Mitsubishi Carisma (1995 - 2004) - 99 1.8 MOT failed on CO emissions

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Wed 30 Apr 2008 20:18
99 1.8 MOT failed on CO emissions - John S
A colleague's Mitsubishi Carisma GDI auto (107,000 miles) has failed the MOT on CO emissions. Natural idle test gave 0.93% CO (limit 0.3%). Two fast idle tests gave CO at 0.37% and 0.47% (Limit 0.2%). HC passed with 104 and 106 (limit 200), Lambda is fine at 1.004 and 0.998.

The car needed a new lambda sensor and an Italian tune up last year to pass. Unfortunately the car gets mainly short runs and is normally fed 95 octane. High CO made me think the air filter was at fault, but I'd expect the CO to be worse at fast idle if that was the problem. Garage are muttering about faulty injectors, and I'm inclined to think that has logic, with poor combustion producing the high CO and highish HC from unburned fuel. Last year there was some discussion about a failed catalyst, and it seems possible this could also cause these results. I know the GDi engines have some problems and I'd be interested to know if the Back Room have any ideas before my colleague has his wallet opened.

JS

Edited by John S on 30/04/2008 at 20:20

Reply | Report as offensive | Link
Wed 30 Apr 2008 22:16
99 1.8 MOT failed on CO emissions - Screwloose

Soot-clogged inlet manifolds are common. This disaster engine is best taken to an expert.
Reply | Report as offensive | Link
Wed 30 Apr 2008 22:31
99 1.8 MOT failed on CO emissions - John S
Thanks, screwloose. I couldn't recall what the 'typical' GDI problems were. Must be worth checking this, which I imagine must strangle performance. I imagine this is caused by excessive EGR. I'm guessing inlet manifold removal and cleaning is cheaper than replacing injectors. Now to find an expert.......

JS
Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide

From which small car to buy at which price point to the best UK-built cars, our Top 10s have the lot. Click now for your shortlist.

Unsure of what to buy? Our Top 10s are here to help you....