stuttering rpm

Ian Patmore

Well-Known Forum User
Not often I have a question....

Changed the coolant and thermostat a few days ago (took dist. cap off with HT leads attached- but took off HT lead to coil), ran the engine up to temp and remove any air. Ran as per usual.
Went this morning to start, would, but would not hold idle, only by keeping on the throttle, and then a bit of a job. Starts without hesitation. To me its missing a spark which is causing the stuttering. This has happened before, broke down, and pushed a few HT leads, and cured it. This time no joy. Replaced HT leads and dist. cap, no joy. One of the wires to the black box on the side of the distributor (280zx) was a bit loose, which has now broke, and now too dark to fix (but not too sure the culprit) though is under top rad hose which I took off one end.

Coil playing up? Can't see anything else obvious, all wires to coil are fine. Rotor arm looks fine, and never touched. Plenty of fuel getting through.

Ideas?

Ta
Ian
 

rallymanDP

Well-Known Forum User
Sounds Ignition-related, doesn't it, Ian ?
A Rolling Road hook-up to the Diagnostic screen would tell you more, but I would suggest the Distributor Black Box or ( less likely ) the Coil might be the culprit.
The loose wire on the Dissy might be broken internally without the covering showing it.
 

Ian Patmore

Well-Known Forum User
Cheers Duncan, it does sound ignition related, will follow up tomorrow. I have a spare dist. and black box thingy, somewhere....
 

Ian Patmore

Well-Known Forum User
MikeB,
It is something else for me to look at. But as this has happened before, I will look elsewhere first.

Cheers
Ian
 

Ian Patmore

Well-Known Forum User
Well, put a new spade on the broken wire, thought I would check the spark plugs (as MikeB suggested). One found to be cracked and subsequently broke. The metal core inside the ceramic is a bit rusty, so could have been like that a while.

Two Halfrauds later no replacement, so had to order a couple (one as a spare) from my local motorfactors this morning.

No, my Rebello engine is not running the usual NGK BP6's, even though it would have been nice to find a used one kicking around my place to test.
 

SeanDezart

Well-Known Forum User
Hopefully you've found the source of trouble (new ones cracked already ?????) - so what do you run please ?
 

Ian Patmore

Well-Known Forum User
Sean, Colder ones than the BP6's. The ones on there are not exactly new, been in since 2007, a slight knock along the way....they can easily be cracked.

Paul, cheers for the offer, you are running something different, and by the time I pop round mine will be here.
 

SeanDezart

Well-Known Forum User
Ian, silly question perhaps but why colder ones ? Is yours such a high revving engine likely to attain great heat outputs ? 2007.....not THAT long - are you sure that your plugs are the best adapted to the engine in a euro climate/your application of said engine ?
 

Ian Patmore

Well-Known Forum User
Sean, its not the time in use I am saying Sean, its the time they have been in the engine and could have taken a knock at fitting of engine in car and associated fitting of engine bay. Plus I could have cracked it taking it out this time or the time before.

your plugs are the best adapted to the engine in a euro climate/your application of said engine ?

Yep. ;) Perhaps some should try it!

Its not all about climate.... generally, the BP6's were recommended for a stock system... as with a performance or more race derived engine, the plugs are something that can be altered, just like compression, cam, etc.... to match how the engine will behave in its new set-up.
 

Throttleton

Well-Known Forum User
I thought that...........

A modified engine running standard heat range plugs may let pre-detonation occur. (bad)
And that running too cold a plug may lead to plug foul up. (not as bad)

Let me know your thoughts as I could do with a bit of advice on another car I am modding!!
 

Sylv1

Well-Known Forum User
Hi Ian

I have nearly the same engine than you

I have 3 years old Ngk "b8e s" and crane lx91 coil

No problem With that setup

Hope That helps
 

Ian Patmore

Well-Known Forum User
The only other Rebello engine I know of runs BP6s.

I have 3 years old Ngk "b8e s"

Not Sylvian's then..... ;) I'm running the same as his, probably like his fitted from when Rebello built them... So who owns the "only other" Rebello engine then?! I suspect Dean is running the same as us.

Hi Sylvian, I don't know about yours but mine is running very well after now bedding in.

Throttleton, I don't know enough about this to be giving detailed advice....maybe a bit of trial and error for your application....
 

ben240z

Club Member
Ian I chased a misfire all season years ago and it turned out to be the rotor arm. For the cost of one it has to be worth trying. Other than that it is back to basics and work methodically through the electrics and intake side of things. A slight air leak on the inlet side will cause these symptons. Vacuam pipes servo pipes etc dislodged while working on the engine.
There is no reason for a plug that has worked perfectly to change it's mind and decide that it is too hot or cold unless something else has changed.
Back to the garage for me
 

MikeB

Well-Known Forum User
From my experience, once you've got a misfire, and done the initial check of all the leads and connections, I'd always pull the plugs to see if it is just one cylinder ( hence a wet plug) or across all six.

Anyhow once Ian gets his new plugs we'll hear if it's a problem that effects more than the damaged plug :)

Hopefully it's not

Cheers

Mike
 

SeanDezart

Well-Known Forum User
Not Sylvian's then..... ;) I'm running the same as his, probably like his fitted from when Rebello built them... So who owns the "only other" Rebello engine then?! I suspect Dean is running the same as us.

Maybe you should ask Dave who has his engines in the Old World and then add some as personal imported cars with his engines that he obviously knows nothing about ;) !
 

status

Well-Known Forum User
Is that why mine has had an oil leak from almost day 1 Sean baby,Ian i have set of said plugs if you need to borrow them
 
Top