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Passing Gear has my 91 brougham changing gears late and the RPMs high....

Started by AC48, August 27, 2013, 09:06:02 PM

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AC48

After a long road trip, I began having trouble once I entered normal traffic with my 1991 brougham shifting gears late.  Normally the Cadillac will shift between 13-16 miles per hour out of 1st gear. But it began shifting around 25-29mph in first gear then at 48 mph out of second gear. (Shifting hard)

After taking it to a transmission expert who verified the tranny was perfect, even upgraded to a 700r4. I began looking for what could cause the issue.  Today, I spoke with the transmission expert again and he asked me to dislocate the passing gear cable.  I did that an it changed back to normal.  Reconnected the cable, started changing late again.  So I finally disconnected the passing gear cable and the car still changed late.  As if something is stuck dealing with the passing gear cable and the thing it connects to behind the drivers headlight.  The cable seemed a little stuck when pulled on before disconnecting the passing gear the first time.

What can be done to correct this ongoing issue.  The RPM's go very high at the shifting point thru each gear. 


Walter Youshock

and the thing it connects to behind the drivers headlight.  Do you have the Shop Manual for this car?  Not sure what that "thing" you're referring to is outside of maybe the cruise control.

Did anyone reset the Throttle Valve cable from the throttle body to the trans?  Sounds as though that may be out of adjustment.
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

Dave Shepherd

If the cable is disconnected from the trans( at the trans) and you still have an issue then  the throttle valve is stuck or the linkage coming out of the trans is binding.

Walter Youshock

The trans shop should have picked up on the obvious.  Did THEY take it for a drive, or just ask you what it was doing?

Does this happen at all times, or after the car has warmed up?
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

Gene Beaird

Quote from: AC48 on August 27, 2013, 09:06:02 PM
<SNIP>As if something is stuck dealing with the passing gear cable and the thing it connects to behind the drivers headlight.  <SNIP>

Picture is worth a million words here, but I suspect what you disconnected was the cruise control cable.  Now it _could_ run between the throttle -> cruise control -> transmission control switch, but I suspect there's another cable leading down to the transmission from the throttle.  That cable does have some adjustment to it, which may have slipped, or been misdjusted.  That needs to be checked.

Gene Beaird,
1968 Calais
1979 Seville
Pearland, Texas
CLC Member No. 29873

AC48

Walt,

It first happened after the car was warm. I drove about 470 miles to SC from MD. as soon as I got off of the highway, it been shifting late.  After the car cooled down, it didn't do it again but I had already scheduled time to meet with the transmission guy first thing in the morning.  He drove the car twice to see what was going on.  Before and after putting it up on the lift.  The fluid was clear and the tranny was perfect in his opinion (700R4).  The late shifting would not happen while at his shop 8am in the morning.  But when I got back to MD getting at off of the highway to the first stop light, the it began again.  Luckily i was a few miles from home so I just cruzed it in.

The picture attched shows the passing gear cable I disconnected and the black  box in the bottom corner it connects to.

AC48

Closer pics of the cable causing all the issue....

Walter Youshock

That's the cruise control.  CC should have no bearing on how the car shifts unless you were actually using the cruise and it was malfunctioning.  Now you're saying temperature is a factor.  Have you had the car checked to see if it's displaying any trouble codes?  Pressing "OFF" and "WARMER" buttons on the climate control will display a series of numbers if there is something wrong.  Did the engine light come on when this happened?  Did your gas mileage drastically change?

You really have to get the Shop Manual.  I'll look through my copy and see if there's anything that adds up to what you describe.  Could it even be vacuum related?  Car is hot, hoses expand and begin to leak.  Car is cold, hoses are contracted, no leak?
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

AC48

No check engine light ever came on but I will run the code on it. I got great gas mileage on my trip as I averaged 28 miles to the gallon with the addition of "Sea Foam" fuel treatment.  I have never used the cruise control since I had the car. 

AC48

I do believe it could be vacuum related because I could troddle the gas peddle as if the car was in neutral while driving

Walter Youshock

If I were getting 28 mpg on my '91 and it was running as you describe, I might just leave it alone!  Best I ever got was 24.

Do you have the 5.0 or 5.7--I can't recall?
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

AC48


AC48

Walt,
I wouldn't mine leaving it the way it is if I wasn't so overconcerned that I could be damaging something else with the high RPM's.  The way it rides now, when I hit the gas...IT MOVES!!!  And I would enjoy it if there wasn't speed limits!!! Because it gets up to speed so fast now, I just know a ticket is around the corner.  After leaving first gear I am at 24-26 mph and second gear takes me pass 48mph...But these camera lights starts flashing at 30/35mph... I'm just getting started at that point on my way to high gear...  I know that "Sea Foam" fuel/oil treatment suppose to restore cars back to original performance but Damn :D!   

I will run the codes to see what it tells me, but my check engine light hasnt turn back on after I had to change the altinater out on my way back home in Wilson, NC.  Yeah that went out on me too.  Luckily I heard it stop before it burnt the belt off.  I went from Wilson, NC to MD on 1 tank and had a quarter tank after I parked it.   

Gene Beaird

Indeed, the part you disconnected is only the cruise control cable.  The black cable nearest the throttle body itself is the accelerator cable.  The other cable, with the green clip on the carburetor linkage is your transmission control cable. 

Hook the cruise control cable back up, and with the engine off, I would have someone slowly depress the accelerator inside the car to verify nothing is interfering with the operation of that TCC cable.  The picture angles are not letting me see if there is any interference between the TCC and the other cables.  You can disconnect it when you're done testing.

If the transmission 'freewheels' in gear, that is, no deceleration braking when you let off the gas, and really hits the gears hard, really sounds like the transmission may be giving up.  A misadjusted TCC cable can cause some of this, but I think the 'freewheeling' is a tell tale of trouble to come.  I hope I'm wrong. 
Gene Beaird,
1968 Calais
1979 Seville
Pearland, Texas
CLC Member No. 29873

AC48

Thanks Gene,

That's great insight on another way to troubleshoot the problem.  I will try that out when I am with my uncle, a retired mechanic.

Walt, as for the running the code, it came back as 150 and 00... I don't have a clue what either mean!

Headed back outside to reconnect the CC cable...

Walter Youshock

Nothing I could find in the manual really describes the problem you're experiencing.  I'll look up code 150, but there are other "parameters" in the self-diagnostic system.  They're called up by pressing additional buttons on the climate control head.
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

AC48

Hi Walt & Gene,
I put a little bit of the "Sea Foam" into the vacuum lines and it seemed to clear thing right up!  The car breathes better and it shifts as normal now!  So I do believe you were correct that it was a vacuum line issue. 

A co-worker informed me that it could be added into the vacuum lines before we went to lunch.  He could feel the late/hard shifting on our way out. Once we got there, I popped the hood, he added a little bit of SF to the vacuum lines then we ate lunch.  Came back to return to work and the shifted like new!  And it issue hasn't happened since.  He also told me "Sea Foam" was developed by GM.

Thank you gentlemen for assisting me in resolving this issue with your Cadillac expertise.  And I need to get a manual as soon as possible!!!!!
AC48

Walter Youshock

Great news, but I'd still try to locate the vacuum culprit before it happens again.  It may be more than one vacuum hose or connector that's bad.

The shop manual covers both '91 and '92 Broughams and has a green cover.  The '90 manual has a red cover but won't apply to you car since the '90 5.0 was the Olds 307 carbed engine.  HUGE differences right down to the climate control.
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

TJ Hopland

So since the 700 has no vacuum modulator the theory is that there was some other issue causing the engine to loose power and force you to add throttle which then made the trans act funny?

Where is the MAP sensor on this engine?  I would look for it and check the vacuum line going to it.  Sometimes its on a bracket off the valve cover and other times its on a bracket on the firewall.  Its a black box about 3' x 1 1/2 x 1/2 has 2 screws and a 3 pin plug and a single vacuum connection.   
StPaul/Mpls, MN USA

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