Hi All,

Been racing my BA Lantis R for the last year and took out 4th in our local 2kCup ($2000 cars) championship over here.

Car is stock because it has to be. I've deburred and cleaned up the inlet manifold and given it a rough port match. It's done 260,000km but runs like a dream. Seems to go okay but isn't a patch on other cars in the series that has even anything like the same power (on paper).

Strapped it to the dyno and it was making a massive 118bhp at the engine. Advanced some timing into it and got it up to 130 at the engine. Thought the engine might have been tired because of its age, but compression tested it and all cylinders are testing at 210-220psi which I understand to be bang on for a healthy engine.

So the question is, where did all my power go? Engine doesn't throw up any faults other than a lambda sensor, but theoretically this shouldn't be an issue on wide-open throttle since it's open loop at that point.

Engine seems really healthy, smooth and happy, just lacking in grunt.

Plugs look okay, perhaps a little sooty, but otherwise ok. On the dyno it definitely didn't want any more fuel as power dropped off as we upped the fuel pressure.

Anything worth checking?

I've tried running without air filter, cleaning the MAF, cleaning out the TB... all of the basic stuff... perhaps worth looking for exhaust restrictions/blockages?

I would check the exhaust and change the knock sensor. Mine was constantly up and down on power. One day I would have full power which is really really quick and next it ould be about 120hp (as I dynod it on a bad day). I ended up removing the complete wiring loom and found an issue with the wiring for the knock sensor

Thanks for the suggestions, I'll check the knock sensor. It's not throwing a knock sensor error code, did you just have to work your way along the loom til you found the bad point in the loom?

Just a thought, I've double checked the error codes on the car and still just getting the O2 sensor on one bank faulting.

Disconnected the knock sensor and it's throwing the code for the knock sensor so the car thinks that the sensor is working.

I was thinking though, it's plausible that the sensor is working, but it not functioning correctly but for some reason has become more sensitive and is detecting a bunch of knock when in fact there is none.

My dyno sheet might back this up, as the torque curve looks awful, it's lumpy and all over the place, and while the engine feels smooth, it almost looks like the car's backing timing out of it all the time and killing the power.

I'm thinking of removing the knock sensor from the block, and just leaving it plugged into the loom just in the engine bay cable-tied up somewhere. This would be a good way of testing whether this solves the problem without having to swap in another knock sensor. At least as a test. I'm sure if I run good octane in the car and set it up on the dyno with a good knock sensor and headphones we can tune it well and just run it with the "dummy" knock sensor plugged into the loom.

So, a quick question, if I pull the knock sensor out of the block, will I need to plug the hole? (Does the hole the knock sensor is plugged into link to any water/oil gallery or is it just a blind tapping?

If it's not a blind tapping, does anyone have an idea of the thread size for the sensor so I can machine up a plug for the vacant hole?

The knock sensor is in a dry cavity so if you pull it you dont have to worry about plugging it. If your o2 sensor is faulty it could make the ecu think its lean and thus would retard the timing and mess it all up

Off to the breakers tomorrow to try and scavenge a lambda sensor or two.

Also trying to figure out whether I can disconnect the knock sensor and just bridge with a resistor to make the ECU think the knock sensor is there but not detecting any knock. I know a lot of modern ECUs actually fault if there's not a sensible signal coming from the sensor but I'm hoping the Lantis R ECU isn't that smart.... this would just save me pulling the sensor out

if it is only the o2 fault then it is probably the rear sensor. Which code is it ?

15- Oxygen sensor or circuit
17- Oxygen sensor (check the fuel and ignition system performance)
23- Rear 02 sensor inactivation error
24- Rear 02 sensor inversion error

Maybe it is simple to check with a volt-meter. Measure between the grey wire and ground, it should be showing some low voltages (0.3-0.5v) when running and slighty oscilating. No voltages at all is a dead sensor

Well I've tried everything, I reset the codes on the ECU and it's not faulting at all any more. I used to have an error 24 with the car, but that seems to have gone away, I suspect it may have had a air leak or a vac leak earlier on that I fixed and I'd not reset the ECU since then.

Compression on the car is good, all the sensors are good, I've swapped out a bunch of sensors for other ones that also test good and the car makes EXACTLY the same ~130bhp.

So the car's got plenty of fuel, it's got plenty of compression, it runs smooth, doesn't burn any oil, runs smack bang on temperature, runs just sweet as a nut.... but only makes 130bhp.... maybe Mazda were just using extremely small horses when they tested the thing, I dunno.... but I'm all out of ideas.

The only thing left to check really is the cam timing, maybe someone's assembled it a tooth out? What's the best way to check for that?

Another thing crossed off the list, the cambelt has been checked and is in perfect nick, ant not assembled a tooth out. I haven't had the cam covers off to check the alignment marks on the cams themselves in each head line up but I suspect they've never been out of the car anyway.

I did find the TPS was a little out of adjustment, and I have reset it, which has cured my high idle problem, but it wasn't much out and I doubt this will make much of a difference if any at all.

Still at a loss to think what it may be. Still at around 130bhp at the engine according to my GPS datalogger, which tallys with the dyno numbers.

Hmmmmmm that really is confusing. What oc5ane fuel you running and have you tried a second ecu

Running it on 98 octane, which is good he best pump petrol we get here. ECU unknown but assuming it's the standard one. Any way of telling a type R ecu from a regular?

Im not really sure how to tell the differences between the ecus to be honest. Something to do with the numbering on them. Open up the side of the ecu and check the actual links as on mine one of the links actually blew but wasnt picking up a code but down on power. Or check for dry joints on the circuit board

Going to try re-setting the timing tonight using the diagnostic mode as this could potentially be out. Will see how I go.

i know its a long shot but have you tried hotter / colder plugs? or 8mm (bigger) maqnecor spark plug leads? will give better spark and probally a bit more hp on the meter. otherwise only other thing i can think of is borrow a aftermarket ecu.

Well first weekend of racing come and gone, and it seems that 130-140bhp is all the car is capable of. I'm going to probably refresh the coil/distributor as a matter of maintenance soon, but I just had a thought.

Has anyone ever actually put a standard Type R on a dyno to see what it actually makes? Given my experience and that of the other Lantises in the series, it seems like Mazda were telling porkies with their factory figures as there's no way we can see that they'll make anywhere like 170ps!

If I could actually get the engine making over 160bhp, that would put us right on the tail of the Honda Integras and Toyota Levins... at the moment they smoke me down the straights so badly it's impossible to actually battle with them since any defensive manoeuvre serves only to delay them until the next long straight.

it would make 170 ps BUT japanese fuel is 100 ron. i do realise the highest nz fuel 98 ron.

you may have to blend the 96 and 98 to bump the octane number up a few points. but i think the computer isnt giving you the power you should have. you are using more throttle than a road car usually uses. and the computer may be restricting power to 'save' the engine.

Thing is though, that should only retard on knock. I have a knock sensor connected that's not connected to the engine, hence hearing no knock... result is the same whichever knock sensor I plug in... that's the only way it can sense which octane is in use.

I dont know what to say here as to what the issue is but I will agree that I have suffered from the same issue only difference being is that mine has definitely run at full power so I knew straight away when the power wasnt there... It is like jekyl and hyde when it is right compared to not right.

Thanks, that gives me encouragement at least Next things to do are to replace the coil, distributor cap, rotor and leads to make sure I'm getting good spark at high RPM, and I'm also going remove the exhaust, inspect it and cut out the middle muffler as it's possible this could have come to bits with age and be restricting things.

I'm sure that someday I'll stumble on the right thing and find the one thing that's causing me the grief! I just hope I don't have to take too long and replace the whole car to find it!

Here's my vids from my two races on the weekend, struggling for power, and also a near complete lack of brakes in the second race, but still having lots of fun!

not quite sure on the rules for the series you race in but a good modification on these engine is to fit an external coil on it as the tiny coil inside the distributor cant always keep up with demand

viewtopic.php?f=19&t=46035

Good tip, thanks! While I can't modify the stock system, there's nothing that says I can't refurbish the old one, and given that I'm guessing my coil is 260,000km old, certainly refreshing should hopefully help me get to where I want to be!

I can always jury-rig an external coil to test whether it's a night-and-day difference on the dyno too, which will at least confirm where the issue is.

hey badge, which cams does your kf-ze have??

do they say KL31 or KF01??

Haven't pulled the cam covers off to check, would guess they're KL31s though.

Good news, the new coil and leads certainly cleaned the car up a little, pulled a bit more smoothly especially when hot.

Then last weekend we took the exhaust system apart and found that whoever replaced the cat, replaced it with a resonator only 38mm in diameter, instead of the stock, rest of system at 51mm! Replaced with a stock-sized resonator and the car is DEFINITELY more powerful now. Will be interesting to get it back to the dyno again sometime soon. It might not be back at a full 167bhp, but I'd guess somewhere north of 150? Will do a dyno pull on my G-meter, since it was estimating 130bhp before, which tallies with the dyno result. Will advise

Looking forward to hear the results of the dyno pull. Also pretty sure it's meant to be 172 or 175hp (can't remember which exactly but definitely meant to be over 170) as standard