Member Since: 24 Jun 2021
Location: West Sussex
Posts: 418
Do I need to replace injector no1
Just hooked up my AP200 to clear a seat rail fault code and thought I’d have a look at live values. Noticed injector no1 was reading, what I think is low. Engine temp just above cold. Thoughts please. Thanks.
5th Nov 2022 4:47 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
Acceptable range is 700-1300, try again with the engine at normal operating temperature, it may well be that injector 1 is being 'reined in' to compensate for another cylinder, it's not always as simple as reading the offsets and changing the highest and lowest.
5th Nov 2022 4:53 pm
Garwood56
Member Since: 24 Jun 2021
Location: West Sussex
Posts: 418
Cheers and will do. That’s given me a bit of relief. Engine actually runs really sweet.
5th Nov 2022 4:58 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
I've seen numbers around 650 before now with no adverse effects, lots of short / commuting journeys can skew the offsets, sometimes all it needs is a good long drive to decoke the cylinders and valve ports.
5th Nov 2022 6:14 pm
Garwood56
Member Since: 24 Jun 2021
Location: West Sussex
Posts: 418
That’s really interesting as for the last 3 weeks I’ve been working locally so small journeys. I think tomorrow I’ll go for a good long run👍
5th Nov 2022 6:29 pm
Breg90
Member Since: 04 Feb 2017
Location: Falkirk
Posts: 348
Had a think about this out of curiosity as these posts come up from time to time. Knowing that cylinder numbering, injector numbering and firing order are not the same I have never been sure how folk interpret the data and chose which injector to look at.
So, I put the data into a spreadsheet with your injector live values with the cylinder numbers in firing order:
Then had a look at the LR Maintenace manual for the injectors. They don't measure flow. But the system knows how long the injectors are commanded to be open for. This is the figure in the 'live values' in my opinion. If the injector has an issue the opening time (the 'live value') may not be the same as the amount of fuel delivered.
My understanding of the system is that crank position sensor monitors crank rotational speed. It can detect uneven rotation caused by either:
1/. An injector over fueling compared to commanded value, then cut back the following injector to even out the rotational speed.
2/. An injector underfueling compared to the commanded value, then increase the following injector(s) to even out the rotational speed.
So, looking at your data. normal range is between 700 - 1400. So 1000 is about the middle. There is no injector commanded to a high figure (compensating for a under fueling preceding injector). However, injector 1 (in cylinder 1) is being commanded to a low fueling value. I suggest that injector 6 (in cylinder 6) is admitting more fuel than demanded and is the culprit. This is causing injector 1 to cut back to compensate.
Other may have far more experience and come along to contradict this!
Adrian
Edited to correct injector numbers on diagram[/u][/i]Series one 1949 - in bits, chassis is strapped to the ceiling in my garage (beside the canoe)
LR 90 - In bits
Disco 3 - currently in bits
5th Nov 2022 10:51 pm
ronald.soak
Member Since: 29 Apr 2008
Location: London
Posts: 516
Thanks Adrian, that's very useful.
5th Nov 2022 11:32 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
Subject to relative compression checks (i.e. cranking speed variance) and injector leak-off measurement, that is the conclusion I would come to, dependent upon usage & measurement variables.
In other words, there's a lot of variables that can affect the fuel trim, it needs to be looked at long-term, not as a snapshot. DTC's need to be addressed accordingly and can cause an upwards or downwards drift in fuel trim.
An example:-
3.6 TDV8 (relevant as it is part of the LION family of engines, as are the 2.7 & 3.0 TDV6) brought in with HP fuel pump & older inlet manifold leakage, both issues rectified and the vehicle used 'normally', fuel trims were in the range of 712-798 across all cylinders after 500 miles. 'Normal' usage is typically 4.5 miles x 2 for five days a week then 4 x 12 miles for 2 days a week. Once a decent (>200 mile) mixed usage trip had been undertaken did the fuel trims (and gear change adaptions) get back to something close to 'normal' - lowest was 910, highest was 1100. If the fuel trim data was viewed in isolation, then a set of eight injectors would have been replaced for no benefit.
ETA - @Breg90
Quote:
normal range is between 700 - 1400
acceptable range is 700-1300, 600 & 1400 are the min & max trims before a relevant DTC are set.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
