What did I find? The 200k bosch were leaking, misfiring, ...I always wondered why the big surge when I started it up, and after driving cross town yesterday and shutting it off, I again noticed the momentary lock-up when re starting. Hydrolock! Them babies were dripping leaky. Had suspected as much.
So this morning in about an hour I threw in the $45 set of new Chinese 4 hole injectors, new O rings included. I had previously changed the O rings with a napa set. What I found was the holes in the manifolds the injectors go in, each one of them was badly caked with varnish. And that varnish is just as hard to get off as the rebuilders say it is! Imagine the inside of your injectors! Tried spray cleaner and Q tips. Did that a dozen times, each time more brown varnish water came off. You need a good strong LED work light by the way. Scraped it a bit with a small driver, that worked ok, but you can see tiny microscopic flakes of what looks like brass coming off too, so that's not the best. Well ended up just repeating the spray cleaning scraping and Q tip method.
Then insert the new injectors in the rail with a shot of cleaner as lube, then press all the injectors at once into the intake.
Started up with no surge, ..idle ok after burning off crap, ...test drive...Man alive. Why did I not think of this sooner.
Smooth idle, none of that pop and poof that I was thinking was valves or plugs, ..strong hard acceleration..I mean like 10 mph more that it was before for the same amount of pedal.

 

A nylon or brass rifle bore brush works the cat's for cleaning the injector bores. When we did the cylinder head on my WJ 4.0, I found 2 of my original Siemens injectors had cracked coil covers. I replaced them with reconditioned Bosch 4-holers and the results were great, but IDK how much the new head and valves had to do with that.

That was 50K miles ago and now I have a problem with cylinder #5. It seems to have a lack of power at idle. Not a missfire, but just a change in the idle exhaust rhythm. Sometimes it will stumble on a hot start, but works normally under power. Now you've got me wondering if it's leaking. The problem is the injectors were sold in a set that had "various numbers" in it, but all looked the same. I think they cost me $140. I ain't buying Chinese, but I'll be looking for another set from someplace.

I should do a fuel pressure leakdown test.

 

My leakdown test was normal, I think. Drops immediately to about 44 and then sits there for way more than 20 or 25 mins. So idk about that test for injectors. However there is a test with a pulser. You connect to this thing and it opens for a selectable # of microseconds or whatever, and you watch the pressure drop. Then do the next one. They say should only be 2 or 3 lbs between them. However I don't think that would necessarily show the occasional sticking pintle but it might be worth considering. Thing is, it's $100 for the pulser.
I also used a stethoscope to listen to each one, and had one or two that were clunking rather than clicking.

 

OK update. So as usual I was full of c*** about a few things. Number one, the Chinese injectors. I rolled the dice with them and what do you think. After experiencing wicked misfire to beat the band on start up from Day 1, which was NOT cured by a pcm reset, I got around to putting my original 200k bosch injectors BACK in.
Misfire gone, and the long term fuel trim ...which was looking way out of whack at -7.6, went to -3.4 in one day. Much better. So I paid the price $45 and got burned. I will say, for whatever reason, my mileage did go up with the Chinese ones, considerably. Will see if it stays there wit the originals...So I will look to do Bosch 4 hole injectors. Anyone know the right number to match the flow of the OE??

Point 2, this was not the cause of my "momentary lock up" at start up which happened every so often, usually when re starting while hot. I believe that was the battery charge, which is the Achilles heel of these jeeps that use the battery temp sensor. Suspecting the battery and despite my impressive electrical background, I took it to AZ for the free test. They couldn't test it because it was not charged! 12.1 volt.s Huh. The woman told me to clean the battery terminals; I suspected otherwise. got it back home and this time with a working VOM tested the resistance at 75 deg F, should be from 9 to 11k, was 6k. Duh! So subbed in a 15 k resistor *ever try to buy a resistor in town these days since Radio Shack closed??* Anyhow went back to charging at 14.2 or so. Mind you a healthy battery should be 12.6. Anything less is actually bad for the battery long term. At 12.1v I was less than 25% charged. Even now it probably isn’t charged all the way.

 

To be honest, the flow rate of the injectors doesn't really matter much because the PCM controls mixture by varying injector "on-time". Unless you'll be running it at WOT, as in racing, you could have injectors with a massive flow rate and never need the fuel! JMHO.

BTW, I was told there still is a Radio Shack store in Destiny USA. I needed a mono phone jack and plug, but I bought it on-line rather than go it THAT nuthouse!

 

Right, but I know when I see a LTFR of -7.5 that the pcm is doing a LOT of compensating.