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| ECM upgrade (1227730) for stock 2.8 (Page 80/107) |
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fieroluke
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OCT 27, 11:39 AM
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Hi everyone.
I have another question regarding the EVAP solenoid/charcoal canister.
If I understand it correctly (please correct me if I'm wrong) there are three lines going to the stock Fiero evap canister.
#1) is the vapor line from the tank - this one stays as it is in the conversion, so I'll mention this one no more
#2) is the larger diameter vacuum line: this is where the engine purges/sucks the fuel vapors from the canister
#3) is the smaller diameter vacuum line: this one controls the valve in the canister and opens when vacuum is applied.
Now, in an early posting on this topic Darth Fiero wrote that an electrical (ECM controlled) solenoid is added in the
vacuum line. I assume this is the larger diameter purge line (#2).
But what about the smaller diameter control line (#3)? If it's left open or capped, doesn't the vacuum controlled valve on the canister
stay closed then? In effect, it wouldn't matter if the solenoid opens, the valve on top of the can stays closed anyway.
Or does the control line (#3) stay connected? In that case I gain ECM control of the canister, but keep both vacuum lines,
one of which I'd love to lose. Or am I mistaken regarding the operation of the system?
Best regards
Oliver[This message has been edited by fieroluke (edited 10-27-2008).]
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Darth Fiero
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OCT 27, 12:43 PM
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| quote | Originally posted by fieroluke:
Hi everyone.
I have another question regarding the EVAP solenoid/charcoal canister.
If I understand it correctly (please correct me if I'm wrong) there are three lines going to the stock Fiero evap canister.
#1) is the vapor line from the tank - this one stays as it is in the conversion, so I'll mention this one no more
#2) is the larger diameter vacuum line: this is where the engine purges/sucks the fuel vapors from the canister
#3) is the smaller diameter vacuum line: this one controls the valve in the canister and opens when vacuum is applied.
Now, in an early posting on this topic Darth Fiero wrote that an electrical (ECM controlled) solenoid is added in the
vacuum line. I assume this is the larger diameter purge line (#2).
But what about the smaller diameter control line (#3)? If it's left open or capped, doesn't the vacuum controlled valve on the canister
stay closed then? In effect, it wouldn't matter if the solenoid opens, the valve on top of the can stays closed anyway.
Or does the control line (#3) stay connected? In that case I gain ECM control of the canister, but keep both vacuum lines,
one of which I'd love to lose. Or am I mistaken regarding the operation of the system?
Best regards
Oliver
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The small vacuum line that goes to the Fiero EVAP canister is connected to a ported vacuum source on the throttle body. This line only sees vacuum at part throttle; therefore the EVAP purge valve on the canister will only open and allow purge flow at part throttle. This is how GM controlled the flow of EVAP vapors from the canister to the engine without a computer-controlled solenoid.
In later years GM added the EVAP purge solenoid because they found they could purge the charcoal canister a little during idle and decelleration operation (the EVAP purge solenoid is under pulse-width-modulated control meaning it can be opened by small to large amounts depending on what the ECM wants; does not have to be full open or closed). Therefore better control could be attained over the EVAP system via use of an electronic purge solenoid.
When doing the 7730 conversion, I recommend disconnecting the small vacuum line from the ported vac port on the throttle body and plugging the port on the throttle body. Next, connect the small vacuum line coming from the EVAP canister together with the larger purge line going to the engine via a vacuum Tee. Now connect the remaining port on this Tee to the "can" port of the EVAP purge solenoid. The other port of the solenoid gets connected to the larger vacuum line coming from the engine that originally connected to the EVAP canister. The reason why I recommend hooking it up this way is because the ECM is going to expect some EVAP flow (when it commands the purge solenoid open) during times when that legacy mechanical ported vacuum control system would normally be closed. It's just best to let the ECM control it as intended.
IF you have already wired up your 7730 ECM swap without using the EVAP purge solenoid, don't worry. The EVAP purge strategy has very little to do (and little impact) with overall engine operation. And for the record, I do recommend leaving a functioning EVAP system on the car when doing an ECM or engine swap. This prevents the buildup of fuel vapors in the gas tank which otherwise could result in a raw gas smell coming from the car on hot days or after extended engine operation. Under no circumstances should you ever plug the vent line coming from the gas tank as this could result in a potentially dangerous pressure buildup in the tank as the fuel is heated (either during engine operation or on hot days).
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fieroluke
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OCT 28, 03:18 AM
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Aaah, that makes perfect sense now. Thanks for the explanation!
Best regards,
Oliver
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fieroluke
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NOV 01, 11:42 AM
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For those who are having trouble removing the pins from the ECM connector, here is a link to a page detailing the procedure (scroll to the bottom of the page):
http://www.chevythunder.com...%20ecm%20pinouts.htm
It has pictures of what the pins look like and what's happening inside the connector i.e. where you have to insert the tool and what it does.
It also shows the lisle tool that can be used instead of a hairpin.
Hope someone finds this useful.
Oh, and *bump*.
Regards,
Oliver
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americasfuture2k
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NOV 01, 07:00 PM
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sweet, nice find luke. i had my doubts about that tool. thinking it was some sorta scam tool. but it looks real anad useful, so i may just need to get one. that lil weatherpack terminal removal tool is very delicate. i bent mine the first day. had just barely enough left to still use it. ------------------
First LX9 Fiero GT, 1987
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americasfuture2k
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NOV 08, 02:39 PM
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alright, got a new one for you ryan!
i built another 7730 harness, made it much cleaner and more organized than merlot's. all the pins and wires are in good condition and in the right spot. but my fuel pump will not come on without forcing it on through the ALDL. i plugged the APU1 in to see what the ecm is seeing. everything looks fine except that the log is showing no voltage at the fuel pump. what could be causing this to not spit out the 5 or 12 volts , whichever is needed? bad ECM possibly?------------------
First LX9 Fiero GT, 1987
If you can't fix it with a hammer, you've got an electrical problem
Fiero's are people too. We pay just as much attention to them, if not more than our loved ones 
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Hudini
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NOV 08, 04:31 PM
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Make sure the C203 is connected. This is the connector under the ECM. The fuel pump wires run through there.
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americasfuture2k
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NOV 08, 05:17 PM
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that is connected. but i dont see how that would explain the ECM not sending out the voltage. that datalog shoes 0.00v on the fuelpump.
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First LX9 Fiero GT, 1987
If you can't fix it with a hammer, you've got an electrical problem
Fiero's are people too. We pay just as much attention to them, if not more than our loved ones [This message has been edited by americasfuture2k (edited 11-08-2008).]
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Hudini
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NOV 08, 08:32 PM
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The ECM would be getting voltage, not sending it. Power to the fuel pump comes from the fuse panel. (Check your fuses?) I would check if the ECM is seeing voltage when you put 12v to the aldl plug. This may be hard if you are datalogging through the aldl plug. May have to stick the 12v wire into the backside of the aldl connector.
BTW: I just ordered the APU1. Should be here on Monday. This is gonna be fun.
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americasfuture2k
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NOV 08, 10:05 PM
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| quote | Originally posted by Hudini:
The ECM would be getting voltage, not sending it. Power to the fuel pump comes from the fuse panel. (Check your fuses?) I would check if the ECM is seeing voltage when you put 12v to the aldl plug. This may be hard if you are datalogging through the aldl plug. May have to stick the 12v wire into the backside of the aldl connector.
BTW: I just ordered the APU1. Should be here on Monday. This is gonna be fun. |
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i just swapped ECM's and still the same thing.
my fuses are good. ive tested the fuel pump relay turn on wire from the ECM and it reads nothing. its that grn/wht wire coming from the ECM to the FP relay.
the datalog doesnt show anything when 12v is applied to pin G on the ALDL. or....wait, come to think of it, i didnt apply any voltage to the aldl since i was logging through the aldl. tomarrow in the daylight i will try this and see what comes of it.
but one question, how would a good/bad fuse, or power applied to the FP itself by bypassing the relay effect what is shown on the datalog for the power on the FP? and why am i not getting any power on the grn/wht wire that goes to the FP relay coil? i know in order for a coil to energize, it needs power(+) and ground (-). my ground is good.
that APU1 is a pretty amazing and useful tool. emulates, logs, live tunes, burns and reads.
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First LX9 Fiero GT, 1987
If you can't fix it with a hammer, you've got an electrical problem
Fiero's are people too. We pay just as much attention to them, if not more than our loved ones [This message has been edited by americasfuture2k (edited 11-08-2008).]
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