Well the temp here today is 100. I am running my A/C and my truck is lagging HORRIBLY! When i was pulling out of the drive thru I floored it and it seemed to take its time to get up and going. Normally it would throw it in high gear and haul. I can't figure out what the problem.

I have a 2001 Supercrew with 125000 miles.

Does this mean its time to trade it in?

The problem does not exist when i don't run the A/C.

 

How many miles on your plugs, coils, and fuel filter? Got 118,000 on my 01 screw, and the AC doesn't make a whole lot of differance when its on. If Im towing, thats another story, but it will still down shift and try to do something. All comes down to regular mantanance, especially when trying to milk power from a 4.6

 

No, I have a 5.4.

There are about 15 k on my plugs. Only like 5k on the Fuel filter. Not sure on the Cops.

 

That's to bad. Yep, she just needs attention. - Things cleaned / Sensors/Parts updated.

Trade it in, -who's knows, maybe someone willing to give her a little time can benefit from it. This way,- you can find another to run into the ground.

 

Yep... Lots of guys running these truck with WAY more miles then that. Trade it in. That will solve your problems till the next one gets some miles on it..

 

I'd say if you have a 5.4 and your AC is putting that kind of load on your engine, there might be a problem somewhere. Needs to be looked at, or dumped, one or the other.

 

is it lagging only with the a/c on? what brand plugs did you use? i'm sure it just needs some sensors cleaned. clean the maf and throttle body. how old/dirty is the air filter? how old are the front o2 sensors?

 

A competent mechanic should be able to pinpoint the problemo, through diagnostics, & a test drive!....Lots cheaper than a new truck!

 

MAF was cleaned when i put in a new Air filter in, that was about 5k miles ago.
I don't believe that the o2 sensors have ever been pulled...

Can this be a major problem?

 

Again, what brand plugs? Front O2's are no big deal and 100k is when they start to deteriorate. You also might be getting plugged cats.

 

Sorry, they are MotorCraft brand.

Who can check those to see if they are bad?

 

Cats? Take it to a muffler shop and they can use an infrared probe to check for clogging.

Have you scanned the OBD2 for trouble codes? If the CEL has ever come on, there should be stored codes.

 

Does it lag every time you use the AC or just that once? Sitting in a drive through will heat soak the engine. With the AC on it will make it worse. The condenser is trying to shed the heat of the AC system and it sits in front of the rad. The fact that it doesn't do it with the AC off should point to a problem with the AC. Does it lag on the highway with the AC on?


.

 

glc: I have never heard of that. I will try to get some time to get over to the shop to try that. The CEL has only come on once in its life. That was when I forgot to hook up that Air Intake Temp Sensor when I was changing the intake back to stock.

JMC: Yes, it lags every time i use the AC. It does it worse when I am sitting at a stop then take off. I don't notice it so much when I am already up to speed.

 

try switching to e-fans and possibly a cooler t-stat in the summer