Failed Injector? (graphs inside)

[fattail95]

Evening all,

Did a long 260mile trip the other day in the 406, and used a can of BG244 injector cleaner as it had started to run a little lumpy and the injector correction value was creeping up on cylinder 1 and dropping on cylinder 2. All seemed fine until today when I started her up, I got an awful misfire for the first five seconds and very strong diesel smell from the exhaust, accompanied by smoke. This misfire got better after a few minutes of running but it still isn't right, but definitely worst when cold. I fired up my laptop today to harvest some data, and these are the injector correction values individually graphed. I believe it is injector 1, as it has a positive value (indicating not enough fuel getting through??) and injector 2 is trying to compensate (hence low negative value??) I've never been totally clear on how these corrections work to balance the engine, perhaps someone could help. Cylinders 3 and 4 seem fine to me, nice low numbers.





Any insight would be great, I bought a spare set of injectors from Kelv which I will get cleaned and fitted ASAP as well as a new fuel filter, just wanted to confirm it is the injector first? Has the BG244 shifted a lump of dirt from inside the HP pump or pipes which has clogged an injector?

Best Regards,
Ben.

[Doggy]

Hi Ben,

I read somewhere that the ecu monitors the crank and camshaft sensors and seeks to even out the acceleration pulses from each power cycle using the correction factors. From this, it follows that small and similar values are good, bigger numbers or difference between values are indicative of problems.

Have a look at my tale of woe: viewtopic.php?f=1&t=14490&hilit=wobble

A leak-off test could be a good place to start.

[Welly]

I can't add anything technically but it would seem that the injector cleaner has caused the issue?

[steve_earwig]

Or the injector was screwing up anyway and the injector cleaner/snake oil did precisely bugger all to change anything

[fattail95]

I'm getting the new injectors sent off to be tested and cleaned tomorrow, hopefully should have them in next week with a new genuine Bosch fuel filter + housing. Touch wood this should sort the problem, if it does I will put up graphs of correctly functioning injectors as it may help someone in the future.

[Doggy]

FWIW I have similar issues when it's cold (0 degrees or less). Mine will start easily, but race/hunt and make a really loud diesel clatter for typically a few seconds, but sometimes longer. With the milder weather of the last few days, it's behaved perfectly.

Tried waiting for the glowplug light too, but it makes no difference.

[fattail95]

UPDATE

The replacement injectors I got were tested by Darwen Diesels, two were close to the limit for a pass, and two failed. They offered me a set of 4 freshly rebuilt injectors for £430 delivered, and since I plan on keeping this motor for a long time to come I thought why not. So the old injectors were removed, the seats recut, new washers, leak off pipes and connectors fitted and fuel filter replaced. At idle it is so quiet, with no vibration across the rev range and smoothness like I've never experienced in her, even in sub-zero conditions. Easily the biggest difference of everything I've done to the car so far, its brilliant. I think we forget just how high tolerance these injectors are, and just how well they perform when they are functioning as intended. I've heard so many HDi's with clackety, old, blocked injectors I'd forgotten how refined the HDi sounded when it was new all those years ago.

Best Regards,
Ben.

[dirtydirtydiesel]

Good result Ben if not a bit pricey , I am considering this myself
but I'm waying up fitting 307 injectors, I've heard that there better quality
But I'm with you I've put too much into this car to stop now & it does everything I need
ps: a bit more power would be nice

[PeterN]

Has it improved the fuel consumption any?

Peter

[fattail95]

Fuel consumption has improved 5-7mpg, however mine is not an MPG hunter and is driven spiritedly most of the time. Still get 45mpg overall though, and will sit at 60+ when cruising on the motorway.

Ben.

[PeterN]

Interesting, thanks. I have two '51 plate estates both of which are averaging around 50 mpg, my original 'Y' reg was doing nearer 60 mpg, I know the cold weather makes quite a difference so although I have had no rough running I am wondering if that could be the problem.

Peter