P1290: CHT Low Input
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Joined: Apr 2020
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From: Alabama
P1290: CHT Low Input
Hey everyone, I’m new to posting in forums. I’m not too sure how all of this works so if I’ve made any mistakes please correct me. I’ve been working on all manner of most everything that goes vroom vroom and doesn’t fly since young teenage years. An educated Parts Changer, if you will.
My truck is a 2001 F150 5.4L OffRoad Package, SuperCab. 155,000 on Body and Trans/transfer case. Engine has 25,000 miles (paperwork from LKQ).
I’m just gonna put everything I know to have been done before I bought the truck and everything I’ve done since.
Original engine was over heated and replaced by a shop local to me. I know the shop owner and he doesn’t tend to employ very meticulous “mechanics”. They installed the engine about a year ago, using the absolute cheapest parts and methods possible. Most everything I have done so far was caused by their lack of attention to detail and to be honest, some of it is just pure laziness.
Misfire on Cylinders 4&6, caused by eBay coil packs.
Limp Mode engaged due to a dead short in the CHT circuit between CHT and main harness plug near battery. Found to be caused by cheap butt connectors without any casing or shrink wrap used.
B1S1 O2 sensor faulty (guy I bought it from cut the converters off), sensor had been nicked with saw blade.
Thermostat stuck open.
I have since corrected every issue listed above. New coil packs (Duralast), Motorcraft Platinum plugs, replaced CHT sensor under intake manifold and soldered original wiring back to new CHT harness plug. New Bosch O2 sensor, muffler shop put pipes in place for the time being as I don’t want to invest too much in the truck before getting this issue fixed for good but I do have an aftermarket set to install once all is finished. Catalytic Converters is kind of what I do for work so those were fairly easy to come by.
After all of that I still had a P1290 and a P1132, however the P1132 doesn’t set and only shows when I use the Ford KOER function with my scan tool. So I bypassed the original harness back to the plug near battery, soldered and 3 layers of heat shrink with 18G wire per factory specs. I now have the same P1290 and system is showing a rich/lean switch. About 10MPG and the throttle is randomly weak. I can get a New PCM from my preferred parts house for about $320 with my commercial discount but I do not want to spend it just to find out I was wrong. My next planned step is to jump around aforementioned plug, soldering directly into the wires going into the PCM plug itself. Any and all help is greatly appreciated.
My truck is a 2001 F150 5.4L OffRoad Package, SuperCab. 155,000 on Body and Trans/transfer case. Engine has 25,000 miles (paperwork from LKQ).
I’m just gonna put everything I know to have been done before I bought the truck and everything I’ve done since.
Original engine was over heated and replaced by a shop local to me. I know the shop owner and he doesn’t tend to employ very meticulous “mechanics”. They installed the engine about a year ago, using the absolute cheapest parts and methods possible. Most everything I have done so far was caused by their lack of attention to detail and to be honest, some of it is just pure laziness.
Misfire on Cylinders 4&6, caused by eBay coil packs.
Limp Mode engaged due to a dead short in the CHT circuit between CHT and main harness plug near battery. Found to be caused by cheap butt connectors without any casing or shrink wrap used.
B1S1 O2 sensor faulty (guy I bought it from cut the converters off), sensor had been nicked with saw blade.
Thermostat stuck open.
I have since corrected every issue listed above. New coil packs (Duralast), Motorcraft Platinum plugs, replaced CHT sensor under intake manifold and soldered original wiring back to new CHT harness plug. New Bosch O2 sensor, muffler shop put pipes in place for the time being as I don’t want to invest too much in the truck before getting this issue fixed for good but I do have an aftermarket set to install once all is finished. Catalytic Converters is kind of what I do for work so those were fairly easy to come by.
After all of that I still had a P1290 and a P1132, however the P1132 doesn’t set and only shows when I use the Ford KOER function with my scan tool. So I bypassed the original harness back to the plug near battery, soldered and 3 layers of heat shrink with 18G wire per factory specs. I now have the same P1290 and system is showing a rich/lean switch. About 10MPG and the throttle is randomly weak. I can get a New PCM from my preferred parts house for about $320 with my commercial discount but I do not want to spend it just to find out I was wrong. My next planned step is to jump around aforementioned plug, soldering directly into the wires going into the PCM plug itself. Any and all help is greatly appreciated.