Discussion
Changed the battery on my Mk1 last night (FYI - Halfords' online "what battery do I need" thing is wrong) and this morning it seems reluctant to idle, the revs drop to 400-500 and it's quite rough, and on one occasion it stalled completely. Is it a simple case of tweaking the idle speed up a touch? And if so, the screw is located..... ??
Was the battery fully charged?
Is it really the correct battery for the car? (not that I don't trust Halfords... but I don't).
Why did you change the battery? If it was because the old battery lost charge it could be that the charging circuits aren't working correctly - most tyre & battery places can test that for you very quickly for nothing.
Is it really the correct battery for the car? (not that I don't trust Halfords... but I don't).
Why did you change the battery? If it was because the old battery lost charge it could be that the charging circuits aren't working correctly - most tyre & battery places can test that for you very quickly for nothing.
Edited by MX-5 Lazza on Wednesday 6th May 13:34
It is an 063 Calcium which is not the right one, although their website says it is. It doesn't fit, for example, but I adjusted the bracket to suit, shall we say.
The old one was definitely dead, brought on by continual draining to flat and then fast charging to get one or two starts out of it. Plus it appears to be the original Panasonic battery presumably from 1998 so not entirely surprised it has given up.
The old one was definitely dead, brought on by continual draining to flat and then fast charging to get one or two starts out of it. Plus it appears to be the original Panasonic battery presumably from 1998 so not entirely surprised it has given up.
Go Google "Miata ISC" (Idle Speed Control).
There is an air by pass solenoid controlled by the ECU. It should be in neutral with a hot idle so you can pull the plug off and the idle speed does not change. If it does change then set the base idle with the idle speed screw (NOT THE ONE ON THE BUTTERFLY).. under a plastic plug on the wing side at the top on a mk1 1.8
But .. more likely the ISC valve is gummed up with oil and gunk.. they do after a few decade of use. They can be cleaned but you need to break into the coolant water to take it off :-(
There is an air by pass solenoid controlled by the ECU. It should be in neutral with a hot idle so you can pull the plug off and the idle speed does not change. If it does change then set the base idle with the idle speed screw (NOT THE ONE ON THE BUTTERFLY).. under a plastic plug on the wing side at the top on a mk1 1.8
But .. more likely the ISC valve is gummed up with oil and gunk.. they do after a few decade of use. They can be cleaned but you need to break into the coolant water to take it off :-(
MX-5 Lazza said:
Why was the old one draining to flat though? Was it ok after a drive?
Anyway, if I was you I'd just order the Westco off MX5 Parts and take that one back to Halfords for a refund.
I assume because the car was stood for weeks, sometimes months at a time with the alarm armed. I wanted the Halfords one because they do a 4-year warranty and if I kill another one due to low use, they are generally too stupid to figure it out and just hand over another one. In any case, it will fit in my Dolomite so I may just stick it in there and get a smaller one for the MX. Anyway, if I was you I'd just order the Westco off MX5 Parts and take that one back to Halfords for a refund.
miniman said:
MX-5 Lazza said:
Why was the old one draining to flat though? Was it ok after a drive?
Anyway, if I was you I'd just order the Westco off MX5 Parts and take that one back to Halfords for a refund.
I assume because the car was stood for weeks, sometimes months at a time with the alarm armed. I wanted the Halfords one because they do a 4-year warranty and if I kill another one due to low use, they are generally too stupid to figure it out and just hand over another one. In any case, it will fit in my Dolomite so I may just stick it in there and get a smaller one for the MX. Anyway, if I was you I'd just order the Westco off MX5 Parts and take that one back to Halfords for a refund.
zac510 said:
If the battery is of poor charge you're more likely to notice the starter motor loping along rather than a poor idle.
The idle issue must be separate and caused by something else!
It seems fine now I've wound it up to about 800rpm. I never did adjust it after fitting the filtercharger to be fair. The idle issue must be separate and caused by something else!
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