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RIPPed
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547 Posts
Discussion Starter · #1 ·
I am finding that when my car gets cold, I have to hold the key and turn the engine over for 4-5 seconds before the car will start. Is this pretty normal or not? Does it get better or not? I've never had problem when I was just running headers and intake. Thanks again.

Constantly looking for problems,
Trev
 

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Kampfbereit
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17,852 Posts
TrevMill said:
I am finding that when my car gets cold, I have to hold the key and turn the engine over for 4-5 seconds before the car will start. Is this pretty normal or not? Does it get better or not? I've never had problem when I was just running headers and intake. Thanks again.

Constantly looking for problems,
Trev
I bet after the "1000 mile learning period" things should get better. If anything barely lay your foot on the accel pedal like 5% throttle and that might speed up your ignition times a little bit.
 

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Trance Addict
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378 Posts
Tearstone said:
I bet after the "1000 mile learning period" things should get better. If anything barely lay your foot on the accel pedal like 5% throttle and that might speed up your ignition times a little bit.
That's what I was going to say. Put a new intake on not to long ago and have noticed it takes more cranks on cold starts then it did before resetting the ecu. Should go away soon.
 

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ol' #4
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225 Posts
Yeah, starts get alittle better but not much. Do not give it any gas though. Just let it warm up on its own and give the black box time to do its thing.
 

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RIPPed
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547 Posts
Discussion Starter · #5 ·
I just went outside and tried something new. Its about 35 degrees outside right now, so I was expecting the car to barely crank at all. I turned the key forward and let it sit there for a second before I actually cranked it, and it fired right up. I guess the fuel pump turned on and primed everything up good??

Still though, while the car is warming up my idle is pretty undesirable. The idle goes up into the 1000s like normal, then it'll dip down to 400-500 then go right back up. It did this like 4 or 5 times until the car got warmed up good. Is THAT normal, and does it get better over time? I know I can't expect the idle to be perfect with a heavily modified car, but I just want to make sure everything is "normal". The car still only has like 50-60 miles on it with the SDS.
 

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Kampfbereit
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17,852 Posts
TrevMill said:
Still though, while the car is warming up my idle is pretty undesirable. The idle goes up into the 1000s like normal, then it'll dip down to 400-500 then go right back up. It did this like 4 or 5 times until the car got warmed up good. Is THAT normal, and does it get better over time? I know I can't expect the idle to be perfect with a heavily modified car, but I just want to make sure everything is "normal". The car still only has like 50-60 miles on it with the SDS.
For the SDS that is normal ... for that "first 1,000 mile learning period".
 

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turbo? unf unf!
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1,972 Posts
i dont think this is normal guys. in my turbocharged setup, i get the same problem just like trevmill described. i hooked up my fuel pressure gauge and i noticed it takes a while for the fuel pressure to rise up. could this be related to the fuel pump or something else?

Tearstone and all you guys FI'ed, do you get the EXACT same problem too or what?

what kind of fuel pressure regulator are you guys using? is it boost-referenced? i don't think i our stock fuel pressure regulators are BOOST REFERENCEd, because i didn't see fuel pressure raising 1:1 while monitoring my fuel pressure gauge and boost. that would explain why i was large injectors were leaning out at the top end.
 

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turbo? unf unf!
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Did you all drill small holes on the bottom of your reservior cup too?
 

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turbo? unf unf!
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the stock fpr is atmospheric. you need a boost referenced fpr to maintain a constant pressure @ your injectors. i don't know why you guys arent using a 1:1 fpr.
 

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turbo? unf unf!
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does your fuel pressure rise under boost though?
 

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turbo? unf unf!
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i'm not talking about a different method of tuning or FMUS here. i'm talking about a needed mechanical fuel component on all cars that will see boost.

what i'm trying to tell you is that factory turbocharged cars have a 1:1 boost referenced fpr stock.

this allows the injectors to see a constant pressure, and never a difference which allows them to work fully and easily. for example:



for the sake of comparison, lets say your stock fuel pressure is 50 psi at 0 psi of boost.

now you're running your car(with a stock fpr) and you're boosted at 8psi, your fuel pressure doesn't raise stock -- so your injectors would see a difference of -8psi of difference making them work harder thus losing flow. but if you had a boost referenced 1:1 fpr, your injectors would see a "0 psi difference" and they'd work at their rated potential and give the right flow.

i calculated, for 8psi of boost and using 450cc/min injectors, you loose around 60cc/min if your fuel pressure regulator isn't raising 1:1, which is bad, because your injectors are acting like they're 390cc/min injectors. this makes it very crucial to have a 1:1 boost referenced FPR in your car to maximize the potential of your injectors. i mean sure you can upgrade to 550cc/min injectors if u're running lean with 450cc/min injectors -- but why not run your injectors at their rated pressure to maximize flow potential?


i'm not talking about a FMU here, i'm talking about a boost referenced FPR. fmu's like in the AAI kit are like 12:1, in that case, you're overloading the injectors and forcing more flow for each pound of boost and since this is adjustable, this is a different way of tuning.


i have an emanage, 450cc/min injectors, and im waiting for my 1:1 Boost referenced FPR to come in on monday or friday. i'll tell you if i lean out on the top end or not.
Stock turbocharged cars all come with boost referenced fuel pressure regulators.

i know for a fact that our cars come with an atmospheric fuel pressure regulator which only adjusts under vacuum and not boost. when it sees boost, the fuel pressure sticks to 49-50 psi.

i hope this clears up what i was trying to say.
 

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Sebring 6G72
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518 Posts
you definitly want a rising rate regulator. there is not really any way around it.

i would love to see the fuel trims on a car with 450cc injectors and no fmu/fpr.

i use a Vortech FMU. Largest disk 53psi idle. 99psi @ 7psi

you want to keep those fuel trims happy. if you raise the pressure dependant on boost(which on a sc'ed car is a constant), along with the larger injectors(which just makes the right combo between min/max fuel pressures and rich/lean conditions) you will see the fuel trims will not have to stray so far from their stock maps.
 

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Kampfbereit
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17,852 Posts
Bottom line, we have 400cc injectors and we do not have any problems with supplying enough fuel at 5.8psi, we have to lean our AFCs out quite a bit to get to 12.5:1 A/F ratio. When we go up in psi, I am sure that having a rising rate fuel pressure regulator will become more important, but as of now... it is not an issue.
 

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Sebring 6G72
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518 Posts
Tearstone said:
Bottom line, we have 400cc injectors and we do not have any problems with supplying enough fuel at 5.8psi, we have to lean our AFCs out quite a bit to get to 12.5:1 A/F ratio. When we go up in psi, I am sure that having a rising rate fuel pressure regulator will become more important, but as of now... it is not an issue.

well im glad to hear that...


do you have any idea of what your short and long fuel trims are?

I know that my ecu(not same as yours) cannot give enough fuel at WOT with just larger injectors.

and while you are leaning out your afc you are advancing the timing.... i would rather adjust my fuel and adjust my timing seperatly.
 

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turbo? unf unf!
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you're running 99psi fuel pressure at full boost? what kind of injectors? :) what boost? etc =) maybe i can help.
 
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