Changed injectors - eventually got code

Status
Not open for further replies.
G

Gary Allan

Joined
Sep 28, 2002
Messages
39,799
My wife's jeep has been plagued with fuel issues. It always responded well to stuff like Gumout Regane and Amsoil PI way too often. All the UOA's showed fuel ..not gross amounts, but enough to upset and confound my 0w-10/20LITE experiments.

Anyway, I picked up a set of 3.7 mopar injectors out of a 2005 Liberty. They were used but appeared brand new. The installation was a snap and no snags. Now I did have to unplug a few sensors off of the throttle body to manage the fuel rail ..but nothing got stretched and everything is back in place. The thing runs perfectly. One interesting note. The OEM Jeep injectors are a single nozzle deal, while the Liberty is a 4 nozzle deal. They're both (allegedly) rated @ 24# ..which I thought was high.

A day later, and I get a P0138 code which is the 02 sensor reading abnormally high. I had also changed out the catalytic converter on the same day and was afraid that I had bought some defective reject that a liquidator had got their hands on. If I had seen a "cat efficiency" code I would have been fit to be tied.

I'll recheck the connections ..but I'm hoping that this is some transitional thing with the PCM factoring the newer injector flow in its short term calculations.

Anyone else have this happen?

btw- for 140k ..the OEM cat only had about a dozen visible "squares" that were blocked. The vast majority of the visible mesh/honeycomb was open.
 
This code refers to bank 1 sensor 2 which would be behind the cat. I'd check the wiring and the sensor since it appears it may be caused by a short to voltage.
 
Usually, but not always, it means a shorted sensor or wire harness. All the code means is the O2 sensor (cat monitor) is reading full voltage for an excessive time. If you have a P0138 with no other codes you can focus on the cat monitor and circuit. If you have other codes, like primary O2 codes for "excessively rich/lack of O2 switching", something is dumping excess fuel in the intake. There is an off chance the secondary O2 will code before the front depending on how much leeway the PCM gives fuel trims. If you know someone with a scanner/data logger keep an eye on long term fuel trims, and primary and secondary O2 voltages. If there is a wiring harness problem in the secondary O2 circuit, it should read high voltage with the key in the run position even with the engine off.
 
My FSM does say 1/2 O2 sensor shorted to voltage (bank one sensor 2) for the DRB scan tool display. In the "brief description" it states, "O2 sensor input voltage maintained above normal operating range". I misread it as "1 of 2" (the rear being 2/2). We did swap the rear O2 sensor to the new cat. There were no issues in the swap ..

I WISH I could get my hands on a DRBII to play with for less than $90/hr.

Looks like I may be grabbing a volt meter.

Thanks much!
 
Originally Posted By: Gary Allan
The OEM Jeep injectors are a single nozzle deal, while the Liberty is a 4 nozzle deal. They're both (allegedly) rated @ 24# ..which I thought was high.


I replaced the single nozzle injectors in my 1988 Mustang GT with 4 nozzle injectors. They worked fine.

What color are the injectors (old and new)? The color tells you the flow rate. Orange is 19#, by the way.
 
Blue and Blue. Just about identical. The 2.5, oddly enough, uses the chubby type. These are pencils.

9f921f27a9aaag8.jpg
 
Reset your computer.
Take the battery cable off for a few minutes.
Drive it to relearn it's parameters, and se if it is OK with no codes.
 
No banging around. Just a disconnect and reconnect. Even if it was unplugged it should read as an open and not full voltage
54.gif


The thing came out without difficulty. I dressed the threads on a wire wheel and never seized it ..in it went.
21.gif
 
That post cat sensor is telling you that the cat is defective. That is all it monitors, it does not effect fuel mixtures etc. Since it was fine before you changed out the cat and you are sure you did not damage it then what else can it be? Lastly - did you verify that everything was tight and no exhaust leaks to lean out the mixture read by the sensor?

Just thoughts..
 
Well, it's not giving me a cat efficiency code. It's a code for shorted to supply. It actually is saying that the supply is bypassing the sensor or that the sensor is internally shorted. No damage or banging around occurred. Removal went smoothly. The only thing that could be related (which I'll check tomorrow) is that the plastic fastener that attached the pigtail to the transfer case was a real pain to get out of its hole. It was one of those "one way" push in fasteners with all the "angled discs" (
54.gif
) ..but no "damage" appeared to be done. Either way, it doesn't effect running. I'll lock it down tomorrow and figure what's up.

Now I'm assuming that this is a correctly set DTC ..but the explanation merely states that the rear O2 sensor is giving a higher than normal input to the PCM. The cat monitoring utility measures the number of upstream switching between lean and rich vs downstream switches lean to rich. When they approach 1:1, separated by a delay, the cat is shot ..but I don't know what happens when it's new and near zero. That is, my rear O2 is supposed to be at high voltage most of the time.

I guess I'll find out tomorrow
21.gif
 
Well, I checked and cleaned the connection for the rear O2 today. I can't believe that I damaged the O2 sensor upon removal installation. It went too smooth and no shock or insult occurred. I had previously just reset the code and it reappeared upon the end of the O2 heater READY cycle. Now I've reset it again and will see if it reappears. I really don't want to spend the $50-$60 for a new rear O2 sensor.

On a bright note, the 4 spray nozzle Liberty injectors appear to work well compared to the single nozzle TJ injectors. I'm going to let the fuel trims normalize on their own. One thing that's apparent from hitting the upper rpm band (in this, it's anything over 3000), the stumble @ 4000 rpm is currently gone. This was even from very early in the engine's life. When you hit 4000 rpm, it was like you were shifting gears sorta. Anyway ..some transition was occurring and now it's gone ..at least for the time being.
 
Did it also fail the O2 heater test?
If the internal O2 heater fails it can also set a 'shorted to voltage' code
 
My Camry's injectors have more holes then Jimmy Carter has liver pills! If I rember right they use something like 9 or 12 individual holes to spray the fuel into the intake track. All I can say is over kill.
 
Originally Posted By: Rabbler
Did it also fail the O2 heater test?
If the internal O2 heater fails it can also set a 'shorted to voltage' code



I just got the shorted to voltage code. I pulled it apart cleaned the connectors ..put it back together ..still got the code. I'll now just unhook it and see if I get the same code or the "open" code. If I still get the same code, in addition to others, then we damaged the wires somewhere up the line. If just the open code, then I figure that I somehow damaged the sensor in the swap.

Edit: The thing runs very nice with these 4 hole type. I have heard some rhetoric that DC used the single nozzle design to make valve cleanliness a longer term maintenance benefit. They apparently use the puddling on the back of the hot intake valve to do the atomization and this promotes cleaning.

These are big for the displacement. Even 5.8liter Ford's use 19# injectors. These are 24# ..so are my 2.5's ..but they're the Design II and the 4.0 uses the Design III connector. I don't know what they were thinking. Chubbies on the 2.5 and pencils on the 4.0.
54.gif
 
Older Design III injectors use the Bosch connector, same as the Design II. There is a newer style connector (called USCAR) which is used with most newer Design III injectors. A bit of trivia is that Ford used this same USCAR connector on some of their more recent models for the speakers.
 
Originally Posted By: Shaman
There may be more space for the chubby ones in the 2.5 intake tract.


You may be correct ..but it still meant that they handled two part numbers. They could have used the Design III's on both. They ran two different #24 injectors side by side.
54.gif
 
Originally Posted By: brianl703
Older Design III injectors use the Bosch connector, same as the Design II. There is a newer style connector (called USCAR) which is used with most newer Design III injectors. A bit of trivia is that Ford used this same USCAR connector on some of their more recent models for the speakers.


Yes, I've seen pencils with rectangles (my terms). No chubbies with ovals though.


Here's something you may know. All domestic injectors appear to be high impedance (oddly you can't measure impedance with an Ohm meter ..only resistance ..but that's how they recommend checking them
54.gif
) but allegedly some imports are low impedance.

Anyone know which import (what's an import these days?) lines use incompatible impedance injectors (they all look alike)??
 
Status
Not open for further replies.

Similar threads

H
P0420 - 05 Jeep Liberty 3.7
Replies
2
Views
331
Vitamin Yoda
zrxkawboy
fuel pump brand
2
Replies
25
Views
1K
zrxkawboy
R
Downstream O2 code.....then immediate US code after change?
Replies
6
Views
846
someonesomewhere
B
2006 Pontiac vibe 1.8 1zze auto help!
2 3
Replies
49
Views
3K
Bry1234
tiger862
Impala lights dimming on acceleration
Replies
4
Views
458
tiger862
Back
Top