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Discussion Starter #1
I'm gonna guess and state that it is likely transmission related, but what can I look at engine wise FIRST to see if the problem possibly lies there?

At around 60mph and over, the pedal seems to get harder, and the engine gets louder, but with no noticeable rpm climb. It's as if the gasoline becomes half water when I hit the accelerator at these speeds.It seems to strain at those speeds.

What can I look at before I take it in to get the tranny checked?

Thank you as always. :)
 

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Fuel pressure, ignition system, clogged cats, bad tps or MAF sensors, restriction in the air intake. It doesn't sound transmission related to me.
 

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Discussion Starter #5
Thank you, MadMikey. I can check all of the things you listed except the clogged cats. Following up on the cats, I literally just got off the phone with the shop that replaced them and they only have about 30K on them. They were replaced at 116K and the car is approaching 145K. Can they still be the problem? I'll try to check those other items you listed on my next day off.

Icortinas: YES! That's what it feels like. As if the exhaust pipes have suddenly gotten smaller in diameter whenever one accelerates. I will check the fuel filter as you and Mikey recommended.

Thanks, guys.

... The only way to check clogged cats that have been welded on is to cut them, right?
 

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No. A very simple way to test them is with an infrared temp gun. Take the car out and get on it for a bit, then bring it in and immediately check the temperature of the cats, before the cats, and after the cats. If one cat is way hotter than the other, and the pipe after that cat is way cooler than the other, then that cat is clogged up.
 

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... The only way to check clogged cats that have been welded on is to cut them, right?
Take out the front o2 sensors, and start it up.


If it blows pounds of soot out, it's clogged up. :)

Don't leave it running long.

Put the o2's back in; you can't drive it like that.
 

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I'll post in with the old stand by, never hurts to clean the MAF!
 

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Could be any of a couple dozen things, but tranny is not likely, unless somehow its dropping into 4th and the TC are locking up at the same time.
However when you add the "the pedal gets harder" i'd suspect a pinched/ rubbing throttle cable or linkage. Most of us get "comfortable" with our cars and don't realize how quick they can be when you put your foot down hard, unless we are shutting down the guy next to us in his 2.8 camaro (another story)so we only push the gas only as hard as we have become accustomed to, to acclerate at a given rate. That's why sometimes a mechanic can't duplicate what the customer says is happening. Get in the car and sit differently, so that your body and especailly the right foot and leg aren't where you usually put them. When the car is off slowly push the pedal down and "feel" for a hard spot. Is it there? if so check the cable from the pedal through the dash to the last pivot (may take two people one to push the pedal one to check). A bushing may have worn to the point where there is a little resistance. And what's happening is you are paying attentionto the car becasue the "normal" feel is gone so you become more aware , of the noise, of the acceleration of just about everything going on. It may been going on all along you just "fee" it now becuase your foot is giveing you new feedback.

If there is no hard spot take the car out where its safe to do over 60 for a few miles, and really feel out the Hard spot. Accelerate through the bad spot several times some times slowly and sometimes more quickly. Is the hard spot there? Is the pedal pushing back at you or just hard to push down?
 

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Cats are a Likely Culprit

Thank you, MadMikey. I can check all of the things you listed except the clogged cats. Following up on the cats, I literally just got off the phone with the shop that replaced them and they only have about 30K on them. They were replaced at 116K and the car is approaching 145K. Can they still be the problem? I'll try to check those other items you listed on my next day off.

... The only way to check clogged cats that have been welded on is to cut them, right?
Your original cats should have lasted way longer than 116K. Aftermarket cats lack the same pricey metals that are found in OE cats and usually not last as long, especially if something was overlooked.

Old O2's might not throw a code, but may not be able to properly sense the A/F ratio and could result in the car running rich or lean. Both of these will destroy a cat. Have they ever been replaced?

Water in the fuel is another killer of cats, and thanks to ethanol, most fuel sold in the US now contains some water as ethanol is rarely free of moisture. If you are in a part of the country where larger amounts of ethanol are in the fuel, or purchasing a fuel that is cheaper due to extra ethanol, you could have these problems.

The advice on testing using an infrared temp gun is spot on. Even a name brand unit like Black and Decker can be had for a little over $25. There is a lot of info on the web about how to test them this way.

A fuel issue would be the next most likely candidate, like a clogged fuel filter or worn out pump. These would likely appear other times you were at WOT like accelerating hard from 0-60.

Fuel filters, air filters, and spark plugs are pretty cheap and easy to install, yet neglecting them can end with expensive repairs. Good luck with your issue.

Brian
96 Saleen Cobra
98 Mark VIII
97 Mark VIII LSC
94 Mark VIII
84 Bronco
66 Mercury Monterey
49 Lincoln 2 dr
70 Mustang Mach 1
 

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Replace the fuel filter. Simple, cheap maintenance that could make a good difference.

I highly doubt the cats are the problem, especially with only 30,000 miles on them.

Clean the MAF, like others have suggested.
 

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my car had that same issue , my old cougar.then the cats blew up like a stick a grenade, blew cat chunks all over and sounded like glass in my exhaust until it all blew out. 2 seconds after the explosion it ran perfect.
 

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Discussion Starter #16
Thank you all for your contributions so far. Other than spray the MAF and check for any vacuum leaks, etc, I have not had an opportunity to do any serious digging into it since I originally posted for two reasons. One, the sun goes down usually just as I'm getting off work so no light. And two, I had an old injury (sciatica) come shortly after I posted this. Not as serious as when I first got it 13 years ago when it would take me 10 minutes to sit up out of bed, but painful and discomforting nonetheless. Back problems and the nerves that are affected are no fun at all. Throw in a little neuropathy for good measure and one doesn't want to do anything. I hope none of you have experienced any of this or ever get it. Not fun!

As far as the car goes, it appears to be more pronounced as the pedal is getting harder, as is the rumble, which starts in the high 50s. Premium gas seems to lessen the rumble, but not much. Once I get past, say, 57mph, it strains and sounds as if I'm suddenly pulling a heavy trailer. Temperature has been stable, oil use is the same, and rpm's are where they should be. The car idles beautifully, but it's just that rough running that's different...at high speeds it's got all the efficiency of a 1930's Buster Crabbe rocket ship (You know, the one that looked like a fire hydrant and sounded like a cross twixt nails on a chalkboard and a fog horn?). Not smooth at all. :)

I did purchase an infra-red temp gun, so that's out of the way.
 

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Sounds like it could be driveshaft vibration, or a bad tire(s).

Premium gas does nothing without a tune, other than lighten your wallet.

Al
 

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Discussion Starter #18
Well, lack of daylight, physical problems, and just time, compelled me to take the car in to have it scoped at a shop as Tbird Bob suggested to see if they could find the issue. They determined that the engine is running perfectly and lean toward it being a transmission or differential problem. My initial thinking was the transmission. I'm going to drive it until the definite problem surfaces. It is running rougher for sure.

As I mentioned in another post, I recently had rear bearing issues (When my right rear wheel fell off on the freeway) and had them replaced. Could there be a connection there with the differential anywhere, and what should I check? I just want to remove that possibility.

Thanks a lot to all of you for all of your help and suggestions so far. :)
 

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Discussion Starter #19 (Edited)
Okay, here's the latest for those following this serial (I promise that no cars will be driven off cliffs with the driver still in it. Ha-ha.)

As I mentioned in a previous post, one shop leaned toward it being a tranny or differential problem, and claimed that the engine was running great.

Okay, so I took it to a tranny shop yesterday. They just called and said they dropped the pan and found nothing unusual in the transmission. They did drive it and noticed the problem and also said they got a code P0306; the number six cylinder is misfiring. Question: Would ONE cylinder of this V-8 engine cause such a noticeable symptom?

What this shop wants to do is put the pan back on and have their most experienced transmission builder drive it tomorrow to get his thoughts before addressing the misfire. They want to first eliminate the transmission as the problem, and then address the code...I thought it should be the other way around, but...

Any thoughts, suggestions, comments, etc? :)
 

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Question: Would ONE cylinder of this V-8 engine cause such a noticeable symptom?
Um.......yes!

I can't remember if you changed plugs/wire/coil packs, but if not, they should be changed ASAP.

Al
 
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