ROUGH DRIVING

[barrett86]

Hello guys i got an 86 bronco with a 302FI and an AOD tranny. ok i guess ill just start with my problem. i turn it on and my rpms idle really high like at 2000 rpms then will dive then spike then dive and spike, then will even out at 900 for awhile, then start again, it dies sometimes,but not an issue while driving, but driving problem is that it stumbles like ill start to go then it like downshifts kinda like when you would slam it into 1st gear and it would slow you down, well it does that and the gas then slow then gas then slow then drives, then while cruzing it feels like my tranny downshifts and it doesnt matter how much peddle i give it it wont go but then it kicks back in like a second later and i zoom along, although get this when it like downshifts persay i can floor it and i wont hear the motor rev or make any noise, but then if im still holding the peddle when when it starts to go again it will just goooooo. i dont know if my tranny is f*cked up or if my fuel pump is going out or a clogged fuel filter, or my cpu is f*cked up or my MAS is f*cked up or what.i cant even fathom what it is cuz i never seen this problem before.i dont think its the motor or my tranny because it really acts up when its cold, and also its making me chew my gas like crazy. ive never seen this problem before ever. i wish my cousin could help me because he is a Senior Master Ford Cert. Tech. but he is 3500 miles away with no way to contact him no phone or email.i can usually fix any problem because i know my truck like the back of my hand, then i get thrown for a loop on this one.ive had it for almost 2 years and never a problem what so ever. i just dont understand while im driving my bronco will just down shift or well it feels like i am, and if i give it gas it doesnt go but then it like kicks back in and starts going again, it does that like every 30 seconds while driving, but only when its cold or when i havent driven it in a couple hours.i thought my tranny fluid was low but i just flushed my tranny 2 days ago, but the problem didnt go away. get this guys when my bronco "downshifts" if i even floor it there is no reving of the engine or any sound, it feels like my truck dies but still has everything working. im going to make a video of it tomorrow and post it on youtube. ill post the link here as soon as i get it uploaded. ok quick edit tonight i started it on my break at work and it acted prefect for like 20 min then the truck was like it was running out of gas, it does that sometimes.but if i stomp the pedal like 2 or 3 times it levels back out

 

[bidibronco]

I don't think your truck has a speed sensor but if it does that would be my first look. Also, I would check the condition of your kickdown cable. Maybe there's something wrong there that keeps downshifting your truck. My t-bird was shifting funny so that's what I did and cleared it up pretty good. Oh, you don't have MAF either, you should have SD (speed density) but I may be wrong. Also, I would try the TPS and check and recheck and recheck and recheck (you get the point) all of your vaccum lines. Now that I think about it, I think the AOD has vaccum to it but again, I'm unsure but it's worth a look. Hope it all goes well for you...

 

[barrett86]

i actually ran the OBD1 tester on it and first test said my TPS was bad, then the second and third time it said everything was working normal. it hasnt been a problem since i ran that test.

 

[Bear76]

I had a problem like what your saying. When I opened up the throttle, the truck would just lay down flat, like it died, but if I let up on it, it would then go back to normal. It ended up being that the gas tank was all rusted inside and between all the gunk in the tank and my pick up tube being clogged, which kept plugging up the fuel filter, it was losing all its power, starving for fuel. I replaced the tank and the pickup, plus flushed out the fuel line/replaced a few lines that were leaking slightly and it was a definite improvement. The only thing mine never did was the wacky idling and what not. To me that does sound something like the TPS sensor or an electrical sensor of some sort. I dunno. I am too old school and I really need to get out and learn how to better diagnos/repair these newer trucks, because whether I like it or not, that is all that will be out there in the next few years. I hope this helps you out a little bit, and if not, well I tried. Have a good day.

 

[Blue beast]

Try 2 bottles of heet and 2 bottles of iso heet, Dump it in on what ever is in the tank 1/2 1/4 run it until a 1/8 tank refill and add 2 bottles of stp

fuel treatment. Adding a bottle of dedicated gas line dryer every oil change will prevent water from building up and causing scale rust like the

above poster had happen or just plain old water blocking the injectors.

 

[Seabronc]

I'd go with the OBD1 tester results. A flaky TPS will cause the idle to jump around because of bad input to the computer which controls the idle speed.

>-

 

[barrett86]

yah guys it was the TPS. she runs perfect now, just need to replace the ball joints, am i able to just replace the lowers or do i have to replace all of them.