DDK - Die Deutschen Klassiker

Couple of people have mentioned my injectors might be at fault & causing all the unburnt fuel in my emmissions.

My CO2 is fine but hydro carbons sky high.

Anyway, where is the best source / price for new injectors for a 1973 2.4S MFI?

I have never needed them but gave enquired about the price from my supplier, who only deals with the trade. They are around £60 each.

Matthew @ Type911 can also get these for you, similar price I believe. All the usual suspects should able to get these to be honest.

Alternatively, Merc diesel specialists should be able to test them at the high pressures required, although can't say i've explored this route.

My local Lucas depot did an ultrasonic clean and test on mine. I think the bill was about £60.00

Bob

I assume the ultrasonic testing & cleaning sorted them out ?

Looks like it will be worth finding a specialist 'up north' to have a look

I bought a bench top ultrasonic cleaner. It works great on carbs and it is certainly the best way to clean injectors.

Alan

Hi, What were the CO (not CO2) and HC readings? MFI run best set to about 4.5 - 5.0% CO at idle when hot - forget the OE specs for when new.
It the CO is too rich OR too weak the hydrocarbons will rise alarmingly.

Chris

the Co was @ 5%

Ok then - how high was the HC reading ?

unfortunatly I don't have a full print out.. when it had its annual full service @ Specialist cars I asked them to check the emmissions, which they did but I'm meant to be taking it back for further investigations. All I know is the Co appears to be fine yet it is making peoples eyes sting who follow me & when 'reving' it n my yard you just can a slight black smoke haze

If you can get the Bosch part number you can get them cheaper than the £60 allegedley, but I haven't pursued this yet.

Is the performance still ok or do you experience hesitation in any part of the rev range?

Hi James

I took my injectors to a diesel specialist to test, but diesel injectors work at a much higher pressure than the ones in our mfi cars, diesel injectors brake off ( brake off is the pressure required to overcome the non-return valve, spring) at figures around 2000 psi where ours brake off at 212 to 250 psi, his guage was at the bottom of his scale but he told me they were all u/s. I took them and tested them myself with a accurate pressure tester and found that some were braking off at lower pressures ie 190psi but it was the fact that the spray patten was poor and that the injector was dribberling/leaking, that was of most concern. MFI cars rely on the fuel being atomised properly to ensure that a proper burn is achieved. If the fuel is not atomised properly then a full burn will not happen and unburnt fuel will exit the exhaust. My car was very smelly when running, to the point that people in other cars wound up there windows if i was stopped in traffic, after installing new injectors the car runs better and no more smells/unburnt fuel.

Hope this is of some help.

John

John,

I assume you bought and fitted replacements? I've read on that there US forum that even new injectors can be fairly hit and miss in terms of release and pattern.

Did you test the replacements before fitting them?

Anyone else have any experience with this?

Cheers,

Chris

butzsi wrote:Is the performance still ok or do you experience hesitation in any part of the rev range?

No hesitation, and it pulls like a train