Engine will not run smooth

[SemperFiCJ5]

I have tried to drive my CJ5 but it will sputter and back fire when I give it any gas. I put in a GM TBI, I Set the timing as required but it is still real rough. At Idle it is good. I smell a lot of fuel in the exaust. Its hard to say if the O2 sensor is bad(how do you tell?)
I have a DUI distributor and it is computer controlled. Not sure what to do at this point.
Any sugestions would be helpfull.

 

[Old Dog]

sounds like a timing isue, are you sure the GM tbi and the dui are talking to eachother. You can put a timing light on it and rev it up and see what kind of timing curve you have got going on.
You can check the co2 sensor with a ohm meter. I'm not sure what it should read though.

 

[kicknjeep]

^
What he said x2

 

[SemperFiCJ5]

How do you tell the timing curve? normally I would just adjust the timing. Now I am lost with adjustments. I set the timing to zero. then the computer set the timing.
If the harmonic balancer is off then my timing is off. I will try to find TDC manually and see if the rotor is on the Number 1 plug.
I havent done that yet, I have just assumed the engine was good.

If there is an Ohm check I need to know how to do that. O2 sensors are not cheep.

 

[Old Dog]

First let me say I'm no expert here. I have a howell gm tbi on a old 350 with a hei dist. (non computer)
From what I have found the 02 sensor should be putting out between .1 volt (lean mix) to .9 volt (rich mix) but should run around .35 to .55 in closed loop.
Are you running a knock sensor?
Are you throwing any codes?
What did the tbi come off of I see you have a 401.
I think your idea of checking tdc is a good plsce to start.

 

[BrockGrimes]

Info about timing and initial startup here:
BustedJeep.Com - In The Garage

 

[SemperFiCJ5]

Are you running a knock sensor?
Are you throwing any codes?
What did the tbi come off of I see you have a 401.
I think your idea of checking tdc is a good plsce to start.

I am not running a knock sensor. Also I am not throwing any codes. The TBI I am not sure what vehicle it came from. When I got my DUI dist they programed my chip.

I still havent found anything on seeing if the ECM and DUI are linked. I would think they are. I will just have to start from scratch I guess.

 

[SemperFiCJ5]

I checked TDC. I was a few degrees off from the line on the harmonic balancer. The rotor was allitle off from the number one plug so I lined it up and tightened everything down. Changed the plugs and gapped them to .050
It was a little rougher running and would die. Was just as bad when I tried to drive it.
I didnt get a chance to pull the O2 and check it. Thunder storms down here keep me from working on it!

 

[Old Dog]

Most of the time backfire is caused by timing isues. Throu the carb is to much timing and out the exaust not enough.
Have you checked your fuel pressure in your RETURN line? if it's to high, over 11lbs it could be flooding. mine is only 5lbs (you said it smells of unburnt gas)
I would also check to be sure you have a full 12v at the ECM fuse block while running.
Oh yea and to check the 02 leave it in, and let it warm up to temp (closed loop) before you check the voltage output.
I'm running out of ideas so I hope something here helps. Let us know what you find.

 

[BrockGrimes]

Your throttlebody is probably from a 454 it's like 2"+- across the opening smaller engines have inch and something I believe. Your running a 401 right.

 

[SemperFiCJ5]

Yes I am running a 401, the opening is at least 2 inches accross.

I havent checked the return line. I have a in line pressure gauge for the feed line but I only have 10-11 psi there. I think I have two different size lines for the fuel though. Maybe if the return line is smaller that could be making it a higher pressure.