Help! Losing Power

Rankin · **Joined:** Mon Dec 27, 2010 4:53 pm **Posts:** 17

2003 Liberty Sport

After it heats up, while accelerating it is loosing power intermittently. I have cleaned the throttle body intake. New spark plugs, changed fuel filter.

Anyone know what would cause this?

fratichelli · **Posted:** Sat Feb 04, 2012 7:26 pm

Have you checked the codes?

It could be a bad coil, or even something like a loose wire around the power control module.

Get it warm and wiggle the wires in the engine compartment.

Rankin · **Joined:** Mon Dec 27, 2010 4:53 pm **Posts:** 17

fratichelli wrote:

Have you checked the codes?

It could be a bad coil, or even something like a loose wire around the power control module.

Get it warm and wiggle the wires in the engine compartment.

It's not throwing any p codes, or engine light. Are there codes that don't throw an engine light?

- David

Rankin · **Joined:** Mon Dec 27, 2010 4:53 pm **Posts:** 17

New battery now (I know low voltage can cause issues). Still no luck. I am reading that a bad TPS can cause these problems. Anyone confirm?

02blue · **Posted:** Sat Feb 04, 2012 10:16 pm

Yes Mine did. But it also threw a code.

Rankin · **Joined:** Mon Dec 27, 2010 4:53 pm **Posts:** 17

New TPS is in. See how it goes over the next few days. Aftermarket with a lifetime warranty for 40$. Not bad.

Rankin · **Joined:** Mon Dec 27, 2010 4:53 pm **Posts:** 17

TPS no go. This is only happening after starting the jeep when it is hot. A cold start wont produce it. It only lasts for about 30 - 40 seconds before going back to running normal. Some sort of vapor lock issue? I had a problem with my evap canister a while back and the purge solenoid has been replaced. 02 sensor going bad?

Hot start
Runs good for about 20 - 30 seconds
Runs like crap for 30 - 40 seconds
Runs good.

I have dumped some $ into this trying to figure it out. Any help is appreciated.

02blue · **Posted:** Sun Feb 05, 2012 9:43 pm

O2 sensor should give a code. How about the fuel pump? Has it been checked? Most of the things I can imagine would send a CEL. :?:

Rankin · **Joined:** Mon Dec 27, 2010 4:53 pm **Posts:** 17

02blue wrote:

O2 sensor should give a code. How about the fuel pump? Has it been checked? Most of the things I can imagine would send a CEL. :?:

Yeah, I am perplexed. Seems like the fuel pump / filter would give more consistent problems. This only happens when there is a warm start up cycle. If it is started cold, it runs just fine even after it gets hot. If I turn it off when it is hot, then let it sit for a few minutes, turn it back on and leave, it goes through the rough idle cycle. I am starting to think it is the evap purge solenoid.

"The engine enters closed loop operation after it
reaches a specified temperature and the time delay
ends. During closed loop operation, the PCM cycles
(energizes and de-energizes) the solenoid 5 or 10
times per second, depending upon operating conditions.
The PCM varies the vapor flow rate by changing
solenoid pulse width. Pulse width is the amount
of time that the solenoid is energized. The PCM
adjusts solenoid pulse width based on engine operating
condition."

I really have no idea. It only happens on hot start, and doesn't last. It is rather annoying and seems to be getting worse.

Rankin · **Joined:** Mon Dec 27, 2010 4:53 pm **Posts:** 17

Looks like it was the air temp sensor if anyone was curious or having a similar problem.

Help! Losing Power

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