16168625 ecm DRP TBI firing
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16168625 ecm DRP TBI firing
guys i am trying to get the 8625 to fire every drp can this be done.
The reason i am looking to do this is because i am having idle and off idle issues.
using this ecm on a 4cylinder application
The current setup uses 2 quad4 low impedance injectors into the intake manifold.
The intake has cylinders 1&2 as common runner and 3&4 as a common runner.
the firing order is 1324 I wonder if I am missing fueling to the adjacent cylinder simply because of the intake design.
MY other option would be to install a single injector TBI ...
and use the 8625 ecm
Thought comments and help appriciated
The reason i am looking to do this is because i am having idle and off idle issues.
using this ecm on a 4cylinder application
The current setup uses 2 quad4 low impedance injectors into the intake manifold.
The intake has cylinders 1&2 as common runner and 3&4 as a common runner.
the firing order is 1324 I wonder if I am missing fueling to the adjacent cylinder simply because of the intake design.
MY other option would be to install a single injector TBI ...
and use the 8625 ecm
Thought comments and help appriciated
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From: Hurst, Texas
Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: 16168625 ecm DRP TBI firing
guys i am trying to get the 8625 to fire every drp can this be done.
The reason i am looking to do this is because i am having idle and off idle issues.
using this ecm on a 4cylinder application
The current setup uses 2 quad4 low impedance injectors into the intake manifold.
The intake has cylinders 1&2 as common runner and 3&4 as a common runner.
the firing order is 1324 I wonder if I am missing fueling to the adjacent cylinder simply because of the intake design.
MY other option would be to install a single injector TBI ...
and use the 8625 ecm
Thought comments and help appriciated
The reason i am looking to do this is because i am having idle and off idle issues.
using this ecm on a 4cylinder application
The current setup uses 2 quad4 low impedance injectors into the intake manifold.
The intake has cylinders 1&2 as common runner and 3&4 as a common runner.
the firing order is 1324 I wonder if I am missing fueling to the adjacent cylinder simply because of the intake design.
MY other option would be to install a single injector TBI ...
and use the 8625 ecm
Thought comments and help appriciated
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Re: 16168625 ecm DRP TBI firing
under the flag
i noticed 2 flags
CPI/PFI MODE ( 0=tbi mode)
Enable CPI port throttle control
Would I select BOTH ?
and Is that all I will have to do to fire the TBI ?? every DRP
i noticed 2 flags
CPI/PFI MODE ( 0=tbi mode)
Enable CPI port throttle control
Would I select BOTH ?
and Is that all I will have to do to fire the TBI ?? every DRP
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Re: 16168625 ecm DRP TBI firing
Don't select CPI Port throttle control. That actuality should read CPI tuning valve control but anyway that valve is not used in anything but a CPI intake so don't hit that one.
----------
Wait a minute. The CPI/PFI option on a v6 makes it fire every 3rd DRP and on a v8 it fires every 4th, but I don't know what it does on a 4 cylinder.
----------
Wait a minute. The CPI/PFI option on a v6 makes it fire every 3rd DRP and on a v8 it fires every 4th, but I don't know what it does on a 4 cylinder.
Last edited by neoblood; Mar 24, 2008 at 08:56 AM. Reason: Automerged Doublepost
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From: Dallas
Re: 16168625 ecm DRP TBI firing
That won't do it. The only thing that happens when you toggle the CPI/PFI mode bit is the PCM calcultes the injector constant differently. What you need to do is find a 4 cyl. single injector TBI Memcal for that PCM which may be next to impossible. This will fire both injector drivers every DRP. How the injectors fire is a hardware function. I dont know what a "quad4 low impedance injector" is but if they are low impedance port injectors, you will also need to modify the injector driver hardware. If they are TBI style injectors that measure 1.2 Ohms, then you are o.k. HTH
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Re: 16168625 ecm DRP TBI firing
using that ECm gm had 6cyl and 8 cyl memcals....
yes the injectors are 2 ohms or less
i have been reading about netres
As far as the memcals looks like 2 ecm's that are 4 cylinder ... 16156691 and 16199982 I wonder if those memcals could work in the 8625 ecm or 6395 ecm
yes the injectors are 2 ohms or less
i have been reading about netres
As far as the memcals looks like 2 ecm's that are 4 cylinder ... 16156691 and 16199982 I wonder if those memcals could work in the 8625 ecm or 6395 ecm
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From: Dallas
Re: 16168625 ecm DRP TBI firing
using that ECm gm had 6cyl and 8 cyl memcals....
yes the injectors are 2 ohms or less
i have been reading about netres
As far as the memcals looks like 2 ecm's that are 4 cylinder ... 16156691 and 16199982 I wonder if those memcals could work in the 8625 ecm or 6395 ecm
yes the injectors are 2 ohms or less
i have been reading about netres
As far as the memcals looks like 2 ecm's that are 4 cylinder ... 16156691 and 16199982 I wonder if those memcals could work in the 8625 ecm or 6395 ecm
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Car: '74 Firebird, '84 vette
Engine: 454 twin turbo, 350 HSR
Transmission: 4L80E, 700R4
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Re: 16168625 ecm DRP TBI firing
If I am not mistaken, there may have been a single injector TBI 4 cyl in an export only model. I seem to remember that but I could be wrong.
I found a definition file for the $83A but cant find one for the $94 which is the one I would need were I not planning to just run a '730 instead.
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Re: 16168625 ecm DRP TBI firing
Found out something interesting today
by installing the jumper indicated in the above notes..netres
This causes the A injector to fire every DRP
and causes the B injector to fire upon adding throttle only ... ( i think it async mode) .... The main A injector does not alternate it still fires every DRP ..but the B injector does not fire AT idle.....only in what i think is async
Does anyone know how to fire both injectors other that batch firing them ?
by installing the jumper indicated in the above notes..netres
This causes the A injector to fire every DRP
and causes the B injector to fire upon adding throttle only ... ( i think it async mode) .... The main A injector does not alternate it still fires every DRP ..but the B injector does not fire AT idle.....only in what i think is async
Does anyone know how to fire both injectors other that batch firing them ?
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From: Moorestown, NJ
Car: 88 Camaro SC
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Transmission: TKO 500
Axle/Gears: 9-bolt w/ 3.23's
Re: 16168625 ecm DRP TBI firing
Its possible to apply a code patch to fire the injectors when you want to in PFI mode. Basically all the memcal does is run a timer in the code. IIRC, the injector drivers could be set up to fire every DRP by basically just overwriting a couple lines of code with NOPs as they are software controlled.
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Re: 16168625 ecm DRP TBI firing
Thanks,,
i do need to understand the code
i need to relearn the basic's it been too many years since i have messed with proms ...
Any help or direction would be fantastic.
what i am doing is running a 4 cyl NOW using the $OD code using 2 injectors the intake manifold has only 2 runners so it shares 2 cylinder intakes on 1 runner.
currently i have tied both injectors together as batch but it obvious that the injector timing for the 2cyl firing is just a bit off... I need to get the 2nd injector to fire on the 2nd DRP ..
2 choices i see
possibly even get the injectors to alternate all the time...
or
fire both every DRP
i do need to understand the code
i need to relearn the basic's it been too many years since i have messed with proms ...
Any help or direction would be fantastic.
what i am doing is running a 4 cyl NOW using the $OD code using 2 injectors the intake manifold has only 2 runners so it shares 2 cylinder intakes on 1 runner.
currently i have tied both injectors together as batch but it obvious that the injector timing for the 2cyl firing is just a bit off... I need to get the 2nd injector to fire on the 2nd DRP ..
2 choices i see
possibly even get the injectors to alternate all the time...
or
fire both every DRP
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Re: 16168625 ecm DRP TBI firing
your posts are a little confusing so far.
If you leave the 8625 ecm alone (no mods) and run a TBI cal, then you can wire each injector to each driver. that should alternate fire them each DRP.
your other thread talked about a single TBI, single injector. That resistor mod made a single injector fire every DRP on the one driver.
I think you have everything that you need already either way, unless I'm confused?(wouldn't be the first time, hahah). Sorry if this sounded blunt, I'm trying to make sure I'm clear, for you, and for me, hah......
you're last choice I would think would to possible use a common plenum, did the engine have 2 carbs previously? sounds like a neat project.
how are you generating the dist ref?
If you leave the 8625 ecm alone (no mods) and run a TBI cal, then you can wire each injector to each driver. that should alternate fire them each DRP.
your other thread talked about a single TBI, single injector. That resistor mod made a single injector fire every DRP on the one driver.
I think you have everything that you need already either way, unless I'm confused?(wouldn't be the first time, hahah). Sorry if this sounded blunt, I'm trying to make sure I'm clear, for you, and for me, hah......
you're last choice I would think would to possible use a common plenum, did the engine have 2 carbs previously? sounds like a neat project.
how are you generating the dist ref?
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Re: 16168625 ecm DRP TBI firing
your right i have been skipping all over the place (sometimes i have a brain misfire and my fingers dont sync to my thoughts)
the 8625 ecm is setup for 8cyl or 6 cyl ( i have both memcals)
unable to get a 4cyl memcal for this ecm
I was 1st wondering how I can fire like a 4 cylinder ... every drp
you suggested the memcal modification THANK YOU
I made the modification on pin 13 of the 16 pin memcal ....
and thought it would fire both injectors every drp or alternate injectors
I found that it only fires 1 injector fires every drp (interesting perfect for a single injector TBI unit option *)
I did also ask that question because i was oscilating between the 2 injectors into the intake ports and option of single injector TBI
Leaving the memcal modification in place
As mentioned
the current intake runs 2 injectors and at idle I need both to fire alternating ..to match the 1342 firing order... cylinders 1&2 are 1 runner cylinder 3&4 are they other runner.
currently we have tied the injectors together to the constant firing injector
The car idles but not as clean as i hope with alternating injectors.
This is why I hope to have alternating injectors based on every DRP.
I need to get a few pictures of the car and system ... FYI we will run this car up Pikes Peak ....once we get this efi system working ....
the car originally had 1 carb ... and we had a gm distribution machined to fit the original distributor location ...
* this was my second option to run a single injector TBI so it apears we now can run that THANKS
----------
i wonder if i check the TBI mode x=0 if it will fire in an alternating state...
right now i have selected the CPI PFI mode ....
the 8625 ecm is setup for 8cyl or 6 cyl ( i have both memcals)
unable to get a 4cyl memcal for this ecm
I was 1st wondering how I can fire like a 4 cylinder ... every drp
you suggested the memcal modification THANK YOU
I made the modification on pin 13 of the 16 pin memcal ....
and thought it would fire both injectors every drp or alternate injectors
I found that it only fires 1 injector fires every drp (interesting perfect for a single injector TBI unit option *)
I did also ask that question because i was oscilating between the 2 injectors into the intake ports and option of single injector TBI
Leaving the memcal modification in place
As mentioned
the current intake runs 2 injectors and at idle I need both to fire alternating ..to match the 1342 firing order... cylinders 1&2 are 1 runner cylinder 3&4 are they other runner.
currently we have tied the injectors together to the constant firing injector
The car idles but not as clean as i hope with alternating injectors.
This is why I hope to have alternating injectors based on every DRP.
I need to get a few pictures of the car and system ... FYI we will run this car up Pikes Peak ....once we get this efi system working ....
the car originally had 1 carb ... and we had a gm distribution machined to fit the original distributor location ...
* this was my second option to run a single injector TBI so it apears we now can run that THANKS
----------
i wonder if i check the TBI mode x=0 if it will fire in an alternating state...
right now i have selected the CPI PFI mode ....
Last edited by walkerscott; Apr 4, 2008 at 09:46 PM. Reason: Automerged Doublepost
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Re: 16168625 ecm DRP TBI firing
It's worth giving it a try to change the firing options.
I suppose you could 'make' a 4 cyl cal from an 8 cylinder one, you'd have to change code though, you would basically be halving the rpm. One of the code gurus around here could probably figure that out quick.
how attached are you to that ecm? You could theoretically use a '7730 or
'7749 with a 4cyl port injection cal. Easier to find that code.
I suppose you could 'make' a 4 cyl cal from an 8 cylinder one, you'd have to change code though, you would basically be halving the rpm. One of the code gurus around here could probably figure that out quick.
how attached are you to that ecm? You could theoretically use a '7730 or
'7749 with a 4cyl port injection cal. Easier to find that code.
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From: Moorestown, NJ
Car: 88 Camaro SC
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Transmission: TKO 500
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Re: 16168625 ecm DRP TBI firing
I'll try to post the code snippet in question up tonight. I assume that you want BOTH injectors to fire each DRP, which can be done without too much effort. The other change you will need to do is change the cyl count to 4 cyls. and the injector constant, which I assume youve probably already done.
If you want alternating firings (one injector each DRP), get a V8 memcal (or unmod teh current one) for a TBI truck along with the G1 adaptor and change the cylinder count, injector constants, and retune for your 4 cyl. The accel enrichment will be a little different, but it will still work.
If you want alternating firings (one injector each DRP), get a V8 memcal (or unmod teh current one) for a TBI truck along with the G1 adaptor and change the cylinder count, injector constants, and retune for your 4 cyl. The accel enrichment will be a little different, but it will still work.
Last edited by dimented24x7; Apr 10, 2008 at 01:25 PM.
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Re: 16168625 ecm DRP TBI firing
Code:
;
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
; Here to continue and return from interrupt
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;
;-Check if its time to fire the injectors
;
L7812 LDD L3FFA ;CPU status
ORAA L0073 ;CPU status word
BCLR L0073,#$40 ;CPU status word, clear b6
;
BITA #$40 ;Test b6
BEQ L7873 ;Bra if ==0, return to skip injector firing
;
;-Check quals for limiting RPM derivative term
;
LDAB L0067 ;RPM/6.25
CMPB L450C ;Upper RPM limit for derivative RPM term
BCS L783B ;Bra if RPMs <
;
LDAB L01FC ;%TPS
CMPB L48D0 ;TPS threshold for idling
BHI L783B ;Bra if TPS >, limit derivative term
;
;-Filter RPM derivative term
;
LDD L0068 ;Filtered RPM/6.25
LDX #L006A ;Delayed filtered RPM/6.25
LDY #L450E ;Filter coeff.
JSR LF116 ;Lag filter routine
;
BRA L783D ;Bra to save
;
;-Here to skip filtering
;
L783B LDD L0068 ;Filtered RPM/6.25
;
L783D STD L006A ;Save it, delayed filtered RPM
LDAA L400B ;Opt. byte
BITA #$01 ;Test b0
BEQ L7873 ;Bra if not in CPI/PFI mode
;
;-In CPI/PFI mode here
;
LDAA L400C ;Opt byte
BITA #$08 ;Test b3
BEQ L7851 ;Bra if async double fire mode
;
BRCLR L0019,#$40,L7873 ;Err. word, bra if b6==0, no err. 41
;
L7851 BRCLR L0051,#$01,L7865 ;Bra if b0==0, not in single fire mode
;
BRCLR L003F,#$10,L7870 ;Status word, bra if b4==0, sync/async flag
;
;-Check if ok to exit single fire mode
;
LDD L0277 ;BPW
CPD L4920 ;Threshold to go from single to double fire mode
BLS L7865 ;Bra if BPW <=
;
;-Here to exit single fire
;
BCLR L0051,#$01 ;Status word, clear b0, not in single fire mode
;
;-Fire the fuel injectors
;
L7865 BCLR L003F,#$10 ;Clear b4, sync/async flag ;
JSR L7874 ;Routine to set up for TOC 5 interrupt to fire
;injector
JSR L78A4 ;Routine to set up for TOC 4 interrupt to fire
;injector
;
BRA L7873 ;Bra to return
;
L7870 BSET L003F,#$10 ;Set b4, sync/async flag
;
;-Jump here if ign. off
;
L7873 RTI ;Return from interrupt 
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Re: 16168625 ecm DRP TBI firing
ok thank you both
i have been glued to the computer reviewing the code ...starting to understand .. there are a few nomenclatures i don't understand right yet...
GUys we swapped the port injection for a single injector TBI ... but now i running into a issue with injector wants to stop firring at idle basically i think we are satisfing the fueling and the injector BPW is .4 steady at an idle .....reving not an issue but idle we get an occasional POP out the tailpipe seems to be timed with the injector missing (or under fueling on a DRP firing) .... or rather fuel cutback due to the BPW of the injector ....
i have been glued to the computer reviewing the code ...starting to understand .. there are a few nomenclatures i don't understand right yet...
GUys we swapped the port injection for a single injector TBI ... but now i running into a issue with injector wants to stop firring at idle basically i think we are satisfing the fueling and the injector BPW is .4 steady at an idle .....reving not an issue but idle we get an occasional POP out the tailpipe seems to be timed with the injector missing (or under fueling on a DRP firing) .... or rather fuel cutback due to the BPW of the injector ....
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From: Moorestown, NJ
Car: 88 Camaro SC
Engine: SFI'd 350
Transmission: TKO 500
Axle/Gears: 9-bolt w/ 3.23's
Re: 16168625 ecm DRP TBI firing
Below 400 usecs or .4 msecs, the PCM will clear out the pulsewidth. Basically you need to either use a smaller injector or use a VAFPR to stretch the pulsewidth so the injector keeps firing. Shoot for a PW of 800 usecs or greater at idle.
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Re: 16168625 ecm DRP TBI firing
I was thinking building a VAPFR and trying that it may be easier than finding a smaller injector
Thanks for the feedback
I would like to try and find a smaller injector ... do you know where i can look ...it's a GM single TBI injector ....
Thanks for the feedback
I would like to try and find a smaller injector ... do you know where i can look ...it's a GM single TBI injector ....
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From: Al Udeid, Qatar-Worldwide service
Car: IH Scout
Engine: 345 V8 TBI
Transmission: 727
Re: 16168625 ecm DRP TBI firing
I know it's a little different then yours but I currently run an Austin Mini 1275 4cyl with a 1227747 ecm and a single inj throttle body.
They used 1 carb, 2 carbs, TBI and MPFI.
In doing research on the siamesed port heads, there seemed to be a lot of problems going MPFI without extensive software to varry the PW on each firing since one cyl will cause a pulse in the intake and shorten the amount of time the fresh air can enter 1 cyl.
So my solution was to simply use the batch fire and I tied both inj driver outputs together and connected to 1 injector in a TBI.
Still making minor tweaks to prevent the async from kicking in and causing a miss but the system works very nice so far.
I also run this with the 4 cyl DIS ignition.
Got a little help from RBob figuring out the proper timing settings to offset the 70*.
Here's a couple links for you to look at.
http://www.starchak.ca/efi/siamese.htm
http://www.canems.co.uk/siameseports.php
They used 1 carb, 2 carbs, TBI and MPFI.
In doing research on the siamesed port heads, there seemed to be a lot of problems going MPFI without extensive software to varry the PW on each firing since one cyl will cause a pulse in the intake and shorten the amount of time the fresh air can enter 1 cyl.
So my solution was to simply use the batch fire and I tied both inj driver outputs together and connected to 1 injector in a TBI.
Still making minor tweaks to prevent the async from kicking in and causing a miss but the system works very nice so far.
I also run this with the 4 cyl DIS ignition.
Got a little help from RBob figuring out the proper timing settings to offset the 70*.
Here's a couple links for you to look at.
http://www.starchak.ca/efi/siamese.htm
http://www.canems.co.uk/siameseports.php
Last edited by Bill usn-1; Apr 13, 2008 at 04:48 PM.
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Re: 16168625 ecm DRP TBI firing IT WORKS couple issues
up and running idles ok to good maybe i am just fussy ...
it had quite the stumble just off idle i messed with synch and Asynch adding to both and BAMM it worked ... .no more stumble...
only trouble is i went back the the $E6 code and now i have MAT 32 & 16 code FYI NO VSS and no MAT on this car
i now have to figure out where to shut these 2 trouble codes off in the $e6 code that hacks that i have are very incomplete and do not list these items ...
it had quite the stumble just off idle i messed with synch and Asynch adding to both and BAMM it worked ... .no more stumble...
only trouble is i went back the the $E6 code and now i have MAT 32 & 16 code FYI NO VSS and no MAT on this car
i now have to figure out where to shut these 2 trouble codes off in the $e6 code that hacks that i have are very incomplete and do not list these items ...
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Re: 16168625 ecm DRP TBI firing IT WORKS couple issues
Just donwload the E6.zip from this address
http://www.moates.net/fileman/index....%20and%20Hacks
The user name is moatesuser and the password is moatespassword
It has the an almost complete hack in it.
For the mat sensor disable the whole code not just the error. The bit is at l400B Bit 6.
http://www.moates.net/fileman/index....%20and%20Hacks
The user name is moatesuser and the password is moatespassword
It has the an almost complete hack in it.
For the mat sensor disable the whole code not just the error. The bit is at l400B Bit 6.
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