Post Number: 381
|Posted on Saturday, 13 August, 2016 - 11:17 am: |
Been a very long time but finally reunited with my car. 4200 km round trip with a trailer, combined weight of close to 6 tons and it's finally with me again. Total respect for the Land Cruiser that did the job.
Anyway on topic. Been getting back into the car and it's getting there. Couple of little gremlins I'm working through but none major. New rear tyres (Avons cough, for those that buy them will know what I mean) about to replace all the accumulators. None of that's an issue.
People probably remember Bentley power annoyance topic a few years back, or rather got bored with my persistence. Well it is progressing. Fitted a new fuel pressure regulator and that has helped a lot. The old regulator pressure varied too much depending on fuel flow from cold through warm up phase to running temperature. Not much maybe 3>>5 psi but that a mile with the CIS system. So at least now I can set AFR to where they are supposed to be and they stay set.
The question I have, and probably only pertinent to people who have studied AFR's on the K, KE or KE2 Jetronic but what can one expect AFR map wise.
Clarify the question, I can set the mixture to 14.1 which approximates to the 0.8% >> 1% CO in the manual when at temperature but under "no load" the AFR's drop quite linearly as the RPM's increase and stay at that AFR if you hold those RPM's say nominally 11.9 at 2500 rpm. Have to dig up my logged charts to be specific about the relationship. Would this be what one would expect from the KE2 (with no O2 feedback). Logically to me they should fall in response to the throttle change then climb back up to some nominal point but below the 14.1. Say nominally 13.5 or so, not stay at the linear response position that I'm seeing. I know there is no electronic feedback to make this change but the manifold pressure would change in response to the throttle change which would affect the air flow metering vane.
Keep in mind when at operating temperature the EHA only has a base current setting (5.9ma) unless boost or significant load as measured by the APT sensor. So there is no extra enrichment from this direction other than the base setting.
Reason I see this as a problem is if I do get to boost conditions or significant load the extra enrichment from the EHA would almost certainly be way too much giving me the symptoms of loss of boost. Effectively almost flooding the engine with fuel. No I haven't taken the car on the road yet after changing the fuel regulator as I haven't been game till I get the accumulators sorted so haven't been able to test under load or boost except in the driveway.
I'll follow up with a good map over the next couple of days to outline what I see as a problem. Have a gut feel what the problem might be, if this map is wrong, but don't want to pre empt valuable opinions to make sure I'm in the right direction.
Anyway thoughts welcome.
Omar M. Shams
Post Number: 757
|Posted on Sunday, 14 August, 2016 - 04:55 am: |
Welcome back mate. It has literally been years!!
I will not be able to help you as I have put my Turbo RL away over a year ago. I am playing with other very nice Bentleys and my old faithful Wraith II these days.
Richard Treacy is your man I am sure.
Keep us posted with your progress.
Post Number: 382
|Posted on Monday, 15 August, 2016 - 01:39 pm: |
Thanks, it's good to be back on the case, and good to hear your still enjoying your cars.
Think I sort of answered my own question with help from Richard and others at the time, did a bit of a search and came up with my previous query. "Air Fuel Ratio Setup with EHA" topic. Noticed I did have a logged run that made sense albeit with the fuel pump restriction depleting the accumulator thanks to an undersized washer on the banjo connection, subsequently sorted out. My current logs are way too rich but otherwise make sense.
Still to get my logger working properly but think the issue is related to my fuel distributor rebuild and how far the control plunger nut was screwed in, but want to confirm before pulling it apart. Been trying to compensate for the problem by richening the EHA to bring the distributor pneumatic/hydraulic pressures in balance. Which works to a degree at the expense of way too rich across the rev range.
Problem I had/have is, before playing with the EHA, under very light throttle the car was too lean until the revs got to a somewhere above 1200rpm. Load or no load. Making the car richer has helped so I can take off without a problem but the AFR's mechanical mappings are too low at the higher revs. This was compounded with poor pressure regulation from the old fuel regulator making it impossible to adjust with any sort of repeatability. That being removed from the equation with a new fuel pressure regulator leaves the distributor/eha left in the equation. There is still a residual clue in that even though I can drive the car the AFR's rise slightly maybe 0.3 before dropping as the revs rise. All I've done is make it a lot richer to compensate, not fixed the problem.
Should have taken note of the depth setting of the nut on the distributor but all I have to go on was a photo before I dismantled it. Hardly a good measure to go by. Aside this depth setting think the rebuild worked fine as the car idles and starts fine minus this issue. Noticed apparently Bosch preset these to 0.6mm (based on a Merc article) so maybe that's a start.
Post Number: 383
|Posted on Monday, 15 August, 2016 - 02:13 pm: |
Thinking a bit more, might be that the nut is screwed in too far, pulling the plunger clear of the roller in the air box. Could account for why even though I've made it way rich I still have slight AFR rise before the air vane acts on the plunger. Just not sure why that clearance wouldn't be adjusted out with the mixture screw!!! These things are beautifully simple in concept but the inter related mechanics, hydraulic and pneumatics are not simple.
I'll have to get those logs happening.