I hate to admit defeat, but I am nearing my wits end trying to find the cause of my crazy idle which goes up and down forever. Has anyone had luck with a dealership being able to at least diagnose the problem? I know they are notorious for overcharging on the work they do, but I am willing to fork over a few extra bucks as long as its fixed properly.

Good idea? Bad idea?

 

Bump, I have the similar problem on my 91 rs especially when starting up. But I'm going to look at it more in depth next week mechanical wise

 

Please keep me posted if you determine the issue. I have replaced every sensor on the car. This is my sons first car and I wanted to be able to teach him how to fix a car, but when all you do is chase ghosts its just frustrating for both of us.

 

I kind of hate to break the news to you, but...

Your car is 3 years away from legally being an ANTIQUE in most states.

New car dealers are STORES, literally FRANCHISES like McDonalds (in fact GM INVENTED the "franchise" relationship as we know it today) that sell NEW CARS. The only reason they service them at all, is to encourage people to buy more new ones.

Most dealerships don't keep their service materials, besides what GM (or Frod or Xler or Honduh or whoever) makes available to them over the network, for more than around 7 - 10 years. Chances are, if you own a Helm manual, you have MORE information about your car, than your local dealer does.

What will happen at the dealership will be roughly like this:

You'll drive your car in there, and it'll take FOR FORKING EVER for anybody to come out and help you; while all the soccer moms in 2012 minivans that let their battery go dead or whatever get helped in front of you. Finally when you DO get helped, they will tell you they can't work on it. After you beg and plead and ... whatever else ... long enough, they'll finally agree to work on it, after you sign a paper that you agree to pay them whatever they charge (which will be, by the hour) whether they actually fix anything or not; the work order will state something to that effect, that they are under no obligation to actually FIX the car, only to WORK ON IT. They will run up several days' worth of labor charges, and replace a couple of EYE-POPPING expensive parts. They'll call you up and tell you to come pick up your car, and you'll owe them probably close to $1000; maybe more. You will get back in your car and BEFORE YOU GET ALL THE WAY OUT OF THE PARKING LOT it will do whatever you brought it in there for. You will bring it back, and they will tell you, hey we tried, we haven't seen one of these in {fill in the blank} years, the guy that worked on these retired, our computers don't go back that far, we don't have the special tools any more, yadda yadda yadda yadda until your eyes glaze over, but we're such nice guys, we'll work on it some more if you sign another blank work order.

If that's the road you want to go down, then the dealership is for YOU.

I think, between your own copy of the Helm manual, your DMM, your own knowledge, and help you can get here, you can fix your car for A TINY FRACTION of what the dealership will spend of YOUR MONEY on NOT fixing the problem.

 

I was going to say you could probably replace every sensor and electrical part under the hood for what a dealership would charge in labour just to look at it for a couple days.

 

Sofa is right,you need to find a experienced guy in a small shop who remembers how to work on them.

There are still a few in my area,luckily one is a friend I went to school with.

 

I heard the horror stories in the past, but not all of the service depts. are evil.

I just took my 07- F150 back to the dealer for AC problems, was there a year before AC compressor replaced, this time a damper actuator that opens and closes vent/defrost etc ..went bad. It was great service- have to say.

Anyway thought I would be raped -wasn't bad and I know it was fixed right.
They do call with estimated prior to doing the work, and it was reasonable so I had some other maintenance work done while truck was there.

At worst maybe they can recommend someone that specializes in your type of engine.

BTW, I hear you replaced all the sensors, but did you check injectors ?
Vacuum leak test ?

 

No; don't mean to say they're "evil"; only, that their priorities, and how they work, are appropriate to NEW cars with INFANTILE type problems (something put together wrong on the assy line type stuff). NOT restoring wore-out old hoopties like these cars.

Complete and utter FANTASY LAND. As far as the dealer is concerned, anybody besides themselves is "aftermarket BS". It's in their DNA (for good reason). If someone working at a dealership "recommended" any other shop while on the premises speaking to an actual "customer" while on the company clock, they'd be fired on the spot, right in front of the customer. Doesn't matter what dealer, or what brand of car they were the store for. Guess how I know this.

Notice anything DIFFERENT here?

There's a time and a place for dealership service depts., don't get me wrong. I have 3 brothers who have worked at them: one a service manager (Misstoobitchy), one a service writer (Buick VW Porsche Audi Saab a bunch of others), one a tech (several Chevrolet stores). They can provide a valuable, high-quality, worthwhile product. But ANTIQUE cars aren't it. That's about like taking your plastic McDonalds Happy Meal trinket to Tiffany's to get it re-sized to your 3-yr-old daughter's finger.

 

Out of stock but you can find them used and cheaper.
http://www.helminc.com/helm/product2...891&itemtype=B

 

Do you have a vacuum gauge? A DMM? A compression tester? It will be worthwhile to invest in at least the first two and rent the 3rd. Diagnose the major important internal traits of the engine. If all of that looks good. All the plugs look good, then you know it's just something with fuel/spark delivery. If you know the mechanical parts are in good condition it's a big mental relief and you'll be more willing to fix wahtever small crappy part is causing the issue.

We did this on my friend's XJ Jeep, and he spent a YEAR chasing a ton of random gremlins that he got after he pulled the engine to replace the rear main seal and take care of some other minor maintenance items. He wanted to repaint the engine and engine bay etc. So, he got it back together and it didnt run right for a year. After it was all said and done, he had the distributor one click off (a little different from ours) and he had a bad O2 sensor. Between the two of them his timing was too retarded to work well under load and the O2 sensor would ensure that it could never go into closed loop so it would run massively rich. Took him a YEAR to figure that out. The O2 sensor was new. He had to go buy a very particular brand from the dealership that the XJ Jeep guys swear by because the parts store ones do not work out of the box.

So just because you replaced everything doesnt mean the things you replaced are good. A surging idle is generally a signal in my experience that you have something a little bit off, because if anythign is seriously wrong, it's just going to run bad, not have a surging idle condition, the surging idle is the computer trying to adjust to meet some parameter that's out of spec.

And I in no way advocate this, especially for a stock car, but there's always the convert to a carb option. I think the end result is a net negative, especially fora stock engine, but if you just cannot figure out you always have that option.

 

On a car this old, quite often there is more to the problem that just the component. Hose and wire connections can decay with time and can cause issues even if the motor and every external part related to it is brand new.

You can probably figure this one out yourself, but if you have had enough, any competent repair shop should be able to find the problem. I assume this is a 305 TBI. These things are not that complicated and they are almost identical to the engine in millions of G10 plumbing vans that are very familiar to the repair trade.

 

You could also head over to Ebay and look for a Factory Service Manual for your car. The diagnostics in there are fantastic! It will literally walk you through every step to determine what is wrong with the car - no guesswork, no throwing parts at it.

 

Our shop could probably take care of it, but its a solid 4 hours away

 

I COMPLETELY disagree.

The FSM's "troubleshooting charts" make ONE very critical assumption: that there is EXACTLY ONE THING WRONG with the car, and it's going to direct you toward it.

PHENOMENAL for a brand-new car with an INFANTILE type problem, as described above; ONE thing got assembled wrong somehow on the production line, ONE thing has failed prematurely, ONE THING is wrong.

A 25-yr-old car w a quarter-million miles on it DOES NOT yield well to such techniques.

The value of the FSM for an old car, isn't in the "troubleshooting charts"; it's in the pictures of how it was built, the wiring diagrams, the descriptions of how things are SUPPOSED TO work, stuff like that. Trying to use those "troubleshooting charts" on some antique car that has no telling how much hacking on the wiring, multiple geriatric sensors, multiple things broke, will drive you just as crazy as having NO manual at all.

I'm reminded of my one little bro (late) who was the service mgr at a Buick dealer. Car comes in ON A HOOK. Little old lady about 80 yrs old, a Buick, she was like grocery shopping or something one afternoon, car was probably 5 yrs old or so at the time if memory serves. OK, think here, ON A HOOK.... that means, it was driving down the road normal as could be, then out of the clear blue, it DIES. Something failed; some ONE PART broke, and took the car down hard. Wrecker hauls it in. My late lil bro assigned it to a tech, who promptly brought back a quote for over $1000 with about 13 hrs of labor or so and a list of parts: pickup coil, ignition coil, spark plug wires, plugs, cap, rotor, set of 8 injectors, fuel pump, fuel pressure regulator, fuel pump relay, .... you get the point; that probably wasn't all that he thought he should swap, just, all I can recall ATM. My lil bro says OK, it came in ON A HOOK; means it was driving down the road JUST FINE, and something died, so, WHAT WAS IT? tech comes back with some mealy-mouth smart-a$$ reply about, FSM troubleshooting chart says replace this replace that replace the other manual says if it does this replace that it takes this many hours I won't even start troubleshooting it until they buy all this stuff you're supposed to sell it to em go do your job and I'll do mine blah blah blah blah blah blah blah. My lil bro FIRED HIM ON THE SPOT. (wasn't the first instance of arrogant dealer high-horse laziness on this particular tech's part)

Do YOU want to be the customer in that situation, in case the service mgr just doesn't happen to have the knowledge and common sense and moral compass that my li bro had?

THAT'S where those "troubleshooting charts" in the FSM take you when working on an old car.

Which, again, is NOT to say that "dealers are evil", or "FSMs are worthless", or "troubleshooting charts are bad"; only, that there are situations in which that approach WORKS, and other situations where it FAILS MISERABLY. Any car with more than about 2 tune-ups worth of miles on it, falls into the latter category.

 

I had problems having the carb adjusted on my 84 Berlinetta. The mechanic who worked on it didn't have a clue. Another before that couldn't do it either. Just told me I needed to drive it more. When I joined the local Camaro club a guy with a 67
SS RS turned me on to his mechanic. The guy had worked for a Chevy dealer from 78 to 92. He worked on tons of 3rd gens. The guy fixes every problem with my car and charges
no more than other mechanics. He does it fast. None of this, we need to keep it for a couple weeks because we don't know what we are doing. The guy works on everything even Model T's. He is truly a GEM. My point is I knew the Chevy dealer is
only gonna care about the newer Chevies. Their current mechanics no longer have the knowledge to work on our cars, but these people that have the knowledge are out there. Do a little research. You'll find someone.

 

UPDATE:
I found a local mechanic (5 miles away) who said he could give my car a try. He not only was able to fix the problem (bad fuel pump), but also put in new plugs/wires, cap and rotor and changed the oil for only $350. The local dealership wanted $425 just to change the fuel pump. The car runs great now and all it needs is a pads/rotors and calipers to make it safe for the boy to drive around.
I did my homework and got lucky. Thanks for the advice.

 

Good ending to the story at least.

Sofas rendition of old cars in dealerships is EXACTLY what I experienced over 10 yrs ago bringing a TBI 87 Van. That was coming straight from another shop that replaced a whole slew of items and...it ran the same.

No dice no refunds, nothing from either. Just a hell of a lot poorer
Found a private run shop who was a GM wiz used to teach their techs at some point. Found the problem right away that the dealership couldnt in over a week. Lousy injector and ecm.

Thank God for the web these days

 

Holy crap that guy must be fast $ 350 is dirt cheap.

Did he drop the tank or was there an access door already ?


Glad it worked out for you. Also good to know where you stand with the fuel pump - no more second guessing if thats a culprit.

 

well said

 

well in 2002 I took my 85 z over to a local Chevy dealer to find out why the ignition would short out occasionally when driving. They had one old guy there who remembered the cars and determined that it was either the capacitor or the tach filter. He was right that it was the tach filter which I never would have even guessed on my own. Problem was....nobody makes it anymore....but I got lucky, my boss had an extra one lying around...

the real answer is....go and ask if anyone there is old enough to have worked on those cars, if they have someone, see if they can look at it....otherwise move to the next shop.

 

As an ex car mechanic (7 years) and a long time car nut (I'm 43) I must disagree a bit. The troubleshooting guides will allow you to narrow down one problem AT A TIME. Once you've solved one, move on to the next. In this manner, I diagnosed a bad fuel pump AND faulty injectors, one after the other. My car is at over 200,000 miles also.

 

You had to kick the bee hive ?