And you're nuts if you don't do this, too.
Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
　
　
If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
　
Revised 11-28-2011

 

Ha!NO!! Post #4 here -V- .................................................
http://www.bimmernut.com/forum/5-ser...injectors.html

Funny, total coincidence! And No..myself, I highly doubt your problem is you need to raise your pressure. I'm learning here myself, (from people like Cruiser and Radi, amongst others) I Do think it is safe to say you want to rule out trouble with your wiring and sensors, (and the map tube), before you suspect they are the wrong injectors. They may be faulty, but 19# really should be OK with your 30 something lb regulator.

 

I agree. Address the known issues with the vehicle, all outlined above, first.

 

Ok... I did the C101 connector cleaning ( that was a mess), Took apart and cleaned the grounds including the battery ground. Also tested the IAT, which is working fine and adjusted the TPS as well. Took it around the block, ran great, idled in my driveway for about 5 minutes and it started loading up a little bit again, hesitating, little bit of a gas smell. Would it matter that the injectors I installed are rated at 43.5 PSI amd have a stock 39 PSI regulator? I'm stumped.

 

Thanks guys, great input

 

I was missing my map hose and it made it run really rich, 4mpg rich.
A $1 piece of silicone hose changed that to 15mpg (in city). I would start there if you haven't already.

 

I just went outside and the jeep wouldn't start until I held the throttle to the floor to cut the fuel. Then it took about 10 minutes to clear up. Jeep was warm.

 

Jeep was running fine after it started with me holding the throttle to the floor. I turned it off for 10 seconds and back on, the jeep started right up idled fine but hesitated like crazy when I tried to rev, almost as though it was missing. Turned it off again, wouldn't start until I held it to the floor, after 3 long cranks it fired up.. No hesitation, ran great. This has been my life for 2 months. LOL!

 

Sure sounds like one or more leaking injectors to me. Or one that's dumping fuel like a fire hose when it's pulsed.

 

Thanks! Are you talking about the tube that runs from the MAP to the throttle body? Mine looks ok visually, however I can't test the suction on it because the jeep dies when I unplug it. I'm getting decent gas mileage, my problem seems to be random, intermittent. But, it's a cheap hose so I'll definitely give it a shot.

 

If one or more of the injectors were bad, wouldn't that be kind of a continuous problem? Mine runs great and then randomly starts to hesitate and stall etc.. I restart it... and then runs great agaiin for a little while, and so on..

 

Honestly, when i think back how all this started.. The stock injectors were leaking and almost started a fire so I changed them out with Bosch 280 155 710. I didn't have this problem before I installed the new injectors so, it's definitely possible one or more injector might be bad.. I'll have to check it there is a warranty on them.

 

Hey Rob. Spent most of the day on the road. Actually got close to being "one" with the road. (again). I just don't have much to offer. If it was steady as opposed to intermittent, you could actually pull the rail and watch what's happening. (with precautions of course!) Seems pointless here. You might or might not learn something with noid lights? Do they come in a set? (it lights when the injector gets power). I'm just swinging here..doubt that might help..but I do get surprised enough. Contacting the seller might make sense, they might gladly exchange another set or have info that could help.
Like Radi points out it seems a bunch of fuel is going past them. Recently another poster got a bad, (one of 6), from Rock auto. It Does seem it would be easy for such a thing to not seat, and leak.

How it holds pressure while sitting might be a give away. IIRC loosing more than 20 Lbs. pressure in 30 minutes is I sign something is leaking. Guess the FPR and the check valve in the pump come in to play there as well. Maybe that was a spec for the later higher pressure system, I should take a look.

Without me looking back, did you change your MAP at the same time you installed the new injectors? If so, maybe try the old MAP???

And last...it looks like I got 20 MPG with the 703's on one 250 mile stretch of highway today. (as opposed to 14.5 running around in open loop 1/2 the time) Where does this go? -V-V-V-?

 

The O2 sensor and PCM might be making a mess of things trying to chase around a sloppy injector, and the injector(s) may behave some of the time.

 

Thanks guys, great suggestions. I think this weekend I'll start with checking the resistance on the injectors. I was thinking of picking up an EFI quick probe to check pulse. One good thing is that I can recreate the issues and then go crazy checking everything to see what's up. Check valve is also a good idea. I'll check pressure at rest. I recently changed the MAP because it was original, it didn't make much of a difference. It ran great with no issues after I changed the CPS and the FPR. Especially the FPR, it ran great for about 3 weeks to a month, I really thought I cracked it and then all of a sudden it started happening again. Flinststone, 20 MPG is KING! What did you hit that would shred your tire like that??? Radi, Thanks.. I'm definitely leaning towards bad injector(s).. But we'll make sure. One good thing is I'm learning a bunch and teaching my son as well. I'll keep you posted!