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I went to Search This Forum, but it did not work. Any one have any INFO. on Fuel Injection Kits for 1985 CJ7 with a AMC 258 i6 / 4.2l I6.How well does it work???
I have the Howell kit for my AMC 258 i6 / 4.2l , which is Ca. smog legal. It is a fairly simple for a computerized fi unit. It does not have a computer controlled ignition and disconnects the existing controls to it. It provides a good seat of the pants performance increase plus improved fuel economy. Howell does have a good record with customer assistance. Going to fi from a carb is a whole new can of worms to learn how to work with. It also works quite well with the Team Rush upgrade for the distributor.
I went to Search This Forum, but it did not work. Any one have any INFO. on Fuel Injection Kits for 1985 CJ7 with a AMC 258 i6 / 4.2l I6.How well does it work???
There are two types of fuel injection that can work on your AMC 258 i6 / 4.2l throttle body injection or multi port injection. Tbi is essentially an electronic carb that can change how much fuel is entering the intake based on the multiple sensors monitoring the engine. Obviously it has a benefit over a carb because a carb is adjusted and remains static and cannot adjust itself based on new parameters unless you physically adjust it. The intake still remains wet like in a carb and relies on the combo of gravity and vacuum to feed your cylinders.
The tbi also can control spark timing in some cases. Again the benefit here is that the computer can change the timing based on unique conditions versus a vac advanced distributor that only adjusts based on the vacuum and centrifugal rotation of the weights on the rotor.
Mpfi basically works the same way as tbi except the injectors supply the fuel directly to the intake runners. This allows for a much more exact fuel to air ratio that is the same in each cylinder. With a wet intake no matter how well it is tuned the outer cylinders are going to get a leaner mixture than the center cylinders. Mpfi also controls spark timing as well.
You can switch to fi in two ways. purchase a kit Or build a junkyard kit. The junkyard kit will probably cost about half our less than your store bought kit. Not allaftermarket tbi kits will control spark timing.
Tbi kits are generally based on gm systems if purchased new or pulled from gm vehicles if doing a jy conversion
Luckily the AMC 258 i6 / 4.2l mates to 4.0 parts easily so mpfi is a very good option. Mopar and hesco both sell kits to convert your AMC 258 i6 / 4.2l to mpfi. These kits are literally 4.0 parts.
Also (I have to put a plug for this in here of course) I have a side business of labeling and thinning out 4.0 harness for people who want to diy their mpfi. I also can put together a complete kit for a little cheaper than store bought kits. You can see more info on that in the classifieds on this site if you would like.
A-1986 CJ-7 with a BLOWN 4.2 litre I-6. T-5 tranny, Dana 44 rear axle with 2.73 gears. Owned 25 years.
B- 2nd '86 CJ-7 out of CA, with all emissions to boot! T-5, AMC-20, factory stock. Owned 2+ years and counting...
Hey guys,
I for one appreciate the posted comments, since this is something I have given some thought to doing myself.
Torxhead...what change in fuel economy did you get with the Howell kit install? I am getting 16~17 mpg (mostly highway) with my '86 CJ that still has the factory emissions in place. While not good, I just don't see it getting a whole lot better.
ThisGuyUKnow...kudos to you for a simple and understandable explanation. Thanks again guys.
I checked mine once on a highway trip when I had the bbd carb, 4:10s, 33s, and the T-18 and got 14. With my Howell fi the fuel economy was improved but I have no numbers to give. Some other info would be having some componets go bad like the throttle position sensor, O2 sensor, and idle control valve. The Howell kit is underwired, but it does not seem to be an issue. I did replace the existing fuel pump wires since they were only #18 wires to a larger size just to make sure. I installed it in '06.
Dan, have you looked at Hesco? They have a complete kit that I thought was in the $2500 range. With some research you can do it yourself with a junkyard setup off a mid 90's Cherokee/Wrangler.
73 CJ5 4.0 head on a 258, HEI, Holley Projection w/ 4.56, Detroit lockers Narrowed D44 front and full float D44 rear T14 w/ D20 4 wheel discs, 38.5 Boggers
I found a Holley Projection for the AMC 258 i6 / 4.2l for less than $800. They are still around and Holley sells parts but not full kits. It's a TBI with minimal sensors.
Fully adjustable without a laptop. Has a feedback loop via an O2 sensor.
I tune it with an Air/fuel ratio gage. Almost too easy.
One of the best mods I did. No more stalling out at the top of a big hill.
i havent looked in to junkyard. was just really poking around after wheelin this weekend and watching the old gas gauge fall i though could i do anything to help..so i started looking at these and this is my DD so any fuel saving would be great.. i work at a jeep dealer so the mopar was the obvious start.. but the howell looks decent
I have a Howell kit on my 360 cj. It has been running on all the original parts supplied in the kit since 1997. It has outlived most of the rest of the jeep including several axle sets (front and rear),several t-cases and 4:1 gearsets. Along with a couple of engine rebuilds as well as a montain of other parts. the howell kit for a AMC 258 i6 / 4.2l is only around $1200 or so. But for us the real selling point is the fact that its repairable at jst abot any parts house using stock gm T.B.I parts. Or in a pinch even a junk yard would have parts in a pinch.
The primary consideration in my mind is, do you need to pass a smog test/inspection? If so the packaged kits have the nessesary carb executive order to make the conversion legal. If no testing req. Then it boils down to how much do want to spend vs how much work do you want to invest? Or somewere in the middle.
One common among the choices seems to be all are good systems and no one size fits all.
And doesnt look like they can even get them anymore
