Pop and backfire,2500-3000 RPM

[cypressfox]

Hi all: Just joined. I'm having a similar problem with my 2003 standard PT. Suddenly started tonight with no warning. At exactly 2500 rpms it starts bucking and it won't go over 2500. I put it in neutral (it's a standard) in my driveway and revved the engine but it will not go over 2500. It has about 104,500 km. Help![:I]

[cypressfox]

This very same problem occurred on my PT- suddenly - over the weekend except that I was unable to get the revs over 2500, even in neutral. My service guy has just told me that it's the camshaft position sensor - thank goodness it's under the extended warranty. Have no idea what this thing is but hopefully I'm not getting the "shaft" (being female and all). Can anyone shed some light?

[quicksilverdon]

Welcome, CypressFox.
If you've read the thread, a likely place to start is with new wires & plugs. When were they last done?
It could very well be the camshaft position sensor, that triggers ignition.
Did you have a check engine light?
Wow, an extended warranty that goes past 100,000 miles?

[elacua]

i have the same issue ,but i left it alone cause ithought it was a governor that cuts off at 2500 rpm so we wont blow the engine(factory) .Please correct me if i am wrong,cause this was my believed.

[littleblueGT]

The cam position sensor will cause what was described earlier, but I found that the map sensor will also cause the same problem. Check for codes by switching the key 3 times to on/off. The cam sensor is easy to replace, and so is the map sensor. You may want to check your intake manifold as after the "pop" you could have damaged the map sensor and split the manifold.

[quicksilverdon]

Originally Posted by elacua

i have the same issue ,but i left it alone cause ithought it was a governor that cuts off at 2500 rpm so we wont blow the engine(factory) .Please correct me if i am wrong,cause this was my believed.

No, the cutoff is around 5,800 RPM - near the red line on the tach. In Neutral, it is is much lower, but in gear, you should ge able to rev well past 5,000 RPM.