04 Mach 1 Power Loss

[mustangguy506]

First Time posting and would love some help!

I have an 04 Mach 1 with about 30k miles on the clock. My mods are as follows:

C & L CAI
Borla Stinger Cat-Back
Custom Tune (nothing crazy - pretty mild and set for street driving)
Steeda Under Drive Pullies
Short-Throw Shifter
4.30 Rear-End gears
Micky Thompson Drag Radials

The car has seen just under 40 passes at the track this summer with good results and no mechanical failures. Last time to the track was over a week ago and everything seemed fine. Drove it for a few days after going to the track without any issues. Yesterday got into the car, it was about 50 degrees outside, warmed up for about a minute, pulled out of the driveway and within 100 yards I noticed the car didn't sound or feel right.

Under normal driving and idle (ie short shifting and not going over 3000RPM with light throttle pressure) the car reacts fine. No signs of any malfunction. Driving more aggressively (anything over 3000RPM) the car pulls but doesn't have the same 'snap' it did before. The exhaust sounds muted and not as open and 'raspy'.

I looked into the exhaust pipe (and I wouldn't have been surprised to see a squirrel inside... it feels sort of like that) everything was open and free with no signs of misuse. The intake filter was just cleaned and shows no signs of any malfunction. I changed the oil 3 weeks ago and added (as I do every oil change) Techron fuel injection cleaner. I checked the oil filter for cracks and the oil level, both are fine. All of the engine gauges are in normal parameters and there are no check engine lights.

Anyone have an idea about what is going on?

 

[twogts4us]

Dirty MAF - clean as directed with MAF cleaner (use nothing else) (about $6 can) You do not have quite the visibility to the MAF wires as you do in earlier Mustangs (as shown in the website below), but you should just do you best using the straw to aim the spray as well as you can. Use the spray liberally!
Dirty Fuel Fiter - around $12 bucks, but you also need a fuel line removal tool, but that's cheap too - get the set of plastic ones shown in excellent write-ups in the link below. (I can chg mine in about 10 mins now, but admittedly it took me closer to an hour the first time!)
BULLITT Archive Mustang Maintenance Basic Mustang Maintenance is available on this Bullitt website. Some things may be a bit different for the Bullitt vs. the Mach, but most is the same or very similar.
Plugs - these should not really be an issue at your low miles, but you might take a look...

I'd start there and see what you find...

Best of Luck - keep that Mach going!!!

 

[wmburns]

IMRC stuck closed?

Isn't a MACH 1 DOHC?

What if the Intake Manifold Runner Control (IMRC) valves were stuck closed?

Don't the IMRC's normally open around 3k RPM? I would think that would really limit the amount of air it could breath if only 1 of the intake valves was actually flowing air. Would also account for the different sound.

I don't have ready access to the service manual for the 2004 MACH 1. Somewhat at a disadvantage with regards to how to test.

OBTW; +1 on clean the MAF.

 

[bdcardinal]

IMRCs werent used on the 99+ DOHC motors, only the Mark 8's and the 96-98 Kewbras.

 

[wmburns]

Well that explains why I couldn't find them in my 2003 reference.

 

[trinity_gt]

Perhaps a catalytic converter bed has broken free and is clogging the exhaust on one bank.

 

[corey97svt]

I second the bad converter

 

[mustangguy506]

Thanks for all the ideas guys!

I'm going to try cleaning the MAF Sensor today after work and possibly replace the Fuel Filter also if I have time. I'll post my results afterwards.

I have a question about checking the Cat... How do I know if its bad? Also... the mid-pipe looks to be cast iron and not stainless steel or aluminum but the mid-pipe on my car is a X-Pipe. Did these Mach 1's come stock with an X-Pipe?

 

[trinity_gt]

Thanks for all the ideas guys!

I'm going to try cleaning the MAF Sensor today after work and possibly replace the Fuel Filter also if I have time. I'll post my results afterwards.

I have a question about checking the Cat... How do I know if its bad? Also... the mid-pipe looks to be cast iron and not stainless steel or aluminum but the mid-pipe on my car is a X-Pipe. Did these Mach 1's come stock with an X-Pipe?

The Mach, as far as I know, had the same midpipe as the later GTs: a 4-cat stainless H-pipe (if not the same partnumber, the same topology.) Keep in mind that some varieties of stainless will allow some minor surface rust, such as those used in OE stainless exhaust systems. They were going for durability, not appearance.

Can you snap a pic of the midpipe?

If your car has an X-pipe, it's not original. In fact, if it's a catted X-pipe and thus aftermarket, it increases the likelihood of cat failure simply because OE emissions stuff is nearly bulletproof (it has to be for federal emissions requirements.) Aftermarket stuff...not so much.

As for checking it, you might be able to get a backpressure meter and measure each side or you could remove it from the car for inspection. If it does have a bad cat, might be worthwhile looking into some weld-in replacement cats (from, say, Magnaflow) instead of replacing the entire midpipe.

 

[Kilgore Trout]

My guess is clogged cats or blown FRPS disk.

Does the oil smell like gas?

Also, visually inspect the air cleaner and the plugs.

 

[mustangguy506]

Thanks again guys for your posts!

I removed the MAF Sensor and cleaned it using CRC MAF Cleaner, let it set for about 10-15 minutes to be sure it was dry before I reinstalled it.

While I was waiting I climbed under the car and shook the mid-pipe as best I could. Then tapped it with a small hammer to see if it rattled and what not. Seems very much in tacked. A friend told me I would hear a very distinct sound if the bed broke free. I think for now I'll have to rule that out.

After reinstalling the MAF Sensor I started the car to warm it up and test out the fix before moving onto the Fuel Filter replacement. Still had the hood open and was putting away the tools. After about 3-4 minuets of idling I heard a strange 'ting' sound that I've never heard before. It was just a single ting and not repetitive. Another 10-15 seconds go by and I hear it again. At this point I am under the hood trying to find the source. It is coming from the back of the engine under the valve cover on the passengers side.

Took the car up the street, same problem as before cleaning the MAF Sensor.

The 'ting' sound has never been there and sounded very unnatural.
Any ideas???

 

[Kilgore Trout]

The tinging is probably the EGR tube making noise as it heats up and expands and is most likely normal.

Does the oil smell like gas? If so you blew a FRPS sensor and you need to change the oil asap! Sniff it!

 

[mustangguy506]

Thanks again for all your help Guys!

Checked the oil... no smell of gas.
The sound does appear to be coming from the EGR, weird that I never noticed this before.

Got a bit frustrated over the weekend and took the car for a drive. Like the say in the military I was driving 'for effect' ie gave it hell! After pulling back into the driveway I heard lots of rattling coming from the car. Turns out the passenger side Cat is gone. You could here the plates hitting against each other.

As suggested here, I looked into weld-in replacement cats... for me, after the cost of the part and someone to weld it in for me (I don't have access to a welder) I've decided to go with a catless x-pipe. The cost is within +50 bucks for the new pipe. I'm sure it is not a common problem that cats blow out, but I am one to deal only with absolutes. The added performance will be fun too.

 

[twogts4us]

Catted vs Catless power differences is minimal...but after having a clogged cat, I'm sure you'll notice the difference. Plus the fact that it'll sound faster without cats!

 

[CopNaStang]

I have to agree with the cats. You will not always have a sound of anything bouncing around in them if it broke off and plugged up the pipe. I would look into that.

 

[twogts4us]

You might have trouble finding a shop willing to remove your cats without putting new ones in. Same with installing an offroad midpipe...
You may have to find a Stang friendly shop...look for a shop with cool cars out front!

 

[mustangguy506]

Hey Guys!

I wanted to report back after swapping out the malfunctioning Cat Converter with a Non-Catted X-Pipe. The installation was a bit more intensive than I had originally planned, but successful none the less. Went with a Pypes X-Pipe and after sealing up all the pine hole leaks (thus where the majority of the extra time was spent) I couldn't be happier! Not only was the problem solved, it also remedy another problem that has been looming over my head since the purchase of the car. I have always had a throttle response issue. When revving the engine it would never 'snap' back to idle... it would always hang high and slowly come back down to idle. With this modification, that issue is gone! Between fixing these issues and the added volume in the exhaust note (she is definitely loosing her 'street manners' haha) this mod has added some life to the Mach.

Thanks again for everyone's help, it was much appreciated!