Hello,

I am having some issues with my 2000 Ford Ranger 2.5. It is throwing codes PO731 (Gear 1 incorrect ratio) P1751(shift solenoid a) PO 401 (EGR Valve & PO 1408 (EGR Valve Circuit Failure.

I recently replaced my valve body gasket because of harsh shifting from 1st to 2nd. The gasket was blown. After I replaced the gasket my truck ran better than it ever has before (like driving a new truck). Nice and smooth shifting! That lasted a couple days

Currently things have changed to the worse. My truck is shifting hard into 2nd. Has a huge loss of power during take off and seems bogged down. Also, my overdrive light will come on after driving for a couple of miles. So, I took my truck to the transmission shop to get the codes pulled. Which are all the codes listed above.

So now I am hoping other people who may have had theses issues & can give me sum advise on what I should do. I figured I would attack the EGR issues as one and the transmission as another. I will also add that my EGR issues didn't just happen with the throttle body gasket change. This is something that has been going on way before. Any help is much appreciated. I have been at this for days now. I found tons of info on cleaning my EGR Valves and trouble shooting this system...so my main concern is the PO731 & P1751 Codes and how to deal with them. Thanks for any help!!!

 

Welcome to FTE.

Good grief, 118 reads & no replys, so I'll see if I can get things started, maybe others will chime in.

Might be helpful to know how many miles on your ride & where you are on All scheduled maintenance replacement parts, like filters, plugs, wires, fluids & any other repairs recently made. Also be sure you've posted All code Numbers you have, as they can offer up good trouble shooting clues.

All that said, the EGR code P0401 insufficient EGR flow detected, usually means the problem is with one of the system controls & the DPFE sensor, its interconnecting lines & a clogged up feedback oriface below the EGR valve, or clogged up line that connects it to the DPFE sensor, belong up there on your suspect list.
If the engine has been using a good bit of oil, move the feedback oriface & clogged up connecting tubing up to second place on the suspect list. Third place is the EVR/vacuum switching valve & its connecting vacuum lines to the EGR valve diaphragm. The EVR is known to leak control vacuum to the EGR diaphragm & cause wimpy EGR feedback & we can do a blow back test to test it.
The EGR vlave itself is robust & is usually ok, unless its damaged, rusted & falling apart, has a leaking diaphragm, or is clogged up inside with carbon from an oil burning engine.

I'm not a tranny guy & probably know just enough to be dangerous, but good idea to have the tranny trouble codes pulled & posted.
If it shifted ok for a while after the valve body gasket replacement, before acting out again, one has to ask if you used the specified Bonded valve body gasket on the repair & torqued the fastners to spec in the specified sequence????

What kind of service has the tranny fluid & filter had over its life & what kind of condition was the fluid in & what kind & level of deposits were found in the pan & valve body when you replaced the gasket????
Also, are the tranny codes you posted the ones Before the repair, or after???

 

Thanks for your response! I greatly appreciate your advise!!!

Ok, here it goes. I've kept up on all my fluid changes, spark plugs, wires...etc.

Recent things I have done to the truck (142,000 miles): 1000 miles ago, I replaced the steering column shifter tube, new fuel pump, new egr valve.

500 miles ago: Dropped throttle body, changed throttle body gaskets, new transmission filter and fluid. Ran great for about 500 miles. Now I'm getting transmission codes: PO731 (Gear 1 incorrect gear ratio) & P1751 (shift solenoid a performance) I also changed out the bulbs in my dash.

Going back to the throttle body gaskets, I purchased them from the ford dealership, and also followed the torq specs:

Here is the video I followed if this may help anyone else:
As far as the tranny fluid: I've had the truck for about 5 years and have never had it changed. Not sure if it was done before I bought the truck. The fluid I changed was very clean. There was no metal shavings or big particles of any kind. Just a little darkness by the magnet when cleaning the pan. All the codes that came up came up after the fluid change. I'm not sure if they had come up before that or not? Like I said, the truck was running great for about 500 miles...shifting nice and smooth.

Now the O/D pops on after about a mile. During take off the truck almost feels like it is in 2nd gear because of the lack of power and its shifting hard into 2nd. I'm hoping I can just change out the solenoid and see if that fixes the issue, as well as the other transmission code.

As far as the EGR stuff goes. I've been cleaning it up today. I'm thinking you 're right about the DPFE sensor. So I'm gonna research how to test it and go from there.

Again, thank you for your insight! You have been very helpful!

 

OK, good feedback on vehicle repair, maintenance history & parts replacement. If you got the valve body gasket from the Dealer you likely got the bonded gasket & thats good. Forgot to ask if you had used Mercon V tranny fluid in it, but if it was shifting ok for 500 miles you likely used the correct fluid. Good that deposits & fluid looked ok.

Since the tranny shift tube has been messed with, are you certain its still hooked up & aligned properly at the TRS on the side of the tranny, because if something has come loose & its off on alignment, it'll confuse the computer about what gear the tranny is in & that can cause it to mess up shifting. I've visited the site you posted a link to & watched a number of his videos over time & most are fairly well done.

If everything checks out ok on the shift tube & TRS but it still acts out, you might try disconnecting the battery B- cable to wipe all trouble codes, then drive it until it acts out again & the OD light blinks to let you know the tranny computer has stored trouble codes again, then let the tranny shop pull the codes once more & post All code numbers, in case you have different numbers.

On the EGR system, there are simple tests we can do to check the vacuum lines, diaphragms & the vacuum switching valve/EVR. The DPFE sensor is by far the most common problem part, so it probably still belongs at, or close to the top of your suspect list. Keep us posted on your trouble shoot.

 

I don't know much about transmissions, other than when I'm over my head.
But my service manual says "All hydraulic functions are directed by electronic solenoids to control: engagement feel, shift feel, shift scheduling, timing of the 3=2 torque demand and kickdown shifts."
So I would suspect the electronic solenoids, check the connection first

 

Thanks guys for your help! So an update. I cleaned my throttle body and EGR System up today, along with a new DPFE Sensor. I also unhooked my positive battery cable for about 15 mins. Then hooked the battery back up and took her for a spin.

My truck ended up running great! She went back to smooth shifting, and seemed to get all her 4 banger power back during take off. I took her for a spin around town for about 35-40 mins and she was loving it. So I kept showing her around town, to see if the Over Drive light would come back on. As I began to get excited, thinking that the problem was fixed and perhaps unhooking the battery could have cleared sum old codes...it happened

My truck began to lose her power on take off and started shifting hard into second...then came the Over Drive light shortly after. Guess she wasn't liking the part of town I was going thru, and started giving me attitude again.

So Saturday I will be jacking her up and dropping the pan again. I ordered a new solenoid, so hopefully this will take care of the problem.

In any case, I appreciate everyones feedback! So far it has been very helpful and seems to be pushing me into the right direction!!!

 

Seriously consider having the tranny codes pulled again before you dig in on the tranny.

 

Gotha! I will do that 1st thing tomorrow morning. Thank you

 

So I went and got my codes pulled again today. PO731 (Gear 1 incorrect ratio) P1751(shift solenoid a) & PO 401 (EGR Valve) all came up, but at least one of the codes dropped.

It's funny, I went to another transmission place to get these codes pulled today and you could tell they were honest compared to the 1st place I went too.

The 1st place, "You def need a new transmission!!!!" The 2nd place, "All we have to do is switch out your solenoid and you should be good to go!"

So words of advise so far..."Don't trust a 1st opinion." People are always out there trying to pull a fast one on you. So spend the time searching around to find someone you feel comfortable with. It could end up saving you $1000's of dollars in unneeded repairs! However, I guess this is the whole purpose of this forum. I''l keep things updated so if anyone else ends up having this issue, hopefully it will help them out.

 

Solution: Cleaned out the EGR System and replaced the solenoid. Everything runs great now!

 

OK, good find, fix, feedback & to hear the second opinion gararge steered you right on the solenoid replacement, all seems well & your on the road again!!!!