red90 driver Posted June 2, 2011 Share Posted June 2, 2011 Well - the 3.9 fired up today on Megasquirt first time! 2 little problems - 2 injectors not working! Now sorted. TPS wired up backwards! Now sorted. One bigger problem..... (NO idle control, no lambda sensors) Initially the engine idled at 800 rpm, but was extremely rich. Then I found out that I had forgotten to connect the MAP sensor. Connected that, then the idle shot up to 1500 rpm, and stayed there. So, I closed the idle screw on the plenum, idle dropped to 1200 rpm. Then I changed the throttle stop to minimum, but that made no difference. I have gone through the Megatune review, but cannot see anything obviously silly. I also can't find out where to adjust the idle speed. This is a map from Nige (Hybrid form Hell) so am assuming there is nothing stupid in there to begin with. Any ideas? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 2, 2011 Share Posted June 2, 2011 What is the MAP at idle? (albeit the 1200 rpm idle) It sounds like you have an air leak... Quote Link to comment Share on other sites More sharing options...
red90 driver Posted June 2, 2011 Author Share Posted June 2, 2011 MAP at idel is 37. I also thought about an air leak, so I've gone round the plenum with contact cleaner spray, but the tickover never changed. The heated manifold under the plenum is still connected to the water system, so any air leak could be???? I've almost blocked up the plenum air entry with a piece of card, and the MAP went up to 47, then blocked it totally and the engine stalled straight away. Quote Link to comment Share on other sites More sharing options...
Muddy 1 Posted June 2, 2011 Share Posted June 2, 2011 You set the Idle, with the Idle valve removed and both ends of the piping bunged up and with a warm engine, set the idle Via the adjusting screw to around 800 rpm. Idle valve isn't fighting what you are trying to change. I had that problem to start with, and the leaking hole I removed a screw from Also the idle settings are in the " More Settings" tab in MT and TS. Quote Link to comment Share on other sites More sharing options...
red90 driver Posted June 2, 2011 Author Share Posted June 2, 2011 I don't have an idle valve! But I will check that I have sealed the bung......Yup, bung is in and sealed........ Does sound like an air leak, but I think the MAP readings are right... Quote Link to comment Share on other sites More sharing options...
red90 driver Posted June 2, 2011 Author Share Posted June 2, 2011 OK, stoopid mode OFF. Have found a solution for the moment. As there was no idle control valve of any description, the tickover was dictated by the fact that the air bypass was receiving full air flow, so have found a 3 wire PWM valve and inserted it into the said pipe, and then adjusted the idle speed on the plenum. Idle is now set at 700-750 rpm. Is this an acceptable solution as my MS is not setup for a stepper driven PWM valve? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 3, 2011 Share Posted June 3, 2011 A PWM valve in 'off' state actually allows for a small amount of air flow. For the moment - an acceptable solution, but bear in mind everything will need adjusting by the time you fit the correct hardware. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.