Engine flat spots

vfrpete · Postby **vfrpete** » Thu May 29, 2014 6:42 pm

After some advice, my nb 2001 has flat spots when dríven at a constant speed, accelerating after it gets over the flat spot seems fine. It idles fine,flat spot appears around the 2000 rpm mark and it takes a bit to get over the flat spot when it does it appears ok. Hope it makes sense, anyone got any ideas?. Thanks

MrRevhead · Postby **MrRevhead** » Thu May 29, 2014 6:45 pm

Firstly, check your timing.

Then check/Replace the following consumables:

Spark Plugs
Ignition Leads
Fuel Filter
Add some fuel injector cleaner additive (or run a few tanks of premium 98)

If you're still experiencing a flat spot, try and borrow an ignition coil to eliminate it as being the culprit before replacing.

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ED_MX5 · Postby **ED_MX5** » Tue Jun 03, 2014 7:25 pm

[quote="MrRevhead"]Firstly, check your timing.

Then check/Replace the following consumables:

Spark Plugs
Ignition Leads
Fuel Filter
Add some fuel injector cleaner additive (or run a few tanks of premium 98)

Also. Try replacing air filter. At around 2000 rpm the engine is under severe load and will need all the air it can get, after that mark it has got the car moving and begins to relax. Much like pushing a car, hard at first then easy when it gets going.
If air filter clogged, car has asthma.

Postby **NitroDann** » Tue Jun 03, 2014 7:32 pm

Yeah at 2000rpm when driving at a constant speed the engine is consuming a lot of air, huge amounts, this particular situation is where the car really needs a clean air filter.

Dann

EDIT: for future reference I was kidding.

ED_MX5 · Postby **ED_MX5** » Tue Jun 03, 2014 7:41 pm

Having though about it, possibly sticky injector. Injector cleaner works well, but not as well as a proper service.
2 options:
1- get them serviced by an EFI specialist( not mechanic because they will just outsource it and put their own markup on it)
2- buy all new injectors (budget allowing) and even if it doesn't fix, at least you'll know they're new.

speed · Postby **speed** » Wed Jun 04, 2014 6:47 pm

Air filter is an easy check. Unfortunately for me, all my running issues have never been something simple as the air filter.
Could it be the TPS? Sorry don't have an nb.

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ED_MX5 · Postby **ED_MX5** » Wed Jun 04, 2014 7:06 pm

It is possible that it's the TPS. A bit of searching on the internet and you should be able to find resistance values for it. Then check that it is operating correctly with a multimeter. That may stop buying an expensive part for nothing. Have you checked ignition leads also, I remember you did plugs.

vfrpete · Postby **vfrpete** » Wed Jun 04, 2014 8:30 pm

Thanks for the help, I have found the fault it was a faulty oxygen sensor. I got a new one from mx5 mania ( great price also) and fitted it, now running good again.