Hi there, I'm a new member. I installed my MJ on my modified 75 Spitfire 1500.
It seems to work great . I have not road tested it yet just preliminary startup and checking to see that the laptop was communicating with the MJ.
The Map sensing is running around 70K at idle, now I have yet to do fine tunning but it is eratic and at a high 70 range. is this normal?
I am using Kehin quad carbs from PRI, I plumbed 1/8" lines from each manifold tube to a 3/4" round by 2" long collector and then out with one single tube to
the MJ. Any input would be great. RT
map sensing and Kehin quad carbs
Moderators: JeffC, rdoherty, stieg, brentp
Hi RT.
Sorry this isn't an answer to your problem, just a fellow sufferer of it...
http://www.autosportlabs.org/viewtopic. ... fire#12974
However, I managed to get my Kpa down to 50 ish. I only have twin Keihins as it's a 63 1147cc spit with only two inlets rather than the four on the later models. I tested the vacuum seal with an old SU carb and the Keihins (nothing technical just a pipe and a suck
). I found that the SU with the butterfly definitely seals better than the Keihins that just have the slide between the manifold and the outside world. This makes me wonder if it would actually be possible to get the Kpa as low as 20-30. (still waiting for answers on the above post, or here in yours )
I started out with around 70 Kpa at idle, but adjusted the slides down as low as possible before re-balancing to the highest one. I couldn't balance to the lowest one as they were both already as low as they would go.
As you've done this too, can I ask you where you tapped into the manifold? I just tapped into the rubber connection part as it seemed the easiest option to begin with as the rubber could easily be replaced if it wasn't suitable.
Until I get any information to the contrary, I'll tune it based on the 50 kpa at idle. I'll need to keep the load bins range the same (10 through 103) as I do see the Kpa getting to 25-30 ish when dropping from high to low rpms.
Nige
Sorry this isn't an answer to your problem, just a fellow sufferer of it...
http://www.autosportlabs.org/viewtopic. ... fire#12974
However, I managed to get my Kpa down to 50 ish. I only have twin Keihins as it's a 63 1147cc spit with only two inlets rather than the four on the later models. I tested the vacuum seal with an old SU carb and the Keihins (nothing technical just a pipe and a suck
). I found that the SU with the butterfly definitely seals better than the Keihins that just have the slide between the manifold and the outside world. This makes me wonder if it would actually be possible to get the Kpa as low as 20-30. (still waiting for answers on the above post, or here in yours )I started out with around 70 Kpa at idle, but adjusted the slides down as low as possible before re-balancing to the highest one. I couldn't balance to the lowest one as they were both already as low as they would go.
As you've done this too, can I ask you where you tapped into the manifold? I just tapped into the rubber connection part as it seemed the easiest option to begin with as the rubber could easily be replaced if it wasn't suitable.
Until I get any information to the contrary, I'll tune it based on the 50 kpa at idle. I'll need to keep the load bins range the same (10 through 103) as I do see the Kpa getting to 25-30 ish when dropping from high to low rpms.
Nige
I would say stability in the MAP reading is more important than the actual value measured. Once it's stable then you can tune from those values. I would encourage you to put a vacuum gauge onto the same pipe leading to the MAP sensor to compare readings.
If you have problems stabilizing the readings you may want to adjust the size of the dampening chamber, or consider switching to a TPS version of Megajolt.
If you have problems stabilizing the readings you may want to adjust the size of the dampening chamber, or consider switching to a TPS version of Megajolt.