www.RX7fb.com

So the latest development is that the hydrocarbon emissions have crept up, so something I'll need to look into. (Hydrocarbons were 688 at the last MoT, but over 2,300 yesterday!) This means there is a fair amount of unburnt fuel leaving the engine and going into the exhaust.

Really not sure where to start but my list of suspects are:

- Throttle Position Sensor. I noticed on the MegaView that the TPS voltage is 13.5v at idle. It then goes to 0.1v at light throttle openings to 5v at WOT, so the 13.5v thing seems incongruous! Does anyone on here know if this is normal, or is it a sensor / wiring fault?

- Leaky injector(s). Maybe if one of the injectors were sticking open, it'd be dumping too much fuel into the system. (Can anyone remember what injectors Steve used - presumably not the standard TL1000R ones?)

- Coils / strength of spark. Will check this.

- Lambda sensor? This is only on the list because I seem to remember Steve had an issue with this in his ownership. Not sure if that would cause running rich at idle though?

- Maybe it's just carbon deposits. Should perhaps take it for a long, hard drive and then go easy on the 2 stroke oil when I fill it up and take it for the test? Can't believe that would cause so much of a difference though...

I'm going to go and have a tinker, but if anyone has any suggestions then please let me know!

Pete

Your first job is to check plugs.

The car is not required to pass emissions remember.

coolant temperature sensor or intake temperature sensor?

Plugs look OK to me - what do you think? I'll have a look at the spark when there's somebody here to crank the engine for me.









TOOL - how so re: emissions testing? I thought all cars after 1975 need to be emissions tested (before that is visual check only), with the standard slower getting harder to achieve depending on the date of manufacture? e.g. http://www.ukmot.com/MOT%20test/Exhaust%20System.asp. I'd be very pleased if you could point me at the relevant info indicating otherwise however!

Coolant temp sensor looks to be reading accurate. (19 degrees at ambient - goes up to about 85 degrees before the fan kicks in). I'll take a look at the intake temp sensor, but the TPS is doing something slightly confusing:

On the MegaView, it's showing TPS voltage at 15.5v (sorry, typo my initial post), then 0.0v at light throttle through to 10.0v at fully open. I can only assume these are "Percentages" however not volts, because on the multimeter it's showing me 0.86v at throttle closed, up to around 4.06v and wide open throttle, which seems to be more accurate.

Confuzzled.

Rotarys before 1986 only require a visual check for emissions it is a add on to the standard mot requirements

Link

http://www.motuk.co.uk/images/730_newnoncat.pdf

It's a fuel only computer?

Check trailing spark is working.

TOOL wrote:Link

http://www.motuk.co.uk/images/730_newnoncat.pdf

Print that off and take it to your MOT tester.

Herman wrote:So the latest development is that the hydrocarbon emissions have crept up, so something I'll need to look into. (Hydrocarbons were 688 at the last MoT, but over 2,300 yesterday!) This means there is a fair amount of unburnt fuel leaving the engine and going into the exhaust.

Really not sure where to start but my list of suspects are:

- Throttle Position Sensor. I noticed on the MegaView that the TPS voltage is 13.5v at idle. It then goes to 0.1v at light throttle openings to 5v at WOT, so the 13.5v thing seems incongruous! Does anyone on here know if this is normal, or is it a sensor / wiring fault?

- Leaky injector(s). Maybe if one of the injectors were sticking open, it'd be dumping too much fuel into the system. (Can anyone remember what injectors Steve used - presumably not the standard TL1000R ones?)

- Coils / strength of spark. Will check this.

- Lambda sensor? This is only on the list because I seem to remember Steve had an issue with this in his ownership. Not sure if that would cause running rich at idle though?

- Maybe it's just carbon deposits. Should perhaps take it for a long, hard drive and then go easy on the 2 stroke oil when I fill it up and take it for the test? Can't believe that would cause so much of a difference though...

I'm going to go and have a tinker, but if anyone has any suggestions then please let me know!

Pete

Hi Pete. Jesse (Hobbawobba) dropped me a txt earlier trying to find out a few of the answers to your questions, figured it was easiest to log in and answer myself directly!

Firstly, yeah as everyone else has said, this car only needs a visual emissions test

I'm not entirely sure how Megaview calculates its TPS value. What you want to really do is hook a laptop up with Tunerstudio (it's free to download the lite version which will be fine for what you need), that should show you all the sensor inputs and outputs at once, much easier than trying to read off the small Megaview I installed in the car. What voltages correspond to what TPS percentage values, are a configurable item in tuner studio, which then downloads those settings the the Megasquirt, so it's possible that after an idle speed adjustment the TPS is reading -1% causing the odd reading.

The injectors are Subaru Impreza WRX ones IIRC, around 400cc/min. They just happened to be the right fit for the Suzuki throttle bodies and I saw a set going cheap on eBay.

The ECU controls fuel and spark. There is a 3d map for the trailing split, but it shouldn't have changed since last year so I think thats unlikely. It might be worth locking the timing to a fixed advance, again do this via Tunerstudio, and ten check it with a timing light, as if the crank sensor has accidentally been tweaked at some stage this could make a big difference to the emissions.

Finally, there is a calibration procedure for the lambda sensor, its an Innovate LC-1 controller, if you google them I think there's some info on their website, if not wit the paperwork I gave you wit the car. Might be worth going through that, after that the sensor readout should be fairly trust worthy, again if it's running rich you can always go into Tuner studio and pull some fuel out of the map at idle till it meets the emissions targets. You want an AFR reading of 14.7 at idle to keep the MOT man happy.

Great, thanks Steve and everyone. Plenty to go on there!

I had Tuner Studio lite before, but yesterday it wanted me to complete a software update to the newest version and I can't get the TunerStudio to recognize the Megasquirt, which is frustrating! Am I right in saying it's the first download file (TunerStudio MS version 3.0.05) on this page that I need, as I can't see a 'lite' version? http://www.tunerstudio.com/index.php/downloads

That aside, I've also been in discussion with the MoT tester about whether or not it needs an emissions test, and he refuses to accept that it doesn't. Apparently he hasn't got time to speak to the Ministry of Transport person on the phone about it until Monday, which is a PITA. If I was being cynical, I'd say he's counting down the clock until my 10 days for a fee re-test expires. Next step is to print out the relevant links above and take them down to him...

In the meantime, I will persevere with trying to get my software to talk to the Megasquirt. Alternatively, does anyone know how they determine the max idle speed for the MoT? If it's OK to have it idling at say 1,200 rpm I might try a re-test with that, as that's giving a TPS reading of "0" (i.e. what it should be) and so maybe the emissions will be better (no over-fuelling)..

The AFR is sitting at about 12 - 13 to 1 at idle, so it's clearing running a little rich.

Thanks all, always a great forum for advice!