A4LD in Park and Drive at the same time?

[natenkiki2004]

A while back I noticed with my 1991 Ex that if I drove it around for a bit and went to park, it sometimes wouldn't roll back/forward until I shut off the engine. I was told it was likely excess pressure not being relieved until the engine, and thus transmission pump, was shut off.


I didn't think much about it until today while I was playing with a vacuum gauge. Engine & trans are warmed up, been driving for 10-15 minutes or so. Go back to park it and I'm looking at the vacuum gauge and it reads at 15 in.Hg where it was normally idling at 16-17.

I gave it a rev to see what would happen (while still in Park) and it was difficult to rev the engine (felt like it was under a load) and it would idle at about 800RPM. I put it in Neutral and the vacuum went back up to 16-17 with around 1000RPM idle and it was then easy to rev the engine again. Back to Park, vacuum was normal and easy to rev. I then put it in Drive with my foot on the brake and the vacuum went down to 15 in.Hg with 800RPM again, curiously, the same it was in Park just moments earlier. I moved the vehicle back and fourth and then put it in Park and it idled high and then slumped down to 800RPM and 15 in.Hg.


With the evidence, the revving, vacuum and RPM, it really feels like the transmission will be intermittently in both Park and Drive at the same time. I guess my first question would be, is this related to a persistent KOEO code 57? I've disconnected my battery several times for various things and not long ago ran the KOEO test right after reconnecting the battery and driving a short distance, the code 57 is always there:
Intermittent in Park/Neutral/ Switch or Neutral Pressure switch circuit – PNP or Transmissions
I thought this was just a switch to detect backup lights and prevent the vehicle from starting when in drive (both of which work as expected). Does it do more than that?


*EDIT*
I should add that all gears work fine although I do have the cold 1-2 shift issue. Once warm, everything works. I have not checked the vacuum modulator yet or adjusted bands. The trans was rebuilt an unknown number of miles ago after a fair amount of hard parts broke apart.

 

[JK080]

The A4LD will apply the forward clutch in park if the manual linkage and valve inside the transmission is out of adjustment.

If you put the transmission in manual 2nd the land on the manual valve should be flush with the edge of the valve body. Bend the "Z" link until the valve lines up with the valve body. Also make sure the hole in the manual valve is round and not elongated.

Sometimes people adjust these out to help with delay's into reverse, so watch for that when you adjust it back.

 

[natenkiki2004]

Thank you so much for the reply James. Do you have any pictures of what needs to be done? I got this Ex to learn how to work on cars so for a lot of the repairs, I'm learning as I go.

I assume that I'll have to engage the parking brake, drop the trans pan and put it in 2nd to take a look?

Is there any harm that will take place if I wait on this fix? I would assume that if I don't rev the engine in Park that the clutches would have the same strain as idling in in Drive with the brake on at a stop light, am I correct?



Also, the Code 57 might be unrelated. I see conflicting results on websites saying it's either the neutral switch OR the octane shorting bar which was removed from my vehicle. I'll be testing shorting it again and seeing if my Code 57 goes away.

 

[JK080]

Sorry I don't have any pics of this, I am building a A4LD this week and if I remember I'll take a picture of what I am referring too. I wouldn't let it idle long in park or rev the engine much, It could scorch the clutches. Other than that you could leave it like it is.

Code 57 or 341 (on vehicles with 3 digit codes) is an informational code indicating that the octane adjust shorting bar has been removed. It was placed in the system by the manufacturer in order to provide capability for a slight adjustment of the ignition timing. If it is removed, the PCM provides about 3 degrees less timing advance under conditions where spark knock is likely to occur. This code will not cause malfunction indicator lamp illumination.

 

[natenkiki2004]

I'd be greatly appreciative if you got pictures I just went through the ATSG manual for the A4LD and couldn't find anything pertaining to adjustment of the shift lever linkage. I think I see what you're talking about in the parts diagram but it's pretty small. The shift lever has always felt 'sloppy' to me but it could be that I'm just used to a different vehicle.

Unfortunately, I've been idling it 5 minutes or so to warm it up when it's cold to overcome the sticky governor. Probably be better to do that in Neutral with the parking brake eh?

Again, I appreciate your time.

*EDIT*
Think I found what you're talking about;
http://www.explorerforum.com/forums/showthread.php?t=155599
Is that right? I haven't yet found info on how to exactly adjust it.

 

[JK080]

This is the Z link on the A4LD that I had, I have the shifter in Manual 2nd and you can see that the beginning of that first land is just about flush with the casting of the valve body.

This is the way it should look, dont get me wrong this is no high tech set up here, there is plenty of movement in the link and valve so a little movement is no big deal. You just don't want to see it sitting too deep into the bore.

I don't think this adjustment is in any manual or anything, this is something I came up with just as a reference point for dealing the some of this transmissions problems. The A4LD has always had delays into reverse problems and one trick people would do is to bend that Z link so that the valve was moving into reverse sooner, and for the most it would help... maybe.

So when the shifter is in park there is a different land on the manual valve that you can't see that can bleed oil into the forward clutch circuit and it would apply the clutch in some cases.

Just bend it back to pull the valve up to flush.

If you have to bend it to get it to line up it might have a delay into reverse.

If its set right then I would suspect some kind of a cross leak in the valve body, but this is the only thing I have seen that caused the forward clutches to be applied in park.

 

[natenkiki2004]

Thank you very much for the picture and info James.

I learned from the previous owner that the trans has been pulled twice and that it's possible as well for the linkage to not be perfect. My issue could have been going on for quite a while as it's intermittent and not easily noticed.

When the weather warms up enough, I'll drop the pan and check this linkage internally amongst other things.

Again, many thanks.

 

[natenkiki2004]

Bit of an update;

The trans has nothing to do with my vacuum level. The lines and modulator are working just fine (downshifts based on load and speed are right on, no consumption of ATF). Unplugging the vacuum line going to the trans had no effect on the amount of vacuum I have.

The KOEO code is also unrelated to the trans. Turns out, that code is mistaken on various charts. It's actually a code for a missing SPOUT/octane shorting bar connector. Sourced one and my Ex has no codes now.

The cold 1-2 shift has been largely fixed by a can of Seafoam TransTune and external spin-on filter. There's a tiny bit difference between cold and warm for the 1-2 shift but I can hop in and drive and it will shift, I don't have to force it anymore. The combination of the two have been installed for about 400 miles.





However, the drive clutch being engaged in park is still there. It only happens when the trucks warmed up, never when cold. If I pull down on the shift lever towards R it will disengage and RPM's will go back up. I don't actually have to put it into the R gear, just close.

I'm getting ready to drop the pan so I had a question or two for you James if you're still reading this

- How can I safely bend the z-link? Just get in there with a pair of pliers or do I have to actually remove it and carefully manipulate it on a vice? In other words, how forgiving is it? Would it be damaged by plier teeth?
- I'm unsure if I'm going to do a flush yet but if I do, is there any benefit/reason not to go with Mercon V? I've been eyeballing the regular Dex/Merc High Mileage from Valvoline but have thought of Merc V. Being a professional, what are your thoughts?

 

[natenkiki2004]

Dropped my pan earlier today. It had a nice dusting inside and a few small pieces. Nothing major to worry about I don't think:

https://dl.dropboxusercontent.com/u...Transmission Pan Drop/2014-06-30 19.11.50.jpg

https://dl.dropboxusercontent.com/u...Transmission Pan Drop/2014-06-30 19.12.19.jpg

But I looked at the Z-Link and the land that you mentioned looks pretty good to me. There was a little play as you said but here's pictures of the full movement:

https://dl.dropboxusercontent.com/u...Transmission Pan Drop/2014-06-30 19.39.44.jpg

https://dl.dropboxusercontent.com/u...Transmission Pan Drop/2014-06-30 19.40.00.jpg


I did re-torque the valve body bolts to 8.5 ft lbs. Some needed more tightening than others. If my Park issue still exists after I'm done with everything (still going to adjust the shift cable after replacing the seal) then I'll just live with it. I know what to look for and how to prevent it from being engaged while in Park. If that's the worst thing my trans does, I'll be pleased