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CAS/backfire and hesitation issues

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ROGUE DSM

Proven Member
49
2
Aug 27, 2015
Iowa City, Iowa
Hello,

Let me start off by saying I've search the site and found great info that has lead me up to this point. However I'm still having some issues, also I apologize if this is in the wrong section.

Vehicle
- 1995 Mitsubishi Eclipse GSX

Issue
- The Issue is the engine will back fire/hesitate randomly around 2k-3k rpm when revving in natural or driving in any gear, I believe this is due to the CAS itself. I have another CAS that I'm plan on swapping out to see if that might've been the cause of my issue.

What I've done so far
- Base timing is at 5 degrees
- Overall engine timing is at TDC (IT on timing cover)
- new CAS
- Changed spark plugs (BPR6EIX and properly gapped)
- NGK Spark plug wires
- Coil pack firing order on 4123 (does not run on 3214)
- Emissions deleted (only kept what was needed)

Related things about my vehicle
- 1995 engine harness
- non dsmlink (95 EPROM)
- CAS rewire (done by previous owner

I can provide a link to a video or if possible upload one to the site if needed. Any help will be appreciated.

Thank you
 
is the cas on right? if its on 180* off it will run but it will run terribly. it'll backfire, misfire and have no performance at all except decelleration, where its not using any fuel or ignition.

also, which cas are you running? on a 95 theres a few things you have to change. firing order and i could be wrong, and its a very good chance, but possibly injectors to
 
you're getting a random misfire caused by combining the crank and cam angle sensors into 1 (1g CAS) you need to disable the check for the misfire code in link or with a black box ecu. if you don't have a way to tune, you need to do this mod.

Many people using the 1G CAS on a 2G head have been running into problems with misfire engine codes
while at cruise. Many different things have been blamed for this and many different fixes have been attempted.
This fix will keep the ECU from looking for misfires at all. This is the criterion that must be met before the
ECU will start to look for misfires:
· 300+ seconds of steady state RPM less than 80% throttle position
· Engine coolant
You must be logged in to view this image or video.
temperature -10C or higher
· Intake air temperature -10C or higher
· Barometric pressure greater than 76 kPa
Now if we can get one of these values outside of the criteria the ECU won’t check for misfires. The value that
would be the easiest to change would be the barometric pressure sensor. We’re going to add resistance to
this value so that the ECU will see less barometric pressure than what there really is. This will also lean the
car out so you should see a performance increase as well. Depending on the car and altitude you might need
to add more fuel with an AFC.
So let’s get started, Parts needed:
· A 10K potentiometer(although a 5K would probably do just fine). These are available at any
electronics store, if you go to Radio Shack ask for a volume control knob because they don’t know
what a potentiometeris.
· Wire strippers
· Soldering iron
Step 1: Remove the access panel on the driver’s side of the center console
You must be logged in to view this image or video.
. You should now see four plugs
with a ton of wires going to them.
Step 2: Pull out the top plug, it’ll be the one that’s the hardest to reach. Locate wire #85. It’s orange with a
white stripe.
Step 3: Cut the orange wire in half. Solder one end of the wire to the center peg of your potentiometer.
Solder the other end to either the left or right leg, it doesn’t matter which. Turn your potentiometerall the
way counter-clockwise.
Step 4: Plug the harness backin and start up the car. It should sound like it did before you did any
modifications. If the idle is choppy or the car won’t run you turned your potentiometerthe wrong way.
Step 5: Add resistance to the barometric pressure sensor by slowly turning the knob on the potentiometer.
Drive the car around; if you get a CEL then add some more resistance. Keep doing this until you no longer get
the CELs.

Even though you may not be getting a CEL it's what's happening.
 
you're getting a random misfire caused by combining the crank and cam angle sensors into 1 (1g CAS) you need to disable the check for the misfire code in link or with a black box ecu. if you don't have a way to tune, you need to do this mod.

Many people using the 1G CAS on a 2G head have been running into problems with misfire engine codes
while at cruise. Many different things have been blamed for this and many different fixes have been attempted.
This fix will keep the ECU from looking for misfires at all. This is the criterion that must be met before the
ECU will start to look for misfires:
· 300+ seconds of steady state RPM less than 80% throttle position
· Engine coolant
You must be logged in to view this image or video.
temperature -10C or higher
· Intake air temperature -10C or higher
· Barometric pressure greater than 76 kPa
Now if we can get one of these values outside of the criteria the ECU won’t check for misfires. The value that
would be the easiest to change would be the barometric pressure sensor. We’re going to add resistance to
this value so that the ECU will see less barometric pressure than what there really is. This will also lean the
car out so you should see a performance increase as well. Depending on the car and altitude you might need
to add more fuel with an AFC.
So let’s get started, Parts needed:
· A 10K potentiometer(although a 5K would probably do just fine). These are available at any
electronics store, if you go to Radio Shack ask for a volume control knob because they don’t know
what a potentiometeris.
· Wire strippers
· Soldering iron
Step 1: Remove the access panel on the driver’s side of the center console
You must be logged in to view this image or video.
. You should now see four plugs
with a ton of wires going to them.
Step 2: Pull out the top plug, it’ll be the one that’s the hardest to reach. Locate wire #85. It’s orange with a
white stripe.
Step 3: Cut the orange wire in half. Solder one end of the wire to the center peg of your potentiometer.
Solder the other end to either the left or right leg, it doesn’t matter which. Turn your potentiometerall the
way counter-clockwise.
Step 4: Plug the harness backin and start up the car. It should sound like it did before you did any
modifications. If the idle is choppy or the car won’t run you turned your potentiometerthe wrong way.
Step 5: Add resistance to the barometric pressure sensor by slowly turning the knob on the potentiometer.
Drive the car around; if you get a CEL then add some more resistance. Keep doing this until you no longer get
the CELs.

Even though you may not be getting a CEL it's what's happening.

The link only applys to thoughs who have sussefully completed the 1g CAS into a 2g but are getting a misfire engine code even though a misfire isn't happening.

I took a look at the previous owners CAS rewire and found that the fuel injector pins have not been switched around. According to the RRE 1g CAS install this should be the reason I'm having these issues. I'll switch the pins out and the firing order tomorrow and let you guys know my results.

- Here is the link to the RRE 1g CAS install.

http://roadraceengineering.com/1gcasin2g95-96M2.htm
 
My car did it and didn't throw a code but actually misfired. Trust me. Switching the injectors isn't going to do anything but maybe smooth yu idle a touch. But you're saying you have a 1g cas but still have your crank angle sensor installed? In order to run the 1g cas you HAVE to use the signal wires from both the cran and cam angle sensors. Regardless of how it was done if you're running a 1g cas in a 2g its going to misife EXACTLY how you described it unless you do the fixes I listed.
 
not exactly. the 95/96 with the other firing order will misfire with a 1g cas. if its a 97-99 ecu it'll run fine. main issue is phantom mis fire. i put a 91 3000gt cas on my 95 3000gt. runs better than it did with stock sensors. my 97 talonger with a 4g64 bottom end and 4g63 top will run a 92 cas on an evo 8 ecu. injector signal in the wrong cylinder will cause an issue. but the main issue is ignition timing. did you set the engine at tdc with both cam gear dowel pins on top? and the cas has a line on the rotor that lines up with a dot on the cas body. ik that these cars will run with the cas backwards. i've done it on accident that way. make sure all the injector wires are in the right spot and that you invert the firing order. it does make a difference and a friend would know what thats like to. same problem. back fire and popping.
 
My car did it and didn't throw a code but actually misfired. Trust me. Switching the injectors isn't going to do anything but maybe smooth yu idle a touch. But you're saying you have a 1g cas but still have your crank angle sensor installed? In order to run the 1g cas you HAVE to use the signal wires from both the cran and cam angle sensors. Regardless of how it was done if you're running a 1g cas in a 2g its going to misife EXACTLY how you described it unless you do the fixes I listed.
I never said the vehicle still has the crank or cam sensor still on the vehicle. It has a 1g 93-94 CAS rewired using both the cam/crank sensor connectors.

not exactly. the 95/96 with the other firing order will misfire with a 1g cas. if its a 97-99 ecu it'll run fine. main issue is phantom mis fire. i put a 91 3000gt cas on my 95 3000gt. runs better than it did with stock sensors. my 97 talonger with a 4g64 bottom end and 4g63 top will run a 92 cas on an evo 8 ecu. injector signal in the wrong cylinder will cause an issue. but the main issue is ignition timing. did you set the engine at tdc with both cam gear dowel pins on top? and the cas has a line on the rotor that lines up with a dot on the cas body. ik that these cars will run with the cas backwards. i've done it on accident that way. make sure all the injector wires are in the right spot and that you invert the firing order. it does make a difference and a friend would know what thats like to. same problem. back fire and popping.

- Engine timing is at TDC (IT on cover)
- Ignition timing is at 5*

I've changed the pins on the ECU and according to RRE (and resources on this site) the firing order is changed from 4123 to 3214.

Results
- Does not run using firing order 3214, only runs on firing order 4123.
- ignition timing is 5*
- engine timing is TDC (IT on timing cover)
- CAS is not 180* off
- when pushing on accelerator RPMS drop before rising.

I've changed the ECU pins back, when revved the RPMS don't drop before rising. At this point I'm fairly confused.
 
what is the correct procedure here? I have a 95 engine in my 97 and am having a similar issue as of late. Is there a check box in EcmLink to check to remedy the issue? I have updated the firing order. Is there re-pinning of ecus i have to do? I have a 97 Ecu that Ecmlink converted to Eprom.
 
both. all you should need to do is invert the firing order on the coil pack to spark plugs. and a few wires on the ecu. i think its for the injectors since firing order is different
 
what is the correct procedure here? I have a 95 engine in my 97 and am having a similar issue as of late. Is there a check box in EcmLink to check to remedy the issue? I have updated the firing order. Is there re-pinning of ecus i have to do? I have a 97 Ecu that Ecmlink converted to Eprom.

Here is a link for the procedure:
http://roadraceengineering.com/1gcasin2g95-96M2.htm

I removed my ECU and it looks to be in good condition, I have another non-EPROM ECU that came out of a 96 GST. I'll give that a try tomorrow morning.
 
both. all you should need to do is invert the firing order on the coil pack to spark plugs. and a few wires on the ecu. i think its for the injectors since firing order is different
I did that, however, is there a check box in ECMLink to click so the ECU knows?
 
theres no point in doing that if you do all the wiring. as much as we know, that just takes all the wiring out of the problem and instead switches injector pins to run it and switches coil signals
 
you're getting a random misfire caused by combining the crank and cam angle sensors into 1 (1g CAS) you need to disable the check for the misfire code in link or with a black box ecu. if you don't have a way to tune, you need to do this mod.

Many people using the 1G CAS on a 2G head have been running into problems with misfire engine codes
while at cruise. Many different things have been blamed for this and many different fixes have been attempted.
This fix will keep the ECU from looking for misfires at all. This is the criterion that must be met before the
ECU will start to look for misfires:
· 300+ seconds of steady state RPM less than 80% throttle position
· Engine coolant
You must be logged in to view this image or video.
temperature -10C or higher
· Intake air temperature -10C or higher
· Barometric pressure greater than 76 kPa
Now if we can get one of these values outside of the criteria the ECU won’t check for misfires. The value that
would be the easiest to change would be the barometric pressure sensor. We’re going to add resistance to
this value so that the ECU will see less barometric pressure than what there really is. This will also lean the
car out so you should see a performance increase as well. Depending on the car and altitude you might need
to add more fuel with an AFC.
So let’s get started, Parts needed:
· A 10K potentiometer(although a 5K would probably do just fine). These are available at any
electronics store, if you go to Radio Shack ask for a volume control knob because they don’t know
what a potentiometeris.
· Wire strippers
· Soldering iron
Step 1: Remove the access panel on the driver’s side of the center console
You must be logged in to view this image or video.
. You should now see four plugs
with a ton of wires going to them.
Step 2: Pull out the top plug, it’ll be the one that’s the hardest to reach. Locate wire #85. It’s orange with a
white stripe.
Step 3: Cut the orange wire in half. Solder one end of the wire to the center peg of your potentiometer.
Solder the other end to either the left or right leg, it doesn’t matter which. Turn your potentiometerall the
way counter-clockwise.
Step 4: Plug the harness backin and start up the car. It should sound like it did before you did any
modifications. If the idle is choppy or the car won’t run you turned your potentiometerthe wrong way.
Step 5: Add resistance to the barometric pressure sensor by slowly turning the knob on the potentiometer.
Drive the car around; if you get a CEL then add some more resistance. Keep doing this until you no longer get
the CELs.

Even though you may not be getting a CEL it's what's happening.

I've replaced the ECU with a known good one without any improvement. I'll try the POT mod next, after doing some research the POT mod makes more sense. Trogador let me apologize if I seemed hostile, I was just frustrated with this problem.
 
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