My 2001 4.6 seems like it is a little sluggish at times. It isn't consistent, and will do it sometimes at take off, sometimes at higher speeds. There are no other signs as to what may be causing this. I have checked to make sure my brakes aren't dragging. Is there a way to check the cats without a code?

 

I'm having the exact same problem except i get the sluggish response daily now.......only when the outside temp gets high. I've been told that the cats are the problem. I just finished reading the net and saw that one indication of a bad cat is sluggish response, and they rarely throw a code due to the O2 sensor being mounted between the cat and the engine. I didn't see if there was any "real" way of testing for a bad cat except removing it and seeing if the engine performance changes. I'll be taking mine into the shop tomorrow to have them removed. I will let post if any change is noticed.

 

Thanks kakings. Let me know what they say. That's what I was waiting for, was for it to throw a code. Good to know that it won't. I have been pricing online, and magnaflow's seem to be the least inexpensive.

 

Other than cutting them out and having them checked out there is no way to check. If your past 80,000 miles you might as well just do a hi-flow cat switch.

 

Well, got all four cats removed today and still have the problem. Kinda frustrated now due to wasting the money and am going to have to pay the same thing to have cats put back on (didn't like the louder noise and the fumes were pretty bad). I found some universal cats at AutoZone.....front $85 rear $60. While at AZ, the salesman mentioned that the problem could be the TPS (Throttle Positioning Sensor). I'm desperate now, so I purchased it and put it on this evening when i got home. I will find out tomorrow if it is the problem. I will post what i find.

 

Could it be your air intake? Idk just something to think about..

 

Im not an expert on this topic but the first thought that crossses my mind is that you have now drained your truck of its low end power by removing all the cats, where as originally you had a similar problem due to the cats being clogged. If it were me i would have done these two things first, let the truck run and get hot, then put an oven mit on and feel the pipe in front of the cat, then behind the cat. If the pipe is not nearly as hot after the cat then its prolly clogged. (this trick could be completely false but i had an ole timer tell me this who new a thing or two about exhaust) Then i would of replaced the cats with some high flows, not cut em all out. To me it seems with no cats a truck can be sluggish but like i said im not an expert just thought i might share a tip and my thoughts.

 

Kakings, thanks fo rletting me know, and sorry you're having so much trouble with it. As far as it being my air intake, I do have a K&N filter, keep it oiled, and keep my MAF cleaned regularly. I cleaned my throttle body a few months back. I might go through and re-clean everything.

 

I've run it fpr a day with the cats re-installed and with the TPS. It's doing better but still not running as smooth as I know it can. I had a new motor put in a few months ago and was experiencing the same hesitation issue. The intake and all sensors were transferred from my old motor to the new one, along with the hesitation. That leads me to belive that the problem mis in one of the sensors..........TPS maybe????

A little history........I had a plug to back out a few months ago. Being that my engine had very high miles, I replaced it with one from a Lightening with 28K miles. I was having the same hesitation issue with my first motor. Once the new motor was put in, I noticed a totally differnt change in the "tune" of the motor......was very deep. I now know that was due to the clogged cats because now the "tune" is in line with the true Harley sound. Since I was told that clogged cats can foul out your plugs, I'm about to go out now and put in a set of plugs to see if that would get me running smooth again.

As far as the hesitation, I'm almost certain that the TPS was the issue. I'll keep you posted as i drive it more to see if the problem resurfaces.

 

Kakings, a new one. While going trhough and cleaning the air intake again, I noticed the number 8 COP looked crooked. The bolt had snapped. I am assuming that whatever it is the F150 has a problem leaking has leaked, corroded the bolt, maybe gotten into the #8 cylinder? I changed my TPS, with a noticeable improvement, but didn't fix the problem. Let me know if you know anything about this. Thanks.

 

The #8 plug is the one that backed out on me, but the bolt was still in place and there was no sign of anything leaking back there. I can't think of anything that would be leaking that far back and long enough to cause corrosion. Did you pull the plug or at least check to see if it was tight? If not, I suggest you do that. I heard a slight tick in mine before it blew out. The tick was due to the plug being loose and the compression was moving it causing the tick. The TPS did make a noticable difference but I have gotten the hesitation maybe twice since I replaced it but it is not near as bad as before. Without a code being thrown, it's hard to diagnose. The only thing remaining are the mass air flow sensor and the air charge sensor.

 

I do have a K&N air filter, but I do keep the MAF and throttle body clean. I replaced the TPS, and now, like you, it happens less. I took it to a place and they ran a compression test on the engine (good), and another place tested the exhaust and that came out fine as well. I guess I will try the other sensor and maybe that will do it. I will let you know what happens.

 

I have a K&N too (hope that's not the source of the problems). I can't see that being the case. Since the TPS made a noticeable difference, maybe there could be issues with other sensors. My engine and sensors were in the 200K range before I replaced it, so I'm not dismissing the need for sensors being replaced. Let me know how it goes.

 

Well the problem has come back. I'm at the end of my rope now and don't know what needs to be done. Adamcordona if you've fixed your issue, please let me know what was done.

 

adamcardoa17, I may have found the issue. I had a hole in one of the lines going to my EGR sensor. Replaced the line and the hesitation is gone. I read that a bad EGR sensor would cause the problems that we experience and that is what lead me to look at the EGR, which is how I came across the bad line.