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3.8L cuts out under load

 
nealyates5
New User
Posts: 8
Joined: 06/13
Posted: 06/26/13 11:32 AM

I'm no mechanic, so bear with me, please. Some of this may be irrelevant.

Car:
1985 LX ragtop. 3.8L with C5 a/t, p/s, & p/b. Car nicely restored at 80K about 12-15 years ago by unknown prior owner. In Connecticut. Used summers only. Now 135K. Dry stored Nov-April.

Problem: Engine starts and runs okay, but dies as soon as lever dropped into Reverse or Drive. Doesn't sputter, just shuts off as if someone threw a switch.

Historical info:Last fall, had run car for five summers without incident. One day, transmission hesitated when shifted into drive, so I checked a/t fluid, Stick read low, so I bought and added correct fluid as called for in my Bently manual. But I am pretty sure I overfilled it (at least, the cold checks indicate very high level).

For rest of season I noticed that whenever I came to a rapid stop or turned steering wheel completely left or right at idle, engine felt as if it would just die off, so used less brake or more gas to keep it running. Then, first thing every morning, after backing out of the garage (R was fine), when shifted into D, it would not upshift to 2 or 3, until I manually moved the lever around from 2 to 3 to 2 or some combination, then it would shift fine for the rest of the day (Tranny as always been very smooth, with no signs of slipping). Same thing happend every morning.

Had linkage adjusted and that seemed to cure most of the shifting poroblem, but continued to come close to stall when stopping quick or twisting wheel to parallel park. Put car away for season. Took it out in April

A month ago, after a 75 minute drive to MA, I stopped for a coffee. I backed into a roadside parking place and engine stopped dead twice in the process. I just ignored it. When I left an hour later, I was able to pull straight out of the space and head down the road. About two blocks away, I stopped for a light, and slid it into neutral to make sure engine would keep running. When I dropped lever into D to head out, engine stopped instantly. Started easily (and many times) in N or P, but as soon as I dropped into a gear, it stopped again (many times).

Finally kept it running in D and I made it to my son's house about a quarter-mile away. Let it sit for a few hours to cool down, and tried again. Started fine (many times) again and stopped (many times) as soon as I hit a gear. Finally took a late-night AAA flatbed ride home.

Since then, reading the Bently and trying to do the simple stuff first, I have changed the idle speed control motor, pcv valve, sparkplugs 4,5,& 6 (1,2,3 too hard for me to reach w/o flex rachet), plug wire set, and distributor cap and rotor. After doing this stuff, car started right up and ran great (and much smoother) in Park or Neutral, and for the first ten times of shifting into gear in my garage, it stayed running! But, suddenly, the same trouble began again (possibly because the idle dropped when engine began to warm?).

I have bought and not yet installed a fuel filter, distributor pickup, and fuel pressure regulator. A mechanic friend is stumped and wants to change the other three plugs and do a compression test before going much farther. He also speculates it might be the torque converter in the tranny and fears either engine or tranny is shot. Tranny fluid dark, but no foul odor.

Always the optimist, I tend to think any engine and transmission that runs smooth does not have a major problem and wonder if (and financially hope) that it's something hard to find but simple to fix, like a wire shorting out the ignition or the neutral switch when shifted into gear or  -- well, I'm guessing -- that's about as far as I can go with zero mechanical knowlege.

I worry that overfilling the tranny last fall, may have prompted this whole thing. The books all say the car should not be driven with it is overfilled, but not why or what happens if it is. Confused

Thanks for anyone who got through this. Any thoughts?  

Post Reply
54packman
Enthusiast
Posts: 343
Joined: 11/09
Posted: 06/26/13 01:52 PM

it almost sounds like the torque converter clutch is not releasing, does it feel like your driving a standard, and forget to push in the clutch when comming to a stop? another thing to check is the throttle body for a build up of gunk around the throttle plate, and the IAC passages, or check for a sticky EGR valve,  will also cause stalling, or rough idle, could make up a block off plate to go between the EGR valve and the intake. and see if that solves the problem  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/26/13 10:13 PM

spend a few minutes and run the voltage drop test.

this is printable...



please post results by number


1...
2...
3...
4...

~~~~~~~~~~~~~~~~~~

Voltagedroptesting


~~~~~~~~~~~~~~~~~~~

find the green squares.. grounds should be located there

1992Mustang50batterycablegrounds  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/26/13 10:14 PM

the voltage drop test is just the place to start  

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nealyates5
New User
Posts: 8
Joined: 06/13
Posted: 06/27/13 09:03 AM

I think I did this correctly.

Engine off:   13.1

Engine running, lights on, digital readouts were

1. 16.1
2.  .02
3.   0
4.   0

I replaced alternator last year.
Just got back from autoparts place to make sure I was using the meter correctly (I was). The guys made a couple of calls and reported the concensus seems to be a stuck or faulty (torque?) converter clutch. Does that make sense?  

Post Reply
nealyates5
New User
Posts: 8
Joined: 06/13
Posted: 06/27/13 09:06 AM

"Converter clutch" is what the folks down at the autoparts store said this morning.
The throttle body seems okay to me, IAC motor new, and I have not found the EGR valve yet!  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/27/13 01:21 PM

wow.. 16.1...

please verify your volt meter on another car by runing the voltage drop test on that one..

and if the readings are that high..  replace the battery in the digital volt meter first..

then RETEST on your car...

you should NOT have 16 volts on the battery.. this will COOK and ruin your battery..

you could have either dirty wiring connections..

16.1 needs a fix.. unless you are running the NON EXISTANT 16 volt alternator..

max voltage should be 14.8 .. perhaps 15.2.. but never 16.1



with that much voltage.. you are going to have serious issues with electronic devices... and perhaps the computer shutting down...

you will also.. want to verify that on test 3 and 4.. that you get some kind of reading other than 0.00...

change the meter setting to 2 volts AC .. retest 2, 3 and 4..

post numbers.. let me sit back and think about this..

you could have a bad alternator connector... or still dirty wiring at the solenoid ..  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/27/13 01:28 PM

since i cannot see your car.. which charging system do you have...

is the voltage regulator mounted on the inner fender??

or is it mounted to the back of the alternator..

????????????

diagnosing the different systems is slightly different..

alternators with 2 plugs into the side of the alternator are internally regulated.. they will have a black or grey box on the back side...

alternators that are externally regulated have several studs on the back where wires are attached..

this is an externally regulated alternator..



take a look and reply..  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/27/13 01:52 PM

Ford Alternator 7078 1G Rear

for those who read diagrams.... this is how the external regulator is wired..

Fordchargelitealtdrawing

i can describe how this works but it will take me a while to type it out..


note that  the FLD on the  alternator is connected to the F on the regulator

that the the Sta is connected to the S on the regulator..

that the A on the regulator is connected to the battery positive..

and that the I terminal on the regulator is connected to the alternator light in the cluster...

there is also a ground wire from the ground connection on the back of the alternator to the mounting foot of the voltage regulator..  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/27/13 02:09 PM

Problem: Engine starts and runs okay, but dies as soon as lever dropped into Reverse or Drive. Doesn't sputter, just shuts off as if someone threw a switch.



yes... it does sound like the TCC is staying engaged...

jack up the rear wheels...  so they are free to turn.. support the rear axle on jack stands...

start the engine .. probably with the gear shifter in neutral...
it will start in park or neutral...


with the engine at idle...     take your foot off the brake.. since the rear wheels are up in the air .. if the engine is at idle speed.. pull the gear shift from neutral to drive.. see what happens....

step on the brake..  does the engine chug to a stop???  

if the torque converter clutch is bad.. you will have that issue..

i don't recall how the TCC is wired on the transmission in that car...

does it have the 3 speed... C5  or the 4 speed A4LD.. or AOD...

how many bolts on the transmission oil pan.??

11 or 14???

11 bolts would be a C5

14 bolts would be a AOD...

its probably a C5 and those have a  spring loaded torque converter clutch thats built into the torque converter...  rarely they will fail...

there are other transmission components that can cause this stalling..

so jack up the rear tires..    

see if the rear tires spin when you drop it into drive..

see what happens when you step on the brake to slow down and stop the rear tires.. does it stall the engine???

it should not...  

Post Reply
54packman
Enthusiast
Posts: 343
Joined: 11/09
Posted: 06/27/13 05:22 PM

Try starting it in neutral, and see if the car can be driven in neutral, i did have a car once that one of the gear sets had been chewed up and locked the reverse drum, so if it was in any gear, the motor was working against the transmission, but it would drive in neutral. or when it acts up put it in neutral and see what happens..  

Post Reply
nealyates5
New User
Posts: 8
Joined: 06/13
Posted: 06/28/13 01:29 PM

I checked my volt meter on my wife's 2010 Fusion Sport, engine runing, headlights on for minimum 30 secs., and it read post-to-post a steady 14.25. I retested the LX under similar conditions andit gave me the same 16.1. I bought and installed a new voltage regulator, did the test again and with motor off, lights on, got a reading of 13.76, but it jumped around about .05 either way. Engine running with lights on gave me roughly 15.3 post-to-post but it fluctuated up and down a bit as well. Negative post to engine block was the same constant 0.02 as before regulator replacement and the post to body and block to body remained at 0 & 0.

The goods news is that the car started right up as usual, but I was able to engage reverse and drive without engine dying. This happened a few days ago after changing plug wires, rotor and cap, but after about 10 such engagementsover a minute to so, the engine began to die again as usual. It seems as if the engine begins to warm, idle drops, and then the problem starts again. I've already changed the Idle Air Controol motor. Could something else be faulty - like a fuel regulator? Could it has something to do with old transmission fluid that sticks the converter clutch after a couple of minutes warming up? That seems somewhat counterintuitive as I would think warmer fluid, as opposed to cold fluid, should be thinner and less likely to plug things up, but I am operating at the outer edge of my abilities here.

My inclination is to have someone drain and flush the tranny to see if new fluid at the proper level would help. I am contempolating driving or AAA-ing down to a transmission shop next week. Sound reasonable?

I'm trying to keep up with all the helpful comments and suggestions folks are offering, but none of this comes naturally. I have yet to read new replies today.  

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nealyates5
New User
Posts: 8
Joined: 06/13
Posted: 06/28/13 01:31 PM

Neutral is still just Neutral, and Park is still just Park. Engine runs fine in either.  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/28/13 07:05 PM

with engine running...  headlights on...

set digital volt meter to 20 volts DC...

probe the  voltage regulator terminal A... and then touch the positive battery post..

post voltage reading... at 20 volts DC scale... and change the meter setting to 2 volts DC...


more to come....

the Computer is not going to like 15 or 16 volts...  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 06/28/13 07:32 PM

lets look at the upper left corner of this diagram...

see the voltage regulator..
the yellow and white stripe wire goes from the bat positive to PIN A on the regulator.

if there is an issue with that circuit from the starter relay thru fusible link A green  thru the AMP meter when equipped  that circuit.. you will have a serious charging issue as you describe..

you can also run a JUMPER Wire... if you are careful from the positive battery post to PIN A on the regulator FOR A TEST TO see if the charging system comes back under control..  this is easy to test... by the post directly above..   battery positive to regulator pin A with the engine running..   you should have only a small fraction of a volt... if you have more than 0.04 volts when you measure there.. you have a wiring circuit issue..



0900C1528004e2a3  

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