No accelaration / loss of power after 60mph

racertracer · **Posted:** Wed Jan 13, 2010 4:46 am

No acceleration.

Last night, I was on my way home from work when I noticed a problem with acceleration.

While traveling at speeds below 60MPH I had a responsive throttle but when I punched it to the floor the vehicle dropped in velocity. The MPH went from 60 to 55 and kept dropping while I had the pedal floored and then it regained velocity when I took my foot off the pedal and slowly pressed the pedal back down again slowly. I noticed that when the needle had reached past 60 miles per hour the tachometer increased but the MPH decreased.

Earlier that day when stopped at a light, I felt the engine slowly surge and then drop in RPM doing this continually for a minute or two but then returned to normal until the last leg of my drive home.

Could this be CAC hoses?

For your info both CAC hoses were replaced with OEM hoses about a year ago.

Any help would be appreciated.

Glend · **Posted:** Wed Jan 13, 2010 4:59 am

You could have a broken EGR pipe - similar symtoms, no CELs, no power, appears to be in limp mode. Undo the three bolts holding on the exhaust manifold heat shield (under the radiator overflow tank) and at the back of the exhaust manifold there is a circular clamp that attached the EGR pipe to the manifold - you should be able to see if it is broken at the flange. If you start the car you will see and hear the exhaust escaping from there. This bleeds off boost power.

Other possibilities: Loose clamp on a CAC hose, since the hoses are new I'll assume its not them but it could be (are you runnng a Provent)?,

It is feasible that it could be a fuel filter problem, or a fuel issue. What at the temperatures like in your area when this happened? Your not running bio are you?

racertracer · **Posted:** Wed Jan 13, 2010 5:11 am

Glend,

The temps are between 10F to 25f, I am not running Bio and I did install a home made provent device.

racertracer · **Posted:** Wed Jan 13, 2010 10:00 am

Update:

I plan to check the CAC hoses and EGR pipe after work today in the meantime I have to use the vehicle to get me to work, so I will drive it gingerly.

This morning I on the way to work it showed no sign of trouble, the throttle response was there and it performed gloriously.

To further elaborate on what occurred during the drive home last night, it actually felt like the transmission was not going into gear when the throttle was pressed down to the floor.

Could the problem have been with the new TC & Pump that was installed?

It did feel like it wasn't going into gear.

Although the needle on the tachometer climbed past 2900, the velocity dropped and felt like I was coasting or standing still. When the velocity dropped to 60 MPH it kicked into gear again.

linewarbr · **Posted:** Wed Jan 13, 2010 10:48 am

Hmmm, that sounds like a trans pump issue to me - not maintaining line pressure to keep the TC locked up. Not sure though, as I have not (knock on wood) experienced any TC/ trans issues as of yet.

Is there a way to check the line pressure?

naturist · **Posted:** Wed Jan 13, 2010 10:25 pm

There are a flock of issues that evidently cause that effect. When it has happened to me, it has been a clogged fuel filter. And it's happened twice.

I now change out the fuel filter every 18,000 miles instead of the 24,000 the owner's manual says. What would cause that? Dirty fuel, water in the fuel, unwinterized fuel, just a fuel filter beyond it's capacity.

racertracer · **Posted:** Thu Jan 14, 2010 12:33 am

Naturist,

You may be right...

I had no problems today it actually performed better than best.

jksuperstar · **Posted:** Thu Jan 14, 2010 3:16 pm

This sounds like what I saw in mine...after 60mph, I lost power, and in one case the engine died and I coasted to the breakdown lane. Felt similar to "limp mode" where boost is gone, and if I pressed the pedal the engine couldn't provide and that loss of power had the TCM all confused.

Anyway, I presumed the engine was demanding too much fuel, and the air bubbles in my fuel filter had starved it. I purged the air (which there was a bit), drained the water, and the problem went away.

So, I can second Naturist's suggestion.

Joe Romas · **Posted:** Fri Jan 15, 2010 8:50 am

If any of you get bored, open up a used fuel filter and unroll the media. You will be shocked with what you will see :dizzy:

I opened one at 12k miles and it was full of a black substance. I've learned it's a asphalt type substance that is a result of the pressure regular used in out high pressue rail :jester:

AZ CRD · **Posted:** Fri Jan 15, 2010 9:14 am

naturist wrote:

There are a flock of issues that evidently cause that effect. When it has happened to me, it has been a clogged fuel filter. And it's happened twice.

I now change out the fuel filter every 18,000 miles instead of the 24,000 the owner's manual says. What would cause that? Dirty fuel, water in the fuel, unwinterized fuel, just a fuel filter beyond it's capacity.

X2

racertracer · **Posted:** Fri Jan 15, 2010 11:29 am

But just one variable puzzles me though, and here it is:

Why would the tachometer needle continue to rise when I pressed the pedal down? Wouldn’t it have gone down the same way the MPH needle on the odometer did?

linewarbr · **Posted:** Fri Jan 15, 2010 2:21 pm

that would mean the speed sensor is still getting info that says the vehicle is accelerating. IIRC, the speed sensor plugs into the rear driver's side of the trans - once again pointing to a trans problem, unfortunately.

racertracer · **Posted:** Fri Jan 15, 2010 3:38 pm

Oh great............ so now what's the prognosis?

MrMopar64 · **Posted:** Fri Jan 15, 2010 5:53 pm

The 545 does have an output shaft speed sensor, but it is not used for the vehicle speed. Vehicle speed comes ultimately from the ABS module through a chain of communication.

It sounds like the vehicle is in limp mode. Stop by AutoZone, borrow a code reader and scan the vehicle's modules for codes. Sounds like there is a bigger issue going on, not necessarily bad.

jksuperstar · **Posted:** Fri Jan 15, 2010 7:14 pm

I saw the RPM climb also, the loss of power, and I don't remember hearing the turbo. However, the Tac did seem completely unrelated to the vehicle speed (and that seemed accurate given my location on the highway, and cars whizzing by). Which sounds exactly like what you saw, so you aren't alone.

I have to say it was very odd to see the engine rev up, but not feel or hear anything happening. With that much loss of power and at that speed, the TCM may have been in neutral and I was just coasting, or it shifted into some lower gear and I was oblivious to it because the engine didn't have the same sound it usually does when hitting 3500 rpm while I'm going 60mph. That sound is usually "Make a hole, and make it big, I'm coming through!!!", not "mmmmeahhh, sigh".

All other shifts for me are perfectly clean (and remarkably smooth compared to my old '95 Cherokee), and the tranny fluid was recently changed, or it's just still pristine. Again, since I purged the air, I haven't had the same loss of power, Tacometer insanity, or stalling. Replacing the fuel filter is at the top of my priority list.

MrMopar64 · **Posted:** Fri Jan 15, 2010 8:01 pm

jksuperstar,

If you had a fuel prime issue, then undoubtedly you were in limp home mode when it happened, and probably also had a P0093 stored in the ECU. The reason why the engine speed is so high is because you punched the accel pedal to the floor and the trans downshifted, but you didn't have any power at that high RPM in limp-home mode, so the vehicle actually slowed down some.

racertracer · **Posted:** Fri Jan 15, 2010 10:21 pm

well that explain that... Many thanks

racertracer · **Posted:** Thu Jan 21, 2010 11:35 pm

Well it happened again.

I am on the freeway cruising steady at 65 mph for 20 minutes then I punch it to the floor to get away fom slower traffic when all power is gone..... the RPM reach 3200 indicating that the engine is responding to my foot on the throttle but the transmission is not responding because of lack of power to the wheels.

This has happened almost everyday during my commute home at night.

What can this be?

bugnout · **Posted:** Fri Jan 22, 2010 12:31 am

Does shutting down and restarting clear the issue? You get all the power and acceleration back?

racertracer · **Posted:** Fri Jan 22, 2010 6:14 am

Yes, Shutting down and restarting restores power and the issue is cleared.

This has been happening only recently and after I had the TC & Pump replaced with the new Updated DC TC & Pump.

No accelaration / loss of power after 60mph

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