Please Help Me Figure Out What's Wrong With My Car

Factual Questions
#1

It’s a 93 Grand Am V6 automatic, and lately it’s been giving me trouble starting and here’s how it happens: I’ll start it after it sits all night and it starts right up, I’ll drive about 5 miles, turn it off at the grocery store and go shopping. When I come back out it will not start. The engine turns over and over, but it won’t catch.

If I leave it sitting there for about 3 hours, then it starts up with no problem. I recently spent about 260 bucks for a new control unit, and the mechanic told me he was “90 % sure” that would fix it, and it did: for about a week. Now it’s doing it again.

This has been going on for about 6 months and everytime I take it to a mechanic, they let it sit and run, and then try to start it, and it starts up for them every time. No one seems to know what this could be, so I’m asking y’all. If I have asked this before, please excuse me, but I did a search and couldn’t find the thread.

My son thinks it’s the crank sensor, but the mechanic claims the sensor is part of the control unit.

I’m at a loss (for money and ideas!). Can y’all shed so,e light on this?

Thanks!

Q

#2

For control unit, please read control module.

Thanks

Q

#3

Might it be a humidity sensor or just plain humidity?

I don’t know anything about your car or the current weather in Georgia, but I have had a problem with similar symptoms.

An old ('93 actually) Volvo which would often not start in the mornings. It’d turn, but not catch.

The car would start later in the day, but not when it was rainy.

After taking it in a number of times with the problem supposedly being ‘fixed’, we finally figured out that it was the computer and had something to do with humidity or moisture control (I don’t remember exactly now, though I could find out when my roommate wakes up). The condensation from the night was part of the problem, as was the generally wet weather.

#4

I don’t think that’s it Eonwe. It starts fine in all kinds of weather, after it sits at least three hours. I thought also it may be the fuel injector needing to “reset” itself? But I’m no mechanic…

Thanks

Q

#5

Here’s one report on dejanews of a corroded connector in the wiring harness for the crank sensor.

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&threadm=20066-3A6FC6EF-112%40storefull-117.iap.bryant.webtv.net&rnum=3&prev=/groups%3Fq%3Dgrand%2Bam%2Bv6%2Bstarting%2Bproblem%26hl%3Den%26lr%3D%26ie%3DUTF-8%26selm%3D20066-3A6FC6EF-112%40storefull-117.iap.bryant.webtv.net%26rnum%3D3

#6

Try searching www.cartalk.com. There’s a good chance you’ll find some help there.

#7

Next time try spraying a little starter fluid in the air intake, it it runs for juat an instant you will know you have a fuel problem, my guess is that you have a bad connection that the heat separates and after cooling the connection is made again.

#8

At Kragen you should be able to find a code reader for your car, if they have one for that model, which they probably do, for about $35 (one that does a lot of cars: $200). Maybe you could use that to see if the computer is outputting a code next time it happens?

#9

When my 73 Volkswagen SuperBeetle (convertible, even) did that crap, I was told it was vapor locking.

I don’t know if that’s what yours is doing, but we like to have never found somebody to fix it. This was many moons ago, but I certainly remember those symptons. Pain in the tail, huh?

#10

Well, I don’t know anything about your particular car, but it sure sounds a lot like what I recently experienced with my Honda. I wonder if your car is similar. Until someone hopefully comes along with more specific info you can consider this possibility, which couldn’t hurt.

Before I start babbling, I’ll give you a link useful for Honda main relay problems: http://autorepair.about.com/library/weekly/aa010301a.htm
It’s a pretty good resource if you want to search around that site for you particular car or type of problem.

IF your Oldsmobile is anything like my Honda, there’s a Main Relay (or something like it) in the interior of the car. The job of the main relay is to tell the fuel pump to turn on and pressurize the fuel system when you turn on the ignition, BEFORE you actually crank the engine and start the car. If you listen closely when you turn the key all the way to the point before actually starting the car, you can usually hear the fuel pump run for a couple of seconds. You should try listening for it when it’s working, that way you’ll easily recognize when it isn’t. Again, I’m sorry, but I’m not sure where you’re fuel pump is. Listen for it coming from under the hood OR from under the back seat/trunk area, if it’s an in-tank fuel pump.

What happens is that some solder joints in the Main Relay start to come loose and are greatly affected by temperature changes. When these joints don’t make good contact, they don’t send the signal to the fuel pump, and your engine won’t get fuel. Usually it’s heat that will cause most problems, so it often happens after the car has been sitting in the hot sun for a while. Most people get in their cars in the morning when it’s not hot yet, so it starts up fine then. If you’re running around with the A/C on and you stop somewhere for a few minutes, the car will usually start right back up. It’s when the interior has had a chance to get very hot that the problem typically arises. This could be why it always works when you bring it to the mechanic.

I wonder if any of this will apply to an Oldsmobile…But like I said, it can’t hurt to just try listening for the fuel pump when it works and when it doesn’t. And maybe there’s a few frustrated Honda owners these hot days. (Note my location…and I don’t want to hear it from people where it’s more hot, we’ve got humidity to deal with too. It’s like a freakin sauna these days!)
::Get’s ready to go outside to install a stereo system in his car::

#11

I guess I should have added that if this is the problem, the car will usually start up as soon as the interior temp cools down a bit. Do these symptoms sound familiar at all?

#12

Aahh…good old American cars! How my family suffered so many times by the roadside with, what we were told was the electronic module, waiting for the contacts to make contact. (Due to contraction, or expansion…I forget.) This seemed highly typical of our late-1970’s/early 1980’s model Fords.

But, we also had Pontiacs where, as we were told, the starter has a ring with a dead-space in it. (In other words, the ring isn’t complete). Some advised us to tap on the car to set up a vibration to move the ring past the dead space.

I’m not sure if latter bit of advice was true, or not…it seemed after the car sat for an indefinite period it would start up again - tapping or not…seemed like that electronic module design again.

I forget if there was an affordable cure for this, or if we had to trade in these cars. It’s a shame, too, because these were nice cars - beyond that one CRITICAL design flaw.

One footnote: Sometimes, the problem would cause the engine to die at red lights, and not restart…so it can be more serious than being stuck at the grocery store. - Jinx

#13

This sounds like a likely suspect here to me as well. I would highly suspect a fuel related component such as a relay or even the fuel pump itself. I do know that a patch of corrosion in the right spot can cause a lot of problems. Dodge had it’s problems with connections and splices over the years.

My poor mother has a similar problem with a honda accord but, I refuse to look at it since it’s a foriegn car y’see. I have reccommended a honda authorized repair shop for this problem. They too, have replaced the fuel pump in hopes it was a loss of pressure when warm or hot. She recently told me it still happens at the most inconvenient times.

I absolutely do not reccomend the starter fluid for any engine but, A quick shot of carburetor cleaner in the induction system could shed a light of whether or not it is fuel starvation. Mind you, this is a trick normally reserved for the technicians that don’t need eyebrows or other facial hair so, your at your own risk with that one.

#14

Well, when all is said and done, an engine which won’t start can always be whittled down to some failed variation of either of the following three options…

(1) A lack of spark…

(2) A lack of fuel…

(3) A lack of oxygen…

Given that Option 3 is provided by the atmosphere, you can usually rule out Option 3 and start concentrating on either a lack of spark, or a lack of fuel.

Recently, a 21 year old chap I know (who works for an automotive store chain and who designs fuel injection systems for a local racing team) well, he was having problems with a “cold start” supplemental fuel injector on his Toyota MR2. His father and I were having a glass of wine and we watched young Matthew go about his work as he wittled down his list of possibilities, and it was very impressive to watch, I must say.

He used a combination of voltage meters, electrodes, and plastic tube. He pulled out the “cold start” injector, but left the fuel line and electronics connected and positioned the injector into a plastic tube and got us to crank the engine with the distributor coil deactivated. His goal was to ascertain if the culprit injector was squirting or not. (Which it wasn’t).

Then he attaced the voltage meters to that injector’s solenoid wiring harness and got us to crank the engine again, and it was receiving the right amount of voltage in the right way. Hence, it was deduced that we were dealing with a fualty injector which needed maintenance of some sort.

Now, I’m pretty sure that I’ve related the sequence of events correctly, (we were, after all having a glass of wine) but what really impressed me is that young Matthew knew exactly the right sequence of steps, and what tools to use, to arrive at the only possible reason for his problems.

What I’m trying to get across here is that if you know someone inventive like this young 21 year old I’m talking about, I’m really sure that with a voltage meter and a good grounding in automotive electronics, you’d be able to isolate your problem without too much drama at all.

#15

Yes but, it’s the things that go BOOM and swell up in a rage of flames that we live for. Well, some of us survived our test procedures in risky environments.

#16

I really appreciate y’all coming to my rescue with your possible answers to my dillema. Unfortunately, I can’t do anything today, 'cause it’s Labor Day, but Tuesday morning I plan to take my car to the Pontiac dealership here in Dallas with the list y’all provided me with.

What’s a puzzle to me is the fact that not one of the places I took my car to in the past could even diagnose the problem and instead opted for “trial and error”, costing me beaucoups of money and getting nothing in return. I mean, the guy who “fixed” the car said himself he was only 90% sure the control module was the problem, and I accepted those odds, but it sure doesn’t obligate him to fix my car correctly for free, now does it?

Thanks again,

Quasi

#17

" but it sure doesn’t obligate him to fix my car correctly for free, now does it?"

That depends on what you asked him when you brought it in. If you asked him to put in a control module & he did, then he did the job you told him to.

#18

I had similar trouble with a leaking fuel injector. The pressurized fuel would leak into the cylinder causing a flooded condition. When the engine was cold, this extra fuel acted like a “choke” of sorts and was no problem, when it was hot, there would be too much fuel for combustion to occur.

In GM cars, if you hold the gas to the floor and crank the engine, the fuel injectors will not operate. This is by design, to cure a flooded condition. The next time it won’t start when it’s hot, try holding the gas to the floor and cranking for 15-20 seconds at a time. Be ready to release the gas immediately as soon as the engine catches.

It’s free, and worth a shot.

MC$E

#19

I had a 89 GM with the same problem.

Turns out I had leaky fuel injectors.

I agree with the people who think it is a fuel problem.

#20

Just for the heck of it did you try replacing the distributor cap? If there is even a small crack and humidity gets in it will exhibit the same symptoms. when you start the car in the morning the heat from the engine the previous night has dried up most of the water in the cap; but once you get going, it forms again. After three hours, it drieds up again from the hot engine. I say this because I have had this problem twice. and distributor caps are cheap and easy to replace. Did you do all the cheap easy things, like fuel injector cleaner in your gas tank? I’m of the school that it’s usually something simple. Of course I drive a 1991 Mazda 323.