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djscrambler 06-06-2013 03:27 AM

Howell 4.2 tbi problems
So shortly after I installed the Tbi set up my motor is now acting up. It feels like it's running out of gas only under load (in gear). It has new plugs wires cap rotor. And plenty of fuel. And ideas? Thanks in advance.

86cj74.2L 06-06-2013 06:54 AM

Is your check engine light on?

walkerhoundvm 06-06-2013 07:25 AM

Check for vacuum leak?

SLO_Ken 06-06-2013 09:13 AM

^ This, especially where the throttle body attaches to the adapter.

Also, what fuel pressure are you getting at the throttle body? These things don't like any more than about 13. Mine seems to run best closer to 11.

djscrambler 06-06-2013 03:49 PM

When it starts to sputter out it's usually when the motor warms up. The light does come for a few min then goes back off.. I'll double check for vacuum leaks. An as far as the fuel pressure goes I don't k ow I'll have to go down and buy a gauge. How do I adjust the pressure if I need to?

walkerhoundvm 06-06-2013 04:11 PM

Have you got the correct EGR in there, or do you know if it's functioning correctly? I seem to remember a thread of yours on hooking the thermal vacuum switch up - how'd that work out?

Normally the EGR should shut off as the engine warms up. I guess it's possible yours is staying open, creating a vacuum leak of sorts and allowing exhaust gas to enter the intake air...possibly setting the CEL off?

86cj74.2L 06-06-2013 06:34 PM

When the light comes on you should figure out why.

They can be read by jumping two wires in the ALDA connector. Or get a scanner

djscrambler 06-06-2013 11:30 PM

Today I checked the erg it was fine, I timed it correctly ran better but still had the same problem. I grabbed the harness and gave it a wiggle and the motor quit and it won't run now... I pulled the harness apart and all the connections are solid. Somedays I have the urge to just burn it to the ground. Lol any more ideas is appreciated.

offroadz 06-06-2013 11:44 PM

So no vacuum leaks, fuel pressure is good(pump and regulator) and you have a decent ground for the computer.

New cap, rotor, wires. What brand and were the wires pre-cut or did u cut the wires and put together?

What ignition setup do you have? What coil are u using(new?). Have you checked all of the fuses related to ignition?

djscrambler 06-11-2013 09:33 PM

I changed coils and finally got it to fire. I can still only drive about 10 to 12 miles before it acts as though it's starving for fuel or air. I am running the stock ignition mod with what Howell calls a nutter bypass.

djscrambler 06-11-2013 09:48 PM

Any one think it could be the computer? Or maybe the idle air control?

TJ-Joe 06-11-2013 10:41 PM


Originally Posted by djscrambler (Post 15525913)
So shortly after I installed the Tbi set up my motor is now acting up. It feels like it's running out of gas only under load (in gear). It has new plugs wires cap rotor. And plenty of fuel. And ideas? Thanks in advance.

Pick up the phone and call Howell - I have found them to be incredibly helpful when troubleshooting a problem, even after it had been on the CJ for many years.

SLO_Ken 06-12-2013 10:50 AM

What codes does the ECU report?

Put a jumper (or paper clip) between terminals A and B (see diagram below) with the ignition "ON" and engine not running. The system will enter the diagnostic mode. In this mode, the computer will display a Code 12, three consecutive times, by flashing the "CHECK ENGINE" light. A Code 12 consists of one flash, a short pause, then two flashes in rapid succession. After Code 12 is displayed, any stored trouble codes will be displayed by flashing the "CHECK ENGINE" light. All codes are displayed 3 times each then a code 12 will repeat.

Then check here to see what the codes mean.
Read more at:

djscrambler 06-12-2013 11:00 PM

I checked for code none came up. Just a continuous "12".

offroadz 06-12-2013 11:39 PM

12 is default. No other codes is good.

You said you revved in GEAR? Does it do the same thing when you are parked and rev from the throttle itself under the hood?

The time now is 06:58 AM.

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