getblown5.9

distributor on the donor motor was never removed and it came out of the donor truck running fine.

if the injectors were not firing properly why do i smell raw fuel when it misfires? can it be injecting too much fuel?

im guessing its got to be something in a sensor or a wire somewhere. was reading something about a grounding strap causing these type issues...but mine is hooked up...

SeriousOffroad

There are multiple grounds for your motor.
One at the back near the valve cover
2-3 wires at the tranny dipstick mounting stud
1 at the coil
3-4 wires next to the PCM

getblown5.9

ive got none on my tranny dipstick...i have about 4 on the engine oil dipstick.

im gonna go through the wiring harness down by the tranny tonight and look for a ground thats damaged or not hooked up.

SeriousOffroad

Sorry, I meant oil not tranny.

getblown5.9

so i pulled the CPS did the ohms test...if i test it with the prongs on B and C one way i get no movement on the meter, basically infinite resistance. then if i switch the prongs of the meter the other way (still on B and C just red and black reversed)...it will pick up a reading.

i went to two auto parts places, got new CPS and tested them and got the same results, this tells me the CPS is still good.

then i went and checked all the grounds, disconnected the battery etc cleaned up all the connections. found one loose ground, the big strap at the firewall going to the back of the head, tightened it up.

went for a test drive and all was well until she got up to temp, it started popping and sputtering and the more it does it, the worse is gets. it got so bad i couldnt maintain 20 mph on a main road and had to pull over and shut it off. started it and tried again with no luck. no power, no rpms, you can give it gas but the rpms just bounce around 1000-1500 and its started backfiring really loud through the intake and the exhaust makes one heck of a racket.

barely limped it home, at this point im struggling to do 5mph with all the backfiring and sputtering. pull it in the driveway and let it idle. it stumbles a couple times and it clears up. rev it up and its running good, so i see if i can make it act up again...another trip around the block and it runs like a champ. im sure if i try to drive it to work tomorrow i will not make it there without it dying.

tomorrow it gets 10 gallons of gas and a match and it goes bye bye.

getblown5.9

bump

getblown5.9

checked the CAT...bumped it a couple times with my fist and it rattles inside. it needs replaced im sure, but would that cause all these other issues?

89Laredo

If the cat is bad enough it could cause alot of restriction and possibly cause problems. If the engine cant breathe its not gonna be happy... I would try changing the cat before you do anything to radical...

Abovetimberline

The head on the 99 is a bit different than the 96,the intake gaskets are even different,which gasket did you use? It is possible you have a vacuum leak on the intake,check the vacuum at idle when it is cold and after it warms up. Also you said this engine ran fine before the swap,but how was your jeep running?

getblown5.9

before the swap my jeep would only run if i put a new gear on the distributor. the gear on the camshaft is worn and was in turn wearing out the dist gear. a new gear would last about 1000 miles before it was worn down so far that it would be out of time and not run anymore. new gear and it would run like a champ again with no issues.

i put the 99 motor in because it was newer, less miles, and actually cheaper than me buying a new camshaft and all the related parts to swap out the cam on my 96 motor. now i wish i would have just did the cam.

getblown5.9

I was gonna try to diagnose/eliminate the O2 sensor...I read that you can unplug the upstream sensor and it will throw a code but if it runs fine then its the sensor throwing the fueling off. I unplugged it and started it and the idle was all over the place, it was up and down and didnt want to stay running. Try to give it gas and it died even quicker. I tried starting 2-3 times and it would not stay running. So i thought I would plug it back in and see what happens. No better, maybe even worse, it was making weird noises, popping thru the TB badly, then I started hearing air rushing back through the intake, a very loud hissing. My first thought was maybe that CAT is plugged and its not flowing air through the motor very well...so I slid under there and gave the cat a hard kick with my boot and all the sudden the idle smoothed out and the motor ran great. So I tried to drive it and everytime I would give it gas, I guess the exhaust stream flipped the broken piece up and clogged the cat because it would bog down. I will be gutting the cat after the weekend to test this theory and if that solves it I will buy a new high flow cat to install on it.

It was fun tho, with my jeep down for the count now, I had to drive my ~700hp diesel sled pulling truck to work, lets just say that a touchy throttle with a full spool in the rear makes for some interesting commuting to work.

Abovetimberline

Check your muffler to those little pieces get in there to.

getblown5.9

ok back to square one...im stumped.

gutted the cat to test and see if it ran better with no restriction before spending money on a cat...no help. it ran fine until it got up to operating temp and the problem came back.

so i unplugged the upstream O2 sensor again...it ran fine while warm/hot last night. start it up cold this morning and it wont hardly run then as it warmed up it was "ok" but still not right. try to go get lunch this afternoon and its cutting out terrible, popping hard back through the intake, not enough power to pull out in traffic doing 30-40 mph so i limp it back to the office on back roads.

now i really dont know what to do. i was sure it was an O2 sensor or the cat, but gutting the cat and unplugging the sensor didnt help at all.

SeriousOffroad

This:
ENGINE WARM-UP MODE
This is an Open Loop mode. During engine warmup,
the powertrain control module (PCM) receives
inputs from:
† Battery voltage
† Crankshaft position sensor
† Engine coolant temperature sensor
† Intake manifold air temperature sensor
† Manifold absolute pressure (MAP) sensor
† Throttle position sensor (TPS)
† Camshaft position sensor signal (in the distributor)
† Park/neutral switch (gear indicator signal—auto.
trans. only)
† Air conditioning select signal (if equipped)
† Air conditioning request signal (if equipped)
Based on these inputs the following occurs:
† Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by
turning the ground circuit to each individual injector
on and off.† The PCM adjusts engine idle speed through the
idle air control (IAC) motor and adjusts ignition timing.
† The PCM operates the A/C compressor clutch
through the A/C compressor clutch relay. This is done
if A/C has been selected by the vehicle operator and
specified pressures are met at the high and low–pressure
A/C switches. Refer to Group 24, Heating and
Air Conditioning for additional information.
† When engine has reached operating temperature,
the PCM will begin monitoring O2S sensor
input. The system will then leave the warm-up mode
and go into closed loop operation.

IDLE MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At idle speed, the powertrain
control module (PCM) receives inputs from:
† Air conditioning select signal (if equipped)
† Air conditioning request signal (if equipped)
† Battery voltage
† Crankshaft position sensor
† Engine coolant temperature sensor
† Extended idle switch (4.0L engine with police
package only)
† Intake manifold air temperature sensor
† Manifold absolute pressure (MAP) sensor
† Throttle position sensor (TPS)
† Camshaft position sensor signal (in the distributor)
† Battery voltage
† Park/neutral switch (gear indicator signal—auto.
trans. only)
† Oxygen sensors
† Power steering pressure switch (2.5L engine
only)
Based on these inputs, the following occurs:
† Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
injection sequence and injector pulse width by turning
the ground circuit to each individual injector on
and off.
† The PCM monitors the O2S sensor input and
adjusts air-fuel ratio by varying injector pulse width.
It also adjusts engine idle speed through the idle air
control (IAC) motor.
† The PCM adjusts ignition timing by increasing
and decreasing spark advance.


Assuming the plug wires are good and based on the open/closed loop sequence, i would suggest the following:
Swap the spark plugs from cylinders 1 and 3 into 5 and 6 and see if the misfire moves to those cyinders. If it does, replace the plugs.

If Your CEL still reports a misfire, swap the injectors from 1 & 3 into 5 & 6. If the misfire is then reported at 5 & 6, replace the injectors.

getblown5.9

i have disconnected battery and cleared codes and got new ones back.

had it checked today (as it limped at less than 15mph to the auto parts store)

1391- Engine management system detect misfire (something along those lines)