Fuel Injector Wire Problem #2 Cylinder?? No Pulse

[Jarrad_GST]

I hooked a stethoscope to the injector #2 and it has no pulse. All the injectors are ticking perfectly fine. I switched injectors to stock and have 8 set of these injectors and no matter which injector I use, the #2 cylinder isnt getting fuel. The engine studders and has terrible rough idle at like 550rpm. I did a compression check, the engine was cold and it was 120 across the board. The engine has 1500 miles on a 6 bolt swap. (8:3:1 blocked decked)

My fuel management is safc, 450inj, afpr aeromotive 1:1, 255lfp.

The car was running fine until I swapped out turbo and injectors. Now it doesnt run at all to drive. Does start and stay on but studders.

I even changed to another injector harness on #2 cylinder and solder the connection, no help. I am going to get a multi meter and follow the wire. Is it my ECu? I highly doubt it.

(97 Eclipse with 6bolt)

 

[boostedgst2984]

hey check yoru ecu if you try to drive it to see if you pop a code right away. I had this problem and figured out it was just a loose wire to my ecu. Sometimes the pins pop out of the harness. I just poped mine back in right and it fixed the problem

 

[IHeartTurbo]

I hate when people jump to the ecu first. That's the worst advice you can give.


First grab that multimeter. T-pin into the "power" side of the injector with the key in the run position. You should have battery voltage. If you don't, grab a wiring diagram and follow those wires back, continually checking for power the whole way. If you do have battery voltage at the power wire of the injector, check the "ground" side. With the car running, it may be hard to see because multimeters are so slow, but you should get a pulsed battery voltage. It will probably just show up as a constant voltage on the multimeter however. If you don't get it, the injector isn't being pulsed. Now, since it's only the number 2 injector, it shouldn't be the injector driver in the ecu. Look at wiring diagrams again and trace the injectors back to the ecu, checking for voltage just like you did before. Most likely you have an open somewhere.

 

[Jarrad_GST]

found the problem, the wire from the #2 harness to like where the CAS looked a little brittle. For some odd reason that wire was not very strong. You could barely tell but the wire there was discolored. I figured this out by using the multimeter and first check the ground wire, that wire was connected and working and then I knew it had to be the other wire. I followed it all the way to the ecu. I then used a wire straight from where I got a good signal to the ecu and eventually I narrowed the wire down to this spot about 5 inches long. I replaced the wire with new wire and solder the connections. So somehow my wire to that injector got damaged, maybe water, maybe fuel who knows. I had a little help from my brother, maybe most of the help was from my brother while I watched. heh He was a life savior.

 

[steve]

fI figured this out by using the multimeter and first check the ground wire, that wire was connected and working and then I knew it had to be the other wire. I followed it all the way to the ecu.

Minor correction, the wire to the ECU is the "ground" wire, it's the one the ECU pulls low to fire the injector. The wire to the injector resistor pack is the power wire.

Now, since it's only the number 2 injector, it shouldn't be the injector driver in the ecu.

The DSM ECU uses sequential firing of the injectors most of the time, we have injector drivers for each injector. It's not a batch fire setup except when cold starting and under acceleration enrichment.

Steve

 

[IHeartTurbo]

The DSM ECU uses sequential firing of the injectors most of the time, we have injector drivers for each injector. It's not a batch fire setup except when cold starting and under acceleration enrichment.

Steve

Ah yes, you're right. I'm so used to seeing batch fire all the time. Damn LT1s.

 

[steve]

I figured you were thinking big iron.

 

[boostedgst2984]

I hate when people jump to the ecu first. That's the worst advice you can give.


First grab that multimeter. T-pin into the "power" side of the injector with the key in the run position. You should have battery voltage. If you don't, grab a wiring diagram and follow those wires back, continually checking for power the whole way. If you do have battery voltage at the power wire of the injector, check the "ground" side. With the car running, it may be hard to see because multimeters are so slow, but you should get a pulsed battery voltage. It will probably just show up as a constant voltage on the multimeter however. If you don't get it, the injector isn't being pulsed. Now, since it's only the number 2 injector, it shouldn't be the injector driver in the ecu. Look at wiring diagrams again and trace the injectors back to the ecu, checking for voltage just like you did before. Most likely you have an open somewhere.

na man i didnt jump to the ecu as being wrong cuz that wasnt the case with mine. i was just telling him to try to drive it to see if it poped a code for the injector and check the injector wires going to the ecu harness

 

[unsivil_audio]

Minor correction, the wire to the ECU is the "ground" wire, it's the one the ECU pulls low to fire the injector. The wire to the injector resistor pack is the power wire.


The DSM ECU uses sequential firing of the injectors most of the time, we have injector drivers for each injector. It's not a batch fire setup except when cold starting and under acceleration enrichment.

Steve

Sorry to bring this back up to the top. But me and my friend have a similar problem on injector #2. First, the car, 96' GST spyder. 1g CAS, T28 turbo, 2.5dp, 3in exhaust. It starts up and runs fine, accelerates fine, but any time you try and hold a steady state driving mode (in a matter of about 5 seconds) the cylinder 2 injector shuts off and it runs on 3 cylinders. It will continue NOT firing until you let the rpms drop to idle again, then it fires again, and you can continue on. We dont believe that its a connection problem (we had to hack up the wires at some point, but we soldiered all connections) its too calculated and can be replicated to be that. We do think it might be a resistance problem with our new connections running to the ecu causing that circuit on the ecu to over heat and shutdown.

Also thought I'd mention, we tried a different set of (known working) injectors (DSM 390's) yesterday and the problem went away for about an hour, until the ecu started adjusting fuel maps (car was sitting at lean on cruising on A/F guage, started bouncing back and forth between lean and rich at cruising, and it started stuttering again, same injector).

 

[boostedgst2984]

hahhahaha yea that happens to all 2gn when u use a 1gn CAS. I have the exact problem with mine. But thats what my pocket logger is for. I just clear the code let it idle and im off again. Make sure you have the wires swaped right when u wire in the 1gn cas. I know thier is a mod from magnusmotorsports that costs about 8 bux. You just soder in a potikemeter and it just puts the barometric reading out of tolerance so u dont have a code again and the misfire is gone. I am not sure since u dont have a 6bolt if you have to switch the plug wires or not.

 

[Hobart]

we are using a hall sensor and has done the sugested wire swaps all the cylinders are firing fine and idle well theres just theis partial throttle problem were injector in cylinder 3 wont fire but the spark does so i don't see how it could be the cam sensor any one want to explain?

 

[unsivil_audio]

hahhahaha yea that happens to all 2gn when u use a 1gn CAS. I have the exact problem with mine. But thats what my pocket logger is for. I just clear the code let it idle and im off again. Make sure you have the wires swaped right when u wire in the 1gn cas. I know thier is a mod from magnusmotorsports that costs about 8 bux. You just soder in a potikemeter and it just puts the barometric reading out of tolerance so u dont have a code again and the misfire is gone. I am not sure since u dont have a 6bolt if you have to switch the plug wires or not.

Thanks we'll try that. And I think I understand why the cps affects fueling. I do believe I read somewhere on this site that the crank sensor controls fuel timing and the cam sensor controls spark timing (at least on 2g's, I dont know about 1g's) and if one fails the other will guess its timing off the other and throw a code (so the car continues to run). If you reset the ecu you lose its memory of where that timing was and the car wont run anymore. Is that correct?

I should've mentioned earlier we are getting the code for random misfire. Also we have switched the plug wires, car runs excellent other than the steady state driving. We are going to try that thing you reccomended tonight we'll report back if it works, once again thanks for your input on the matter.

 

[unsivil_audio]

The magnusmotorsports fix worked. No more CEL (random misfire) and no more stuttering under steady-state driving.

IF CHECK ENGINE LIGHTS OCCUR! TRY THIS:

(Blake Heisler's Fix for misfire Check Engine Lights (CELs) when putting a 1G Cam Angle Sensor (CAS) on a 2G)

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:

1. 300+ seconds of steady state RPM less than 80% throttle position

2. Engine coolant temperature -10C or higher

3. Intake air temperature -10C or higher

4. 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 potentiometer is

Wire strippers

Soldering iron

Step 1: Remove the access panel on the driver’s side of the center console. 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 potentiometer all the way counter-clockwise.

Step 4: Plug the harness back in 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 potentiometer the 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.

That’s it, special thanks to Marco for pioneering this mod and to all the guys on the DSM1Gina2G Yahoo group for all the discussion, ideas, etc.

-Blake Heisler
All content is Copyright © Magnus Motorsports 2004

Thanks again guys, you've been very insightful in helping us remedy our problems with this car.

 

[Happys_TSI]

Minor correction, the wire to the ECU is the "ground" wire, it's the one the ECU pulls low to fire the injector. The wire to the injector resistor pack is the power wire.


The DSM ECU uses sequential firing of the injectors most of the time, we have injector drivers for each injector. It's not a batch fire setup except when cold starting and under acceleration enrichment.

Steve

When u say the wire from the ecu is the ground are you referring to pins 51,52,60 and 61?

 

[steve]

Yes, the four injector wires to/from the 1G ECU on pins 51, 52, 60, and 61 (2G ECU pin 1, 2, 14, and 15). The voltage to activate the injector coils comes from the injector resistors to the injector and the ECU pulls it's side low to ground to complete the circuit and fire the injector. When it's not opening the injector the voltage floats back up to battery voltage.

There is also the inductive spike created when the current stops and the snubber circuit to handle it and protect the injector drivers but I usually ignore all that in most discussions.

What problem are you having, Happy?

 

[Happys_TSI]

Yes, the four injector wires to/from the 1G ECU on pins 51, 52, 60, and 61 (2G ECU pin 1, 2, 14, and 15). The voltage to activate the injector coils comes from the injector resistors to the injector and the ECU pulls it's side low to ground to complete the circuit and fire the injector. When it's not opening the injector the voltage floats back up to battery voltage.

There is also the inductive spike created when the current stops and the snubber circuit to handle it and protect the injector drivers but I usually ignore all that in most discussions.

What problem are you having, Happy?

Well I have a 1990 talon tsi. Have everything I need for the car to run but the injectors aren’t firing. I tested with a noid light and no luck. When I crank the car the tach bounces to about 3 grand. CAS was Tested and I have spark. The one day I cranked the car trying to start and injector resistor box got pretty hot so I assumed it was bad. Replaced it and have the same problem. Since I replaced it the resistor box hasn’t gotten hot just like warm.