2WD Expy 4.6-Slow Acceleration

[BattleRat]

Yea. I was thinking its the TPS as well. Lets see if stamp as anything to say.

Also! Happy 4th of July guys!


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[stamp11127]

Stamp hasn't been paying attention...been on the sidelines of a forum soap opera. I'll look into it...

Just for sheets and giggles:
1) how many rpms is it turning at 65mph? making sure it is in OD
2) then go wot for 3-5 sec, does it down shift?

This next one is an option
3) if it doesn't downshift to drive, foot off gas, over drive button off - (should downshift and increase rpm @500), back on the gas a little to check acceleration

BattleRat send me your email address for info on the tps

This is just one of the refs:
While opening and closing the throttle, is there a change in the TP PID (TP V PID) between 9.85% and 93% (0.49 and 4.65 volts)?

There's quite a bunch of things to check on this.

 

[JUST4FUN]

Thanks for looking stamp ,hopefully the soap has gone belly up

 

[BattleRat]

1) At 65mph its turning right around 1,600

2) it does not down shift

3) when i hit the overdrive off button, it downshifts, car slows down, and rpms jump up 100 or so


The tps at closed is 19.22 and open at 93.33. Seems like the closed one is too high


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[stamp11127]

If I'm understanding correctly, the trans is not down shifting from OD at WOT. If so try other speeds once it is in OD to see if you can get it to down shift.

How is the acceleration with OD off?

 

[BattleRat]

Wait, you wanted me to go to 65mph with overdrive on, and then go to WOT right away for 3-5 seconds, am I correct? I think I misunderstood that part. Sorry!

 

[stamp11127]

Yes, if it downshifted at that point it tells you that the trans is working correctly and that you're not stuck in OD. If you were stuck in OD it would accelerate slower.

 

[BattleRat]

Hey sorry about this.

Yes, it does shift, and the RPMS jump up to 4000

When I drive it almost feels like the car isn't getting enough of something... really confused. I have already replaced a lot of things, and still not fixed.

What do you think?

 

[FordandPolaris]

My money's on plugs and coils. Unless the cylinder is missing every time, the truck will not throw a code. Old plugs can run fine at idle but still crap the bed once you put a load on the motor.


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[stamp11127]

On the engine that was installed, what was done to it prior to the install? Was it a complete rebuild or an engine that had some new parts put in to make it run?

In other words is this a fresh engine or a junkyard special?

I would get some basic readings before really diving into the problem. See the following link to check for a clogged cat or restriction in the exhaust system.

https://www.youtube.com/watch?v=d-jp1IIJVVk

 

[BattleRat]

Thanks guys!

It was a fresh engine.

I will test out the exhaust restrictions today. Might check the plugs too.


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[BattleRat]

Alright so I check the vacuum/exhaust leaks and it seems that everything is running fine. The reading was about 19in, but I will check it 1 more time to just make sure I was testing the correct vacuum part.

I did notice something about the EGR valve though, and I am not sure what it is supposed to be doing.

The little green vacuum hose that goes to the top of the valve feels like it is blowing air out, but in short little puffs. I am not sure if that hose is supposed to be doing that or if it is supposed to be a full on push of air. Or maybe its supposed to be sucking air? Im not sure.

Thanks for the replies guys! Glad you didn't forget about me!

 

[stamp11127]

Watch the video, 19 inches is low vacuum. A fresh engine should be in the mid to high 20's.

 

[BattleRat]

I watched it, but I will check it again to make sure I got the correct reading.

Any ideas on the green vacuum hose?


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[stamp11127]

If it is the one that has a 90 degree elbow at the end, it is a vacuum line.

 

[BattleRat]

Just found a vacuum leak. Going to try and fix it!


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[bedrck46]

kindly say where the leak was or post a pic it may help others

 

[BattleRat]

Of course! I was planning on doing so, but I wanted to get home first

The vacuum leak was in the back right side of the throttle body. This was because of a loose screw(no idea how I missed this the first 3 times I checked it)

What I did to find this leak was to spray brake cleaner around all the areas where there could be a gap. So I left the car on, in park, and then began to spray the brake cleaner around the throttle body. As soon as I got the the back right side of the throttle body, the car started to sound like it was going to stall for a few seconds, and then returned to normal. That is how I knew there must have been a gap there.

My Results: After fixing this issue I went ahead and reset the learned memory in the PCM, and hit the road. Right away I saw a very very big improvement in the acceleration, and power, but it was still not as good as it was before.(might be because the PCM was still in its learning mode)

My Next Steps: I am thinking of either bringing the car to a trans shop to get the trans checked out since it hasn't been looked at for 195k miles.... or taking it to the dealership, and having them scan the PCM to see if there are any issues with it(or even flash it), and maybe even go into mode 6 to check cylinders and all of that stuff.

What do you guys think? Let me know.

I had a longer write up, but my internet decided to crash and deleted the whole post, so this is my second attempt

 

[Bedrck47]

Well now that you found the problem at the throttle body what are your new vacuum readings and again kindly post a pic of the screw you found loose