Wcreech8

Fellas, I’m kinda stumped on an ongoing issue with my ‘93 XJ project. So as a pretense this is a freshly rebuilt engine and upgraded to four hole Bosch injectors (part # 0280155758).
Any recommendations or opinions would be greatly appreciated. The Jeep has never had working A/C so I decided to replace the system. Basically everything besides the evaporator core. In the process I disconnected and removed the battery for more room to work with but whenever I reconnected the battery to charge the system I noticed the engine running extremely rich and flooding out the cylinders. Whenever I accelerate plumes of black smoke come out of the exhaust . The engine idles sporadically, almost like the computer is trying to adjust the fuel. So far I’ve replaced the MAP sensor (NTK), O2 sensor (NTK), and got a new battery but to no avail. I even cleaned all the grounds hoping maybe it was sensor signaling issue. I took it to my local mechanic and he concluded it was bad gas or bad PCM which I don’t believe is the issue. I’m thinking maybe the upgraded injectors might be sticking open but the mechanic said they were signaling fine. Before throwing parts at it I wanted to see if anyone had any suggestions. Thanks

robsjeep

Remove the spark plugs, compare them, see if some show signs of rich running. a stuck open injector will reveal itself with a gasoline soaked plug, sooty appeance. once the bad plug is found, you can then test that injector for being stuck open.


I assume there was no problem before you did the AC work, correct? charging the AC and removal and reinstall of battery likely wont effect engine running unless some electric component was dislodged during that work.

Was the injectors upgraded at same time as AC charging? did these injectors work ok before, or never before?

maybe put original injectors back in?

Does exhaust smell rich?

If catalyst equiped, dont drive while rich running, else catalyst maybe ruined$$$$$$$$$$.

good luck

Wcreech8

I’ll check plugs tomorrow and attach a picture of all of them. I checked all electrical connections and everything is tight. I replaced the injectors when getting the engine rebuilt. After injector install the engine has smelled a bit rich but exhaust smells extremely rich now. I’ll put the original injectors back in and see if that solves anything. How would go about testing the current injectors?

bluejeep2001

Could you confirm the part numbers of those injectors...having a hard time finding them on google search..they will be on side of the injectors

lawsoncl

Part number translates to 20 lb/hr 16-ohm injectors.
https://motorwestperformance.com/fue...tes-and-specs/ (look under top feed)

Seems close enough to replace the stock 21 lb/hr injectors
http://www.jeep4.0performance.4mg.com/tech_specs.html

Wcreech8

I'll take a picture of injectors tomorrow and measure resistance with multimeter to make sure they are within spec. I'll keep you updated

cruiser54

My money is on the tube/hose to the MAP sensor being clogged, melted, split or loose fitting.

Wcreech8

Tested all injectors with multimeter. All injectors read 16.1 - 16.4 ohms which i believe is spec for this injector. Pulled the plugs, all were fouled up pretty bad. I cleaned them up with a wire brush and checked the gaps. Cylinders 3, 5, 6 were gapped around .25. Cylinder 4 was gapped around .40…I cleaned them up and gapped all plugs to spec .35 and reinstalled. Noticed a dramatic difference in idle and engine performance. And best of all no more excessive black fumes coming from exhaust when hitting the throttle. Could incorrect gap plug cause engine to run so rich?

exasemech

If the plug gaps on your "freshly rebuilt engine" were that messed up I gotta wonder what else is off. You are assuming the fouled plugs and smoke and rough running are from running rich, could be misfire .

For starters were the rotor,cap, and coli&plug wires replaced?

bluejeep2001

First....040 down to .035 will not fix anything unless your coil is garbage, and even then not likely. Those injector part numbers look like 0280155759 to me...those are 30 lb injectors Every plug there is running super rich. You have the wrong injectors

Wcreech8

Honestly it’s my ignorance, I replaced the coil, plugs, and wires about 2 years ago and reused these parts after rebuild. The plugs were supposed to be pre gapped but I didn’t check before installation, lesson learned.

Wcreech8

Im planning on going to the junkyard this weekend and grabbing some original injectors . I can’t find the ones I originally took out. I bought these Bosch injectors on eBay for $85, which was probably my first mistake. After cleaning up the plugs it’s running a lot better but if the injectors are rated at 30lbs that means it putting more fuel in cylinder than spec and the plugs will foul up again, right?

robsjeep

Correct. The wrong gaps are not bad enough to cause the running issues. But injectors that deliver too much fuel will cause problems.
does she smell rich?

use care, rich running will eventually ruin the catalyst.

Wcreech8

Yes she's always smelled rich since injector install but its definitely more prominent the more I've driven it. Which makes sense because plugs just kept getting more and more fouled up. I'm going to park it for a few days until I get original injectors back in. Will update when thats complete. Preciate all the help fellas!

cruiser54

Plugs are never pre-gapped except by us before we install them.
There is someone on Cherokee Forum that provides the correct injectors all refurbished.

There are MANY cheap chinese knock-off injectors out there. Get original rebuilt ones!! trevor.skankfootracing@gmail.com