After driving the car in today's heat (90 degrees) I shut it off and came back about 10 minutes later. Car kept dying when I tried to start it. After I was able to give it enough gas to keep it running, it never died out and ran fine. Could it be a bad sensor like egr, O2, etc.? Does this car have an idle air control sensor? Thanks for any help.

 

Is your temp gauge look normal ? The hot weather can cause vapor lock in some systems, my z31 was kind of prone to that, if I took it for a short drive on a really hot day, it would be really hard to start afterwards. There is a heat shield between the intake and exhaust manifolds on the L28, it might be ugly, but it is really needed to keep your intake cool, if that shield is missing, or a gas line is getting to much heat it could cause your problem.

 

The temp gauge was normal (straight up, around 190-200 I think). Could that air pump that pumps air over the injectors be faulty? What is that for and when does it come on? I'm not sure where to look for the shield but here are some pics. Maybe you can spot it. Also can you tell me where the sensors are in my pics? Looks like I have two egr valves. I have no clue what is going on under the hood!

 

Some times, but not always...If it's hot, and you have experience this problem before..Before starting two things...
1: Open your gas cap and see if you hear a whoosh sound . If you do, there was a vacuum, and it needs to get some air in there...
2. Pump your gas pedal a few times with the key on, but don't start it just yet. Then start it. Your electric fuel pump will purge the lines and put fuel up to your injectors.

Also, What fuel are you running in it? Try and get non alcohol based gas...The alcohol also has a tendency to evaporate faster than the non alcohol fuels. I know, any more a person really has to search out who sells the good stuff any more.

Note: Corn alky is for drinkin, not for putting in the gas tank!!!!!!

Old Codger

 

Thanks old codger. I will try your suggestions. Also, I was reading my Haynes book and on page 118 they talk about the AAC valve. It is vacuum operated and controls the idle speed. They also mention a vacuum control modulator which directly controls the EGR and AAC valves. Could either of these parts be bad? They don't show a pic so I don't know if my 82 has them or even where they are located. Can anybody help me out?

 

Vacuum, Smackuum....Quit guessing...Get some real mechanic tools....A VACUUM GAUGE...a mechanics best friend.

Your car doesn't run right, so according the the books, it says, trade it in for something else? Nah...Find out for sure what is wrong...Guessing is just that....You'll be replacing parts till you've replace the whole car.

I don't know if it is the so called AAC valve or EGR valve, or any other valve or switch without testing it. The so called repair books might talk about such and such a part controlling this or that, but without testing for the problem.....

Well..it's like going to the Dr. and he opens you up and replaces your kidney, then your gall bladder, then your spleen, without ever testing to see if they were good or bad in the first place. Eventually throwing "stuff" against the wall, something will stick.

A vacuum gauge is just that...It's a tool for testing and diagnostic work...Helps test your car's lungs...Is it breathing like it should, or is there a hole in your lung somewhere causing a wheezing???????

It's pretty easy to tap in just about anywhere that has a vacuum line...Usually you'll get some extra "T's", for tapping into a vacuum line when you buy the gauge and some vacuum hose....If they don't come with the gauge, get some while you're at the store...There''ll be some different sizes for different size vacuum hoses.

Yes, these Z's are a vacuum plumbing nightmare. So having a vacuum gauge is pretty much a MUST HAVE for your tool box.


A person will be so proud of themselves, when they've diagnosed the problem on their own. But a person has to have the right tools to be able to do it. Vacuum gauges are not expensive...(I had to get the one with the large face on it so I could read it.) You'll know what I'm talking about when you get older and can't see anything without having your cheater glasses on.


Old Codger

 

Next:.... Must have in the tool box....

Get one of those hand held, One man operation Brake Bleeders... They can be used to either pump pressure, or suck vacuum in a line..As well as bleed your brakes. Open your fuel line and apply suction, is the gas coming thru? Lots of good things can be done with one of those hand held brake bleeders.

If a valve is supposed to open when vacuum is applied, then your trusty dusty hand held brake bleeder will come to your rescue. No more guessing is the valve good or not.

Old Codger

 

Sounds like good advice. Where is the best place to tap in to measure vacuum? Reason I ask is because if I tap in upstream I might miss a leak further downstream from the engine. Or is my logic flawed? I also have a smoke machine which is great for finding leaks. Haven't tried it on the Z yet.

 

The purpose of having is vacuum gauge is to find out what's going on....If you start out at the source of your vacuum.......X.......Y.....Z.......at X, then you know what the reading should be......Then you take a sample at the end of the route.....Z...if the vacuum is low, then you have a problem between...Then you sample at Y..That will tell you the problem is between Y and Z, or X and Y.

If you have a hose connected at X...(the vacuum source) and there are no middle connections...The vacuum ends at Z, and you have a low reading, then I would first suspect the hose...If there is a vacuum switch, then I would suspect the vacuum switch...Then is when the brake bleeder comes into play...You can use the bleeder to hand vacuum to the valve to see if it is operating.


A vacuum gauge will also tell you what's going on with your valves and timing. If you have low vacuum from the start, then that might be telling you have a valve(s) leaking or not seating properly. Might be a cylinder is low, from rings, and instead of "sucking" on the intake stroke, the suction is going right past the rings.


Most of the time, I said MOST of the time, a vacuum problem is at the end of the hose, where it stretches over the nipple of what ever the hose is connected to.

In the middle of a hose, if it leaks there, then most of the time is was because of a cut.



As far as a smoke machine????? They are good for some purposes..But In My Opinion....Testing for a vacuum leak????? There is a lot of suction going on. The smoke is going to get sucked right past the leak and continue on to the end.

Why? Because the smoke is going the direction of the vacuum. A leak is sucking outside air into the system.....What you are thinking of, is the opposite of a vacuum...Pressure would force the air out of a leak. The air is trying to escape, not be drawn in.


Old Codger

 

Well that makes sense.....except for the smoke machine which is done with the engine off. The engine is basically filled with low pressure smoke. If the smoke leaks out, that is the source of the leak. So you fix one leak and check again. Keep going until there are no leaks. The machine even comes with a bright spot light to help spot the leak. I would probably have to block off the intake at the air cleaner with a plastic bag or something. On my 1987 Buick, I can hook up my scan tool at the ALDL port and check the BLM (Block Learn Multiplier) with the engine at idle. Ideal number is 128 +- 10.....so if it reads over 138 this indicates that the computer is adding fuel to match the extra air entering the motor. Doesn't tell you where the vacuum leak is, which is where the smoke machine comes in handy. Is there a way to tap into the ECU on the Z and get this reading?

 

Well why didn't you tell me you had a smoke machine? Here all these years I've been a smoke machine myself...A cigar smoke machine...I've done the same thing using my cigar smoke blowing back thru a vacuum line...and enjoyed the cigar at the same time!!!!!!!


Old Codger

 

Ha Ha I see why you call yourself Old Codger!!!!

 

Whipper Snappers!!!!!!!! Get off my yard!!!!!


When in doubt, I'll go back to driving my 52 Olds 98. I know it works, without all these _)((&^_)(*O*^)( *)(*& contraptions..

All this air pollution control stuff...Ain't done a thing to make the feed lots around here smell any better, and driving by a Micky D, it still smells like old burnt grease..


Old Codger

 

I would never drive a car without headlight washers.....does yours look like this? 1952 Oldsmobile 98 Holiday Coupe at Fast Lane Classic Cars

 

Nope...Mine is this....

.

Now if you want to get serious about it, I'll get out my grocery getter.

.

And if the grocery getter doesn't, get it, then I'm going to up to the joint and have a drink!!!!

.


Old Codger

 

Nice rides! Do you have a pic of the Z? I ASSume you have a Z. What kind of motor is "under the hood" of your grocery getter? Any interior pics? Hey do you have a license to drive that barstool?

 

My Z is posted under,,"What am I doing Wrong"...a few posts back.

The grocery getter is a 406 Chevy. It's a drag car with head lights...No it doesn't have headlight washers!!!!!


Old Codger

 

And one very bad motorized bar stool, now drinking and driving take on a whole new meaning... and added skill !

 

And NO, it's not turbo charged

When I lived in Phoenix, we really did race them around the building.

Great on a straight run, I guarantee you'll fall over making , or trying to make sharp corners.


Old Codger

 

I replaced the coolant head temp. sensor and I think that fixed the hard start problem. Also replaced the oil sender and now I have near 75 psi on hwy and 25 psi hot idle. When I first bought the car I had 0 psi at hot idle. The oil sensor was definitely broke!