Hello,
Having a hell of a time getting my '89 Cherokee (Wagoneer LTD) 4.0l to run correctly again after doing some work on the fuel system. Here's what's up;

Had some leaky (squirting) injectors and all around old and worn components. So I replaced:

Injectors - (stock w Bosch 4 hole, all o rings)
All fuel line o rings and clips for lines
Fuel pressure regulator - (stayed w Duralast)
TPS - (stock w NTK)
MAP Sensor - (stock w Walker)
Cap n Rotor - (stock w ACCEL)
Entire vacuum harness as well as lines directly to ICM
Spark Plugs - (champion platinum w NGK iridium)
New Bosch Fuel Pump and Filter about a year ago
Plug Wires (went w 7mm)

About 6mos ago:
Air Filter (stock w K&N)
New exhaust from header back (stock w 2 1/4 pipe and Flow FX single chamber muffler)

I did the ECU reset procedure although I'm not sure how much affect this has on an '89. It seemed to help w the firing after warm up I guess.
Reverse flushed all the injectors
Cleaned all grounds and plugs
Messed w the TPS until there was no more smoke when warmed up
Among other housecleaning and such

So now I'm getting a lot of smoke and a very hard start. It actually runs w less power than it had before w the old injectors and parts than w the new goodies.
After about 50mph when shifting into 4th (auto transmission) I lose most of the power altogether. It stills fires but chugs very badly and causes some bad vibration. Still some smoke when in gear (there was none before the repairs).
Temp runs just fine at about 190

I've read these symptoms are most likely too much fuel from the injectors or an issue w the ICM not advancing the timing as it should.

Should I go back to stock injectors? Is there a way to adjust or advance the timing manually? Would a bad EGR sending unit cause this? Or maybe some other valve or head issue? But, as I said, it ran so much better before the "repairs". Maybe a whole new distributor?

Really at a loss here now and I miss my Jeep.

 

What color is the smoke?

 

I'm not sure how much it will help you but if you want to see live data you can get an REMII

https://nickintimedesign.com/

 

+1 this... got one in my '90 and it helps very much in diagnosing and constant readings

 

grey - ish
definitely rich fuel smelling

 

Does it still run poorly with the oxygen sensor unplugged?

 

Good question. I will have to check

 

If it was just running rich, then that would be black. Have you ever had cooling problems?

 

No cooling issues. All components of the cooling system were replaced in 2020. I haven't done the head gasket but there's no sign of any leaks or holes.

 

I'm gonna bet the integrity of the throttle body to MAP sensor hose/piping is compromised.

 

I will order one. I know it's come loose before

 

Inspect it. They're no longer available. Here's how to fix it.CRUISER'S MOSTLY RENIX TIPS

THROTTLE BODY TO MAP SENSOR HOSE FIX

JANUARY 23, 2016 CRUISER54 45 COMMENTS EDITThe Renix throttle bodies have a strange and failure prone connector on the side where the MAP supply originates and then runs up to the MAP sensor located on the firewall. This hose/pipe assembly is no longer available for purchase.

The real kicker here is how critical this line is in supplying the correct vacuum signal to the MAP, the most relied upon sensor for the ECU to read regarding air/fuel ratio. Any cracks, melted spots, or loose rubber connectors can cause major starting and driveability issues.

There’s a simple fix though. All that’s required is a 1/8” NPT tap, a new throttle body gasket ( Napa FPG 60742 ), a vacuum fitting (Napa 05703-B102), two vacuum elbows (Napa CRB2670), and a length of new plastic piping (Napa CRB2672).



Remove the throttle body and take it to the workbench.

Using an oiled tap along with a driver, carefully thread the lower of the 2 holes of the throttle body where the old fitting was plugged in. Don’t go too deep. These are pipe threads.

Flush the hole with carb cleaner and inspect for any left over cuttings.
This is an excellent time to do a complete throttle body and IAC cleaning. See Tip 11.
Take the vacuum fitting (05703-B102 ) and apply a LITTLE bit of thread sealer on the threads only. I prefer Permatex #2 but almost anything is fine.

.

Carefully screw the fitting in until snug.

Install one of the vacuum elbows on the MAP sensor so it points toward the throttle body, and the other vacuum elbow on your new throttle body fitting so it points up to the MAP sensor.
Cut a length of the new plastic tubing (approximately 13 inches) to fit between the vacuum elbows and install it making sure there is enough slack for some engine movement. Route it according to the photo. We don’t want any rubbing or chafing with engine movement. Not a bad idea to use some contact cement or Gasga-Cinch sparingly on the tubing to elbow connectors.

 

For giggles - re-install your old injectors and see how it runs. I've dabbled in 4 hole injectors and ultimately went back to factory ones because i was tired of chasing running issues. If you put the factory ones back in and it starts running fine again well i guess you've narrowed your problem down obviously. I also say this because if you do still have your factory injectors they don't take long to swap out and then its also no added cost of parts- just time.

 

Ty for responding! I have definitely thought I should do that as well as the MAP vacuum hose mod. As you say, to narrow the possibilities. The new stock injectors are just so damn expensive compared to the 4hole Bosch's. I guess we know why now

 

Time is really to most valuable thing tho