NB8A useless low rpm

[EGG80X]

Ok, with the idle dip problem gone, now I face another challenge!!

Some of you may remember me whinging about my car bogs down on low rpm when air con is on...


Last couple week I been able to pin point the problem:

When my car is been dríven for about 20-30 minutes I notice the engine hesitates or bogs down on hill starts (not even a steep incline at all)... Like really really bad as if the car barely moves no mattter how much throttle i give. Hence whenever I do a hill start, I literally have to rev up to 2500 rpm and sit on the clutch and not let the rev drop below 1500rpm or else the car just down move at all. Similarly if the car is slowed down and rev drops to 1500rpm, engine bogs down and hestate to rev up. If I have the air con on its even worst.

Another thing I notice today when I was just reving the engine to about 3-4000rpm in neutral, when the rpm return back from about 1500rpm to idle the engine sounds and feels abit rough too.

One more thing I like to add is the spark plugs, I had normal NGK spark plugs about a few weeks old but just changed back to my old NGK iridium plugs to see if there is any difference... Just a slight improvement

Here are abit of a stat on my NB8A
-112,000km
-only use 98ron fuel
- NGK iridium plugs
-done the major 100k serivce with regular 5k service intervals
-replaced the coil pack, magnecor 8mm spark plug leads about 1.5 year ago
-blocked off the egr valve with recent idle dip problem
- K&N Typhoon CAI and 40mm radiator are the only engine mods

Please Help!!

[RaYmO]

Hey Kelvin,

I had identical symptoms (no power whatsoever on slight inclines)

Took it to Mania and they changed the Spark Plugs and the Leads (with the magnecor leads)

My car was running a lot stronger after that, I think if your leads are on their last legs then the sparkies may need to be replaced as well.

This may not be the solution but it worked for me mate.

Best of luck getting it sorted.

[AJ]

as a few people have had problems with short life on magnecors...i'd look at them before anything...........depending on how many k's you do, 18 months is enough age for me to suspect them......chuck a set of OEM's on it.............it'll probably help with the idle dip as well.

[marcusus]

Odd. I'm keen to hear how this pans out as my car is for the most part identical, but without this random idle dip problem. I've noticed that when I cold start the car it takes a little bit for the car to rev up to about 1500 before dropping back, which it never used to do before. Was that something you noticed when this all began?

[Okibi]

Find a Mazda dealer that has the computer to plug into the diagnosis plug.

That might really narrow things down.

[Wotsa]

It might help to check your Throttle Position Sensor (TPS). Mine failed and the symptoms you describe were the same as I experienced.

[Craig]

Sounds rooted...come and buy our used silver SE!

[SuperMazdaKart]

coilpack?

seems the NB ones aren't as good as the NAs

[bruce]

Sounds rooted...come and buy our used silver SE!

You will give him a 6-pack (of Coke) as a trade?

[EGG80X]

I got new spark plug leads today and swap them over... seem to be a bit better but since not performing the way it should, I might try out if my local Mazda (Tom Kerr) dealer have the diagnosic plug to see if there is any error code pops up.... I might even try to change the tps as well

[EGG80X]

ok here something i tried this morning out of curiousity, I disconnected the TPS and drove the car. It seems to drive a lot better but notice sometimes it idle dips here and there when I stop the car which is no biggie I guess, since there is no sensor telling the car where the position of the thottle hehe. I wonder if it is the TPS then, or should I just get the car plugged and scanned?


One big puzzle the car it is

[Okibi]

Depends if the TPS is cheap enough to just go \"bugger this i'll replace it and see\" OR if you could borrow a working TPS off a mates car then go for a blat.

All the times i've put my car on the Mazda diagnosis machine its found nothing wrong but i'm still kicking myself i haven't got around to doing it with the new donk.

[Garry]

If you unplugged the TPS and drove it around then you will get a TPS fault code if you take it to Mazda to get it checked. You will have to clear the ECU memory and drive it around for a few weeks and then take it to Mazda for an accurate fault diagnosis.

Strange that you get idle dip with the TPS disconnected. My car idles at a steady 1500rpm with it disconnected, or 1200 rpm if it's not connected properly.

[Steampunk]

One big puzzle the car it is

Patience you must learn

[ampz]

Have you tried unplugging your Idle Air Control valve?, It could be letting mpore air in that it should be.