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Old 08-02-2007, 12:57 AM   #1
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Default Last minute questions before install

Alright, I have a handful of small questions before I finish up my PNP harness for my 97 and install MS.

1. On the 97, what is the proper way to control the fuel pump? Can I just wire up the light green wire to the fuel pump wire on Megasquirt? I know the 1.6 cars use the AFM to trigger it, but wasn't sure on the later cars.

2. Can I run MS without an AIT sensor initially? I'm installing it while N/A in parallel with the stock ECU, but plan on using the GM sensor when the turbo goes on (within the next few weeks). Is the AIT crucial for tuning when N/A?

3. Also, when having it initially installed, can it share the O2 sensor line with the stock ecu? I have an LC1 that will be installed, but I am waiting to have it installed with my downpipe when the turbo goes on, so for now, just using a NB.


I appreciate any help given, I am planning to get MS installed by the end of this weekend!
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Old 08-02-2007, 08:27 AM   #2
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I can answer #2

NO, the MS needs the IAT signal.
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Old 08-02-2007, 08:52 AM   #3
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Quote:
Originally Posted by karter74 View Post
Alright, I have a handful of small questions before I finish up my PNP harness for my 97 and install MS.

1. On the 97, what is the proper way to control the fuel pump? Can I just wire up the light green wire to the fuel pump wire on Megasquirt? I know the 1.6 cars use the AFM to trigger it, but wasn't sure on the later cars.
cut the fuel pump signal line and attach it to your harness.

Quote:
2. Can I run MS without an AIT sensor initially? I'm installing it while N/A in parallel with the stock ECU, but plan on using the GM sensor when the turbo goes on (within the next few weeks). Is the AIT crucial for tuning when N/A?
not a chance it'll never start. don't be lazy and hook the sensor up, it takes 5 minutes to drill into the stock airbox/crossover tube and use a bit of silicone sealant.

Quote:
3. Also, when having it initially installed, can it share the O2 sensor line with the stock ecu? I have an LC1 that will be installed, but I am waiting to have it installed with my downpipe when the turbo goes on, so for now, just using a NB.
I'm not sure if you can share, but when I installed mine I just cut the line and gave the signal to the MS. stock ECU is too dumb to know any better. (what's it gonna affect anyway, you're controlling the suel and spark
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Old 08-02-2007, 09:34 AM   #4
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Thanks, the reason I'm asking about the fuel pump is because even though right now it will be installed with the MAF (so the stock ECU can switch the fuel pump on/off), I will be deleting the MAF when I go turbo, so I figured MS would then have to take care of the fuel pump.
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Old 08-02-2007, 09:57 AM   #5
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Originally Posted by karter74 View Post
Thanks, the reason I'm asking about the fuel pump is because even though right now it will be installed with the MAF (so the stock ECU can switch the fuel pump on/off), I will be deleting the MAF when I go turbo, so I figured MS would then have to take care of the fuel pump.
The MAF isn't the same as the AFM in the 1.6. there's no Fuel pump switch in the MAF. i.e. the MAF isn't used to switch the FP on and off, the ECU does all that gubbins

I hooked up the Fuel pump straight away, and then deleted the MAF about 6 weeks later.
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Old 08-02-2007, 10:30 PM   #6
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If it's true that the ECU does all the fuel pump work and doesn't rely on the MAF like the early 1.6 cars, then would I even need to bother with hooking it to MS? I mean, if its gonna be installed in parallel with the stock ECU, then couldn't the stock ECU control it just as well?

Also on cutting the O2 line to the stock ECU, while it may not affect the stock ECU in any real way, I find it hard to believe it wouldn't throw a CEL, something I'm hoping to avoid altogether by installing MS in parallel with it.
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Old 08-02-2007, 10:36 PM   #7
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The lc-1 can simulate a nb sensor which you can hook to the stock ecu. With it hooked up there you wont get any cel's.
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Old 08-03-2007, 05:06 AM   #8
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Quote:
Originally Posted by karter74 View Post
If it's true that the ECU does all the fuel pump work and doesn't rely on the MAF like the early 1.6 cars, then would I even need to bother with hooking it to MS? I mean, if its gonna be installed in parallel with the stock ECU, then couldn't the stock ECU control it just as well?
Correct, it does, It's one wire, and I've tied stock and MS controlling and and didn't notice one jot of a difference. I left it with MS control tho, then I can tweak the priming pulses etc
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Old 08-03-2007, 11:04 AM   #9
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Originally Posted by richyvrlimited View Post

not a chance it'll never start. don't be lazy and hook the sensor up, it takes 5 minutes to drill into the stock airbox/crossover tube and use a bit of silicone sealant.
Not true.

It starts and runs. Just a very stupid idea to do so. I had (past tense) it running with no AIT, not sure how, but it did.
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Old 08-03-2007, 11:49 AM   #10
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Ms does not need ait it is just better to have it CLT is however needed most of us dont even bother with air temp related retard etc. and go off coolant temp for everything i like mine for the novelty and recording of conditions though.
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Old 08-03-2007, 12:40 PM   #11
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Originally Posted by reddroptop View Post
Not true.

It starts and runs. Just a very stupid idea to do so. I had (past tense) it running with no AIT, not sure how, but it did.
Tis true on mine, I was messing around and unplugged my sensor, when I'd finished I forgot to plug it back in. It refused to start.
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Old 08-03-2007, 12:42 PM   #12
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Originally Posted by magnamx-5 View Post
Ms does not need ait it is just better to have it CLT is however needed most of us dont even bother with air temp related retard etc. and go off coolant temp for everything i like mine for the novelty and recording of conditions though.
?? I presume you're n/a as with FI and especially a charger you NEED an IAT. the coolant based intake temp compensation curve is way off for my higher than normal intake temps (fully heatsoaked 35-40 degC)

I also need to use air temp related retard or on a good hard run it'll induce knock.
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Old 08-03-2007, 05:40 PM   #13
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No rich i am running 15 psi of 16g fury With the stock timming maps un modified. My ait would do me no good what so ever with the sensor before my nozzle coolant temp compensation is all i use, and that is only for warm up realy. So to recap 14 psi + no IC or timming devices=lots of fun.
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Old 08-04-2007, 01:34 AM   #14
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IAT is a vital part of the fueling equation, you need to have this sensor hooked up. If the sensor isn't used, how is MS supposed to calculate the 'density' part of the speed density fueling equation?

http://www.megamanual.com/v22manual/mfuel.htm#equation
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Old 08-04-2007, 08:36 AM   #15
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Quote:
Originally Posted by mschlang View Post
IAT is a vital part of the fueling equation, you need to have this sensor hooked up. If the sensor isn't used, how is MS supposed to calculate the 'density' part of the speed density fueling equation?

http://www.megamanual.com/v22manual/mfuel.htm#equation
exatamly
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Old 08-04-2007, 08:40 AM   #16
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Originally Posted by magnamx-5 View Post
No rich i am running 15 psi of 16g fury With the stock timming maps un modified. My ait would do me no good what so ever with the sensor before my nozzle coolant temp compensation is all i use, and that is only for warm up realy. So to recap 14 psi + no IC or timming devices=lots of fun.
14psi, no IC, stock timing curve and you're engine is still running?

wait, you say the sensor before a nozzle? you running WI? that makes more sense. You still *need* the IAT as MS uses it for it's calculations the fact that the reading is inaccurate is inconsequential really as you've tuned the map around to compensate.
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Old 08-04-2007, 07:04 PM   #17
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Exactly WI. I havent gone so far as to just disconnect the AIT but seeing as i dont have anything setup to use AIT it shouldn't matter. Yeah i like to live on the edge, flogged a few gallons out of my WI yesterday in high 85-90% humidity with 95 or so degrees ambient temps it worked very well. No knock and good power all around
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Old 08-04-2007, 09:12 PM   #18
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Exactly WI. I havent gone so far as to just disconnect the AIT but seeing as i dont have anything setup to use AIT it shouldn't matter.
Um, no. See my link above. You can not run a speed density EFI system without an IAT. Period. You are using MS for fuel, right?
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Old 08-05-2007, 02:21 AM   #19
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yes
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Old 08-06-2007, 04:42 AM   #20
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Quote:
Originally Posted by magnamx-5 View Post
Exactly WI. I havent gone so far as to just disconnect the AIT but seeing as i dont have anything setup to use AIT it shouldn't matter. Yeah i like to live on the edge, flogged a few gallons out of my WI yesterday in high 85-90% humidity with 95 or so degrees ambient temps it worked very well. No knock and good power all around
won't work mate, you still need the sensor for the fueling calculations
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