Weird NB8B Issues

[npcan2]

Hi guys,

I need some advice on what could be causing these 2 weird issues I'm having with my NB8B.

Background:
The car is a manual 2001 NB8B (non OBD2) with 160xxxkms, stock.

Issue 1:
When sitting stationary the car idles at 800rpm (normal).
When I push the depress or release the clutch pedal whilst in neutral, still no change from 800rpm (still normal)
However, when I put the car in ANY gear (and obviously keep the clutch depressed), the revs jump up to 1300rpm and stay there. As soon as I select neutral, the revs drop back to normal...
I don't even know where to start looking, so any advice would be appreciated.

Issue 2:
When I get on the loud pedal for even a short period of time <15 seconds, there is an extremely strong 'rotten egg' smell that takes a good minute or two to clear.
I removed the charcoal canister, no change to the smell.
Check spark plugs, all ok.
Could it be a clogged or dodgy Cat?
Could it be a dodgy exhaust o2 sensor?

Cheers,
Nick

[SileNceR]

Rotten egg smell will be catalytic converter failing.

I can't suggest cause of rev raise in-gear though; perhaps try cleaning your idle speed controller?

[beavis]

Idle:
I thought about the idle issue. I think the idle has been set wrong, too high. Probably just needs adjusting... http://www.miata.net/garage/ignition.html
The reason you get the jump when in gear is because the neutral switch tells the car to go to closed loop idle control when not in gear.

Rotten egg:
Could be a battery/alternator issue. I have seen overcharging of batteries causing them to cook, and resulted in the most Anus like stink ever.
Test the alternator/battery etc and make sure its at around 14v when the car is running, and when at higher revs?
Alternator is ECU controlled so perhaps that's not working properly and is frying the battery at high revs?

[Okibi]

I'm guessing the smell is a dead cat

[mattyredlocks]

I'm guessing the smell is a dead cat

Just hanging out in the boot?

[npcan2]

Ok, if I'm going to replace the cat, I might as well get a full exhaust (it was only a matter of time).
Does anyone know someone in Melbourne (preferably south east) who could make up a full stainless system?

I'll have a look into the idle controller and report back. I May also check the boot for any dead cats... lol

Thanks for the input guys.

[93_Clubman]

Also a detailed idle setting procedure here:
http://www.miata.net/garage/KnowYourCar/S7_Idle.html

[Mr Morlock]

Interesting symptoms- plenty to learn methinks. Re the exhaust - consider Town and Country Exhausts Geelong who have a sporty system for NB's - it gets a good rap from users and fair price.

[hks_kansei]

Talk to your exhaust shop, but in my experience there's not that great of a need for full stainless systems.
Mild steel works just fine, and rust won't be an issue for years and years. The factory system is mild steel, so that should give an idea of the lifetime.

I'd get the alternator voltage tested, since as mentioned earlier the overcharging battery may be a possibility (and it's maybe 5mins to test, a multimeter can be bought for $15)


I've never heard of a dead cat converter stinking, the ones i've seen have all either just clogged with carbon, melted internally, or blown the guts out the back of them. None of them had any bad smells (other than fuel or exhaust)

[Steampunk]

When pulling away in 1st gear does the car accelerate normally? or does it seem like the revs climb but the car doesn't move according.
What I'm getting at is it could be a slipping clutch for the "rotten egg" smell.

Easiest test for a normal clamping clutch is when moving at low speed, say less than 40km/h, put it in 4th or 5th gear, and dump the clutch while you stomp on accelerator. If the RPM's drop significantly and the car labours, then your clutch is fine.
If the revs rise and the car doesn't move much faster then it's slipping.

[npcan2]

Report time:
I reset the idle (which was a couple hundred rpm low), but it made no difference to the issue. The revs still jump up when you slot it into gear. I still have no idea what this could be.

I ran a multi-meter over the battery and recorded 14.7v at idle and 14.9v at 5000rpm. Not a significant change and seems normal.
The clutch is fine. It still bites hard and doesn't slip at all. I know the smell of a dodgy clutch and it's not that. This is a very strong sulphur/unburnt fuel smell, like the car is running very rich maybe?

So, I expect to get a new exhaust system within the next few weeks (and new cat), but is there anything else I should be checking? Could it be a crack in the headers?

[pezchops]

im not sure if a dead O2 sensor could give your RPM problem, but when mine died recently i had that smell.
after fitting a new one i got from a member here the smell disappeared and i get an extra 50klms a tank.
may be worth checking it to at least put it out of the equation.

[93_Clubman]

Yeah, worth checking the O2 sensor. Also worth checking the neutral switch on the GB & maybe the clutch switch - not thinking that they're dead - thinking that they're malfunctioning. Check TPS also.
Might be something in one of manga_blue's posts re one of these:
search.php?keywords=neutral+switch&terms=all&author=manga_blue&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

[npcan2]

I've just ordered a new o2 sensor. For $85 it's probably with changing anyway, and my fuel economy has been pretty high (around 10l/100kms).

I'll check the neutral switch on the Gearbox, the clutch switch and the TPS, but I have a very strong feeling that it could be the clutch switch.
I was under the dash a few months ago, and I recall that the switch wasn't connected to anything..

Hopefully this'll do it.

[chefie]

dragging an old thread up, any update on the idle issue and solution

I have the same problem, on start up the rpm is normal then ramps up to 1500 before settling down to 1050-1200rpm

when pulling up at lights the idle stays high up to 2000 rpm and then slowly drops to 1100<>

when the car is hot the clutch starts to squeak not when cold its a new buy so working through the issue