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MAF issues?


Ben

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Hi all

I've encountered a problem with my Cayman which I'm hoping someone may have some advice on.  Driving home on Monday night, accelerating along an A road at about 60MPH, and the car suddenly starts decelerating for no apparent reason.  Not sure whats happening so I dropped down a gear, and the revs picked up again, but almost straight away it starts decelerating again.  Pulled into a lay-by.  No warning lights on dash, and checked I hadn't inadvertently turned on the speed limiter or something like that.  Turned off the engine, left it and restarted without issue a couple of minutes later.  Set off again and seems OK but within 1/2 mile the same thing happens again.  Pulled into another lay-by, again switched off the engine and left for a minute or 2, still no warning lights or messages.  Decided to try and make it to the next village, so set off once more but within a few hundred yards, car starts to lose all power, and eventually cuts out completely (luckily only travelling very slowly at this point).  Engine turns over but won't start.  So had to get it recovered :(.     

Dropped the car at a garage who I use near home, and the next morning the mechanic runs a diagnostic.   No error codes.  Turned the car over and it started, so drove sheepishly home.

Not sure what's going on here.  Searching on Google seemed to suggest it could be the MAF being either dirty or faulty, but most instances of MAF issues seem to appear gradually - this was very sudden.  Thought I would attempt to clean the MAF sensor anyway, but does anyone have any other ideas?  Fuel pump maybe?  Doesn't inspire me to travel very far at the mo!!

Thanks in advance

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9 hours ago, extanker said:

sounds like fuel system but much testing to be sure 

Yes its weird that no error codes are being thrown up.  Started the car again last night, seemed to idle OK at first, then after a few minutes the engine started to labour, then completely cut out.  Was going to remove the MAF to clean it but realised I need a TT20 tamper proof Torx bit which seems a bit tricky to get hold of.  Will try just disconnecting the MAF tonight, and also check the fuel pump relay.

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I suspect the quick connect for your fuel pump feed line is loose.  It's a high pressure pump - the slightest looseness on those connectors and the engine's operation goes to s**t.

 

I would bet on the pump connections based on your symptoms - no error codes and it happening suddenly.  Injector issues would cause a misfire/poor running.  It can only be the pump to completely cease engine operation.

 

This same issue happened to my CR after OPC Cardiff had my fuel level sender out.  You'll need a special tool or a lot of wrist strength to get into the fuel tank.  There's a lock ring.

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On 26/04/2019 at 22:55, Aaron said:

I suspect the quick connect for your fuel pump feed line is loose.  It's a high pressure pump - the slightest looseness on those connectors and the engine's operation goes to s**t.

 

I would bet on the pump connections based on your symptoms - no error codes and it happening suddenly.  Injector issues would cause a misfire/poor running.  It can only be the pump to completely cease engine operation.

 

This same issue happened to my CR after OPC Cardiff had my fuel level sender out.  You'll need a special tool or a lot of wrist strength to get into the fuel tank.  There's a lock ring.

 

Thanks for this Aaron.  Yes as I investigate further, it does look increasingly like a fuel pump/supply issue.  I had the MAF out on Saturday and it looked all good to me, no oil or any other deposits on it, but I did clean it with some contact spray just in case.  No change.  The engine sporadically fires up but dies almost immediately, then turns over but won't start.  Checked the fuses and they all look OK but can't check the relays as they are in the most awkward location imaginable in the drivers footwell and I can't work out how to release them from the carrier.  Gave up after a couple of hours of frustration.  One other potential area of investigation is a high pitched noise and then crackle (not sure how else to describe it) that seems to emanate from the area of the throttle body when the ignition is in the third stage position.  Not sure if this is a new thing or not.  I've passed the keys to a mechanic friend who is going to try and do further diagnosis this week.  Hopefully at some point I'll get the croc back on the road!!!

BTW I was also stumped for a while by the special 5 starred TR Torx bit required to remove the MAF.  Not many places seemed to sell it.  But if it helps anyone, this is where I got mine from:

https://www.ebay.co.uk/itm/Torx-TR-Tamper-Resistant-Bit-Set-10-Bits-Torx-with-5-Corners-5-Star/192383908838?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

 

 

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Make sure your mechanic friends ensures the connectors "click" after reattaching them to the fuel pump assembly.  If they don't click, check the plastic tab inside.  If it's loose, remove it and weigh it down a little for a while.  It's fiddly to do but they come out.  

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  • 1 month later...

Just to close this one off - it was indeed the fuel pump - according to Brookspeed the 987.1 has the low pressure pump, and mine seemed to have failed for some reason.  New pump fitted and the car is back on the road again, seemingly performing better than ever.   Thanks for everyone's advice, and to Brookspeed who pulled out the stops to have me back on the road in time for Beaulieu yesterday. 👍 

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