Well, yesterday, I was leaving Best Buy, got on the access road, which was clear, and the on-ramp to MOPAC north is about a 1/4 ahead, so I gunned it. I hit the on-ramp doing a little over 100 and started coasting back to the speed limit before I merge onto the hwy. I actually end up coasting down the hwy, its a downhill slant and my exit is at the bottom of the hill. Anyway, by the time I turned onto my street my car was starting to surge and stutter a little bit, the tone from the exhaust also changed from a growl to that of a throaty gurgle. This morning, I noticed the same tone from the exhaust. The car seems fine when I excelerate, but once I hit 40 and cruise, it begins to stutter, when I come to a stop at a light, it idles rough, like its misfiring. It seems to me that the timing is off, maybe somethings wrong with the harmonic balancer. Its not throughing any codes so any ideas on where to begin to check would be appreciated.

 

check the IAC and MAF, then check you plugs and injectors. if ur plugs are fouled replace them and see what happens.

 

Thanks, first thing tomorrow, I'm going to pop the hood, check the COPs, IAC, MAF and plugs. I'm hoping its not anything major, it certainly doesn't have the feel of something major, and according to my finely tuned sense of audio-economics, it doesn't sound expensive lol.

 

Hehe, I love this city, moved here in June of '93 and by god, I'll be buried here when I die.

 

Haha sweet I live on Riverside near Ben White. Maybe we should get a group of Austin Stangers to go downtown for some 6th street action. Good luck with the car, wish I had enough knowledge to make useful suggestions.

 

Cool, I've seen your car around, I live off of Barton Hills Dr behind Zilker Park, check out Central Texas Stangs.com. I just recently hooked up with them and they are a pretty active group.

 

Problem solved, changed the plugs, oil and oil filter. The old spark plugs look like the factory originals, they were really worn out:



Thanks for helping to point me in the right direction.

 

Oh yeah those needed to go....how many miles did you have on those?

 

If I were to guess, I'd say those were the factory plugs, so 68k miles.

 

If those were factory platinums, they should have looked a lot better then that I would think. The tips are actually worn away. Have you been getting detonation?

 

don't forget that the factory tunes on 96-04 have been notoriously lean from off idle to 3500rpm or so and they're still kinda lean after that in untuned form. That would account for the added wear of the electrodes. They don't look that bad to me. I've seen a lot worse.

 

Nope, no detonations. Until this last monday, the car ran fine. TTT for the problem. It runs great now with the new plugs, although when I was coming back from taking my dog to the park, it still idles rough when in Drive (around 600rpms), if I put it in neutral, its ok and the rpms go to 800. So there's another issue I need to check into.

 

What you don't know is if the plugs go like this over time or if they went bad over the last few thousand miles. I would pull them again soon, or at least one or two to check them out.

Your idle issue may be related to what wore the plugs.

 

Good point, at least changing the plugs was a good place to start.

 

Absolutely! What we don't know is if the plugs are the problem, or what lead to the plugs being the problem.

My stock plugs came out at 55k miles when I installed coppers. They looked fine. Unlike yours, there was no sign of metal loss. The tips were still squared and had sharp edges.

 

Just wanted to give a final update. The GT is running badas* now.

Changed the plugs.

Cleaned the injectors and changed the fuel filters.

Changed oil and oil filter.

Cleaned the IAC and TB/Plenum.

Bascially, it needed a 70k tune up.

Now its running smooth, no idle problems or acceleration problems.

 

Well, I actually still continued to have that misfiring problem. It got bad enough that I just parked the car and used the mach as a dd. This past tuesday, I dropped off the GT to get new heads installed. My mechanic, Kirk just called, he's tearing the engine apart tonight and found that the rear timing chain tensioner was shredded. He's going to be taking some pics of it and emailing them to me, so hopefully I'll post them soon.

 

Here's the pics:



Bad Timing tensioner arm:



Good tensioner arm:

 

Jesus Christ, that's nuts. Hope that none of that stuff clogged your oil passages...

 

I would suspect the IAC might be dirty. Also, if you have a CAI with a filter you have oiled a few times in the last few thousand miles you might want to clean the MAF sensor as well. These are easy fixes that require no money to try.

 

 

Ummmm shut it...read the whole thread before offering suggestions on a half torn apart motor with the problem already stated

 

Thanks, those were some of the first things I did. The list started with changing plugs, cleaning the IAC, TB/Plenum and MAF. Had the fuel injectors cleaned, flushed the fuel lines and new fuel filter. Nothing really helped.

I bought a set of P&P heads from R3dn3ck and parked the car until I could get them installed. I was hoping that when we tore the engine down for the head install, we'd be able to find the culprit... bingo !!

By the looks of the it, I was on the verge of doing some serious damage to the engine. I did some research and found out that this is a known problem with the modular engines, first discovered with the 5.4L Lightnings. The materials used to make the right bank timing chain tension arm have a tendency to fail when the engine was under load, i.e. accelerating. Thats what happened to my GT.

I reached the 500 mile break-in point with my 4.10 gears and went out to play. I got onto an access road to Mopac and punched it. Around 90 or so, I felt something give and the car started to misfire, especially when I was coasting down to the speed limit and getting off the highway. I drove it straight to my driveway and parked it. ttt for the rest of the ordeal.

Ford redesigned the tension arm for the Lightnings. Then, the '03 cobras started to show the same problem and they recommended using the Lightnings tension arm as the replacement. Now, since it works so much better, its the only Ford right bank tension arm sold for modular engines.

Forgive me if I have some of my facts jumbled, I'm really just covering the basics.

 

Edit: meant "right"

 

No kidding, It'll be getting new oil and filter when everything is installed. I'm praying that the old filter caught all the metal flakes. If it goes boom, then I'll be putting a 5.4L in.

 

Sorry guys. I only read the first page after I got home and brainfarted the whole thing. My bad. Sorry for the retard moment.