Mk2 fails to idle/starts poorly and only under throttle.

Technical Area Engine, Transmission, Exhaust etc
2

Hi from a rail replacement service.

My five last week blew it’s fuel inj fuse. Which had meant the immobiliser appear with a failure saying it couldn’t see the PCM. Replacing the fuse fixed this however today on re way into London the car stalled and refused to start except under throttle. I eventually got her into a station car park. But she stalled the whole way unless I held the throttle up. Any suggestions?

I’ll be going to visit it tomorrow so any suggestions would be helpful. I have Rac so will get them to move it of all else fails. I couldn’t hang around today as had to be in London.

3

Okay, collected her on Sundays and it seems the fault is not there when cold, but it re-appeared on the way back. Cleaned the idle valve and throttle body, and while she’s got better the fault is still there. Today took her out for a trip and she ran okay, stalling only once, however when I tried to start her after parking out side some shops she needed throttle to turn over.

 

I’m wondering if the fuse going means something is wrong with the fuel pump/filter? or if I really need her to go in to diagnostics at the local mazda place (£85 charge)?

4

Sounds a bit like air leak symptoms.

5

Any suggestions to diagnose if that is the case/where to look for damage?

6

You need to check the compenents downstream of the airflow meter upto the intake manifold gasket. What caused the fuse to blow initially?

7

I don’t know for sure, it happen after a drive home was chatting the wife in the car and she stalled at idle, restarted her thinking it was odd and she stalled again after a few seconds. Went to try a third time and the car refused to spark.

8

Just followed this guide, http://www.mx5oc.co.uk/forum/forums/t/204.aspx and found no fault codes and I couldn’t hear/find any air leaks on first glance.

9

Sprayed over the joints to too if there an air leak again today. Still nothing, yet if I drive her for more then 15-20 mins she starts stalling when you pull up to the giveway line. Then refusing to start taking lots of attempts and throttle. I swear the thing hates me.

I’m going to get the fuel filter changed as I don’t think it has ever been done, but does anyone have any ideas other than that and air leaks? 

Or is it time to point her towards a mazda dealer? If so what would I say for the greatest chance of success?

10

Go see Roadster Robbie at EMG Cambridge. He’s the top technician there and a true Roadster fanatic. You can ask for him to work on your car

11

I had a similar problem with my MK2 1.8…advised to change coil pack…car has never missed a beat since.

 

12

Coilpack, that not a suggestion I’ve heard before. Is there anyway to test that theory? They’re not exactly a cheap fix so it’s not something I want to jump in and try on an off change.

Maybe I will have to take her to Robbie.

13

 Evath,

I believe the coilpack can be tested.

I guess if you test the coilpack whilst cold it will show no fault ie when you are able to start the car

I believe the coilpacks fail when warm ie after 15-20 minutes, causing the car to stall and fail to idle, so you should be able to identify if faulty.

goodluck

14

Well I replaced the fuel filter, as it hadn’t been changed at the last service. Now the problem has gone away.

However as the problem was worse in sunny weather, and it has been miserably wet since, it might just be hiding. 

 

 

15

Sadly seems hiding drove to Nottingham yesterday from Cambridge and just out side notts she stalled. Started her a few times under throttle with effort then she completely refused to start. Pulled over and waited 15/30min and sprayed some car cleaner into the idle valve in some vain hope of recovering her and eventually she started. The time before she successful turned over it sounded like something hit the inside of the bonnet?
She then recovered idle as I drove here but I’m not sure when as I was careful to keep the trottle high.going to drive home today see how it goes but will probably book her into Robbie for a check.if anything this post is so I can had a print of this with it with the car when I drop it off.

16

I’d be looking at the mass air flow sensor and the engine coolant temperature sensor next. It really needs a fault code check.

17

She’s sitting in the EMG car park waiting for you!

Booked in for tomorrow.

 

18

 

Looking forward to it! I noticed it in the car park today.

 

19

Good luck and hope you find the problem. I have a horrible feeling it will be elusive.

You’ll probably see this after you’ve looked at the car so finger crossed.

20

Got a phone call to say it’s fixed and something about the water pump’s electrics?! Seems an odd thing to cause a stall at idle, anyway will collect it tomorrow!