before I got it resolved the car shut down after almost every WOT or over 50% throttle run on a highway. Turned out my filter in the box was too thick and the rubber hose that meets the throttlebody was warped from being old (2005). I placed electrical tape around the edge of the throttle body where the clamp went and I also put tape on the inside of the box where the foam of the filter was suppose to seal. After suffering with power loss and shutdowns for 6-7 months, the problem was gone. I didn't always get a light or code either. The engine was having debris enter the MAF from the unsealed airbox and unmetered air from the unsealed TB/hose. This caused instant shut downs under load. Also check the gap on spark plugs and make sure they are the correct heat range. Going one step colder on an NA set up with misfire like crazy under load.

Stacie

No, I haven't put the manifold on it yet, simply because I was having issues. I attempted to return it to stock and reflash it when I was sitting in the lot trying to troubleshooit why it died on me. That's when the tuner said "this device is returned to stock" and then errored out. I don't have any clue if that was the scanner fuzzing out on me since it errored out. I have to send it back to SCT or bring to SCT dealer which I may end up doing! But, no the manifold is one of the parts in my arsenal that I've been Jonesing to put on but haven't because of my problem

Diabolical!

REMOVE THE GMS COILS. Replace with stock. Report back.

*Edit. Damn. I see you tried that. Remove them anyway. Permanently. GMS coils are junk. There is also a fuel pump TSB out for '05 and early '06 GTs due to hesitation and stumblimg under acceleration after open cruising. It was a common problem. I had the TSB performed within 3 months of buying my car new.

*edit. *edit When's the last time the fuel filter was changed?

*edit. *edit. *edit. Have you gone over the system for vacuum leaks?

JCON

Ok so can you completely return the vehicle stock? Like no cams, no after market intake, and return it to stock without the errors? Also do you still have the stock fuel rails? I haven't heard of the BBK's starving the engine but best to return everything to stock that you can and start one component at a time. Also make sure all hoses to the intake are secured and not cracked or blocked. A small leak somewhere can cause major drive-abiltiy issues.

Stacie

As I said, that was the very first thing I tried. No dice.

Second was replacing the spark plugs just in case they fouled out. No dice.

In fact it only seemed to increase the roughness of the jerking and frequency of the problem.

None of this would explain the complete loss of systems...100% loss of power-died while driving. Just shut off completely (lights, stereo, heater were all still on by the way) on the highway at 50MPH cruising. Took nearly 10 minutes to even turn over. Zero ignition response what-so-ever.

Zero explanation to date!

I have about 11 years experience working on these cars, my ex has about 20 years experience. I let him test drive her and he was baffled... I'm hoping someone has an idea other than the mundaine things I have already tried!

Last fall I thought it was the fuel pump...replaced that and no dice.

Replaced fuel filter. No dice.

Cleaned fuel injectors and had them sonic tested. No dice!

I'm willing to look into anything I haven't tried...but I tried all of the above before hopping on the forum...I read through a plethora of TSB's online, none fit my scenario.

I even looked up GM issues and other OBD car issues because it really seems to be a computer issue-a sensor or some other electrical phenomenon.

Nothing I'm reading seems to fit the description.

It's not dropping cylindars like coil issues or plug issues either, but I swapped those just in case and it's done nothing for the problem.

It's like it's giving no value to the throttle body under load. It doesn't matter what RPM you are at, if you try to accelerate hard it's as if it gives a window where it kills injector pulse but doesn't (when it typically has the issue) totally drop RPM or anything.

When it's in neutral, it has a very smooth increase throughout the entire RMP range. If you accelerate slowly, it also has no issues.

We're talking "I'm cutting into traffic on a busy highway at 5pm" type of load that seems to cause the issue...that is until it died while cruising down the highway.

And it was completely intermittent.

I haven't put the cams or manifold on the car yet simply because of this issue, but I don't have the stock fuel rails or stock exhaust or the stock CAI to place back on the car.

I'm stuck with the Steeda CAI, headers, fuel rails and exhaust as-is. I do have the stock throttle body on it, put the correct BAMA tune in the ECM with what is on the car and that had been a bandaid for the problem last fall.

It's been very intermittent. So much so in fact that whenever I would take someone on a ride with me to show them I looked like a liar! (Until recently)

Just has gotten out of control the last 4000 miles or so until the peak on Friday when she lost systems on me.

Sorry for the frustration, I just really have tried everything logical and I'm looking for people who have suffered a similar issue that every-day fixes (which I've already tried) have not worked to correct!

Stacie

I religiously change my fuel filter when I change my oil simply because I live out in BFE and I don't trust that the gas is any good out here... I only use premium-either 76 or Chevron.

Yeah, I had an issue with the fuel pump a couple years ago when I thought someone who didn't care for me too much put diesel in my tank...