Transmission Slams into gear....Making the whole Bronco Bang once. One Jolt [Archive] - FSB Forums

: Transmission Slams into gear....Making the whole Bronco Bang once. One Jolt

05-11-2009, 04:11 PM
At low speeds normally coasting in the parking lot the Transmission seems to slam into gear and bang the bronco. (Jerks/slams the bronco once) Something seems to be making it not shift correctly. Does this have anything to do with fuel pumps or filters? It almost seems as if the exaughst is also clogged up some how. The bronco just does not have the power that it should have.

I believe the exhaust and trany problem are related. This transmission only has 4000 miles on it as it was replaced under warranty by a Ford Dealership a couple of years ago. I don't drive this bronco all that often anymore. Several years ago the transmission was slamming into gear similiar to how it is today, and it would not accelerate over 55 miles per hour. It even started blowing out black smoke. I had the transmission fluid flushed and the black smoke problem went away, but it still would not accelerate past 55 MPH. The Ford dealership said I needed a new transmission when I told them it felt like the exhaust was clogged. So I got a new tranny anyways and still no fix with continued slamming of the transmission. What a waste of money. I then had the catalic converters replaced and it seemed to fix the problem temperarly. The bronco began to have power and accelerate again, but a few miles into the new tranny something happened and the transmission went out and dumped trany fluid all over the ground. I ended up having to get it towed over a 100 miles to the nearest Ford dealership who replaced the trany because the one I just bought was still under warranty. Now it is slamming into gear again with the third transmission. I was told online that it may need a new TR sensor. But wouldn't this been replaced along with the new tranny? How much does TR sensors run and do you think it is really causing the problem from what you are hearing from me? Could something be clogged the ehaust higher up? Could spark plugs be an issue? Could a faulty fuel pump cause these problems?

05-11-2009, 04:16 PM
You've got 3 threads going and 2 have issues that are common with a TPS going bad.
Test your TPS.

What is a TR sensor?

05-11-2009, 04:32 PM
i agree with sack...Although, mine was doing the same thing and it was the speed sensor.

05-11-2009, 05:05 PM
I'm assuming the TR Sensor is a Tork converotr sensor but not sure on that one.

What is a TPS? Yes it has been very frustrating lately trying to figure this all out.

Shane C.
05-11-2009, 05:31 PM
TPS = Throttle Position Sensor.

Pull codes as stated in the other thread you have going... post up what you get and we can go from there.

05-18-2009, 02:43 PM
OK I took my Bronco to the shop last week and the first thing they noticed was the Idle was high around 1400 RMPs. They put on a new idler valve and it fixed the idle. They hooked up a computer and it said my Throttle sensor was out so they changed the Throttle position sensor. The computer also said my Temp sensor was out so they changed the temperature sensor as well. I left the shop and instantly took it down the road for a test drive. It seemed to be shifting into gear without slamming or knocking, but the Temperature gauge started to rise towards hot as I gassed the accelerator. I slowed down and turned around and the Temp Gauge started to go below normal towards the cold reading. I got the bronco up to 70 MPH and the Temp gauge started to rise towards hot again. I slowed back down to a stop and it went towards the cold reading again. My father and I have owned 6 broncos and the temp gauge never moves once the car is warm. It always reads straight up in the normal position. Also the Oil Pressure gauge was reading Low. Could the computer possibly short something else out? Or is something else going out?

I drove it the very next day and the transmission starting slamming into gear again. While it is in Park I shift into Overdrive or reverse and the transmission slams into gear with a loud bang. Similar sounding when you shift it into 4X4 Low Range....except it is one loud bang instead of the "click click" you hear when shifting into Low Range. It also slams into gear in first and second gear while accelerating and it slams into second gear when slowing down. This slamming problem seemed to be fixed the day before when I test drove it out of the shop after they fixed the things mentioned above. What could cause it to start having this problem of slamming again?

Finally I got a flat tire yesterday on the front right passengers side and the tire shop didn't have time to fix the flat so they put on my spare. The tires I currently run are 33" tires and my spare tire is a 31" tire. I drove it from the tire shop back home. When doing so my ABS sensor light came on and the Speedometer started floating from current speed (say 55MPH) and then would flip to zero MPH. It did this a few times and then got stuck on zero. This morning I went back to the tire shop and had the 33" tire put back on. After a few miles of driving the speedometer came back on for a few seconds and then went to zero again. I drove it about 17 miles and it keeps flipping from zero to current speed, plus the ABS sensor light is still stuck on.

Questions Highlighted:
What is causing the transmission to slam into gear? A new Idler seemed to fix this temporarily for a day, but then the slamming came back.
Why is the Temp Gauge fluctuating so much? Would read cold until the engine warmed up and then always stayed right in the middle reading normal in the past.
Why is the Oil pressure gauge reading Low all of the sudden?
Can a different size tire on one side of the front throw off the ABS sensor? How can I reset this ABS sensor so the light goes off?
Can a different size tire on one side of the front cause the speedometer to jump erratically? How can I reset the speedometer so it will run like normal again?

05-18-2009, 06:22 PM
So I read the entire post about the PSOM maybe needing to be reset. Could this be causing some of the problems I am having? I only do a little mechanic work and I promise I read the entire post.

I even read the front page three times. I'm a little concerned however that this might not fix the problem. As mentioned above the ABS sensor did not come on until I put on the smaller 31" spare on one side when I got a flat and left the 33" on the other side. I only drove it a few miles when the speedometer started acting up and the ABS light kicked on.

Any advice would be greatly appreciated

05-18-2009, 09:54 PM
As I said truck did the same damn thing. it was a speed sensor. It is in your rear axle and tells your trans when to shift and also controls your speedometer. It is a cheap fix and 15 mins of your time. Check out this link: This will solve your issue with the speedometer jumping all over the place, and the tranny slamming into gear. Check the water pump and radiator for the temp issues.

05-18-2009, 10:11 PM
I don't feel fully confident that the speed sensor in the rear is the problem. Everything was working properly until I had the flat tire on the front.

Now that the tires are the same size on the front: Today I let the car sit for several hours while I was at work. When I went for lunch the ABS light was turned off and the speedometer was working fine again. Also the Bronco started shifting smooth again. I think the problem was the smaller front tire that was temporarily on while I was having a flat fixed. It seemed to cause a big problem.

I will let you know if these symptoms start happening again. The transmission slamming into gear, the abs light being on, and the speedometer fluttering from zero to current speed.

Also would a 1993 351 Ford Bronco have the ability to set this PSOM I am reading on other post? I believe this might be why I have been having porblems in past years.

Thinking back I only started having shifting issues in the tranny when I added the larger tires to the truck.

05-19-2009, 09:17 AM
Change the speed sensor. My truck was doing the exact same thing, as soon as you take off the tranny would slam and then shift into second way too soon. It would always slam but would shift differently, and at different shift points and sometimes it would shift fine and sometimes it would go crazy. I changed the speed sensor and it is like a brand new truck. Shifts great and consistent and feels like it has more power. I spend 15 bucks and 2 minutes, that includes getting the tools out and putting back up.
Change the speed sensor.

05-19-2009, 03:21 PM
You are right. Having a different size tire on the front will affect your temp gauge, speedometer, and tranny slamming into gear. STOP WASTING OUR TIME. If you know what is wrong with it, stop asking us for help, and don't start 3 threads. Change the sensor, or take it to the shop and waste more money (and let them break other shit for you).

By the way:
if changing the sensor does not fix the issue, follow the wires coming from the sensor. The second time I had this issue (speedometer & tranny) the wires fell across my exhaust. You can guess what the outcome was.

Di Lullo
05-19-2009, 08:10 PM
Speed sensor was the problem on my 95' when the same things happend. Like they said, don't waste anymore money and change it out. It's an easy quick fix. Hopefully that is your problem, sounds like it.

05-20-2009, 05:25 PM
[QUOTE=selms501;2056665]STOP WASTING OUR TIME. If you know what is wrong with it, stop asking us for help, and don't start 3 threads. QUOTE]

First off stop being an A$$... I started three threads for three separate issues that I did not know exactly what was going on at the time. This is a place for people to post problems, find answers, and others to give advice. So back off with the attitude.

Many of us that come to this site are trying to get solutions so the dealers and mechanics don't rip us off, and to figure out what is going on with our vehicles so we can enjoy our Broncos.

It just so happens that I had six to seven different issues going on with my bronco that I put into three separate threads. Again..don't know why some of you give off this cocky attitude.

Now for those who need and want answers. Here is what I have found out.

1. AC would not work on Max. Found that my line had broken off. Cut it and reattached and now AC works great.

2. At first my Bronco had an idle problem and the Idle was running high around 1400 RPMs without ever coming down while in Park or Neutral. The check engine light also was coming on and off. Once I shifted into gear the idle dropped, but I had problems with the car shifting and choking out when trying to accelerate. I changed the Idler valve and it started idling correctly and the choking out went away.

3 & 4. My temp sensor went out and my Throttle sensor also needed to be replaced. Changed all three above and the car started to shift properly and run at normal idle

5. After these changes where made the car started to run great except I had a fluctuation in my Temperature gauge and Oil Pressure gauge. This never happened in the past.

6 & 7. Flat tire, Speedometer stop, ABS light.
A couple of days later I got a flat tire and placed a smaller tire temporarily on the front. I don't know for certain if this messed up the speedometer, but the speedometer stopped working and the ABS light came on. The bronco then started slamming into gear again. I put the bigger tire back onto the bronco and the ABS light went off and the speedometer started working, and it shifted properly again for only a day. It then stopped working again the very next day and the ABS light came back on plus the hard shifting came back. So I took the advice from this site and went and bought a speed sensor. The speed sensor made the speedometer to start working again and the ABS light went off.

5. replaced the Temperature gauge and the fluctuation of gauges stopped.
Note: I also changed the "Temperature Sender" Now my temp gauge reads more accurate.

Everything seems to be ok as of today.

Last thing I need to complete is programming my PSOM for the large 33" tires I have on the vehicle. Any help would be appriciated.

05-20-2009, 06:45 PM
Just got back after test driving the bronco on the Highway and the speedometer is working and the ABS light went off and the tranny is shifting smooth again.

Question: Now the speedometer seems to be working great until I get the Bronco's speed up around 70 MPH. Once i reach this speed the needle starts floating between 70 & 75. Is there another part that effect this speedometer fluttering? Has any one else had this issue? If the speed sensor controls the shifting....wouldn't this fluttering cause problems later down the road?

Note: I also changed the "Temperature Sender" Now my temp gauge reads more accurate.