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Discussion Starter · #1 ·
Who out there has the Howell throttle body setup on their 4.2 and what are your opinions of it? Just curious what other think of it and the pluses and minuses you've seen with it.
 

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I loved it on mine. It is a big chunk of money, but it was a great upgrade. You may want to look in to a junkyard version if the money is an issue. It is just parts off a GM 4.3 re-purposed to fit a Jeep.
 

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I've had mine on for a couple months. Only issue i had was a TPS that went bad out of the warranty. No big deal to fix. I would do it again. Easy to install, no hassles.
 

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Love mine, it runs awesome!
 

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Discussion Starter · #6 ·
I’ve been having a bit of a problem with mine. The PO installed it and it seems that he did a solid job. Also, luckily the service manual from Howell is really thorough and the flow charts are good.

It fires right up and runs for 2-3 seconds before dying. When it got up to normal operating temp by holding at about 1500 RMP it would stay running, but pretty rough.

It wasn’t storing any codes so today I did the tests in Field Service Mode and got it narrowed down to a lean exhaust and to use the code 44 chart. Code 44 is Oxygen Sensor Circuit (Lean Exhaust Indicated). So it was either bad fuel pressure or a bad O2 sensor. I threw a new O2 sensor today because it was only $15 and easy to do. It definitely helped some, but still idles a bit rough.

So, tomorrow I’m going to check the fuel pressure to see how that looks. Am I right in my thinking that a lean exhaust would point to low fuel pressure? I’ve never checked fuel pressure on any engine before so I’ll have to figure that out. If you’ve been down a similar road with yours or have advice on checking the fuel pressure I’d sure appreciate any help.
 

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I’ve been having a bit of a problem with mine. The PO installed it and it seems that he did a solid job. Also, luckily the service manual from Howell is really thorough and the flow charts are good.

It fires right up and runs for 2-3 seconds before dying. When it got up to normal operating temp by holding at about 1500 RMP it would stay running, but pretty rough.

It wasn’t storing any codes so today I did the tests in Field Service Mode and got it narrowed down to a lean exhaust and to use the code 44 chart. Code 44 is Oxygen Sensor Circuit (Lean Exhaust Indicated). So it was either bad fuel pressure or a bad O2 sensor. I threw a new O2 sensor today because it was only $15 and easy to do. It definitely helped some, but still idles a bit rough.

So, tomorrow I’m going to check the fuel pressure to see how that looks. Am I right in my thinking that a lean exhaust would point to low fuel pressure? I’ve never checked fuel pressure on any engine before so I’ll have to figure that out. If you’ve been down a similar road with yours or have advice on checking the fuel pressure I’d sure appreciate any help.
Checking fuel pressure is not a bad idea, but I'd be more inclined to think it has a bad vacuum leak from your description. Lean exhaust is a condition where there is more air than fuel in the mixture. Check for a clogged fuel filter as well.
 

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X2 on a vacuum leak. Make sure the bolt holes on the adapter plate beneath the TBI are siliconed per the instructions and check that the MAP sensor is working and connected properly.
 

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Discussion Starter · #9 ·
Did you all keep your pulse air system intact when you installed the TBI? I found a hole in one of my air tubes.

Thanks for the tip, I'll trouble shoot that before I get into the fuel pressure.
 

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Discussion Starter · #12 ·
I'll have to look into that. I'd love to get rid of it, but wonder if it had to be there to pass a visual inspection here in UT.

I also think the vacuum lines to the CTO valve are installed wrong. I'll check that out too.

Thanks.
 

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Discussion Starter · #13 ·
Would one of you mind posting a pic of your CTO valve and the vacuum setup to it? I have the vacuum diagram, but a pic would be helpful too. Thanks a ton.
 

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as you look at the TBI from the front down near the bottom mounting plate there is a vacuum port that is blocked off , on mine it backfired one time and blue the block off plug off and it ran like yours does now .
 

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Discussion Starter · #15 ·
Yea, I've got the J port capped off. Pretty sure I've got some other vacuum issues though. I found this diagram online if anyone finds it helpful in the future.
 

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