The first point I would check is the MOT tester equipment with a reading that high, especially if its running fine. That is a high reading.
As previous recommendations – temp sensor.
Temp sensor reading should be ?? approx
0deg.C 5.0- 6.5 komhs
20deg.C -2.2-3.0 khoms
40degC 1.0-1.5kohms
80deg.C 250-400 ohms
Most of the GTI and 16v ECU air and water temp sensors should fall within the above ranges
The only other possible point, one or two of the injectors are leaking by.
Help - MOT failure due to emissions
- MULLEY
- Over 2k
- Posts: 8406
- Joined: Thu Jun 22, 2006 11:10 pm
- Location: Derbyshire
- My Cars: 1999 Xsara LX 2.0HDI (90) Hatch - Fern
2002 C5 2.0 HDI (110) Estate - Jasmine - SORN
2011 Mini Cooper D Clubman - SOLD
2016 Mercedes A180D Sport - Auto refinement
1992 TZD Turbo - Bluebell - SORN
1992 TZD Turbo Estate - SORN
1991 Gti 16V - Blaze - crash damaged, will get repaired - SORN
1990 Gti 8Valve SOLD - looks like it's been scrapped
2002 Mini Cooper S - SOLD - i miss this car
1992 TXD - Scrapped in March 2014
1988 CX 25 GTI Turbo2 - SORN
1996 - AX Memphis 1.5D - Dream - SORN - x 8
- Brian King
- BX 4x4 Owner. Brave.
- Posts: 116
- Joined: Sun Sep 03, 2006 1:06 pm
- Location: Stroud, armpit of the Cotswolds
Help-Mot failure due to emissions
I went down to the MOT station to beg for more time and mentioned to him that I had another Jetronic box in the shed. He said swop them over and let's put the analyser on it again, nothing to lose. So that's what I did, cleaning everything including the SCART plug and socket. Connected it all up, pushed and pulled the plug a few times, and the car started first time. Warmed it up and took it down to the MOT station and hey presto, 3.5. He wrote me out the MOT on the spot. It could be that the spare Jetronic box I had was good and the one on the car was bad, but I have a strong suspicion that one of the tags on the SCART plug or socket may have not had a good connection, and putting the plug in and pulling it out several times might have cleaned the blades and sockets. I shall put the old jetronic box on again and have him put the analyser on once more. If it shows 3.5 or thereabouts, it's almost certain to be the SCART connection that was playing up. I'll report on the result.
I've still got a dud vacuum unit on the dizzy and I'm going to phone Independent Ignition Supplies of Bideford and Express Autoparts of Kettering to see if they do one separately. Otherwise I'll be looking for a S/H dizzy. There is one school of thought I've come across that says the vacuum unit doesn't do much and you can do without it !!
I've still got a dud vacuum unit on the dizzy and I'm going to phone Independent Ignition Supplies of Bideford and Express Autoparts of Kettering to see if they do one separately. Otherwise I'll be looking for a S/H dizzy. There is one school of thought I've come across that says the vacuum unit doesn't do much and you can do without it !!
- DavidRutherford
- BX Digit man!
- Posts: 2706
- Joined: Wed May 18, 2005 5:07 pm
- Location: Placing comments on YouTube.
Re: Help-Mot failure due to emissions
In terms of the engine running well, and producing full power, yes, the vacuum advance does very little. What it does do is provide proper economy when running at anything less than foot-to-the-floor. When you have vacuum in the inlet manifold, the engine is running at a reduced volumetric efficiency, and so increasing the ignition advance will provide increased efficiency.Brian King wrote:There is one school of thought I've come across that says the vacuum unit doesn't do much and you can do without it !!
Thus, you set up the engine with no vacuum advance (just dynamic advance) and get it running correctly, and then add vacuum advance afterwards.
this might be a signature
- Brian King
- BX 4x4 Owner. Brave.
- Posts: 116
- Joined: Sun Sep 03, 2006 1:06 pm
- Location: Stroud, armpit of the Cotswolds
Help - MOT failure due to emissions
Thanks David. That is the very first time this has ever been explained to me in a way that I understand. Are you an engineer by any chance?
- docchevron
- The Immoderate half of the admin team
- Posts: 7524
- Joined: Sun Jun 04, 2006 7:03 pm
- Location: A Bucket of Fish
- x 7
- Contact: