Morgans Exocet build thread

[themorgster]

I warmed the car up (20mins at idle + 20mins at 2500rpm) and the inlet was a fair bit higher than the outlet...

Inlet:


Outlet:


Defo not working properly. I’m going away for a week so I’m going to leave it to soak in a mixture of degreasing agents... if that doesn’t work, new cat time!

[snowbird1]

If the lambda (HO2S) sensor is not working it should have flagged a OBDII fault, the sensor needs to be working for the cat to operate. When the system is in closed loop the fueling will be switching rich/lean, the O2 available during the lean part of the cycle is used by the cat to function, if the downstream HO2S senses O2 in the exhaust it ‘knows’ that the cat isn’t working.
If the HO2S is not functioning or the system is not going into closed loop a new cat won’t help. You can monitor sensor operation with a DVOM connected to the sensor output, on the MX5 this means back probing the sensor connection although the scan tool may show it.

[themorgster]

Thanks for your comments, you are of course correct, a stuffed lambda will cause incorrect fuel/air mix and will probably produce so much CO, the best cat in the world wouldn’t be able to turn it all into CO2. I probably should have mentioned that I replaced the lambda sensor before I temp tested the cat. Also my car doesn’t have a post cat sensor, so it has no way of knowing if the cat works or not, so no codes. While the temp delta test is indicative of a defective cat, I think the only real test will be a proper (Mot) emissions test. I hold out little hope for my cat cleaning efforts, but all it’s cost me so far is 2.5 litres of engine degreaser.

[snowbird1]

I've never tried to clean a cat but my feeling is that solvents won't work very well, cooking it might be more successful, I would try burning it out with a blow torch, cats can run up to red heat so you probably can't hurt it.

[wishful4444]

carbon-cleaning.co.uk/catalytic-converter-cleaning

[russhowell]

Sorry to read about the fail. Cant understand the 'touch the engine' thing.
My tester had no issue about this and actually said, no problem with the openings into the engine bay.

Hope you get it sorted. Its a shame the retest has to be at the same test centre

[stuli]

Forgot to ask if your fuel drip tray was necessary or even mentioned during the IVA test?

[themorgster]

While it was up on ramps while I was in it and the inspector and his apprentice was below, he said something to the apprentice about the drip tray I had made, something about checking the drain on it to make sure it didn’t output over the exhaust. I forgot to ask afterwards (as I was up there for 30mins) but he definitely noticed it.

[themorgster]

Talking of fuel leaks, a new day, a new problem... so I rinsed the degreaser out of the cat that it had been soaking in, reattached it and ran the car at 3000rpm for 15 mins to warm it up / dry it out. As it was running I smelled fuel so I shut it off and went sniffing around for a leak. I found some fuel weeping from the filler. I undid the filler 1/4 turn and it literally gushed out, like under pressure! WTF!!! I soaked it up with an old towel as it kept pouring out. When it finally stopped (less than 500ml - ish) and I got the cap all the way off, I could see that the neck was full. It went down after a few minutes, but why the hell is fuel coming up the filler neck? The filler is physically located on the side but above the top of the tank. I am using the original Mk2 filler neck and flexible pipe. Also worth mentioning is that when I tried to fill it up 2 weeks ago (on the way back from the IVA) it would only take 20 litres when the gauge said 1/4 full. It was also a pig to get the fuel in, slow with plenty of spit back. I just assumed that the sender was knackered, but now I’m not so sure...

[wishful4444]

Do you have a charcoal filter in the fuel tank vent? If so it may be blocked. Tanks have to vent to allow air in to replace fuel pumped into the engine. But to prevent fuel fumes being emitted, the vent system may be be fitted with a charcoal filter.

[themorgster]

I have removed the charcoal filter, as have almost everyone else. I have a small filter on the non-return valve on top of the tank (see picture) to allow air in. If it were blocked, that would cause an excessive vacuum issue... I appear to have the opposite.

[wishful4444]

Is the fuel vent pipe clear? Maybe remove it and see if the problem persists.

Is the tank getting hot?

[Stiggy]

there is useful info in the link here regarding filling with fuel.
www.mevltd.co.uk/forum/discussion/66/fuel-cap-location?new=1

[themorgster]

So I got the emissions retested today after my cat washing efforts... my friendly mechanic tested the CO and it was 0.6% (same as the IVA) at 2750rpm. He gave it lots of beans (~5000rpm+) for a couple of mins (and also turned the lights on???) - retested to 0.34% at 2750rpm (a fail). He said that given enough time he could probably coax 0.3% for 5 seconds (a pass), but the IVA/VOSA guy will never do this - fair point. Conclusion: Cat washing efforts were fruitless and a new cat is required.

[camspeed]

I kind of waited for this.....done it all myself in the past. You get my sympathy vote mate!

So thanks for sharing this story. It makes me feel better that I am not the only person hell bent on getting a cat cleaned myself.

My Exocet already has a new cat but an MX5 I ran recently failed emissions repeatedly even after a top end engine rebuild and a remap, so I changed the cat. I think I got £30 trade in for the old one from the motor factors so it pulls the cost down a bit.