Boxster 2.5 trouble - can anyone advise?

CharlesBanbury · Nov 13, 2021

Good afternoon. Boxster 2.5 1996
please could someone read my tale of woe and give me an idea?
So, the car isn’t used very often and, over the summer, developed a misfire on a local journey. This was just after I cleaned out the rear hood drain holes. I assumed that I had managed to get water into the electrical system when I flushed them through. I left it for 24 hours to dry and all was back to normal. Then the car went for a full service (oil and filter, air filter, fuel filter, plugs) and returned in fine fettle running beautifully. However, I did notice a tiny cough on a couple of occasions. I put this down to my own paranoia! However, today - it started up fine but soon began to faulter very badly. Foot to the floor and 10MPH. On a very short journey I had to stop three times as it died completely. However, it would restart and managed to make it home. The issue wasn’t constant and suddenly it would clear and go back to normal and even when it was faltering seemed to be running on all cylinders. The engine sounds fine at idle but under load driving will go from normal to complete death in a matter of 1/2 a mile. I have the RAC coming. Does anyone have any ideas?
many thanks,
charles.

Ian_959 · Nov 13, 2021

Have you got a simple OBDII Fault Code Reader, if so has that given any codes? (You can buy a simple one from amazon or halfords etc or perhaps a local owner has one you could try) It's difficult to advise but a bad mass air flow sensor causes various driveability problems, such as a no-start, stalling, lack of power and poor acceleration and may cause the Check Engine or Service Engine Soon light to come on. On the early 996 / 986 there was a cold idle valve that would give poor running until the car warmed up.Fuel related misfires can be caused by many different things such as low fuel pressure, faulty or dirty fuel injectors, a faulty O2 sensor, a dirty or failing mass air flow sensor, a faulty or dirty idle air control valve or a vacuum or intake leak. The RAC may be able to diagnose

Ian

Boxstercol · Nov 13, 2021

I’d start by checking the coil packs, if they’re cracked then any sign of moisture can cause issues similar to what you’re experiencing.

Beru are OEM, usually about £150 for the 6 using an offer code from the usual online parts retailer. Easy enough to change with rear wheel taken off on each side.

CharlesBanbury · Nov 13, 2021

Thanks so much. RAC diagnosis attached. He thinks moisture in the fuel as it has so little use and, having to use some fuel From a can in the ‘crisis’ will report back with the mechanic’s diagnosis. many thanks once again.

Charles

malarcy · Nov 14, 2021

I would still vote coilpack(s) - moisture in the fuel sounds less likely to me and doesn't explain why it works then doesn't and honestly has anyone ever had that as a problem unless you haven't driven the car for years.....

Hope its simple/cheap to resolve ( if it is fuel then a tank fuel of nice fresh fuel and a good thrash tell you )

CharlesBanbury · Nov 23, 2021

Many thanks again to everyone. The resolution was this:

The garage took the advice of the RAC man and completely drained the fuel from the tank. It was very dark and smelt very bad. Subsequently, with fresh fuel and a new filter all is back to form. In fact, it seems to run better than ever. I can only assume that as the previous owner hardly used the car for years, I have been topping up the old dirty fuel since I bought it. This combined with me using my can of petrol in the fuel crisis caused a sort of fuel quality tipping point. Well, you live and learn. Many thanks again for your help and advice.

With regards,

Charles