MOT emission Test

[DamirGTI 342]

Fair point , seems like the exhaust is still "porous" then ? ... otherwise , i'd be really concerned about those numbers .

 

Lean burning engine will in fact smell weird and hurt your eyes !

 

D

[petert 588]

Where did you mount the sensor? Idle readings are always dubious as there’s not enough flow. Make it idle at 1250 for the test.

 

The best east way to search for leaks is suck up some break fluid into the inlet, using a vacuum tube. Only put 50mL in a jar, as it happens fast. It’s a two person job. White smoke will piss out everywhere and you’ll instantly see any leaks if you’re laying underneath.

Edited May 30, 2020 by petert

[pug_ham 244 3 Cars]

15 hours ago, jackherer said:

Or it's got an exhaust leak

After reading through this topic again today, the last time I remember having a similar things on one of my cars was due to the exhaust.

 

IIRC, it was on my mum's old 205 spi auto after I'd replaced the backbox & due to manufacturers tolerance differences, the tail pipe was just inside the rear valance so fumes weren't being drawn away properly stood or at lower speeds and you could smell them inside the cabin.

 

We weren't happy with the fit of the backbox (Klarius iirc) so I got the local motor factors we'd got it from to find me a better one & they exchanged it which solved the issue.

 

If you had problems getting the system sealed previously, as suggested, I'd be checking for even the smallest leak as it can make a big difference.

 

g

[Telf 224 2 Cars]

On 5/30/2020 at 11:13 PM, petert said:

Where did you mount the sensor?

about 4 inches from the downpipe section, i thought it would need a suitable amount of space to allow the gases to merge post the split in the pipe.

 

I'm going to try your brake fluid suggestion , thanks very much

[Telf 224 2 Cars]

22 hours ago, pug_ham said:

the tail pipe was just inside the rear valance

hi graham, the exhaust is pretty much a standard system that i bought from andy. the tail pipe is clear of the valance as you would expect of a 'proper' system. I did notice whilst refitting the exhaust after the sensor modification there are five 3mm holes running down the floor pan on the passenger side. it looks like the same holes the brake/fuel pipe clips sit in. They are open to the underlay so I'm going to seal them up later today. 

[jackherer 543]

On 5/31/2020 at 10:19 AM, pug_ham said:

If you had problems getting the system sealed previously, as suggested, I'd be checking for even the smallest leak as it can make a big difference.

 

1 hour ago, Telf said:

the exhaust is pretty much a standard system that i bought from andy

 

To be clear the exhaust from Andy replaced the system I had trouble sealing, it isn't the same one.

[petert 588]

3 hours ago, Telf said:

 

I'm going to try your brake fluid suggestion , thanks very much

Please get someone to video it. It's an insane amount of smoke.

[Telf 224 2 Cars]

Clips added here... As I had some spare

[Leslie green 111]

Those holes are for cars with  power steering the cooling loop clips along there .

[Telf 224 2 Cars]

small up date.

 

took the exhaust off again and re positioned the Wideband sensor. Rebuilt. I've driven it once this week and kept an eye on the AFR gauge. At idle its displaying 14.1 to 14.2. At speed but only very light throttle so cruising it reads between 15 to 15.6 so leaned out. Throttle fully open accelerating onto a motorway reading about 13.5 so richening up and blipping into 12.8/9 region momentarily.

 

I've no experience of this but as far as i can tell this seems about right? 

 

Here is some info from an article i found online

 

AFR Values & Characteristics in Four Stroke Engines
 6.0 AFR - Rich Burn Limit (engine fully warm)
 9.0 AFR - Black Smoke / Low Power
11.5 AFR - Best Rich Torque at Wide Open Throttle
12.2 AFR - Safe Best Power at Wide Open Throttle
13.3 AFR - Lean Best Torque
14.6 AFR - Stoichiometric AFR (Stoich)
15.5 AFR - Lean Cruise
16.5 AFR - Usual Best Economy
18.0 AFR - Carbureted Lean Burn Limit
22.0+ AFR - EEC / EFI Lean Burn Limit

Lean Conditions - Common Side Affects
Hotter Engine Temperatures
Detonation / Pinging
Hesitation in Throttle Response

Rich Conditions - Common Side Affects
Engine Flooding
Decel Pop / Backfiring
Lethargic Throttle Response
Excess Carbon Build-up (sooty pipes)
Fuel Smell from the Exhaust

[Telf 224 2 Cars]

still stinks of something- gotta be a fuel leak. im going to disconnect everything fuel related and check again.

[welshpug 1,661]

I had the fuel pipes from tank to filter start leaking on my zx a few years back, filter is on the front right corner of the tank, only noticed it when rolling along in slow traffic through Aberystwyth in summer with the window down.

 

the 2 pipes from tank to hard line are 400mm long rubber, fuel feed in the engine bay are both plastic with a rubber coating, rarely give issue, fuel return is rubber

[Telf 224 2 Cars]

I think it's got to be a union as all the pipes and clips are new. Everything. Nothing was reused from old.onnthr build 

[Telf 224 2 Cars]

Work continues as new ideas spring to mind!

 

Attached a smoke machine last night and found the bloody exhaust leaking . Tiny leak but there. All sealed up now. Exhaust is completely sealed . Initial checks seem to still be around the figures I quoted before. So not sure if that's ok or the map is wrong now.

[welshpug 1,661]

if the leak was before the lambda then its possible the readings will be a little different.

[petert 588]

14 hours ago, Telf said:

Work continues as new ideas spring to mind!

 

Attached a smoke machine last night and found the bloody exhaust leaking . Tiny leak but there. All sealed up now. Exhaust is completely sealed . Initial checks seem to still be around the figures I quoted before. So not sure if that's ok or the map is wrong now.

You mean you weren't game enough to try brake fluid? It's the best.

[jackherer 543]

17 hours ago, Telf said:

found the bloody exhaust leaking . Tiny leak but there.

Where was it leaking from?

[Telf 224 2 Cars]

5 hours ago, petert said:

game enough to try brake fluid?

we used some light gun oil - created a hell of a smoke screen

[Telf 224 2 Cars]

2 hours ago, jackherer said:

Where was it leaking from?

the union at the down pipe just forward of the wideband. 

 

hardly noticeable until the smoke appeared