Topic: Issues with 19# injector swap

[FourbangerYJ]

So I swapped the injectors this morning. Upon start up I got a CEL. ( I have no idea how to tell what code is thrown). I took it for a short drive and found it was really lacking power. Came home to find I did not connect of one the fuel lines right. So I fixed that. But still get the CEL.
Also it does not idle right. Normally on start up it will idle high for a bit then drop to normal. It does not idle high upon start up and has a rough idle.

Ideas?

[FourbangerYJ]

I found a code checking deal online. So I am throwing a 12, don't know that that one is and (2) 27 fuel injector control. I checked the wiring where it connects to the injector and found that the #1 plastic clip has a crack in it. It seems to attach OK but I wonder if it's enough to throw a code?
I re-started it and it still does not idle high, also runs real rough.
The change in sound is nice. It's much throatier than before.
I am gonna try resetting the ECU.

[Jeffy]

Yes, a crack in the plastic clip, especially the part that holds down the connector is enough to throw a code.  BTDT, mine is #3...  I just make sure it's on tight and it seems to hold ok since.

[FourbangerYJ]

Yes, a crack in the plastic clip, especially the part that holds down the connector is enough to throw a code.  BTDT, mine is #3...  I just make sure it's on tight and it seems to hold ok since.

Is this a dealer only thing? It seems to hold but pulling off is fairly easy compared to the others.

After resetting the ECU the code 12 is gone and one of the code 27's.
But it still does not idle right. It's real boggy. Sounds like it's loaded up with fuel.
 What would cause the idle not to run high after starting?

[chardrc]

this is speculation as the knowledge / concept is based off of how the TBI system works (but i think this part would apply to both tbi and mpi)... the idle air controller (or was it idle throttle position thingamajig) fully extends when you turn off the key (so that at idle you will get the most air coming in as the system allows) so that when you start the jeep you will get more fuel / air in than at running idle giving you an elevated idle until the computer throttles back that setting after start up.... so if that idel air / idel throtel positin thing got messed up and isn't extending you wouldn't get elevated idle at start up...

in short i would check any connections on the Tb in case you bumped them or something.. although if that was the problem you would probably of issues at other times when driving.. worth a check either way since you where working near there.

[aw12345]

Scott after you reset the ECM it takes awhile for the idle to stabilize and also the ECM has to relearn rework it's fuel adaptive tables.
If it doesn't miss go drive it for about an hour and see how it does.
To reset disconnect the battery clamps and hold then together for a couple of minutes to discharge the capacitors in the ECM

[Jeffy]

Is this a dealer only thing? It seems to hold but pulling off is fairly easy compared to the others.

After resetting the ECU the code 12 is gone and one of the code 27's.
But it still does not idle right. It's real boggy. Sounds like it's loaded up with fuel.
 What would cause the idle not to run high after starting?

High idle is usually a vacuum leak someplace.  But if the connector on one injector is questionable, unplug it and see if there is any change.  The engine should still idle but with a slight change in tone.  If you try driving it, you'll really feel the loss of power.  You should be able to buy a replacement connector and swap out the connector itself without having to cut and solder since the pins are ok still.

Are you sure the injectors you're using are good and firing?

[sharpxmen]

if it runs rough first thing i would think of is one of the injectors is not working (also based on the code) - you can unplug one at a time and see if the idle changes, when it doesn't that's where the problem is. Second thing (i assumed you checked this already but just in case) is to make sure they are high impedance. and the third thing (which should throw a different code however) is to make sure they are the correct flow - what P/N are they?

EDIT: Jeffy already suggested the unplug test, i missed that the first time around.

[sharpxmen]

What would cause the idle not to run high after starting?

does it go lower in rpm once is warmed up - if only 3 cyl are working the idle would be lower, that can be one cause. Also, if you're too rich or too lean can cause the same issue - lower idle rpm.

[FourbangerYJ]

I unplugged and repluged the AIS and TPS. They looked fine but you never know. Started it up and it was more normal. Idle was high upon start then went to it's normal RPM. While it was idleing I messed with the injector plugs one at a time. There was a couple I messed with and the RPM's changed. I am going to hit up the dealer to get new plugs for all of them.

Went for anther test drive. It's much better with the gas lines plugged in. When I started driving there was no CEL, pulling into the driveway the CEL came on.
I noticed starting out there is a bit of a bog then it gets going. Also coming to a stop it bogs down a bit.

[sharpxmen]

I unplugged and repluged the AIS and TPS. They looked fine but you never know. Started it up and it was more normal. Idle was high upon start then went to it's normal RPM. While it was idleing I messed with the injector plugs one at a time. There was a couple I messed with and the RPM's changed. I am going to hit up the dealer to get new plugs for all of them.

Went for anther test drive. It's much better with the gas lines plugged in. When I started driving there was no CEL, pulling into the driveway the CEL came on.
I noticed starting out there is a bit of a bog then it gets going. Also coming to a stop it bogs down a bit.

it could also be that one of them is leaking, you can check that with the rail off and put the contact on a few times to make pressure in the rail. Sometimes injector cleaner would work for that but it is unlikely to be a long term fix.

[TahoeYJ]

Went for anther test drive. It's much better with the gas lines plugged in.

I would hope so!   

[YJ KiD]

u get it all straightened out? what did the injectors come out of are they the other set of cobra injectors?

[FourbangerYJ]

I would hope so!   

I know,right! 

[FourbangerYJ]

u get it all straightened out? what did the injectors come out of are they the other set of cobra injectors?

I went to the stealership this morning. First he said the clips were not avail. Then he looked again and said they were $25 each. So I said I would try and glue them.
So I tried some Krazy glue gel. That failed! So I went out and got some Elmers model glue. I just got done glueing the connectors. There is 2 that are broke. It cures in 24 hours. I might try a zip tie too.
I'll fire it up tom. and see what's what.
They are the same type Cobra injectors you have. I have another set here, so I might swap them if it does not run right after some miles get put on it.