Hello all, I have a 1995 Audi A6 2.8 V6 and I love it but it recently began to not start, If it sits overnight it starts 100%, but if you drive it then it may or may not start, no spark! OBD I =(

5

Asked by Jul 02, 2017 at 07:31 PM about the 1995 Audi A6 4 Dr 2.8 Sedan

Question type: Maintenance & Repair

My 1995 Audi A6 2.8 V6 recently began to not start sometimes. It will start everytime if it has sat over night or for more than 4-6 hours but it you drive it (distance is regaurdless apparently as it can do this if I drive it to the gas station (6-9 miles) or the doctor (61 miles) away. I thought it had something to do with the check engine light that sometimes turns on, but I have written down notes the last 2-3 months and it is also regaurdless of if the light is on or off. So you get somewhere and turn the car off, it doesn't matter if the car is off for 10-15 min or 2-3 hours, it seems like there is a 50/50 chance it will start or not, and when it does not I have taken the plug out and set it against the block, NO SPARK! YET if I cycle the ignition and let the engine turn over 6-8 times, then let it sit for a few minutes and then try again then it usually starts. Only a few times has it taken more than 20-30 minutes of this process being repeated before it has started. The idle seems a little off (around 700 RPM, as opposed to the 800 RPM it has been at for 22 years), I have checked the fuses, relays, fuel pump, fuel filter, and all are fine. I have narrowed it down to Ignition Coil, Crankshaft Positioning Sensor, Barometric Pressure Sensor (above the ECU on the passengers side) or possibly a bad phase on the fuel pump for starting as it seems to help if I hold the gas pedal down when attempting to start, after the car turns over but does not start, and this usually helps or expedites the process but if it was a fuel pump issue wouldn't I have the problem everytime I turn the car off? I have found new or refurb parts for very reasonable prices but I don't want to start tearing parts out and swapping them without having a better idea about what is wrong. Finally because it was a early 1995 it still has OBD I as they switched mid year to OBD II and no one around me (within 200 miles) has a OBD I diagnostic machine so there it is, any takers to throw me some ideas? I have worked on cars (everything from Audi, Aston Martin, Alpha Romeo, BMW, Buick, Chevy, Chrysler, Dodge, Eagle, Ford, Ferrari, GM, Honda, Infinity, Jaguar, Jeep, Land Rover, Lexus, Mercedes Benz, Mitsubishi, Mazda to Porsche, Renault, Saab, Toyota, Volkswagen, Volvo and more and this is the first time (since a issue with a Mazda Rotary engine that had issues) that I haven't been able to solve a problem within a week or two so any help would be greatly appreciated and much respected. Thanks

2 Answers

865

I have two ideas, you mentioned no spark, has the crank sensor ever been replaced? They can manifest issue from heat. If your not into just replacing parts they can be ohm tested out of the vehicle however the part may be encrusted in it's place. The second idea is hydro-lock. Engine might be worn enough were fluid is making it's way into the cylinder passages and preventing the engine from doing it's job. Other thoughts are getting an obd 1 software and see what comes up on that there are many choices out there for different hook ups and software for tablet or laptop. Good Luck!

5

It has been very wet and I believe it has something to do with the humidity as it started right after winter when the weather started to shift, IE; 40-60 degrees during the day and high humidity and 30-40 degrees at night, it also does it a lot when there are sever weather swings as we have been getting a lot of rain for 2 months now. I found a CPS for the car for $55 plus S&H on ebay so I might give that a shot, I WAS WONDERING IF THE PROCESS OF STARTING THE MOTOR (TURNING IT OVER, AS IT WONT CATCH, UNTIL IT DOES) MAY MOVE THE CRANK UNTIL IT LANDS IN THE RIGHT PLACE, HENCE THE CPS WOULD BE THE CULPRIT) THOUGHTS? I HAVE A FRIEND THAT HAS A OBD I READER BUT WE CAN'T SEEM TO FIND THE RIGHT ADAPTER TO CONNECT IT =( GRRRR, ANYWAY, THANKS FOR THE 2nd OPINION AND THOUGHTS, ANY CONFIRMATION OR IDEA THAT VALIDATES SOME OF MY IDEAS OR NEW ONES ARE VERY GRATEFULLY WELCOME, THANKS BRIAN =)

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