cam and EFI problems
03-16-2003, 05:59 PM
#1
Guest
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cam and EFI problems
I've got a '75 coupe, and I put a big loppy race cam in my car. Well now I'm running really rich at an idle and lean in the high end, I've never been able to find a chip for this car so how do I re-work my fuel injection to match my cam?
03-17-2003, 04:37 AM
#3
Guest
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Adjustable fuel pressure regulator, and I'd like to have an adjustable timing box with a MAP sensor, but I am very picky since I am used to being able to fully program my EFI car.
You can't really do anything with the 280Z computer as far as 'programming', supposedly it is analog. The 300ZXT computer is being used though, with ECCS, you are going to be burning your own chips and programming in HEX, so its not as user friendly as Tunercat or other commercial packages.
Ask around about an adjustable fuel pressure regulator, and check to see that you are happy with your timing, timing is very important on a big cam without crappy low end.
You can't really do anything with the 280Z computer as far as 'programming', supposedly it is analog. The 300ZXT computer is being used though, with ECCS, you are going to be burning your own chips and programming in HEX, so its not as user friendly as Tunercat or other commercial packages.
Ask around about an adjustable fuel pressure regulator, and check to see that you are happy with your timing, timing is very important on a big cam without crappy low end.
03-17-2003, 10:52 AM
#4
the Dude
Join Date: Mar 2002
Location: Bay Area, California
Posts: 381
mudge, do you think he could piggyback an s-afc type unit, or maybe replace the 280z ecu with an sds fuel management unit?
I was driving to work actually thinking about this question, and I was going to recommend an FPR as well.
I was driving to work actually thinking about this question, and I was going to recommend an FPR as well.
03-17-2003, 12:49 PM
#5
The Evil Twin
Join Date: Mar 2001
Location: Seattle, WA
Posts: 9,294
Do you really think its running rich at idle, or is the long duration just causing you to have lower compression at low rpms? That is typically what you have with a race cam and that gives you a rough idle.
However, it is true that the Z fuel injection leans out at higher rpms. Richening up the mixture through all rpms and adding the rising rate fuel pressure regulator are ways to help keep the fuel flowing at high rpms. Don't worry too much about your low rpm power. If you want that back, either try advancing your upper cam sprocket to the #2 position (with a new timing chain) or just put in a shorter duration cam.
The advanced cam will close the intake valves sooner and help raise the static compression of the engine. High end power may suffer slightly, but mainly above 5500rpm.
If you have a high lift cam and/or have shaved your head make sure you are going to have enough clearance for the valves to clear the pistons.
However, it is true that the Z fuel injection leans out at higher rpms. Richening up the mixture through all rpms and adding the rising rate fuel pressure regulator are ways to help keep the fuel flowing at high rpms. Don't worry too much about your low rpm power. If you want that back, either try advancing your upper cam sprocket to the #2 position (with a new timing chain) or just put in a shorter duration cam.
The advanced cam will close the intake valves sooner and help raise the static compression of the engine. High end power may suffer slightly, but mainly above 5500rpm.
If you have a high lift cam and/or have shaved your head make sure you are going to have enough clearance for the valves to clear the pistons.
03-17-2003, 01:38 PM
#6
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Posts: n/a
if you want to play with your fuel injection, goto this site, it gives you values for the different resistors inside to lengthen the width of the injectors, and other tricks you can play on your computer via the temp sensor and the AFM... along with some other stuff. i would reccomend finding another ecu on ebay though, and play with that one in case u manage to screw things up!
http://demo.cs.brandeis.edu/postscri...Injection.html
this isn't the manual site that everyone sends you to when you're having problems. this gets into programming and such.. a pretty good read even if you aren't going to hack the computer apart. it might be easier, and to a point maybe more cost and time effective to goto carbs. you can pick up webers and dellortos pretty cheep on ebay... i am going to be running dhla 40's. right now the motor is stock, however i will be putting flattops in, headers, exhaust, and a "fun" street cam...
http://demo.cs.brandeis.edu/postscri...Injection.html
this isn't the manual site that everyone sends you to when you're having problems. this gets into programming and such.. a pretty good read even if you aren't going to hack the computer apart. it might be easier, and to a point maybe more cost and time effective to goto carbs. you can pick up webers and dellortos pretty cheep on ebay... i am going to be running dhla 40's. right now the motor is stock, however i will be putting flattops in, headers, exhaust, and a "fun" street cam...
03-17-2003, 02:28 PM
#7
Guest
Posts: n/a
Originally posted by auxilary
mudge, do you think he could piggyback an s-afc type unit, or maybe replace the 280z ecu with an sds fuel management unit?
mudge, do you think he could piggyback an s-afc type unit, or maybe replace the 280z ecu with an sds fuel management unit?
I wouldn't mind having a fully programmable aftermarket unit, but it eats up $. I was looking into a Typhoon setup, but it would probably be easier to work with the 300ZX stuff, other than the hex editing which might turn off some people. How much is an SDS fuel management unit? I imagine its not cheap. I would love to have the real deal over a bandaid any day, but if it works, and its cheap, then I'd consider it whatever it is.
If you wanted adjustable timing there are boxes out there that will do this, but they aren't cheap either. By the time you bought seperate timing/fuel boxes, it would cost about what an entire setup would be all in one unit, and be programmed of course by only one software package.
There is also Megasquirt, but without starting out with a fuel map, there would be some learning curve and time involved. When you buy the expensive FAST/MoTeC stuff they give you software which will calculate a base setup for you, how nice.
03-17-2003, 03:34 PM
#8
The Evil Twin
Join Date: Mar 2001
Location: Seattle, WA
Posts: 9,294
I have heard of some people who built the forced induction Megasquirt for the turbo six. Maybe if we find someone who has a built unit for an L6, they can give us some numbers for a base to start from. Then it just needs to be put on a web page for reference.
That actually is a good idea for a fuel injection setup. It sure is a lot more time consuming.
That actually is a good idea for a fuel injection setup. It sure is a lot more time consuming.
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