I have a 97 f150 4x4 4.6L auto w/ 205k miles that has put me through the ringer. I had 4.10 gears installed back in July to help compensate for the 6" fabtech and 35's. After a couple weeks all of my power suddenly dissappeared when the CEL came on. It started kicking misfire and lean codes for bank 1. After going through the usual vacuum leaks in elbows and PCV valves, and replacing coil packs, plugs/wires, MAF, o2 sensors, IAC valve, it made a trip to the dealer. The dealer did all of their tests on fuel systems and said cylinder 1 was shot. Said it was not holding compression and failed the leakdown tests, and assured me this was my problem. I had a Jasper installed, and still the same problem. I noticed the cat converters on bank 1 were running significantly hotter than on bank 2. I replaced all 4 cats. After going BACK to the dealer and them coming up with nothing and pretty much telling me to buy a new truck, I decided to persue it with some friends. We chased ground straps and harnesses, pulled/cleaned/dielectically greased everything, no improvement. I ordered a rebuilt brainbox from Adv Auto Parts for $125 and installed it. It ran the same, then wanted to shut off and kicked transmission pressure related codes. I ran into a buddy who does mechanical work, he said his brother put gears in a 92 f150 and ran into the same problem. He said there are 2 speed sensors, one in the transmission and one in the rear diff and since one computer controls both the tranny and the engine, if they are not corrected by a tru-speed or a programmer then it puts the motor into a "limp mode" and it runs on half power due to the confusion of when to shift. I've ordered the Edge Evo CS and hope this fixes it. I've sunk way too much into this truck chasing ghosts. Has anyone ever heard/ran into this problem? PLEASE HELP!!!

 

Ok, so I was really hoping to knab a quick response on here from someone. Anybody that has installed gears in a 97-03 truck and has or has not had this problem please let me know! The Edge CS programmer gets here tomorrow so I guess I'll let you know what it does for me and maybe my truck is just destined to be stripped out and sold for parts.

 

yeah you need to have your computer reflashed to let it know you've changed gears. thats why programmers has all the different ratios

 

hang in there man, i don't know if it will remedy the problem. but, i know when you install the edge it will prompt you to select which gears you're running and hopefully fix the issue when it programs you're pcm.
Let us know what happens.

 

Thanks guys! Yea I knew I had to program for the speedo correction, but I never knew it would mess with the way the motor ran. It spits/sputters and sounds as if it's going to completely shut off when you hit any incline and it tries to downshift. I had put ring/pinions in past vehicles and never ran into this problem. If it does turn out to be this, I can't wait to go tell the dealer and thank them for causing me to sink around $6,000 for a $450 fix... I'll post as soon as UPS delivers tomorrow and let the f150online community know of the outcome.

 

so what you guys are saying is that if i change my gearing in my 01 f150 that i will have to have my computer reprogrammed or get a programmer for it in order for the truck to function normally?

 

I think you're on the right track. After having my truck go into 'limp' mode, due to a severed CHT wire-that was severed by a Factory mechanic, who failed to disconnect it, while doing a warranteed motor swap-the only thing you CAN trust is your own investigation.

A programmer WILL make your PCM think straight, in terms of modifications.

I'm not an EDGE guy though--unless they changed it to accept custom tunes.

A Dyno, custom tunes, and a smart tuner is a good investment.

 

Ok so I got the EDGE installed... that's not my problem. Yes it corrected my speedo and shift points but I've still got an issue with my motor causing it to run lean on bank 1. I guess this is just another $450 added to what I'm blowing on trying to fix this truck... I guess I'll try swapping injectors around next... I can't take much more.

 

Yes.

 

So essentially a set of 35"s that cost about 1200 are really gonna cost close to 2000 if not more?

 

Yes.

Done correctly - regear + tuner.

You can add larger, more powerful brakes to the list as well, for completeness

MGD

 

you guys are making me rethink the 35's lol, it didn't seem like my truck changed hardly when i went from the stock 31's to the 305/65/17's i have now. is that because it's only a 2 inch taller tire instead of a 4 inch taller tire like the 35? thanks for all the info guys, and im glad i found this post before i went and did all this

 

You can throw 35s on a stock truck and be fine, but it will cause unwanted stress on the tranny, this is why you regear. Then after you regear you have to reprogram otherwise the speedo and such will be off. The brakes are put on to help stop the now larger rotational mass of the tires.

Basically, you can do 35s now and within a few months do gears, and then again soon after a programmer, but you would definitely be better off doing it all at once. You might even want to get the programmer first, and run it on the stock truck, then regear with stock tires, and then get the tires. A programmer wont hurt the vehicle, when you regear you can change it right away in the computer. Later on when you get tires, you can simply put them on and be done with it.

 

NPI 4.6, auto and 35's so you chose 4.10's??????? wow!!!!

what else has been ignored on the truck???? when is the last time it had a tune up?? what was done and what parts were used???

 

The speedo regearing on 97'-98' trucks has to be done mechanically by changing the vss driven gear to the closest possible corrected sized.
Item # 82 here. http://www.transmissionsone.com/spee...#Misc.%20Gears

More importantly, the Vehicle Speed Sensor tells the pcm how fast the vehicle, trans, diff, etc are moving. If this info is skewed the pcm can only use the input available. This can be corrected with custom tuning, but not with a typical hand held programmer like the 99'+ trucks.