Catalytic Converter and sluggish takeoff
05-12-2016, 09:03 AM
#1
Catalytic Converter and sluggish takeoff
Just recently had a remanufactured engine installed in my 2004 Fx4, 5.4L (260k miles). Mechanic said the truck is throwing a catalytic converter code (not sure which one) but often times its not a problem. He told me to drive it for a while to see if it feels different. Honestly, after driving the truck with that many miles on it, I probably wouldn't be able to determine if the truck felt different because just about anything would be better.
Anyways, I am noticing that the truck accelerates a bit sluggishly from 0-30mph. Once it hits around 30, it seems to take off and accelerate much better. I was towing my boat yesterday and it really struggled to get out of what I believe was 2nd gear. I barely accelerated at all until shifting out of 2nd. After that, I could step on the gas and it would accelerate like I was not even pulling the boat.
Any thoughts on this?
Anyways, I am noticing that the truck accelerates a bit sluggishly from 0-30mph. Once it hits around 30, it seems to take off and accelerate much better. I was towing my boat yesterday and it really struggled to get out of what I believe was 2nd gear. I barely accelerated at all until shifting out of 2nd. After that, I could step on the gas and it would accelerate like I was not even pulling the boat.
Any thoughts on this?
05-12-2016, 09:32 AM
#2
To be honest, you are probably going to get a gazillion people offering all sorts of things from "change your spark plugs" to "your cats are clogged", to etc.
I would use a code scanner that can read permanent codes to see if a P2006 (IMRC stuck closed) is hiding in there. My inexpensive Actron code reader would not read it, but when I connected with a bluetooth adapter and the Torque Pro app on my phone (which is actually cheaper than the Actron!), there it was. The P2006 code caused the PCM to retard ignition timing a ridiculous amount at low rpm and the retard was exacerbated by high intake air temps.
Anyway, it is something to check before you start throwing parts at it.
I would use a code scanner that can read permanent codes to see if a P2006 (IMRC stuck closed) is hiding in there. My inexpensive Actron code reader would not read it, but when I connected with a bluetooth adapter and the Torque Pro app on my phone (which is actually cheaper than the Actron!), there it was. The P2006 code caused the PCM to retard ignition timing a ridiculous amount at low rpm and the retard was exacerbated by high intake air temps.
Anyway, it is something to check before you start throwing parts at it.
Last edited by BigBlockRanger; 05-12-2016 at 09:42 AM.
05-31-2016, 12:32 PM
#3
Another thing I noticed recently, the inside of the exhaust pipe it colored soot black. I rubbed my finder along the inside of the pipe and it felt as if I had rubbed to surface of a lump of charcoal.
05-31-2016, 01:02 PM
#4
Mark
iTrader: (1)
Your old motor may have been dumping raw fuel into your catalyst system and may have either fouled 1 or more 02 sensor's or even clogged your cats...do your smell rotten egg odor from your tail pipe...jump out after a drive and look at the cats...are the glowing red...or extremely hot ?
05-31-2016, 07:11 PM
#6
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Clogged cats tend to make the higher RPMS sluggish. The higher your rpm & gear the more air your engine consumes and the more gas it exhausts. A clog obviously slows the vacuum and makes it harder to push that air out and let more in.
Cat efficiency is fairly as easy to detect, a professional scan tool and know how is all you need. You go into the engine data and check O2 sensor PID's. the front O2 sensors will change rapidly as the ECM rich's and leans out the fuel. The rear O2 sensors should change much less rapid, if they they are changing with the front or to be honest even close that catalyst in your converter is likely reached its threshold for chemical reaction.
Judging from your post I would think its more possible that its a sensor issue (common). I've worked on plenty of cars with clogged cats, and NONE of them was less noticeable the faster you drove. If anything they couldn't even get up to speed but coming out of park was more or less normal. Or as your mechanic said not a issue at all. It's not impossible for a sensor to malfunction and then work again.
Black smoke is typical or a engine running rich, which could be effecting the efficiency of the converts as well.
Cat efficiency is fairly as easy to detect, a professional scan tool and know how is all you need. You go into the engine data and check O2 sensor PID's. the front O2 sensors will change rapidly as the ECM rich's and leans out the fuel. The rear O2 sensors should change much less rapid, if they they are changing with the front or to be honest even close that catalyst in your converter is likely reached its threshold for chemical reaction.
Judging from your post I would think its more possible that its a sensor issue (common). I've worked on plenty of cars with clogged cats, and NONE of them was less noticeable the faster you drove. If anything they couldn't even get up to speed but coming out of park was more or less normal. Or as your mechanic said not a issue at all. It's not impossible for a sensor to malfunction and then work again.
Black smoke is typical or a engine running rich, which could be effecting the efficiency of the converts as well.
06-01-2016, 08:09 AM
#7
I forgot to look at the catalytic converters last night to see if they are glowing red. Also, I do not see any black smoke but only black residue inside the tailpipe. Are the O2 sensors difficult or expensive to replace?
FYI, I pulled the boat to the gas station again over the weekend and it did the same thing. It struggled a little in first gear and then then really got sluggish in second gear. It took way too long to get the truck up the 25-30 mph. Once it reached 30 mph (give or take a few mph) and changed gears, the acceleration improved immensely.
FYI, I pulled the boat to the gas station again over the weekend and it did the same thing. It struggled a little in first gear and then then really got sluggish in second gear. It took way too long to get the truck up the 25-30 mph. Once it reached 30 mph (give or take a few mph) and changed gears, the acceleration improved immensely.
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06-09-2016, 08:40 AM
#8
The passenger side catalytic converters did appear to have a slight red glow to them compared to the drivers side. We had a cool day this week (highs in 70s and raining) and the truck seemed to run a little bit better that day compared to the normal hot/humid days.
