Stumble at low RPM's and part throttle

[Drewstang]

My car has a "stumble" at low RPM's with partial (1/4 or so) throttle. This occurs usually below 30mph, but has occured as high as 40-45 with OD off. The "stumble" is around 2600-2800 RPM's and feels as though I lifted off the throttle and then back on. Any ideas? I've got no Check Engine Light, and I was thinking it could be the TPS acting up. Is this a Trilogy thing?

[RF Overlord]

The only definitive answer I can give is that it is not a Trilogy thing.

TPS on its way out?
Dirty MAF?
Small vacuum leak?

Some have reported a similar condition that seemed to be cured by installing the Granatelli COP connector kit...

[Krytin]

Bad plug/week coil?

[Drewstang]

I'll go through and check the plugs this week sometime. I also need to change the oil this week. It didn't do it at all today. Weird little gremlin.

[Drewstang]

A little update. After putting in about a half of tank of gas this morning, the CEL came on as I turned out of the station. I checked the rearview to see if I left the cap off, but I did not. I went straight home and grabbed the SCT tuner, and checked the codes. P0190 and P0174 came up. 190 is a Fuel Pressure Sensor malfunction, and 174 is Bank 2 too Lean. I cleared the codes and babied it to work and back home after work. I'm going to look it over very close in the morning to look for fuel leaks or anything else that doesn't look right. Any suggestions? Anyone else have this sensor go bad? Could this be related to the BAP?

[Zack]

I changed both O2's when I had it, along with a new fuel filter.
Make sure the BAP is turned all the way up, thats where it was dyno'ed at.
Also make sure an O2 wire is not touching any part of the exhaust, although I highly doubt that is the case.
FPR's do go bad, any tuner will tell you to keep a spare in the glove box just in case cause you're dead in the water when it goes south. however, it is my understanding that they either work or dont.
I will help in any way if I can.

[Paul T. Casey]

P0190 FRP stuck in range, with FRP sensor ok.
Entry conditions: FRP sensor input Minimum 0psig, Maximum 46psig

Fuel pressure error (demand -actual) > 5 psig.

From the official Ford book.

[Paul T. Casey]

Also, codes may be gone for a while. If cleared by tool, it could take up to 6 duty cycles (start up and typical drive pattern) to re-light the CEL. If cleared by battery, then between 2 to 6 to re-light. I'll try to read more as the day goes on.

[Drewstang]

I changed both O2's when I had it, along with a new fuel filter.
Make sure the BAP is turned all the way up, thats where it was dyno'ed at.
Also make sure an O2 wire is not touching any part of the exhaust, although I highly doubt that is the case.
FPR's do go bad, any tuner will tell you to keep a spare in the glove box just in case cause you're dead in the water when it goes south. however, it is my understanding that they either work or dont.
I will help in any way if I can.
The BAP is exactly where you told me to leave it, but i will double check tonight to make sure nothing touched it. I had some boxes back there last week and its possible one may have rubbed against the switch.
I'll go by the dealer tomorrow and get a new FPR and the FP sensor just to be safe. I'm going to change the oil in just a few minutes and I'll look for any wires out of order.

[Zack]

I'll go by the dealer tomorrow and get a new FPR and the FP sensor just to be safe.

Make sure you have 60-80 dollars in your pocket. :bigcry:

[Drewstang]

I think I found the stumble. I've noticed over the last few days that the car was louder and has less low end power. After hearing a large exhaust leak while driving under a highway, I finally got a chance to take a look under the car last night. The x-pipe was rusted completely out where it meets the mufflers. No big deal. $60 bucks later and she's as good as new. I had a local muffler shop make new ends for the x-pipe and weld them in. They also replaced a rotted hanger for me in the quoted price. No stumble all the way home. We'll see for sure on my way to work in the morning and on the way home. It seemed to be isolated to warm temps.

[Marauderjack]

I think I found the stumble. I've noticed over the last few days that the car was louder and has less low end power. After hearing a large exhaust leak while driving under a highway, I finally got a chance to take a look under the car last night. The x-pipe was rusted completely out where it meets the mufflers. No big deal. $60 bucks later and she's as good as new. I had a local muffler shop make new ends for the x-pipe and weld them in. They also replaced a rotted hanger for me in the quoted price. No stumble all the way home. We'll see for sure on my way to work in the morning and on the way home. It seemed to be isolated to warm temps.


What "X" pipe do you have and why would it be rotted out so soon??:confused: I thought most of the OEM and "After Market" exhaust components were SS and should last indefinitely!!??:eek:

Just curious??:rolleyes:

Marauderjack:burnout:

PS: Hope that's all it was!!!:beer:

[Zack]

First edition Kooks system on that car.