I'm hoping someone can point me in the right direction here.
The car seems to shift "hard" when going between gears (it's an
automatic). Regardless of speed the car seems to "jump" into the next
gear. I had the idle speed lowered as it was "jumping" when moving
from park to drive.
I've never owned a Mustang prior to this and I've had this one for 3
weeks now. It's a nice car with the exception of this shifting issue.
Now the garage adjusted the shift indicator (little pin near the left
gasket cover) and that helped a little (it was shifting at almost 4000
RPM in overdrive).
If I drive and let go of the gas pedal it seems to shift ok. If I do
not let go of the accelerator it will shift at approximately 2800 RPM
at a low speed. I think this is still a little high but like I said I
don't know these cars.
Any suggestions as to what the problem might be.
Just in case someone asks. The idle RPM is currently near 750 now. It
was brought up to about 1000-1100 and it started to "jump" when going
from park to drive so I lowered it again. The shift indicator pin is
now set a the "line" on the pin. Should I play around with this.
Also any suggestion on what can be done to improve performance on the
car would be appreciated. I've bought a FlowMaster exhaust (not yet
installed) and a BBK Air flow kit. Are there any other "minor" changes
that can be suggested?
Bad move. Idle speed cannot be adjusted. Only set the base
idle. IAC control actual idle speed. Never screw with that
"adjustment" unless you know what you are doing with a very
good reason. It sounds like someone was covering another
problem with a false high idle.
I believe what they may have adjusted the nuetral switch.
Not likely a problem on an AOD for the problem you describe
as the AOD is not electronic.
Sounds like a bad trans throttle adjustment or worn
No. Don't touch that for now. It was slamming the hell out
of the drive train. You may have a broken engine mount if
that went on for long.
I love the sound of the Flowmaster on a healthy 'Stang. You
are probably better to spend your money on something other
than either until you get it healthy "stock" and understand
exactly what you have now.
As you say, you don't appear to know the car. No big
problem as long as you are willing to learn.
First, have you done any modification away from "stock" at
this point? You mention the BBK air flow kit which I believe
is a throttle body. Maybe not. In any case, you should
stay away from it for now and make sure it is performing
properly in it's stock form before you start modding.
The '88 year model used the AOD automatic trans. One of
it's weaknesses was the bushing for the trans throttle cable
at the throttle body connection. They tend to wear out or
break allowing the cable adjustment to get off. If you
continue to drive in this condition, the trans will be
operating with low line pressure which also controls the
shift points and quality in the AOD. This will destroy the
trans in short order. You need to get to a dealer pronto -
today - and get the new type bronze bushing for the cable
connection. It is not expensive. It is easy to install
but, the adjustment is a bit tricky especially if someone
has monkeyed with the throttle idle stop adjustment to
correct engine idle speed. The base idle speed has to be
set using a very specific procedure very carefully. Actual
engine idle speed is controlled by the IAC. If you do not
have a manual, get one now. Once that is done, the
transmission throttle cable can be adjusted. If you drive
the vehicle with low line pressure, the trans can destroy
itself within very few miles. You should not drive the car
until this problem is corrected unless you are ready to
invest in a new transmission.
Once this is done and the ECM reset, you should drive the
vehicle a couple of days to watch for any engine fault
codes. You can buy a scanner for that one very cheap or go
to the site below for a cheap way to read it along with the
codes if you have a good helper. If you have codes, post
them back here with the description.
As far as the air flow kit(s), they are pretty much useless
on an otherwise stock application. Your exhaust system will
help but, only well above normal operating speeds. The best
thing about the exhaust is the sound quality and the
illusion of more power via being louder. The best thing you
can do before you start anything is get it running right in
stock form if for no other reason than to make sure the
engine is healthy enough to be modified reliably. Many
engines that old are just plain tired just like people when
they get old. It will do it's job but, may not take well to
being leaned on without a rebuild. This may be the start of
your best-bang-for-the-buck education. You can run out of
bank account long before you get anywhere near what you want
if you are not careful.
Cheers and good luck
I also meant to mention there is a Mustang group with a
wealth of knowledge if you can tolerate the condecention,
bullshit and flaming. Once you figure out which are willing
and capable of helping and which just like to stir up the
s**t, you can learn a lot specific to your Mustang.
Thanks Lugnut. I'll bring the car into another dealer as the one I've
visited here is not helping at all.
I'll have them check the items mentioned above. The BBK unit I have is
a replacement for the stock air filter.
On Tue, 14 Aug 2007 16:01:38 -0700, "88 Mustang GT Conv."
Thanks for the info on the BBK. If the air filter is the
oiled mesh type, I am generally not in favor of them in any
mass flow system. IIRC, the 1988 Mustang was a mass flow
EFI system - not speed density. If your vehicle has a MAF
sensor in the air intake, you must be extremely careful not
to over oil the air cleaner element as it will contaminate
the MAF sensor making it inaccurate or malfunction
completely. Another aspect of these filters is that they do
tend to pass more particulate abrasives than a paper element
introducing the prospect of accelerated engine wear. The
ability to flow more air is usually accomplished while
reducing filtering efficiency. There are only a few ways to
increase air flow thru a filter. In an EFI system, the fuel
mix is controlled by the electronic sensors with the EGO
sensor having pretty much the final say. The ability to
pass more air to the engine ultimately has no effect at less
than about 80% power operation in most cases. Not to be
critical of the BBK or any other system in particular but,
most are simply eye candy and increase the sound level to
give the illusion of more power. Some even reduce actual
Lastly, if you want to give the 'Stang a big boost in around
town driving punch, a 3.73:1 rear gear will do wonders with
not too great a hit on fuel economy. This will give you a
immediately recognizeable kick. Cost to make the switch
will run around $600US including parts by a tech competent
to do the job. Do not install used gears or bearing off
eBay. This is not a driveway job for a beginner nor anyone
else who doesn't have some experience unless, of course, you
are will to pay for their experience. Done right, it is the
best performance gain for the buck in a stock vehicle. You
will also need to change the spedometer gear in the 'Stang
which is a cheap easy swap for a novice.
On Sat, 18 Aug 2007 23:03:18 -0700, Ashton Crusher
Thanks. I don't remember when they changed. The Mustang
was one of the first to switch. The speed density is less
capable of handling modifications than the mass air system.
The speed density can be updated with an overlay harness and
an ECM from a later model mass air system for a few hundred
bucks unless you can get it from a doner vehicle and don't
mind a little extra work.
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