View Full Version : I6 fuel injection
02-02-2004, 12:43 AM
I am considering swapping the carb on my 83 Cherokee for a EFI system. I'm thinking of going with a "MegaSquirt" (http://www.bgsoflex.com/megasquirt.html) system with a 4.0 manifold and injector setup. On reading some posts on swapping a 4.0 into a 258 FSJ I am wondering if the brake boost clearance problems are related to the engine of just the manifold. Does anyone know if you use a 4.0 manifold to convert a 258 to EFI you'd have to go hydroboost?
02-02-2004, 03:25 AM
I believe the problem is with the 4.0L exhaust manifold interfering with the brake booster. A previous poster claimed that you can work around it, and that a Borla header will work too.
02-02-2004, 04:18 AM
There have been three stock Jeep EFI manifolds made: the Renix manifold from 1987-1991, the OBDI manifold from 1992-1997, and he OBDII manifold from 1998-later. No way any of these fit any FSJ without removing the vacuum brake booster.
Zorm (I believe) has endured brakes with a manual master cylinder since swapping in a coplete 4.0 engine. I gave a lot of thought to having a Clifford intake modified so that the injectors and all other items could be transferred from a 1995 HO manifold; even so, that would be a tight fit.
This week I'm sending a booster and a rebuilt brake cylinder out to Paul at www.hyrdoboost.com, (http://www.hyrdoboost.com,) so he can select components for that conversion. I'll keep you posted.
02-02-2004, 11:11 AM
Has anyone looked into using a 9" booster to clear the intake.
02-03-2004, 11:58 AM
Bummer, well at least now I know. Please keep us up to date on the hydroboost, and in the mean time I guess I'll just start looking for a throttle body injector.
02-03-2004, 12:04 PM
I did a 4.0L swap in my 82 Wagoneer with an ODB I engine ('93 YJ). Click here to see my webpage writeup about it (http://www.paradise.raleigh.nc.us/mark/jeep/4.0swap.html)
I think I was the first one that ran into problems with the intake manifold and brake booster. I don't know of anyone else who has gotten a 4.0L into a FSJ without the brake booster problem. I am running manual brakes and like having manual instead of power brakes now.
I looked into the Megasquirt system awhile back.. at the time, the code for it only supported batch injection to fire 2 injectors or 2 sets of injectors. This is exactly what is needed for a typical TBI setup with two injectors. However, the 1991 and up use MPFI with sequential injection (one at a time). I'm not sure what the '87-90 Renix systems used.
If I were going to fuel inject a 258 (which I'm considering for my CJ), I would go with GM TBI and the stock 2bbl 258 intake manifold. You can use mostly junkyard and off the shelf GM TBI parts with a GM ECM re-programmed or use the Megasquirt controller.
[ February 03, 2004, 07:13 PM: Message edited by: sloop ]
02-03-2004, 04:29 PM
Here's a picture of the MonsterSlayer engine, which is a 258 with a 4.0 HO head, Mopar MPI, and a HydroBoost. True, it's a CJ engine bay, but I think this illustrates the fitment problem we FSJ'ers would have with that dual-diaphragm vacuum booster in the way.
02-04-2004, 12:23 AM
How do you like the 4.0 in your Wag? What kind of MPG do you get?
02-04-2004, 12:49 AM
Mikel, I like the 4.0L. I had 2.73 gears and the power of around the town driving was not noticably much different than the 258. However, the nice thing is just that it is fuel injected and I never have to worry about stalling or the engine not starting up. The power was enough for me, but some people who are used to V8s might find it lacking. I have the TF999.
A few days ago I switched to 3.73 gears which makes it perkier around town but I havent driven it on the highway yet. With the 2.73 gears, I would get about 14mpg around town and 19-21 on the highway (65+ mph).
[ February 04, 2004, 07:50 AM: Message edited by: sloop ]
02-04-2004, 01:38 AM
Thanks Mark. A FSJ that gets 21 MPG on the highway is a beautiful thing smile.gif
02-04-2004, 01:07 PM
but a POS when it comes to a hill
02-04-2004, 04:13 PM
with the 2.73s, I could take any hill if I was approaching it at 65mph or higher. but, drop below that speed and my RPMs werent high enough to keep up.
and of course, off road it can tackle anything in 4-lo.
02-05-2004, 01:33 AM
I meant mountain roads. I agree though, top speed is the issue with low hp, as long as theres enough torque to keep going it shouldnt be as much of an issue. Not knocking it, just saying that the 258 (even though the numbers say it ought to) does not even pull up a pass road like my Mercedes turbo does (and that has only 120 hp and 170 torque)
02-06-2004, 06:41 AM
In regards to the brake booster, just get a big hammer and bash the side of the brake booster in. I used hydro boost on my 258 w/ 4.0 head and fuel injection and it worked like a dream.
02-06-2004, 08:33 AM
So my 75 cj with no booster ain't gonna have an issue.. hehehe.
I have 11" drums on it.. with a planned change to disc front later on.. but I don't have a problem stopping it now.. shouldn't be too much of a difference later. Now, Any good sources for 4.0 heads with all the efi goodies?? :D
02-06-2004, 09:00 AM
Popeye, if the board doesn't shoot us for discussing baybe Jeeps... smile.gif
The stock 11" drums on my '75 worked well. Consensus on the early CJ board seems to be that there's not that much advantage of the stock D30 disks over 11" drums except in water. You can improve the performance of your drums in the wet stuff by drilling them. Here's a couple of links:
<edit> here's a better link:
BTW there's an "Intermediates" forum on earlyCJ5.com specifically for the lost generation of '72-75 CJs.
best regards :cool: Tim
[ February 06, 2004, 04:22 PM: Message edited by: tgreese ]
02-06-2004, 09:40 AM
There was a company in Florida selling rebuilt heads on ebay for about $200. check there. Not sure of a good source for an intake manifold with injectors, wiring, sensors, etc except for junkyards.
The PIG Smith
02-06-2004, 10:18 AM
Hydroboost sounds like it is 'the' solution!
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