re-heats up, 2500 rpm bogs down

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deyule

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, 2500 RPM BOGS DOWN

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Relaced head gaskets, intake gaskets, no leaks, compression good. R&R fuel filter, fuel pressure 50 psi. Read out map, MAS sensor, EGR ok. R&R plugs. Air cleaner clean. Cooling fan good. No codes.
2001 pontiac grand am 3.4 naturally aspirated engine. Checked fuel pressure under load, fuel press. 50 psi. How can i check the cat? can I disconnect it, an check it? The engine does not heat up at idle only under a load. The engine seems to be struggling at RPMs above 2500 to 3500, like its out of time.
 
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Is the fuel pressure you mentioned at idle, or under a load? If it's at idle, you might want to hook your gauge back up and tape it to the windshield and watch the pressure under a load as when it bogs down. Also might be a good time to have your catalytic converter checked as they can cause engine bogging under a load.
 
re- bogs down at 3500 an heats up.

Checked fuel pressure under load, fuel press. 50 psi. How can i check the cat? can I disconnect it, an check it? The engine does not heat up at idle only under a load. The engine seems to be struggling at RPMs above 2500 to 3500, like its out of time.
 
re- heating up bogging down

msmith1956 said:
Is the fuel pressure you mentioned at idle, or under a load? If it's at idle, you might want to hook your gauge back up and tape it to the windshield and watch the pressure under a load as when it bogs down. Also might be a good time to have your catalytic converter checked as they can cause engine bogging under a load.
Click to expand...

Checked fuel pressure under load, fuel press. 50 psi. How can i check the cat? can I disconnect it, an check it? The engine does not heat up at idle only under a load. The engine seems to be struggling at RPMs above 2500 to 3500, like its out of time.
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If the cat is clogged your idle vacuum readings will be very low. If it's not heating up, have you considered your thermostat is stuck open.
 
I am going to pull the Cat. I will check the thermostat, thanks.
 
I found 2 specs for the feul pressure, 52-59 and 53-59. At 50, fuel delivery shouldn't be a problem.
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re- fuel pressure

CatSkinner said:
I found 2 specs for the feul pressure, 52-59 and 53-59. At 50, fuel delivery shouldn't be a problem.
Click to expand...

Thamks for your info, I will disconnect the Cat. tomorrow an see if the engine will rev. up normally.
 
re- heating u, low power

Disconected cat from manifold, it runs much better. I will check aft of cat also for any blokage, although its probably the cat.
 
glad you found the cause of the problem
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