Howell Engine Development TBI Kit Reviews, Ratings, Specs & Prices
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Throttle Body Next Product

Howell Engine Development TBI Kit

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Product Information

MSRP: $1,000,000,000.00
Average Price: $27,028,056.24
Manufacturer: Howell Engine Development
Yes: 36 / No: 1

This kit will only fit AMC or after market intake manifolds that have the Holley bolt pattern. Air filter not included and must be purchased separately. Howell Throttle Body Fuel Injection Kits have owners reporting smooth operating on all angles and inclines and improved starting and drivability with noticable power gain. Gas mileage improvements vary depending on the condition of the replaced carburetor. Since the system operates in a closed loop using the oxygen sensor to maintain an average 14.7:1 air to fuel ratio, improved gas mileage can be expected. The benefits of this Throttle Body Fuel Injection system over the competition, is the almost exclusive use of GM parts making them available through any GM dealer worldwide, should you experience trouble on the road. All GM on-board diagnostics and limp-home features are retained and, with our service manual, you can troubleshoot most problems yourself. You get the benefit of millions of dollars of durability development by GM, used to perfect their late model vehicles, at no additional cost. This kit is installed with the production distributor. Production GM TBI air cleaner can be used or several aftermarket designs can be adapted


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Registered User
ThatYellowYJGuy's Reviews
08-09-2016, 12:40 AM
Price: $1,200.00
Pros: It made the jeep more reliable and gave me better hp and mpg
Cons: It took 3 days to install, it was well worth it though.
Recommended? Yes

Comments: Its a throttle body fuel injection system, what else do you need to convince you haha

Registered User
JeepCJ71985's Reviews
12-14-2014, 03:00 PM
Price: $1,200.00
Pros: Makes the OE 258 work as designed. No more sputtering up hills. For CA vehicles owners, makes it a breeze at smog time.
Cons: peripheral wiring harness, fuse block, and OBD port seem a little cheapish, but they work just fine.
Recommended? Yes

Comments: I would highly recommend this product. There are many benefits, especially for California vehicles. Remove all of that spaghetti from under the hood, clean smog readings, smooth performance. Awesome. Something to consider for CA vehicle owners: build in the price of a new cat, egr, and exhaust to make a complete job of it. Made the process through the smog station a lot easier. Very clean, smooth running vehicle. Also, spend about three or four hours of reading time to one hour of wrench time if you are a shadetree mechanic like me. There are a ton of resources here on this forum, on the Internet, Youtube, etc. Take each step carefully and you will get through it. Don't cut corners.


Registered User
jfox90's Reviews
08-02-2014, 01:26 AM
Price: $1,000.00
Pros: Great for emissions and improved gas mileage (1 mpg)
Cons: Vapor lock from inline fuel pump
Recommended? Yes

Comments: The inline fuel pump can't keep up with the hot dry summers here in CO and so I have to insulate the line and figure out what to do with the pump in order to keep the heat out of the fuel injector and lines.

Registered User
Wyman's Reviews
07-22-2014, 03:59 PM
Price: $1,195.00
Recommended? Yes

Comments: One of the best modifications you could do for a carbureted vehicle. It eliminates a lot, (and I mean ALOT) of cluster under the hood. The best part of the update is that the BBD carb is now in the trash can. No more having to think about soak time and temps when starting the Jeep. Just touch the ignition switch and its running smooth as butter. The old fuel system ran great once it got leveled out but now it's even better. Instant throttle response and smooth acceleration. The fuel economy seems to be about the same in the warm weather but I know it won't drop much when the Elk are rutting in the high country.

Registered User
bugazon's Reviews
04-07-2013, 01:28 AM
Price: $1,200.00
Pros: Easy install Excellent tech support
Cons: Instructions could be better
Recommended? Yes

Comments: I installed the Howell unit as i live in california and the carb sucked and I had miles of tubing. I am not a very good instruction reader. I like pictures and text. I was able to install this in 2 afternoons. I was intimidated to do this but overall, it was straight forward. I did revearse the vacuum lines, so that would have been nice to see actual pictures. But my Jeep runs great now. It would be nice to have the Mopar unit if you have the $$. but I think this is a great california update!

Registered User
cwbyhrs's Reviews
04-02-2013, 11:38 PM
Price: $1,200.00
Pros: improved fuel mileage.
Cons: Not the original buyer..can't buy parts from Howell..
Recommended? Yes

Comments: I like the TBI upgrade.. when it runs it runs not like the fact that since I'm not the original purchaser of the equipment I can not buy replacement parts from Howell.

Registered User
gunrun45's Reviews

05-01-2012, 09:38 AM
Price: $1.00
Pros: .
Cons: .
Recommended? Yes

Comments: I discovered a few things after about a year of running this kit on my daily driver 82 CJ7 with 258 and CA smog.

1- Make sure you bypass your factory metal return line and upgrade it to a fuel injection rated 5/8 inch diameter or better fuel return line. Back pressure will result if you don't.

2- the CA smog compliant version uses a 4 wire oxygen sensor instead of the one wire described in their parts list/install instructions. It's GM part number is 25312184 (about $50)

3- Howell tech support SUCKS. Rely more on what you read here. My phone calls to them netted me techs that acted like I was bothering them and a snotty receptionist who treated me like an idiot because I wanted a real part number rather than their Howell part number.

4- Call Howell and get their filter kit so you can install the MSD ignition upgrade per jeephammer's how to series on this site. It makes a HUGE difference.

5- get a backup speed sensor (CA smog compliant only kit) I've broken 2so far. They screw in at an angle that puts torque on the unit where it sits on top of my T5 transmissions. I'm currently looking for a right angle adapter to permanently fix the issue.

6- take some time in your initial set up and figure a way to seal those air tube holes well. Leaks will cause you issues later. Getting the wrong size/leaking bolts out later will be a serious PITA. The original bolts WILL NOT WORK as some others have claimed. I recommend going to an ACE hardware store with the originals as guides to find the proper thread pitch.

7- double check all of your vacuum connections. Finding proper manifold vacuum pressure will be an issue. Most of the write ups online aren't for CA smog legal units. 4x4 explorer's web site is and has lots of good info.

It's still one of the best things I've ever done to a stock jeep. Yes, I'd do it again.


Registered User
dozer217's Reviews

04-23-2012, 11:13 PM
Price: $1,200.00
Pros: Smoothed out idle very nicely and cleaned up engine compartment very well. Wiring harness is weel done and labeled well.
Cons: Instructions and pictures/diagrams are horrible. Several items were not addressed at all and trouble shooting, such as add a relay for low voltage was not explained at all. Tech support line was not helpful at all. For price of kit, instructions, mounts for components, and better tech support should be provided.
Recommended? Yes

Comments: Installed Howell TBI kit on an '82 CJ7, I6 258. I tackled this project this last weekend and was able to have it running by Sunday afternoon, despite the incredibly horrible instructions. I ran into a few install issues:
- Plugging exhaust manifold holes after discarding the air tube to the catalytic converter. No guidance about this in the instructions. I ended up using brass pipe plugs with fine pipe thread and it worked well; no exhaust leaks.
- Initially had low voltage issues with the ECM that prevented the engine from idling. Trouble shooting instructions advised adding a relay, but gave no other info. I scavenged a relay from my old wiring harness, but was never able to get it working. I eventually went straight to the source (hot wire when in "on" position and "cranking) and wired the unit in straight at the ignition switch (heavy gauge red wire with white stripe) which solved the problem.
- The vacuum connections at the CTO valve also had problems. As I understood, the distributor vacuum advance was supposed to connect to a ported vacuum line at the valve. That connection proved to be inadequate to provide advance and I moved that connection to a port just below the TBI, in the intake manifold that I had previously plugged.

After getting the idle issue dealt with my test drive was not great. Acceleration was poor and top speed was 50-55 mph in fourth gear. Fifth gear would not sustain that speed. I suspected a vacumm leak, but none were obvious. A call to Howell tech support was futile. The guy seemd grumpy that I was calling and offered no suggestions, other then test my fuel pressure. When I mentioned that I live at 7800' elevation and everything is up from here, he just said I should have mentioned that prior to purchase. I never saw anything stated that I should provide that info when purchased from Quadratec.

Tonight I pulled the TBI off and started checking for vacuum leaks. I noticed that the passenger side TBI bolt was not threading properly (would never tighten). Fortunately, I had a bolt that was a 1/4" longer and was able to grab threads deeper in the adapter plate and tighten the TBI properly. I siliconed several possible leak areas and will hopefully get this dialed in tomorrow.

Overall, I like the kit and the initial impressions of smoother idle and easier starting. If the top end speed issues get handled and I get better mileage and power, this will be well worth the money, just don't expect Howell to be helpful. Jeep Forum was a huge help on this project, from initial research and then trouble shooting install issues that should have been outlined in the instructions provided.

Registered User
YJeeps's Reviews
03-22-2012, 12:00 AM
Price: $1,000.00
Pros: Engine runs much smoother No more dying while idling More power Gets rid of the Carter carb and the pulse air emissions lines Cleans up the 10 miles of vacuum lines that I hated.
Cons: Pricey, yet worth every cent.
Recommended? Yes

Comments: What a difference this made. Engine now runs smooth at idle and has moe power. No problems with this tbi for 8 years now.

Registered User
gunrun45's Reviews

01-08-2012, 11:17 AM
Price: $1,000.00
Pros: Imediate increase in throttle response and no more issues on hills or altitude differences. I also got to toss the maze of smog lines and keep in smog legal in CA. Jus needed to keep the cat, canister, egr and PCV
Cons: It can take a bit to get it it really dialed in if you're picky like me. I didn't have a prom code reader so it was more trial and error for me. Buy a prom code reader and be done with it. It's a no brained after that.
Recommended? Yes

Comments: Great product that really made a serious improvement in the jeep! I recommend it to everybody I know who has one


Registered User
rsg1963's Reviews
11-17-2011, 09:37 AM
Price: $1,100.00
Pros: Reliability, cold starting, off-camber running.
Cons: None
Recommended? Yes

Comments: One of the best upgrades I've ever made to a Jeep. I should have done this a very long time ago. Wheeling has never been easier, cold weather starting is a snap and that's saying something for Jeeps!

Registered User
todbld's Reviews
10-30-2011, 01:26 AM
Price: $1,200.00
Pros: Great fuel economy, always starts, No running rich, easy install, unlocked lot of power.
Cons: None
Recommended? Yes

Comments: I bought the Howell TBI last spring to replace my rebuilt carb. I was tired of the 8 miles to the gallon that I was getting. Plus it always smelled of gas in the cab. It was super easy to install, I did it in about 6 hours over to evenings. I decided against the Mopar kit due to a few vendors detailing a bunch of problems with the factory kits. I have taken it into elevation and had no trouble at all. I ask the guys at Howell to flash me a chip for altitude incase I ever run into trouble up in the mountains. I had been to 12,000 foot and the jeep ran great with the stock program. I think it is a great kit for the price.

Registered User
thegladiator's Reviews
09-26-2011, 11:05 AM
Price: $1,199.00
Pros: got rid of the stalls on the slopes
Cons: none yet
Recommended? Yes

Comments: Been Deployed since before this was installed. Hope to come home to a totally easier to keep runnin Jeep


Registered User
Jacoby22's Reviews
08-30-2011, 03:16 PM
Price: $1,300.00
Pros: Start Up First Try,Passed Emissions No Problem.
Cons: None Yet
Recommended? Yes

Comments: Easy install took about 4 hours total! only problem I ran into was with the cto switch, wasnt correct from PO. So make sure you have the correct one in there.

Registered User
debri81's Reviews
06-18-2011, 10:58 PM
Price: $800.00
Pros: Runs great
Cons: No compliants
Recommended? Yes

Comments: To save some cash I got several bone yard TBI's and rebuilt one of them keeping the other as a spare. Save several hundred. I added a Clifford intake and Jacobs Milemaster ignition and Ultra coil at the same time. I should have installed the TBI kit and got it working and dialed in the then went and added the other items. But I had pulled the motor to rebuild it and then had to try and remember what connected to what... Major PITA but self inflicted. No digital cameras back then...

Registered User
85McJeep's Reviews
09-16-2010, 01:53 PM
Price: $1,200.00
Pros: Performance
Cons: Tuning it...
Recommended? Yes

Comments: Jeep drives much better, specifically on the highway. Better fuel economy. Easy to install, I am not a mechanic. A little difficult to tune...they don't tell you that you need a larger fuel return line.

Registered User
mlittle's Reviews
08-03-2010, 08:07 PM
Price: $1,200.00
Pros: engine performs better, better gas mileage
Cons: wiring harness too short, mounting bracket not included for MAP sensor, instructions were very general, should use knock sensor and control timing
Recommended? Yes

Comments: The wiring harness supplied with the kit is just barley long enough to reach all the components, this prevents a neat installation as all the wiring is stretched.
I also don't care for the use of hose and screw clamps for the connections of fuel lines to the throttle body, I don't feel that they are safe over the long term.
I would have preferred the Mopar system but could not afford it.

Registered User
Karma's Reviews
07-11-2010, 09:32 PM
Price: $1,200.00
Pros: Starts in all weather, perfect idle, never stalls due to trail angles, engine will run down to 300 RPM which is a huge advantage.
Cons: Except for price, none.
Recommended? Yes

Comments: Upgrading to the Howell TBI system may be be the best mod on my Jeep. The installation is not hard, and getting rid of the miles of vacuum lines I had with the Carter BBD carb is wonderful.

This TBI system has no drawbacks. Trail manners are perfect. It always starts quickly even in sub-zero temperatures (yes, we have extreme weather in the New Mexico mountains).

Do not expect huge power gains or improvements in gas mileage. There may be some improvements but they are small. I would not buy the Howell system for these gains. The main improvement is basic engine runability which is first class. The Howell tuns the 258 into a modern engine.

Howell makes a version of this kit that will pass California emissions tests.


Registered User
L12graffix's Reviews
04-07-2010, 09:33 PM
Price: $1,200.00
Pros: So long carb and Pulse air system
Cons: cost
Recommended? Yes

Comments: With the CA emissions system it can replace the pulse air system on your CJ that you can't find parts for and runs so much better without the stock carb.


Registered User
cthompson8846's Reviews
03-06-2010, 12:39 AM
Price: $1.00
Pros: Turn Key
Cons: Idles high at times, I'm sure it's a vacuum problem just need to figure out where.
Recommended? Yes

Comments: Still working out some kinks, just need a little more time to figure it out.

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