Good thread.

I think I'll replace mine also, as it is displaying the same symptoms as you guy's trucks.
Slight uneven idle, shifting with various degrees of hardness, etc.

Thanks,

Rob

 

put map on did`nt seem to help much but i haven`t driven it much

 

That is to bad. It certainly did the trick for me.

Missing while idling or under load and hard 1st to 2nd shifts. Is your engine running any hotter?

Missing tends to indicate plugs, rotor, cap, coil, etc. Did you check those? I once had a bad plug but assumed it was good because they were only about three weeks old. I spent a lot of time looking and some money until I ran out of options, checked the new plugs and found that one had lost the point, and I was having harder shifts then as well. It can also be caused by the MAP or anything else that could alter the timing. Have you checked the timing?

Shifting hard can be the MAP, TPS, IAC, speed sensor, vaccum leak, low fluid, etc, but I would think that the engine performace is what is causing the harder shifts.

I will have to think some more on this.

Have you tried pulling any codes as was suggested by one of the others?

 

i just bought the truck he told me he had changed plugs`wires but i thinck i`m going to check them and the timing the moter was replced 18000 ago the trans is brand new he said it probaly didn`t have 500 miles on it it has the radiater is also new with new trans cooler on ithe said it started that miss right after replacing transchanged computer said that was what was wrong with trans in first place i`ll keep trying thank you very much.

 

where is the tps located

 

The TPS is the throttle position sensor and it is located under the air intake. You need to remove the two large air hoses and then remove the throttle body. It is mounted on the underside of that. It is a fairly easy job. While you have the throttle body off you should give it a good cleaning and make certain that there is no debrise keeping the butter fly open or sticking.

The TPS is basically like a potentiometer or dimmer switch on your lights.

If the TPS is not working properly then the computer does not know where the throttle position is and therefore can run at an uneven idle or high idle, cause the engine to race, as well as causing the tranmission to shift abnormally, but in my experience is does not produce the feeling of missing.

 

thank you ijust don`t know what to try next

 

If you haven't done anything since the MAP then start with the basics. Replace your cap, rotor, wires and plugs. I would also do the air filter and PCV while you are at it. This should have been done before the MAP because for the cost of a new MAP your could have purchased the rotor, cap, wires and plugs and they could have solved your problem. Always start with the basics before you start looking at the controls and sensors.

Replace your plugs and wires one at a time so you do not get them mixed up. If you do not already have one some type of a shop manual will be a big help such as a Haynes catologue.

They have newer designs of plugs that do not reguire gapping and give better performance. I have a set of Bosh like this and they made a difference.

Once you change the above items and if the problem still exists then look into your vaccum lines. They can look good but be cracked after several years under the hood. I have found a few of mine that were not leaking but after years of exposure to the heat they had kind of metled shut, so there was no obvious leak, but the vaccum was not making it through the line. They tend to become brittle also. Again do them one at a time so you do not get mixed up. I like taking photos with my digital camera so if I forget where they went I have pictures.

If you still have the problem this is when your start looking at the more exotic items such as your TPS, IAC, MAP, coolant temp sensor, etc.

Try the basics first that I have listed. You may be able to resolve your problem without needing to look into these controls and sensors.

 

Just rereading some of your previous posts....

You said that the previous owner said it started missing right after he replaced what? This is what you wrote but I do not undrstand...

"he said it started that miss right after replacing transchanged computer said that was what was wrong with trans in first place."

I understand that the transmission was replaced and the engine was rebuilt 18000 miles ago. What else did he also replace? If the missing started right after he replaced something and it was running fine before that that could be your next area to go to after checking the basic items that I listed.

Do you know the previous owner? Can you trust what he tells you? I am wondering if he screwed something up and then got rid of the truck. I just wonder why someone would rebuild a motor 18000 miles ago, then install a "new" transmission and then sell it 500 miles later.

 

it has new plugs wires cap and rotor but still same itacts like it`s not getting fuel but you can open it wide open and it taker off fine or steady highway speedit runs good tell it pulls down a bit then it starts to jerk then you canfloor it and takes off good again i had a1993 f-250 with dual tank it acts like it did when one tank was running out of fuel. thanks

 

Mine was doing the same type thing. Take the vac line off of your fuel pressure regulator, if it drips gas, or smells like gas, this could be your problem. You could also take off your IAC and clean it with some carb cleaner blow it out with an air hose. This worked for me. I had a couple of vac lines that were old and brittle, it replaced them, all is back to good now.

 

The problem that you are describing sounds different from what you initially indicated. It does not sound so much like a missing problem now. Is it still shifting hard from 1st to 2nd?

I like the previous poster's suggestion, I was also starting to wonder about fuel pressure or fuel delivery problems. Give his idea a shot and check your vaccum lines.

 

could you describe where the fuel pressure reg. is located thanks

 

it is on the drivers side towards the back of the engine on top. It should have a vac line directly on top. It is a small round metal part usually a gold or silver color.

 

thank you i will try this today