Mechanics

SOMETIMES WON'T START OR DIES SHORTLY AFTER ST

1997 Audi A4

Computer problem
1997 Audi A4 6 cyl All Wheel Drive Automatic 75000 miles

I have been having a problem with my car not wanting to start or dying shortly after start.I think this problem may be from a recent jump start I received after my car battery had been dead for a few days at the airport during a trip I took out of town. A interior light had been left on. My mechanic said he doesn't think that could mess up the computer, as long as it was performed correctly, but after reading up on the subject I am finding that it doesn't take much of a power surge to affect your computer.
Do these symptoms seem like it could be that of a faulty fuel injection computer? When I took it to the mechanic, they couldn't find anything wrong with the car and it started and ran every time.
There are a few things that I think it could be, but I'm sure.
Another thing is that I recently had the timing belt, water pump, roller tensioner, and thermostat replaced. The car ran fine up untill the jump start a few weeks later, so I doubt it has anything to do with the timing belt work.
When the car is running, it runs fine, no hesitation or other issues. The car always starts after acting up eventually, sometimes the battery dies from trying to turn it over so much, but after a jump it starts back up. The gas is good and I even used octane booster and fuel injection cleaner in the last tank and it didn't help.
Could this be an alternator issue? I know that they usually just doe and don't go in and out like this, but it has happened before in another car of mine that was in and out of the shop a few times before the correct problem was fixed.
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Chadfsr
August 23, 2008.




Get the battery and alternator load tested and also have the electrical system checked out for short circuits that may be eating up the battery.

Rasmataz
Aug 23, 2008.
I have been having a problem with my car not wanting to start or dying shortly after start.

This issue can be a fuel or spark problem-In my book fuel comes before ignition-What I want done is have your mechanic actually check the fuel pressure with a fuel pressure gauge designed for your fuel system with and w/o the pressure regulator and report back with those readings for evaluation. If it checks out have them Scope the ignition system for irregularities.

Stalling: Sensors such as the cam and crank sensors signals if the computer don't see it-it will not fire the coil and provide injector pulses. And Idle Air Control Valve not targetting the idle speed and an EGR valve that's cracked open will lean out the air/fuel mix causing it to stall to include the MAF sensor.

Refusing to start at times could be the coolant temperature sensor is out of range and computer not adjusting fuel as needed during initial cold starts.

Fuel Injection Stalling Problems

On fuel injected engines, stalling can be caused by anything that upsets the air/fuel mixture. This includes vacuum leaks or unmetered air entering the intake manifold downstream of the airflow sensor, a faulty throttle position, MAP or oxygen sensor, dirty fuel injectors, or low fuel pressure to the injectors (weak fuel pump, faulty fuel pressure regulator or restricted fuel filter). Like older carbureted engines, a defective thermostat may be preventing the engine from warming up quickly or reaching normal operating temperature. Or, a defective coolant sensor may be telling the PCM the engine is colder (or warmer) than it really is. Any of these conditions can upset the fuel calibration of the engine and cause a problem.

Idle Speed Control Circuit

One of the most common causes of stalling on fuel injected engines is the idle air control (IAC) solenoid or idle speed control (ISC) motor. If the idle speed control device fails to provide the correct idle speed, the engine may die when you slow down or come to a stop. In many cases, the idle control solenoid or motor is gummed up with carbon and fuel varnish deposits. Cleaning the idle port in the throttle body, and the IAC or ISC valve with aerosol throttle cleaner can often solve the stalling problem. If the situation is not improved after cleaning, however, the IAC solenoid or ISC motor may have to be replaced. Check the connector to the device to make sure the connector is not loose or corroded.

Engine Control Issues

Sometimes stalling is the fault of the Powertrain Control Module (PCM) or the inputs to the PCM. The factory programming may not provide enough idle speed when the A/C is on, when the alternator is under high load or when the temperature is unusually hot or cold. The fix here may be to reflash the PCM with the latest OEM update.

A faulty MAP sensor can sometimes mislead the PCM into thinking the engine is under a greater or lesser load than it actually is. The MAP sensor senses intake vacuum, which the PCM uses to estimate load so it can adjust the air/fuel mixture accordingly. If the MAP sensor isn't reading right, the PCM will receive bad information and possibly add or subtract more fuel than it should causing the engine to stall.

The same thing can happen if the throttle position sensor on a speed/density EFI system (no airflow sensor) is out of calibration or had a dead spot. The PCM may not realize the throttle is at idle, and may give the engine too much or not enough fuel causing it to stall.

When attempting to diagnose an intermittent stalling problem, therefore, it's important to always use a scan tool to first check for any trouble codes that might shed light on the condition, and secondly, to look at all the essential sensor inputs to see if they are within range and are supplying accurate information to the PCM.

Intermittent stalls that seem to happen at random are often ignition-related. A sudden loss of spark will kill the engine cold and prevent it from restarting. The most common causes for loss of spark include hot shorts/opens in ignition coils, ignition modules and crankshaft position sensors. Loose or corroded wiring connectors that cause a sudden loss of voltage in the ignition circuit will also stop an engine dead in its tracks

Rasmataz
Sep 2, 2008.
The car dies SOMETIMES shortly after beginning down the road, when I come to my 1st COMPLETE stop. There are a few stops sign before the main stop, that I kinda stop at, then I come to a main road where I usually have to wait 5-10 seconds to pull out onto the road. That's when it dies, then it will usually start right up and be fine for the rest of the trip. It seems to only happen when the engine is cold ( I live in Miami, so it is never Cold Cold). I have tried to put the car in neutral and continue to give it gas while breaking, then put it back in gear, but she still dies.
This seems to have started shortly after (2 weeks) I had the timing belt, water pump and thermostat replaced. Another thing that happened right before the problem started was I had to jump start my wife's car a few times. I know I did not cross any wires or anything, but I have read that you could still mess up your computer.
I took the car to my mechanic and he did a load test and determined it was the battery($200). Two days later, it dies again. I take the car back and he checks the fuel pump pressure and test drives it over a period of three days, driving it cold, hot etc. NEVER dies on him. I pick the car up from the shop and it dies on me on the way home, 2 blks from the shop!
So I take the car to a German car repair shop.
Their diagnostic is that it is a bad breather tube and dirty throttle body. $500 later, I pick the car up and the next morning on my way to work, it dies again. I take it back to them and they keep it for a few days and perform several road tests, NO PROBLEMS FOUND!
I take the car home and 1 day later my ignition switch goes bad and the key is very hard to get in and out and the starter begins cranking out of no where and the AC doesn't work. So I call the German specialty shop and they tell me it is going to be $400 more dollars. Luckily I found out through the web that Audi had done a recall on that part and I was able to get it fixed for free.(You think the German shop is going to tell me I can have the work down for free through the dealer?) I thought that may have been the problem all along, but NO. It died on me last night in the mall parking lot. I am at a total loss as to what this could be.
PLEASE PLEASE PLEASE HELP ME!

Tiny
Chadfsr
Sep 17, 2008.
Hi chadfsr,

Can you please provide the engine variant in order to understand the system better.
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KHLow2008
Sep 18, 2008.
It is an 1997 A4 2.8 v6 Quattro, if you are asking if it is a B6, B7, or what ever, I'm not sure.
I can call the shop and get it for you if you aren't able to determine by the year and engine size.
Thanks!

Tiny
Chadfsr
Sep 18, 2008.
Hi chadfsr,

Let us start form the basics again.

ENGINE STALLS 
Ensure air intake system is unrestricted. 
Ensure PCV system operation is correct. 
Check EGR system for correct operation (2.8L). 
Check Idle Air Control (IAC) valve. 
Check for cracks and poor connections at throttle body. 
Check Throttle Position (TP) sensor operation. 
Check Engine Coolant Temperature (ECT) sensor operation. 
Ensure fuel system pressure is correct. 
Check for poor quality fuel, fuel with high alcohol content or contaminated fuel.
Page 1 of 1 TESTS W/O CODES -1997 Audi A4 Quattro 9/19/2008

Since this seems relevant to engine temperature, I would suggest checking/testing the ECT raw data.

KHLow2008
Sep 19, 2008.

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