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Unread 02-22-2013, 12:05 PM   #31
86cj74.2L
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If your nutter bypass was done correctly since your running fuel injection you should be able to remove the mcu completely with no effect.

Are you using the red #10 wire that feed the DuraSpark ignition module as the power feed for the PCM, injector power source, and your HEI setup?

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Unread 02-22-2013, 03:45 PM   #32
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Exactly, the stock computer shouldn't be in the loop anymore.

As has been said multiple times, you need to figure out what the TBI computer is seeing to really diagnose what's going on. Your wiring sounds like a complete crapshoot, so who knows how to diagnose what is going on.
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Unread 02-22-2013, 04:30 PM   #33
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I'm just going to throw this out there.A while back a member was having cold start problems with his Howell.He had them for 2 winters in a row.Summer time he was fine.After his engine warmed up it would start everytime.Simplest thing,it turned out to be the battery.Just me 2cent worth.
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Unread 02-23-2013, 09:40 AM   #34
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Quote:
Originally Posted by 86cj74.2L View Post
If your nutter bypass was done correctly since your running fuel injection you should be able to remove the mcu completely with no effect.

Are you using the red #10 wire that feed the DuraSpark ignition module as the power feed for the PCM, injector power source, and your HEI setup?
i guess im not sure what the "duraspark" is, but i do not have anything running off the power feed for the ignition module im using. (which is the one for a 91 chevy s10 4.3) and i do not have an HEI setup, i opted to go with the bigger ford cap/adapter setup with the TFI coil.
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Unread 02-23-2013, 10:26 AM   #35
86cj74.2L
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Are you or are you not using a HEI module for spark?

The factory ignition was the DuraSpark (Ford) ignition located on the drivers side fender down low. It has two roundish plugs. One of them is a fat #10 wire. That wire is what I would use to feed power to everything associated with the fuel injection. Ignition included.

If you unplug the MCU with the engine running and the Engine shut off while running off the GM fuel injection and ignition you just installed you did something wrong.

If you think the check engine light and the ALDA connector is not needed how much do you really understand about engine management systems and how fuel injection works and especially how all them sensors interact with each other.

Learning to read wiring schematics is key to doing what your trying to accomplish. It's nice to just do what you saw in the Internet. Troubleshooting is a whole nother animal when things go wrong.

I'm not trying to be a jerk on purpose but some have asked what your using for power feeds to certain wires and you never answered them to my knowledge. Or me for that matter.

To me the only benefit of fuel injection is the cold starting. It is better for four wheeling than a carb and it easily passes emissions as well.

But their is nothing simpler than a carb that's operating properly and a stand alone ignition system. To my knowledge no one with fuel injection has ever got stellar mpg. Let alone better then some of us running carbs and getting 18 to 20 mpg. (One guy in Canada gets 22 to 23)
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Unread 02-23-2013, 01:52 PM   #36
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Quote:
Originally Posted by 86cj74.2L View Post
Are you or are you not using a HEI module for spark?

The factory ignition was the DuraSpark (Ford) ignition located on the drivers side fender down low. It has two roundish plugs. One of them is a fat #10 wire. That wire is what I would use to feed power to everything associated with the fuel injection. Ignition included.

If you unplug the MCU with the engine running and the Engine shut off while running off the GM fuel injection and ignition you just installed you did something wrong.

If you think the check engine light and the ALDA connector is not needed how much do you really understand about engine management systems and how fuel injection works and especially how all them sensors interact with each other.

Learning to read wiring schematics is key to doing what your trying to accomplish. It's nice to just do what you saw in the Internet. Troubleshooting is a whole nother animal when things go wrong.

I'm not trying to be a jerk on purpose but some have asked what your using for power feeds to certain wires and you never answered them to my knowledge. Or me for that matter.

To me the only benefit of fuel injection is the cold starting. It is better for four wheeling than a carb and it easily passes emissions as well.

But their is nothing simpler than a carb that's operating properly and a stand alone ignition system. To my knowledge no one with fuel injection has ever got stellar mpg. Let alone better then some of us running carbs and getting 18 to 20 mpg. (One guy in Canada gets 22 to 23)
no, im not using HEI, as i said. i was going to originally but could not locate all the pieces i needed fast enough, so i stuck with the originial jeep distributor (but replaced it with OEM new), and added the ford distributor cap adapter and the larger ford cap and wires. we arent worried about fuel economy. we want instant startup regardless of weather and more power. which it seems to have accomplished until this little issue. and im thinking you skipped over the several spots i mentioned i have NOTHING tied to the factory ignition switch except the starter signal wire which also has the c9 gm computer connection tied to it so the computer knows when its cranking over to start. that being said, i have 2 add-on switches i put into the dashboard. one of them runs as follows: battery positive, inline fuse, then into switch. the output of the switch goes directly to positive on external fuel pump. the next switch runs from battery, inline fuse, to switch. the output of that switch goes directly to the key-on power for the GM ecm. the constant power wire for ecm has an inline fuse also and goes directly to positive on battery. that way i didnt have to mess with anything in the steering column. when i go out of town to work on this guys jeep, i usually only have a couple days at a time, so you can frown upon my methods all you want but i had good reason to cut certain corners. got the same results doing it that way as i would have tying into the ignition switch. plus easier to diagnose if one or the other fails. there is a tan wire that goes from the computer to the 4 wire plugin on GM igition module that i had to disconnect in order to let it run properly. not sure what that runs without going back over the schematic, but if its hooked up it runs like **** and cant hardly keep it running, if i cut it, runs fine. so i left it unhooked. not sure if maybe its fighting the nutter bypass when hooked up or what.
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Unread 02-23-2013, 03:00 PM   #37
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What is making the spark? Your using the factory distributor which is ok.

Where is your ignition module?

What feed are you using for the injectors? One of your installed switches?
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Unread 02-23-2013, 06:44 PM   #38
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Quote:
Originally Posted by 86cj74.2L View Post
What is making the spark? Your using the factory distributor which is ok.

Where is your ignition module?

What feed are you using for the injectors? One of your installed switches?
the GM ecm run the injectors. the ignition module (GM) is mounted on the passenger side fenderwell, with the heat putty between the heatsink and the body of the jeep. it has a 4 wire connector comming from the computer, which is where i mentioned i had to cut the tan wire to make it run right. also has a 2 pin connector next to that, and i dont remember off the top of my head where that goes to. and on the opposite end of the module, theres 2 prongs sticking out of it, which go to the coil pimaries. i also have the jeep computer (nutter bypass) spliced into the same coil primaries. and again, the only reason i had spliced those wires back into this setup is because it would not run when i first hooked it all up without them. maybe i misunderstood the write up for doing the tbi wiring for the ignition module, but idk. i THINK i did it right minus the lack of ALDL connector and ck engine light.
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Unread 02-23-2013, 06:50 PM   #39
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But, if you unplug the mcu connector while its running it shuts off. Correct?

And your ignition for now is with the nuttered ignition?
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Unread 02-23-2013, 09:54 PM   #40
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The wires you cut from the ECU when it stopped, were they orange and purple?

The original computer was mounted above the glove box and referred to as the MCU I believe. The mcu controlled the spark and the carb yes. When you nuttered it you ran a purple and orange from the distributor over to the drivers side fender to the ignition module (DuraSpark).
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Unread 02-24-2013, 08:59 AM   #41
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The wires you cut from the ECU when it stopped, were they orange and purple?

The original computer was mounted above the glove box and referred to as the MCU I believe. The mcu controlled the spark and the carb yes. When you nuttered it you ran a purple and orange from the distributor over to the drivers side fender to the ignition module (DuraSpark).
yes orange and purple, but im not sure exactly where this duraspark thing is ur talking about. maybe i did that part wrong too, cuz i just ran new wires directly from the mcu to the coil.... X( maybe i got it alllll kindsa goofed.
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Unread 02-24-2013, 09:17 AM   #42
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But, if you unplug the mcu connector while its running it shuts off. Correct?

And your ignition for now is with the nuttered ignition?
He's using a mix of the 8-pin GM ignition module and the factory ignition somehow. The 8-pin isn't wired correctly at all.


Quote:
Originally Posted by motormike24 View Post
the GM ecm run the injectors. the ignition module (GM) is mounted on the passenger side fenderwell, with the heat putty between the heatsink and the body of the jeep. it has a 4 wire connector comming from the computer, which is where i mentioned i had to cut the tan wire to make it run right. also has a 2 pin connector next to that, and i dont remember off the top of my head where that goes to. and on the opposite end of the module, theres 2 prongs sticking out of it, which go to the coil pimaries. i also have the jeep computer (nutter bypass) spliced into the same coil primaries. and again, the only reason i had spliced those wires back into this setup is because it would not run when i first hooked it all up without them. maybe i misunderstood the write up for doing the tbi wiring for the ignition module, but idk. i THINK i did it right minus the lack of ALDL connector and ck engine light.
Here's how it shold be wired. The two wire connector right next to the four wire connector should be wired to the coil. The two on the other side of the module should go to the orange and purple wires that come from the distributor. The factory ignition module should be in the trash at this point.
duraspark-8pin-hei-module.jpg  
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Unread 02-24-2013, 09:21 AM   #43
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Referring to the orange and purple wire scenario, I wrote this in another thread where a guy was having problems with his Howell TBI system.

Did you make sure to have both your purple and orange wires go all the way from the dist to the ford duraspark module? If I remember right the purple wire was the one that needed to be "added" on to and extended over there.

Also make sure the black wire from the duraspark module is grounded to a known good ground. stock it used the dist for ground, but in moving everything around you might have got it moved. i ran a 3ft section of wire from the battery ground into this harness just to be sure.
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Unread 02-24-2013, 09:23 AM   #44
motormike24
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He's using a mix of the 8-pin GM ignition module and the factory ignition somehow. The 8-pin isn't wired correctly at all.




Here's how it shold be wired. The two wire connector right next to the four wire connector should be wired to the coil. The two on the other side of the module should go to the orange and purple wires that come from the distributor. The factory ignition module should be in the trash at this point.
i was incorrect about how i had it wired up, yes, that diagram is exactly how mine is hooked up
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Unread 02-24-2013, 09:29 AM   #45
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How many wires are going to your coil?
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