Post Reply 
 
Thread Rating:
  • 1 Votes - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
1990 Merc Grand Marquis
03-20-2011, 04:12 PM
Post: #11
RE: 1990 Merc Grand Marquis
Hot rodding days?Rolleyes

The last car I "built" was about 10 years ago for someone else. The last car I modified for myself was near 30 years ago! This is why I said "normal" shift points instead of maixmum shift points.... which brings to mind.... if you really push hard will it stay in 3rd gear for any amount of time or does it still jump right past into high / lock up? IOW, a kick down at say 75 mph should only go to 3rd and not 2nd gear. You may need to use a scan tool or tach and watch the rpm to make sure.
Find all posts by this user
Quote this message in a reply
03-20-2011, 11:49 PM
Post: #12
RE: 1990 Merc Grand Marquis
Sorry, but I don't have access to any of the technical information, pressures, or settings anymore. What I provide has to come from memory and what I can find on random web pages. I Emailed the guy that would have all of the answers but he never got back to me. If I can find any new information I'll be sure to post it.

Thanks for using the forum,
Garner

Interested in Mining? Look here: Coal Mining, PA
Visit this user's website Find all posts by this user
Quote this message in a reply
03-21-2011, 09:52 AM
Post: #13
RE: 1990 Merc Grand Marquis
Ok some new information Smile

No matter what I do, I can not get this thing to go into 3rd gear. When the engine is cold or hot, it's still the same. If I go easy it shifts like this in normal OD, easy acceleration: 1st, shifts into 2nd at 10 mph, and straight into OD at about 20-25 mph, and locks in. If I start out in regular D, then it does the same thing except it goes into 4th, and still seems to "lock in". The only difference is that, after I reach a cruising speed above 35 mph, it has a little more power in 4th, probably because of the higher rpm's, making it easier to pick up speed and hold it. Under heavy acceleration, it acts the same way except the speeds it shifts at are different, which would be normal: 1st, shifts into 2nd at 20mph, and into OD at about 35mph. I did notice while driving that in order for me to get into passing gear, I really have to hammer the throttle. At 60 mph in OD, it seems as though there is not enough power to hold. It does fine on a straight road, but as soon as I get to a little uphill grade, it wants to buck and shake. In order for it to kickdown, I either have to hammer the throttle, which puts it into 2nd, or move the gear shifter to D, and it goes into D, giving me enough power to climb the grade. In OD at 75mph, it seems to hold on the highway pretty good, again, probably because of the higher rpm's. If I try to kickdown, it goes to 2nd. At 90mph, passing gear is 4th gear. I tried both ways, hammering the throttle, and moving the shifter, it's the same. I'm just glad there were no tickets involved in this test. Tongue So that's all for now. I have to get ready for work so I'll check the forum after. Hopefully I gave enough information. If anyone thinks I forgot to try something, please post it and I will do it. My wife HATES driving my truck, but I hate her driving it even more HA HA. Thanks for all your help.
Find all posts by this user
Quote this message in a reply
03-21-2011, 12:08 PM
Post: #14
RE: 1990 Merc Grand Marquis
OK, I had to read this several times and really think about this. You said that you can pull the shifter into Drive & it goes into Drive. If that is really happening then you aren't missing 3rd gear as 3rd is drive. This is all very confusing since I can't drive the car. You mentioned that you took it to a place in Pittsburgh. I'm half tempted to drive there so I can test the car myself. I am only an hour and a half away from Pittsburgh. Just the other side of Punxsutawney from you.

Here's something different to try. Find a place that you can drive without to many other vehicles around. Get up to about 50 and be sure that you are in O.D. Now pull the shifter down to "D" and pay close attention to the "Feel" of things and the engine rpm's. Does it act and feel like you are in 3rd? Will it pull the car up a hill or does it slip? Now pull the shifter down to "2nd" and again check everything. Did it drop a gear, still will pull, etc.? You should be going quite a lot slower now and do it again. Pull it down into 1st and note everything again. If you can unplug the torque lock up wire before doing this test it would be even better. That way you don't have to guess if the torque is coming on or not. Another item that helps with these tests is a tach. Is your car equipped with one?

Let us know what you find.

Thanks for using the forum,
Garner

Interested in Mining? Look here: Coal Mining, PA
Visit this user's website Find all posts by this user
Quote this message in a reply
03-22-2011, 07:10 PM
Post: #15
RE: 1990 Merc Grand Marquis
Awesome, thanks for the info Garner. Sorry I missed a day yesterday. I had to work 16 hour shift and all I wanted to do after I got home was sleep.

This is exactly what I mean when I say I know nothing of transmissions. If what you say is the case, then My car is shifting way too soon. Too soon, in fact, that the rpm is too low to hold in that specific gear. But since you seem to know more than I do in this area, let me ask you this: Even if this were the case, would the car not shift into a lower gear automatically? I have no idea how it would work. It may be a TC problem? If the tranny is in good health, why would there even be an issue, and what would cause this problem? There is enough power in 1st, and 2nd to get up to speed, maybe 3rd kicks in way too soon, making me think it's skipping that gear, and going into 4th, and then the next shift above, is making me think it's going into overdrive, when in fact its just the TC locking? I think I kind of get it now. So now that we figured that out (Or you did) Then why would it shift so soon, and why would it buck and shake instead of downshift? Maybe it's out of adjustment, AND maybe the TC is messed up somehow? I have no idea.

Does anyone know what would cause this? I think for the next few hours I am gonna spend some time on Google to see if someone else is having these symptoms, and read those forums. It seems as thought every time I try to look up my car I get all the Mustang forums. I know they used this setup on the Mustang and a few other cars and trucks, and reading about those can help also, but not all 5.0 302's with the AOD tranny had the same setup.

So now I think we are getting somewhere. Thanks for all the help. I'll see what I find and get back ASAP. Thanks again
Find all posts by this user
Quote this message in a reply
03-22-2011, 09:43 PM (This post was last modified: 03-22-2011 10:00 PM by Garner.)
Post: #16
RE: 1990 Merc Grand Marquis
Well, as I mentioned earlier, I can only go on memory from several years ago & the AOD wasn't "my" specialty. As a general rule a mechanical transmission determines shift points from "mechanical" inputs. Most have a TV cable, vacuum modulator, and a governor. The governor is inside of the transmission so lets look at the other two. The cable lets the transmission know where the throttle is. If it is stretched or out of adjustment your shift points will be off. This could be one problem? If it has a vacuum modulator you first need to make sure that vacuum is reaching the modulator as this is what tells the transmission about the load that the engine is under. While the line is off you can look into the spout that the vacuum line slides over. If you see a screw head it is an adjustable modulator. If you have good vacuum and the TV cable is properly adjusted, try turning the screw one turn In to see what happens.
The governor is internal. It has weights that spin out against spring tension to tell the transmission how fast things are turning. These can gum up & stick causing poor shift points.
I really don't think that you have a torque converter problem. What usually happens with them is they stick on. When you come to a stop the engine stalls because it's like stopping a standard without pushing in the clutch. If there is a way to unplug it for testing, that is what I would do.
Here are a few things to look at. Anything that isn't adjusted properly will cause erratic shifting.

Throttle Valve Adjustment

Throttle Valve Adjustment Video

Just curious. You mentioned taking it to 3 shops. What kind of tests did they preform before telling you that it was OK? That one really bothers me since it obviously isn't OK. I have seen plugged fuel filters, air filters, and poorly tuned engines make it seem as though there is a transmission problem. But you said that the engine is fine. Even if it was the engine, why didn't those shops tell you that you needed engine work? Also, you mentioned that it was a new transmission. What kind of warranty did it come with? Is it still under warranty?

Thanks for using the forum,
Garner

Interested in Mining? Look here: Coal Mining, PA
Visit this user's website Find all posts by this user
Quote this message in a reply
03-22-2011, 10:01 PM
Post: #17
RE: 1990 Merc Grand Marquis
Just to add something on top of Garner's sugegstions...

If the vac hoses to the vac modulator are dry rotted (hey, over 20 years old) then it would act like you have low vac(high shift points and soft shifting) but if you pull that vac hose off at the modulator and there's ATF dripping out there's your clue! See, fluid on both sides of the diaphram (because it has a hole in it) will keep the modulator from responding properly and this is a common problem. This may also explain why you need to "mash" the gas for a down shift. Basically the trany may be confused because the throttle cable says one thing but the modulator says another.... but the kick-down over rides both when push comes to shove.
Find all posts by this user
Quote this message in a reply
03-29-2011, 10:06 AM
Post: #18
RE: 1990 Merc Grand Marquis
Sorry I haven't been on in a while. Work keeping me busy. I haven't had time to run any more tests, but I will this weekend. I really do appreciate all the help and knowledge from you all. Will talk later.


http://www.speedtest.net/result/1225946688.png
Find all posts by this user
Quote this message in a reply
Post Reply 


Forum Jump:


User(s) browsing this thread: 1 Guest(s)