Guru's help needed (rough idle, tranny problems)

[geosnooker2000]

Vehicle in question: 1996 X EB 4.0L auto Tranny 4X4 with 300,000 +/- miles

Last year in the spring (?) I had my tranny rebuilt by someone I now do not trust. I think he did NOT use new parts to rebuild, just bought a used one he new to be in working order, and traded out parts into my tranny housing. At first it didn't shift into OD, so he tightend up on a band, and it shifted fine after that.

Fast forward to 4 or 5 weeks ago.
It started slipping out of gear (or down-shifting, hard to tell) in 2nd or 3rd grear on medium acceleration. As the whether got colder it stopped doing it. But when it is really cold in the mornings (below 35deg F, let's say), when I start the truck and pull it down into drive and/or reverse, it takes up to 6 or 7 seconds to engage into gear. As the truck warms up, that problem goes away. However, as the truck gets hotter and hotter, or if it's a warm day out, the truck refuses to stay in OD at highway speed (say 55). Especially if I have to drive a distance that has me running it for an hour or so. When this happens, it is usually accompanied by a flashing OD light.

2 weeks ago, new problem. It starts idling very rough. So rough, in fact, that I have to pull it into N at stoplights and hold my foot on the gas, or it will die on me. If I don't (and here's where I am wondering if it's related to my transmission) it will jump between 500, and 900RPMs and the truck will surge with it. Even with my foot on the break, it will try and surge forward. Strong. About 2 days after this started happening, I dropped by AutoZone and got the codes pulled. Guess what? No Tranny codes. Here they are....

P1450
P0401
P0171
P0153

By the way. All this without a "check engine" light.

So my question is, should I start with the transmission problems, or the "running rich" problems? 'Cause it's hard for me to believe I get 4 problems in the engine compartment all within about 2 weeks. Could a transmission cause all this?

 

[geosnooker2000]

Forgot to mention. When the truck is cold, it idles fine. Strong and steady. Hope that helps anyone who can help me.

 

[dynamite196]

Autozone can't pull transmission codes, only the check engine codes, yup you guessed it, will only show problems with the engine. As far as not having a CEL light, that's most likely caused by a burnt out bulb unless you have the problem I had where some ding dong put in the wrong cluster in your truck, you can read about that here: http://www.explorerforum.com/forums/showthread.php?t=232673

Since the transmission and engine are synched so closely it is entirely possible the power and rough idling you have could cause some of the transimssion problems although I highly doubt the overdrive problem is related. I would start with the evap system, once that's straightened out I'm willing to bet the idling problem will go away too. Then go to a shop or dealer and have them pull the transmission codes for you, this shouldn't be more than half an hour of diagnostic work. So if they ask more than $40-$50 take your money somewhere else.

 

[geosnooker2000]

No being a smart-a** here, but what's an evap system? Thanks for your help.

 

[96eb96]

No being a smart-a** here, but what's an evap system? Thanks for your help.

Wow 300K miles on a 96 EB thats impressive!

First check basics on the trans like proper fluid level, make sure you do it in park after 10 min of driving. This may or may not be your issue. Delayed engagement could be low fluid, especially if very cold. What color is the fluid? is it burnt?

Evap helps pull gasoline vapors from the tank into the engine to be burned when you drive. Its a pollution thing. If something is amiss extra air can enter the engine and cause codes and terrible idle. I've seen evap lines rot away and let extra air in. If you look near the battery there is a cap with a note on it saying EVAP test port, this is where (if you know what you are doing) to start checking for leaks.

Those codes and symptoms point to a gross air leak somewhere. 401 is an EGR code, but the code is a restriction code so that may not be your air issue. (But the system must be tested, the sensor can go bad too).

The other codes simply say your system is running too lean. The P0153 may be be a bad 02 sensor, but also may be from this air problem.

Things to think about...(probably like the other poster said a pro diagnostic would solve this if you don't have skill/scan tool)

Evap Solenoid and system, check for leaks, obstructions, etc. Could be a broken or clogged connection.

There is a MAF (mass air sensor) in your airbox, at this mileage it may be diry and it *may cause* some of these codes. I would suggest cleaning it anyway.

Then naturally the lean and oxygen sensor codes will fall into place.

These engine sensors DO have a major impact on the trans, you have to straighten them out first and then do a trans diagnostic. I believe the maf has an impact on shift points.

 

[geosnooker2000]

Wow 300K miles on a 96 EB thats impressive!

First check basics on the trans like proper fluid level, make sure you do it in park after 10 min of driving. This may or may not be your issue. Delayed engagement could be low fluid, especially if very cold. What color is the fluid? is it burnt?

Evap helps pull gasoline vapors from the tank into the engine to be burned when you drive. Its a pollution thing. If something is amiss extra air can enter the engine and cause codes and terrible idle. I've seen evap lines rot away and let extra air in. If you look near the battery there is a cap with a note on it saying EVAP test port, this is where (if you know what you are doing) to start checking for leaks.

Those codes and symptoms point to a gross air leak somewhere. 401 is an EGR code, but the code is a restriction code so that may not be your air issue. (But the system must be tested, the sensor can go bad too).

The other codes simply say your system is running too lean. The P0153 may be be a bad 02 sensor, but also may be from this air problem.

Things to think about...(probably like the other poster said a pro diagnostic would solve this if you don't have skill/scan tool)

Evap Solenoid and system, check for leaks, obstructions, etc. Could be a broken or clogged connection.

There is a MAF (mass air sensor) in your airbox, at this mileage it may be diry and it *may cause* some of these codes. I would suggest cleaning it anyway.

Then naturally the lean and oxygen sensor codes will fall into place.

These engine sensors DO have a major impact on the trans, you have to straighten them out first and then do a trans diagnostic. I believe the maf has an impact on shift points.

Thanks for the detailed response! Checked the trans fluid level this afternoon, and it was way too high. I think this indicates that the filter screen may be clogged, and that may be why it is shifting funny. The fluid isn't flowing into the valves properly. It was also brown......not good. Got the filter this afternoon. Plan on doing the "full fluid change" this weekend. Does anybody know if my torque converter is going to have a handy-dandy drain plug????

I asked Santa for a new EGR valve for Christmas, and he came through for me. So I will put that on in the morning. I was also told by the local gearhead down at the Zone today that I ought to "get a piece of "T"shirt material and a coat hanger and clean the carbon build-up outta the rubber tubing attatched to it". I'm all for clean parts, so I will do it, but would anybody recomend a particular cleaner to use (i.e. carb cleaner or the like)?

This site is killer. Thanks to all who help a bro. out.

 

[geosnooker2000]

WeLLLLLLLLL. Thought I would go out in the driveway just now and pop that EGR valve off and replace it. Turns out there ain't no poppin' it off. Whom ever designed this engine compartment needs to be strung up by his thumbs. Seriously, I don't know how you 5.0L guys do it. The damn break resevour is in the DAYUM WAY!!!!! MAN I hate not having the correct tool. Channel locks are too big, and the biggest wrench I have is a 19mm. Does anybody who's changed one of these on a '96 4.0L know what size wrench I need to borrow? (The 2 mounting bolts are no problemo)

 

[geosnooker2000]

WeLLLLLLLLL. Thought I would go out in the driveway just now and pop that EGR valve off and replace it. Turns out there ain't no poppin' it off. Whom ever designed this engine compartment needs to be strung up by his thumbs. Seriously, I don't know how you 5.0L guys do it. The damn break resevour is in the DAYUM WAY!!!!! MAN I hate not having the correct tool. Channel locks are too big, and the biggest wrench I have is a 19mm. Does anybody who's changed one of these on a '96 4.0L know what size wrench I need to borrow? (The 2 mounting bolts are no problemo)

Bump I really need that wrench size if someone can help.

 

[geosnooker2000]

Bump I really need that wrench size if someone can help.

Anybody?