well i will be tuning the car with megasquirt and have begun reading the mega manual, what version are you guys using? also where are you guys mounting the brain unit? i want to tune fuel and data log can i just buy the megasquirt-1 also do i have to add anything once i buy it preassembled, or do i just piggy back it?
thanks
jason
I'm running Megasquirt-II on the 3400. It's mounted in the trunk. Down side is that I had to run a vac. line through the car for it, which i'm slightly worried about over time. I'm not sure what firmware version I have on it currently. And It's kinda sorta piggybacked in. The stock ECU controls only my speedo and temp gauge at this point.
You'll want dedicated temperature sensors for Megasquirt. You can't splice two sources into one GM temp sensor, and you need the stock J-body computer's sensors for spark control and transmission control. A CLT and IAT are the only extra sensors you'll need that I can think of off of the top of my head right now. Considering you only want to control fuel, MS-I is fine. Just be warned though, if you go with the MS-I pcb2.2, you won't be able to upgrade to MS-II. Only pcb3.0 boards can upgrade to the MS-II processor.
As far as myself: I run MS-II (spark and fuel) on an automatic LD9 and I just keep the box behind the driver's seat since I almost never have more than 3 people in the car at any given time.
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Quote:
You'll want dedicated temperature sensors for Megasquirt. You can't splice two sources into one GM temp sensor
GM 3 wire CTS FTW! One sensor, 2 computers. And I happened to have a TPS plug laying around, which plugs into the sensor.
That's what I use anyways. You order it for a 93 Cavalier 2.2. On the 3400 at least the problem is that the sensor is a bit longer (or I think maybe it just has more threads) so on mine at least you thread it in and it bottoms out before you get all the thread in like you're used to seeing. But you have enough thread in there for it to not leak or blow back out.
^^^^ lol. That's my bad. I should have been more clear. I was refering to the typical GM 2-wire temp sensors found on stock j-bodies. Thank you for correcting me.
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so i have to have 2 coolant temp sensors and 2 iat sensors? where will the 2nd ones go? do i have to just kinda make them work? the motor is a 95 2.2 by the way. and i am still reading the megamanual!! lots of info!
thanks
Here's the deal.
You'll need that stock ECU still in there in order to operate your gauge cluster and you can use the Megasquirt to run the engine. I run MS-II (spark and fuel). I think that's the best way to go so you have full tuning, and not interruption from the stock comptuer freaking out.
In this case, you only need the one IAT sensor, since the only computer needing one is the MS. If you use the stock computer for timing, then you'll need the 2nd IAT for the stock computer. But only if you use the stock computer for timing, if you let MS do it, you only need 1 IAT.
For the coolant sensor you need 2 of them regardless. The CTS will have to report the temp to the stock computer, the computer then sends the temp through the datastream to the gauge cluster, in order to point the needle in the right spot. If you hook both computers to the stock sensor what happens is your gauge points to the right spot, but MS never sees more than about 90*F of coolant temp, therefore never putting you in closed loop mode (where it uses the O2 for fuel correction). So you'd need a second sensor.
However, I saw the 2nd gen guys would come up with this problem because 2nd gens with a 3.1 have 2 coolant sensors, one for the computer one for the gauge, and thus the 3.1 has to spots for coolant sensors. On the other hand a 2nd gen with a 2.2 uses a 3-wire coolant sensor. So when they do 3400 swaps they use this sensor, which has 2 outputs. One to run the gauge and one for the computer, which is what its made for. So I put the 3 wire CTS in my 3400, and ran one lead to the MS and one to the stock computer. Works perfectly. It's a way to get away with just having one sensor, and not having to drill and tap the head or anything for the second sensor.
so if i have no cluster then i still need the stock coolant temp sensor ??
thanks for all the help
jason
jason norwood wrote:so if i have no cluster then i still need the stock coolant temp sensor ??
thanks for all the help
jason
Torque convertor lock-up and I believe shift firmness is coolant temp dependant. That is assuming you still have the automatic transmission like you list in your registry. If you have a manual trans, then you don't have to worry about that. I know in Megatune 2.25 and the Extra code, there is a function for cold spark advance. So, if the J-body pcm has something similar, then that is another reason you'll want a coolant sensor. The only other reason I can think of though is to monitor coolant temp. Even though you don't have a cluster, I would highly reccomend you have some way of monitoring your coolant temp at all times. You never know when a thermistat might get stuck or fail...and then there goes your engine build.
If I were you though, I would go with MS-II. I don't know much about your engine build, but if you're running a hotter cam, then the stock spark control won't do you a great deal of good. A part of the J-body rev-limiter involves spark retard, so you will lose all of that higher rpm torque that a performance cam gives you. I believe JCavi ran into that problem before when he was running fuel only with Megasquirt.
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ok cool , ya i have 16 digital guages in a custom fiberglassed dash which include the water temp, but ill leave the stock ecu there as i still have the auto trans. my msd will control the spark and rev limiter but i don't have a custom cam yet
jason
Quote:
GM 3 wire CTS FTW! One sensor, 2 computers. And I happened to have a TPS plug laying around, which plugs into the sensor.
That's what I use anyways. You order it for a 93 Cavalier 2.2.
GM actually put one in the 'Retta around 93? There was a service bulletin with the part number. You'd do a coolant service then the dash gauge would show overheating, so GM used the 3 wire to provide a new location for the dash gauge.
Bulletin no 338118 says the sensor number is 10096181 and the harness that connects the temp gauge and the old CTS plug to the new CTS is 12154414.
HTH
-->Slow
if you have the all aftermarket guages, couldnt you get a FAST Trans controller to do trans shifting, and totally delete the factory ECU?
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
Nukkinfuttz wrote:if you have the all aftermarket guages, couldnt you get a FAST Trans controller to do trans shifting, and totally delete the factory ECU?
He has the LN2, so it heavily depends on whether he has a 3t40 or 4t40e. The 3t40 won't work with an electronic trans controller regardless for the obvious reason that the transmission is not electronically controlled for which in that case, the coolant sensor probably isn't necessary. I don't think the 4t40e will work with the trans controller either. From the different manuals I have seen for the TCI Transmission Control Unit (The "FAST" trans controller is just a rebadged TCI), the only transverse transmissions it works for are the 4t60e, 4t65e and 4t80e. I know the "A" and "B" gear select solenoids establish the gears differently between the 4t40 and 4t65e for sure, so unless the 4t60e or 4t80e have the same gear select as the 4t40e (or at least inverse), then no. Plus, the controller is near $800 alone without the wire harness. Your looking at close to a grand with the harness. I was going to build a cheap simple controller for the 4t40e last year, but never really got around to it. I think Ron (Shifted) was going to put a 4t40e control code in his PCM.
Here is the FAST Transmission Control Unit compatibility list
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