MX5 stuttering/hesitation issue

thecremeegg · 25 Aug 2015 at 18:17

Cross posting this from another forum - it's an MX5 mark 1

So car was running fine until this weekend I undid the airbox and moved it aside whilst I changed a hose. Put it all back together and it ran fine - did a 15 mile round trip and it was faultless.
Come to drive it today and if you press the accelerator down it stutters and hesitates quite badly. I drove the 5 miles to work and it was doing it all teh way. I then stopped, dropped the missus off and drove onto work, whereby it ran fine.
Come to the end of the day, problem is back!
It was lessened by the end of my journey home but still there. Happens primarily at low revs, however I sense a tiny hesitation a bit higher up but not sure if that's just me.

Now I'm thinking after googling that things like spark plugs, coil pack etc, however halfway home on the test drive I did put £20 of fuel in.....would dodgy fuel cause this problem?

OpenToSuggestions · 25 Aug 2015 at 18:19

Check the air seal on the air intake.
Could be a poor joint on the plastic that is only leaking just a little bit now and then.
I doubt fuel would be in issue.

No harm in giving the air flow sensor on the air box a quick wipe too.

p1RATE · 25 Aug 2015 at 18:32

Yea i would be checking the MAF sensor first.

thecremeegg · 25 Aug 2015 at 18:57

Checking in what way? The intake pipe is sealed well from what I can see/feel?
Sorry, not that good at this stuff!

cravin penut · 25 Aug 2015 at 19:13

I had this exact issue, new leads and spark plugs sorted it out

p1RATE · 25 Aug 2015 at 21:45

With the MAF you can clean it with carb cleaner or some sort of solvent. If you do that and the problem goes away i say you have found your problem but you will probably need to replace this sensor at some point soon.

It could easily be ignition related too. You can pull the plugs out using a deep socket and check to see what condition they are in. (there are guides online for what to look out for) They are cheap to replace and if they haven't been done in a long time you might as well do it.

If the problem persists after those two checks consider HT leads and coil pack. There could be a few things that give you these symptoms so start with the cheapest/easiest to narrow it down.

Nursie · 25 Aug 2015 at 21:58

I had what felt like a flat spot in rev range last year. Was sorted by new plugs leads.

Gaijin · 26 Aug 2015 at 10:28

As others have said - I'd check the MAF connections and then the coilpack - these are reknowned for being a bit of a weak point on some models.

thecremeegg · 26 Aug 2015 at 12:55

Well I found a split in the crossover pipe thing that might be the cause? Will get a better chance to look at the weekend so will probably try some new leads etc as well.

fastwunz · 26 Aug 2015 at 13:06

check the fuel filter too if you get a chance

pepsilol · 26 Aug 2015 at 13:19

thecremeegg said:
Checking in what way? The intake pipe is sealed well from what I can see/feel?
Sorry, not that good at this stuff!

Why were you moving the airbox if you're not good at this stuff :confused:

Anyway, definitely an air leak somewhere. Unplugging the maf will confirm it.

Sonea Fifer · 26 Aug 2015 at 14:08

I have the Mk2.5 and had a similar issue a few months ago - turned out to be the coil pack. MX5 has two of them (not sure if Mk1 is the same) but I replaced both of them and it's running fine . . . . . .