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Author: Subject: Coolant Temperature & AFR

posted on 18/5/16 at 08:15 AM Reply With Quote
Coolant Temperature & AFR

I have the E Type running on megasquirt now and have done a few runs to get the fueling somewhere near.

It will not run smooth under normal driving at anything leaner than 12.5:1, it tends to hesitate and backfire in the plenum.

I'm still running the stock carb 74 degree thermostat, but with a high efficiency alloy radiator, which at first cooled the engine enough to pull it back onto WUE, re calibrating the temp sensor and adjusting the enrichment decay fixed that.

I am wondering if changing to the 82 degree thermostat would help with the running, I believe the carb fed XJ6 S1 and 2 ran 74 degrees, then the S3 on EFI ran 82 degrees.

I just want the car running well enough to do the 100 mile or so trip to Dale's for a RR setup, without risking wrecking the engine on the journey, any advise welcome.



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posted on 18/5/16 at 09:04 AM Reply With Quote
I got to the point with my MS where the engine was running but just could not get it sorted. Dale picked my car up on a trailer and brought it back finished with new Jenveys, dual fuel injectors and 193 BHP.

Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016

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posted on 18/5/16 at 10:36 AM Reply With Quote
74c should be okay

What is you ignition advance curve like classic hemi engines like the XK and old Lotus Ford Twink need a quite a lot of advance as the RPM rises compared to modern engines, and weaker mixtures need more advance than rich mixtures.

Aside from that it could be a single cylinder or pair of cylinders running weak to duff injector(s), only way to test for that would be an injector balance test.

[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.

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posted on 18/5/16 at 10:55 AM Reply With Quote
All the injectors were cleaned and flow matched, I acquired about 20, and selected the closest 6.

I have 15 degrees static advance, I've been as high as 18 as per late XJ6 efi, no load its pretty linear up to 36 degrees all in at 2800rpm.

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posted on 18/5/16 at 02:59 PM Reply With Quote
Quite a few older engines don't like to idle leaner than 13.5 or so, but they should be able to drive around quite nicely in the 14's (obviously richer at wot).

Daft question, but are you sure the wideband is reading correctly/calibrated. It might not be as rich as you think....


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posted on 26/5/16 at 06:58 PM Reply With Quote
How have you got your injectors wired and setup
In MS?

You'll probably find your injector timing is out. Your firing into a bloody massive port, if the fuel is not drawn in very quickly it falls. Making or richer glosses over the problem.

Try batch fire (all 6 at some time) 3 times per engine rev

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