Intermittent rough/slow start

[Flibby]

Hi all,

I mentioned this briefly on my Reader's Rides page but hoped that it was more of a one/two off but it seems to be becoming more regular so i'm asking to see if anyone has had similar issues!

On cold starting (engine, not weather) maybe 1/3 or 1/4 attempts at starting take longer before coming to life. If you persevere or try again it will start up just fine. The cranking feels consistent itself.

The idle when running is fairly steady around 650-750/800 once the engine is warm. The idle just after start goes to 1500 ish for a few seconds before going back down through 1000 to it's usual resting place. I believe this is normal, but perhaps more pronounced than it should be?

I've recently changed their air filter and the battery reads fine when engine off and running. It's a Yuasa and i've cleaned the terminals up, albeit they weren't corroded anyway.

I've not changed the plugs, but i doubt that they would cause such an intermittent issue (happily corrected) but will do this anyway over the weekend.

I thought about fuel filter but again, if i didn't have pressure post filter/in the manifold it wouldn't start at all and would cut out. Could be worth changing the filter as it looks such an easy job given the location.

This brings me to the hopeful answer that my MAF is dirty/knackered, again a fairly easy job and something i'll be doing first if the consensus is that this has helped people. I've seen 'MAF cleaner' available but this seems to be akin to 'Neurofen for headaches' which is just fecking paracetamol. I've got a can of Electrical Contact Cleaner which is residue free - surely this will be very similar/identical stuff?

I read Carolyn's helpful advice to a chap in another thread regarding ground faults. Hopefully this isn't a rabbit warren to go down just yet if the problem is so temperamental as surely this would show up in other electrical foibles too?

PS - I've plugged the car into an OBD2 reader and there weren't any codes showing or stored. Weirdly it showed the throttle reading as 20% at idle but i think this is just a foible of the program given that i don't have high idle all the time etc and the cable looks fine, not too tight. If anything i need to tighten it up a little as there's some play in the pedal.

I tried to video the problem but it started up first time anyway. I've shown the revs coming down in the other video here which seems fairly sluggish to come down to resting point but I've not got another '2' to compare with!

I apologise for the loud sounding (Irish?) people in the background - they seemed to be having an angry dispute with one of my neighbours about a driveway 

Grateful for anyone's advice you has had similar problems.

Cheers,

Nick

https://vimeo.com/user100433084/review/345980503/ca9830fb42
https://vimeo.com/345980850/recommended

[Carolyn]

I know it sounds bloody obvious.

Are you occasionally allowing your foot to rest on the throttle pedal?

You'd be surprised how fresh sparkies can make a big difference.  The kind of basics one does anyway?  So worth doing.

A dirty throttle body can also cause such symptoms.  Disconnect the rubber inlet and spray carb cleaner into the throttle body - especially the hole for air to the Idle Air Control Valve.

If that lot makes no difference, throttle body off and thorough clean on the bench?

I use carb cleaner on the MAF, but I reckon contact cleaner is fine. 

[shnazzle]

20% throttle is too high. It should be 11%.
But as you say, the idle rpm is fine, so it's likely to just be your reader. Although I'm not sure how it would interpret this incorrectly. 

As per Carolyn's text. The difference a fresh set of correctly gapped spark plugs can make is not to be underestimated. Depending on thr state of the old ones of course. 

As for contact cleaner... I've always found it to leave a bit of a residue. And it stinks like hell. 
Carb cleaner, again as per C's advice, is what I've used for years. 
That or Wynns EGR cleaner

[Ardent]

Utter decadence I know, but if sparkies are in question. Sod it, and throw the £8 delivered at it.

To off set the expenditure, check and clean the earths.

[Topdownman]

The only fuel filter is the one in the pump housing in the top of the tank. Not easy to get to but so rarely touched but can cause problems.

[Flibby]

I know it sounds bloody obvious.

Are you occasionally allowing your foot to rest on the throttle pedal?

You'd be surprised how fresh sparkies can make a big difference.  The kind of basics one does anyway?  So worth doing.

A dirty throttle body can also cause such symptoms.  Disconnect the rubber inlet and spray carb cleaner into the throttle body - especially the hole for air to the Idle Air Control Valve.

If that lot makes no difference, throttle body off and thorough clean on the bench?

I use carb cleaner on the MAF, but I reckon contact cleaner is fine. 

Thanks Carolyn. All good ideas for some preventative maintenance. Definitely not pressing on the pedal though I remember having to change a throttle body in an old Astra which was easy enough

[Flibby]

20% throttle is too high. It should be 11%.
But as you say, the idle rpm is fine, so it's likely to just be your reader. Although I'm not sure how it would interpret this incorrectly.

As per Carolyn's text. The difference a fresh set of correctly gapped spark plugs can make is not to be underestimated. Depending on thr state of the old ones of course.

As for contact cleaner... I've always found it to leave a bit of a residue. And it stinks like hell.
Carb cleaner, again as per C's advice, is what I've used for years.
That or Wynns EGR cleaner

I appreciate that. I'll have a look for some carb cleaner anyway. New job being next to a retail park with a Halfords is bad for my bank balance...

[Flibby]

I wanted to give an update. It really annoys me when I'm reading a thread and the OP doesn't do so when yiure looking into a problem.

I cleaned the MAF which was utterly filthy, and changes the sparks out. Touch wood it seems to be much better starting and the idle is smoother too. I disconnected the battery for an hour so the ECU had time to reset which may have helped the learning procedure too.

The sparks thay the previous owner had stuffed in were some frankenplug 4 earth electrode jobbies. Interesting pointless oneupmanship from Bosch...

Thanks to all - the club donation is well overdue now and will be sorted 😁

[shnazzle]

I wanted to give an update. It really annoys me when I'm reading a thread and the OP doesn't do so when yiure looking into a problem.

I cleaned the MAF which was utterly filthy, and changes the sparks out. Touch wood it seems to be much better starting and the idle is smoother too. I disconnected the battery for an hour so the ECU had time to reset which may have helped the learning procedure too.

The sparks thay the previous owner had stuffed in were some frankenplug 4 earth electrode jobbies. Interesting pointless oneupmanship from Bosch...

Thanks to all - the club donation is well overdue now and will be sorted 😁

Brilliant! Hope that sorts the problem for good. 

Servicing is king. Fresh plugs, good quality oil and filter, clean air filter and MAF = a happy MR2 for years.

[Ardent]

I wanted to give an update. It really annoys me when I'm reading a thread and the OP doesn't do so when yiure looking into a problem.

I cleaned the MAF which was utterly filthy, and changes the sparks out. Touch wood it seems to be much better starting and the idle is smoother too. I disconnected the battery for an hour so the ECU had time to reset which may have helped the learning procedure too.

The sparks thay the previous owner had stuffed in were some frankenplug 4 earth electrode jobbies. Interesting pointless oneupmanship from Bosch...

Thanks to all - the club donation is well overdue now and will be sorted 😁

And satisfying having done it.
Unless done and I've missed it. Might as well throw an air filter in as well.

[Flibby]

And satisfying having done it.
Unless done and I've missed it. Might as well throw an air filter in as well.

[/quote]

Already did that with the first oil change  actually. Otherwise great shout.