Ozz1967

iTrader: (4)

Hey guys,

I'm having problems with the cruise control on my 84 T/A. When I set it, it drops several MPH before stabilizing but that's ok...easy fix from what the Haynes Manual says, but the main problem is that it surges. once I set it, it will decelerate a few mph, then accelerate to what I set it at...then decelerate, then accelerate. It won't stay steady and I eventually wind up motion sick from it and just turn it off. Any help on this would be greatly appreciated. Thanks!

Psycho_91Camaro

My RPMS stay the same but I can hear the throttle blades open up more once in a while

82CrossFire Z28

iTrader: (1)

"The Cruise Control System uses vacuum to operate a throttle servo unit. The servo unit maintains a desired car speed by receiving a controlled amount of vacuum from the transducer unit to regulate throttle position. A speedometer cable, from the transmission drives the transducer and a second speedometer cable from the transducer drives the speedometer. {Last sentence only applies to mechanical spedo cables. I am not sure how electrical spedo units are connected,, but the operation should be the same, at least for the Cruis Control Trasducer} The cruise cnotrol transducer contains a low speed limit switch that prevents system engagment below a minimun speed, raninging between 25 and 40 mph (40 and 48 kph). The operation of the transducer unit is controlled by an engagement switch button located in the end of the directional signal lever and the off/on/resume slide switch also located in the turn signal lever. To disengage the system, two brake releases are provided. An electrical brake release switch is mounted on the brake pedal bracket (clutch pedal bracket on car equipped with manual transmission) disengages the system electrically when the brake pedal (or clutch pedal) is depressed. A vacuum release valve also mounted on the brake pedal bracket (and clutch pedal bracket), vents controlled vacuum to atmosphere when the brake (or clutch) pedal is depressed, allowing the servo unit to quickly return the throttle to idle position." 1982 Camaro Service Manual, Section 9, page 9-1

Since your caar is hunting for the setpoint speed, it sounds like you have a vacuum problem.

Step 1:
Inspect all vacuum lines for the crusie control unit, including the line going through the fire ball to the brake (and/or clutch) pedal bracket(s). There is also a vacuumm switch on the break/ clutch pedal(s). If the switch is bad it must be replaced.

Replace any lines which are found to be bad. Does this clear up the problem??? If no proceed to Step 2

Step 2:

Check the Throttle Servo Unit.....

Remove vacuum line to transducer unit (the other end of the vacuum line that has the speed adjustment nut refered to in the Haynes' manual)
Apply a 14" vacuum with a hand vacuum tester. Hold this vacuum for one minute, if it leaks down below 9" of vacuum, the servo is bad and will need to be replaced.

If the servo holds vaccum, all vacuum lines are ok and the vacuum switch(es) on the break and clutch pedal(s) are ok, the transducer unit is badand must be removed and serviced by a GM service center or replaced.

At this point, I am assuming that the electrical circuits are ok because you can engage the system and apparently adjust it. So check out the vacuum portions of the system first.

Hope this hepls

Dave

Ozz1967

iTrader: (4)

Dude...that was awsome. Thanks. I don't have a hand vacuum tester...I have one I can check vacuum with, but not sure how that would help. I'll run through my lines tomorrow to see if I can find any that are obviously bad and well...probably replace them anyway. I had no idea that there was lines from the break pedal (Mine is an automatic). The main problem will be finding the transducer. I have no idea what it looks like or where it is on the car. I can try to follow the speedo cable down, but...it gets crowded down there really quick.

For the switch on the break pedal...I don't know how I could tell if it's bad or not, other than just replacing lines and doing it through elimination.

Again, thanks for the info. Now at least I know how the system is set up so I can start to look in the right places.

Oz

82CrossFire Z28

iTrader: (1)

I will scan and post some diagrams this evening. The transducer is in the left front of the engine compartment. Should be just in front of and to the left of the window washer fluid resivor. The servo is below the transducer and tucked a little farther to the front of the car. There is a way to test the servo on the car without the vacuum pump but you have to disconnect some other items, probably easier to test it with the pump.

My is on a bad transducer, as the system is hunting for and cannot find the set point speed you set it at. I am not sure a vacuum leak would cause that type of behavior, but I could be wrong.

As for the hand vacuum tester, I may be using the incorrect name. It is a device you hook up and squeez (sp) the handle to draw a vacuum. It also has a guage to show what vacuum you have drawn.

By the way, is your engine carbed?

Dave

Ozz1967

iTrader: (4)

Yes the Engine is carbed. For some reason, they did away with the Fuel Injection completely for the 84 model Firebirds and Trans Am. I've already swapped probably 70% of the vacuum lines in the front of the motor so now it's just finding the ones I didn't know were vacuum lines or couldn't get to easily.

Ozz1967

iTrader: (4)

Ok, I don't have anything to the "left" of the windshield washer fluid...its bolted to the wheel well...but there is something to the front of the car, just inside the canister...it's got some vacuum lines coming off of it. I"ll see where that leads me.

82CrossFire Z28

iTrader: (1)

Sorry for the confusion, but LEFT when you are looking into the engine compartment from the fron left side. Take a look at the first photo attached here, Cruise_Control_001M. 002M shows the throttle servo. In 002M, on teh front of the servo is the vacuum line the goes to the transducer. It is routed around the outside (towards the fender) of the canister.004M shows the back of the transducer, with the spedo cables. Top cable goes to the speedometer, bottom cable goes to the tranny.

More photos to come

Dave

82CrossFire Z28

iTrader: (1)

OK here are some more photos. 006M is a close up of the front of the transducer. Quite a rat's nest of vacuum hoses here. 008M is a close up of the throttle servo. I have lifted the vacumm hose to the transducer up so you can see it going around the canister. This is the hose you disconnect to do the vacuum test on the servo described in my first post. 009M is a close up of the rear of the transducer. There is a vacuum hose visible at the bottomm of the photo, on the top of the wheel well, whcih is the vacuum line from the transducer to the vacuum switch on the brake and or clutch pedal(s).

Please excuse all of the dirt and grease. One of my spring time projects is to clean up the engine compartment. If you don't see the name of the photo in the attachments, just hoover your cursor over the picture.

I have not found the vacuum source for the transducer, and it may be different on your car. So I will leave that for you to trace out.

82CrossFire Z28

iTrader: (1)

Ok, one last photo. 010M shows the vacuum line from the transducer to the brake switch. I have pulled it up above the flex conduits so you can see it. It goes back to the firewall and then through it to the brake pedal. Again you will have to do some tracing as you get close to the fire wall...


Let us know how you are progressing.

Dave

coolram62

iTrader: (2)

82Crossfire Z28 those are great pictures.I had a similar problem as Ozz1967 with the cruise on my '83.I went thru the procedure checking for vacuum leaks.All the hoses were original so I replaced all of them.That alone eliminated 95% of the problem with surging.And as you know CFI motors don't like vacuum leaks.I also had to replace the brake assembly switch.The body was split and leaking.

Just a side note on the windshield washer tank.'82-'83 cars with cruise use a different one than those without.Have you noticed this?I don't know if this is true of '84 up since the cruise setup was changed somewhat.

Xophertony

good read. my CC has been surging a little bit, i always assumed that was just how it was suposed to be. i'll have to replace those vaccume lines and see whats up. i have been meaning to add one on the clutch pedal anyway. (swapped to stick, but have no clutch vaccume switch)

Ozz1967

iTrader: (4)

Ok...

I have the Throttle servo. Round thing with the slinky looking rubber boot. That's up front near the canister. I most certainly do not have the transducer that you show...at least it is not installed up on the top of the engine bay or anywhere in the front of the engine compartment that I can see from the top of the car.
It may have been moved further under the car nearer to the transmission...I don't know. Does anyone with an 84 know?

5678TA

just be happy your 84 TA has cruise control.. you try keeping a motor with weak lowend power steady at 1700 rpm in 5th..

Ozz1967

iTrader: (4)

True...true. I am thankful for what I have.

coolram62

iTrader: (2)

Ozz1967 I keep thinking that '84 is when GM went to electrical/electronic controls on the cruise control for the F-Body.There are still a few vacuum lines but the system is tied into the ECM I believe.One thing I know for certain is the '84 up stalk switch connector/wiring is different than than my '83.

Ozz1967

iTrader: (4)

Well, I can try and replace the throttle servo up in the front of the block. There is a vacuum line running to it and if it's not holding then that could cause problems. Otherwise, I just don't know. I've got a long week ahead of me so I probably won't get to it again till the weekend, but who knows. I hate working long shifts. I can't get anything done.

Ok, did some reading...unless my haynes is completely off...it doesn't say anything about an electronic nothing for the cruise. I know I have the mechanical Speedo (Or I should...unless the last owner changed it in the past and they didn't remember when I called them about it two weeks ago). From there...who knows. Maybe it'll be easier if I just take it in and see if the dealership can fix it. I hate doing that though..half the time they just say "Oh we can't get that part anymore..." which I know is a crock...it just means they dont' want to work on it.

82CrossFire Z28

iTrader: (1)

OK you have the servo. Where does the vacuum hose go???? The other end should be the transducer. I don't know if your car has a mechanical or electric speedo. I did see a suggestion in one of the other boards that an easy way to test was to have the car rolling in a parking lot, etc., with the engine running and in neutral? Shut the engine off and continue to roll. If the spedo dies when you shut the engine off you have an electric speedo. If it winds down as the car costs to a stop it is a mechanical speedo.

Do you have any pics of your engine compartment you could post, espically in the area where we though the transducer should be mounted????

My Haynes (82-92 Camaro) manual has a picture of the transducer and servo from above. It also states that the manual does not show all the possible installations and combinations due to variations from year to year.

I think as a first step you need to find where the transducer is located. It has to be there some where. Next, since you have a carbed engine I would replace ALL the vacuum lines. A leak in any one of them could be the source of your problem. Next I would get a vacuum pump and test the servo. Do you know any body else at the base who works on cars? Maybe they have one you could borrow. Or you can pick them up at any parts store, probably for $20. or less.

I hate spending money to throw parts at a car to try and fix a problem. Seems like I spend $$$$ and don't get the problem fixed. From my 1982 Camaro Factory Assembly manual the Servo is #25031120 and the transducer is #25031907. www.gmpartsdirect.com no longer finds these two numbers. Either they are discontinued or they have been replaced by another item with a different part number. Call the parts dept at you local dealer and ask what they have or can order.

You can also PM 82 IronDuke (think I have the correct) here on the board. He runs a parting out business in Santa Fe. He might be able to fix you up with both parts, used of course.

In the mean time take a deep breath and let it sit for a day or two. You can get around without the CC, but I suspect it is nice on the long trip.

Dave

82CrossFire Z28

iTrader: (1)

Coolram62 regarding the pics. Wonder what they wil look like when I get the engine compartment cleaned up I never noticed that the washer resivors were different. Guess I can look in my 82 Factory Assembly manual and see if they have different part numbers

82CrossFire Z28

iTrader: (1)

Xophertony
For the positive feed back. I am curious, are the throttle servo and transducer located where my pictures show them or somewhere else in your engine compartment???? Do you have an electric or mechanical speedo???

Would you like me to post a few diagrams from the 82 Camaro Factory Assembly manual showing the installation of the switch for a manual transmissio? I assume the installation would be about the same for a bird.
Part numbers may be different for your 88 though.

Dave

fbodyorbust

ive got an 84 z28 camaro.......same deal....i just got done putting a new carb on it.........literally yesterday.....i seem to have the vacuum hooked up right due to this web site......if you want to look at the vacuum diagram its noted in my thread called "!@#@$@ vacuum " but if the car is running fine i wouldne mess with the vacuum lines. i will take some pictures and show you how i have my vacuum line hooked up for cruise.... THERE IS NO CRUISE TRANSDUCER!! ive looked and looked and looked.....the only place it could be is drectly in front of the charcoal canister in front of the radiator behind the font clip....which is impossible to get to unless you take it off. but never the less it sounds like your system is working its just fluxuating....so dont go pulling any tubes left and right!!!!! pull them one by one and check for cracks....and dont loose where its suppose to hook back up to ....guaratee there is a dry rotted hose somewhere with a itsy bitsy crack in it.......

also there is a manifold absolute pressure sensor aka the map sensor right next to the brake booster on the firewall....there is a vacuum line that runs from that all the way across the firewall to the back or your carb....if its not hooked up hook it up....... 84 ecms are so retardedly simple that theyre retardedly hard.......one loose or messed up sensor fubars the whole system.

82CrossFire Z28

iTrader: (1)

fbodyorbust

Yes some pictures would be nice. I do have to ask thought are you sure you got ALL the vacuum lines for the cruise control

Your comment "show you how I have my vacuum line hooked up for cruise" implies you only hooked up ONE line. However there is more than one vacuum line associeted with the cruise system. Did you get the line from the vacuum switch on the brake pedal in the drivers compartment????

There also has to be a transducer some where on the car. It is the brains for the cruise control system. I don't see how the curise could work without a transducer This is not to say that it is mounted in a different location. Since you found you throttle servo, how about some pictures of the vacuum line to it all the way to the other end of the line. That should be the transducer assembly that the line is connected to

The vacuum diagram you referenced in the other thread DOES NOT show vacuum connections for the cruise control. Cruise Control is an option, K35, so not everyone ordered it. For some reason(s) GM decided to not include the curise vacuum lines on the diagrams. Neither does the vacuum diagram in my car. It appears that the vacuum source for the crusie contorl is a tap in the canister vacuum supply line. That is how it was done on the 82 cars.

So yes, post some pictures. I supsect that if you trace both the vacuum line from the brake switch and the throttle servo you will find that the both connect to the transdcuer somewhere in the engine compartment or under the dash.

Thanks for your assistance in helping to locate where the transducer is located in the 84 models.

Dave

Ozz1967

iTrader: (4)

Alright...

From the transmission, the speedometer cable connects near the rear of the transmission housing correct? I can see two lines on the left (drivers) side of the tranny. One of them is the shift cable and one goes up to the front of the car, under the brake booster, and into the firewall (this I'm assuming will be the speedo cable). I have no transducer (as you have described) in the engine compartment. It could be that they moved it into the cab under the dash somewhere? Seems unlikely but... I don't know where to go from here. My wife has the digital camera until saturday (she's out of town with relatives) so I can't get you any pictures before then.

fbodyorbust

The cruise control servo is part of the cruise control unit that by use of a vacuum line. It receives a signal from the cruise computer that tells it to control engine power and vehicle speed. It can be disengaged with a light tap of the brake pedal and generally provides optimum fuel efficiency.



When the cruise control is engaged, the actuator moves the cable connected to the pivot, which adjusts the throttle; but it also pulls on the cable that is connected to the gas pedal -- this is why your pedal moves up and down when the cruise control is engaged.

The actuator is powered by engine vacuum to open and close the throttle. These systems use a small, electronically-controlled valve to regulate the vacuum in a diaphragm. This works in a similar way to the brake booster which provides power to your brake system.

Check the the vacuum seal inside the actuator. This is right in the front of the engine compartment.........forget about finding a transducer...........

hope this helps brother

82CrossFire Z28

iTrader: (1)

See fbodyorbust's post. It sounds like the cruise control system was mondernized in the 84 model year. It souunds like there is only one vacuum line to the servo. There should also be some electrical wires to the servo to control the electric vacuum pump. He gives you some suggestions on what to check. I suspect that the service procedures I have for my 82 will not work to trouble shoot your car because the parts are different, at least for the electrical signals.

No need to worry about pictures for this. Hope you get this resolved.

fbodyorbust......

Thank you for the clarification. So they changed the cruise system in 84 and it works slightly differently than in 82. I was scratching my head wondering how they controlled the vacuum siginal to adjust the speed. Now I know. Hopefully Ozz1967 now has enough informtion to fix his problem.

Dave

Ozz1967

iTrader: (4)

Aye...

Hopefully this will do it. I am working long days right now so I get about 30 min tops each day to take a look at it before heading to work. I hate 15 hour days. That's military life for ya though! I'll concentrate on the servo. I think I have some extra vacuum line laying around from when I re-did all the other lines. It might be that simple. How do I check the seal on the servo though? Probably with that tester you told me to get... hehe Right, it's early and I just got off work. I'm going to bed. I'll take a look at this when I get up. Thanks for all the help guys!

fbodyorbust

Yea man..... the first thing i would check is to see if theres any cracks on that vacuum bell up front..........if not that theres a few connections that go to it...its very possible that theyre dry rotted............somebody should call haynes manual and tell them that there is no transducer in some damn models.......i pulled my hair out trying to figure it out.....but from what i came to all the cruise controll links to that vacuum bell.......all the electronics are behind it............of course so you cant get to it easily.......but i think those things are like 40 bucks if that.............
rock on man

Ozz1967

iTrader: (4)

I checked it over and didn't see any cracks on the vacuum bell...though it does "wheeze" when I push on it. I checked the vacuum line going to it and it "seems" ok...however where the vacuum line goes to the canister it "T's" off and goes down the fender...I can't see where that goes to. All of the rest of the lines are still supple and have no cracks though I'll probably replace them come pay-day. Any idea what the vacuum line that goes down the driver's side fender is? As I said, it's easy to see. Follow the line from the vacuum bell to the canister. Where it T's there is one that goes into the engine bay and one that goes down the fender. It's got me curious now.

fbodyorbust

i think that line t's off of a goes to the fuel tank if we are talking about the same thing........ its connected to a circular valve.......it could be possible that that valve is bad and is causing surges in tank pressure that will cause surges in fuel delivery.....if its only when cruise is activated its a very very very good chance that that valve is bad now that i think about it......that could be an easy fix.........doh.

heres a diagram

Ozz1967

iTrader: (4)

Well, we are in the same neighborhood anyway. I'll take a picture of what I am talking about to see if maybe you know what it is because I don't.

Ozz1967

iTrader: (4)

Well, I went to NAPA, and the evil Twins...Auto Zone and Advanced Auto Parts...I can get the Servo...but they want $135.00 for it. Not too bad, but too expensive for me right now. I guess I'll just have to live with it for the time being.

KITT1983

iTrader: (3)

my car is in park. my dad accidentally put the cruise control on. so i press the cruise control reset button and my cruise control surges to 7000rpm red zone . i shut it off immediately. it never did that before. my idle also went up to 1500- 2000Rpm

babadioum

I have exactly the same problem I just posted as a new topic because I couldn't find this thread earlier. So what was your problem if you have managed to successfully fix it? Was servo bad?

KITT1983

iTrader: (3)

the throttlle cable had a kink and it had vacuum leaks basically the whole unit was shot

babadioum

I have exactly the same problem I just posted as a new topic because I couldn't find this thread earlier. So what was your problem if you have managed to successfully fix it? Was servo bad?

Ozz1967

iTrader: (4)

I tore the boot on my servo during my engine swap, so I had to replace the unit. I am still getting the surging issues even now. I also have speedometer hop...where the speedo bounces. I replaced the cable from the transmission so I can guarantee for a fact, from the speedo to the transmission, there is nothing but cable. However, the speedo still bounces and it almost seems the surging is in time with the speedo bouncing though I am highly skeptical that they have anything to do with one another. So, that leaves me with the conclusion that I have to have a vaccum leak somewhere in the system that's slight enough to hold for a bit but leaks down enough, thus slowing the car down for the cruise to want to surge back up to speed.

I also believe that since the cruise is manual in nature as opposed to electronic like on my 06 Avalanche, you will have a bit of surging as the computer finds the "vaccum" or speed it's looking for. I have shipped my car to england so when I get there I will replace every line to and from the servo to see if that changes anything.

Sorry I don't have a good fix for you.

mmadden55

Try replacing all the hoses, it is cheap enough to do.

KITT1983

iTrader: (3)

i might upgrade my cruise control to this unit http://www.dakotadigital.com/index.c...prod/prd46.htm
http://www.summitracing.com/parts/DAK-CRS-2000-3/
http://www.restorationperformance.co...h--push/Detail
http://www.streetrodhq.com/detail/18...MOST_POST.html
http://www.dakotadigital.com/index.c...prod/prd57.htm_

http://www.summitracing.com/parts/DAK-SEN-01-1
the stock unit makes me want to hit it with a BFH

curtalert89

where is the cruise control located at on my 91 firebird v6? Pics would help. thanks

TranzamAidan

So, does your '84 T/A have a transducer or no?

TranzamAidan

So, if there's noting between the speedo and the tranny, does that mean there's no transducer?

Ozz1967

iTrader: (4)

Unless it's behind the dash, the only place I haven't looked, then no, I don't think it does.

Joshua Mozdzier

Ok, Hoping someone can help me, My speedo has stopped working, It is not the speedo, i have a replacement speedo and both are affected. replaced the upper cable from the cruise transducer, still won't work. I put the rear end on jack stands and can see the lower cable spinning when vehicle is in gear, so i replaced the transducer, worked for about 50 feet then stopped. so i'm guessing at this point the lower cable might not be making good contact with the lower connector on the transducer. I attempted to pick up 'an exact fit' lower cable from advance auto but it was the wrong cable. the one that says should fit my car with cruise does not have the spiral gear in the end of the cable that meets with the transducer, it only has a square shaped inner cable. Will this still work or am I just screwed?