3.4 swap into 91 Trooper

[Canyonero]

I talked to a guy at fuelinjection.com. Got a quote of $495 for a standalone engine harness and $175 for reprogramming the ECU. I must say, I'm tempted. It's a fair chunk of change, but will simplify my project.

I've been going over the Firebird and Trooper wiring diagrams. Troopers are simple. Or complex, however you want to look at it. The ECU appears to only manage the engine, no A/C, cruise, gauges, etc - those things have their own controllers and sensors. So I think the Trooper will be fairly ignorant to what engine is actually in there. A standalone harness that terminates all the extra functionality of the 3.4's ECU should do fine.

But, that also means that it may not be a big deal to use my 3.4L current harness. Only thing I'd really need to wire up is the power, fuel pump relay and check engine light. I think I have the ECU and harness from an auto though, in which case the F.I. guy said I'd need it reprogrammed, hence the $175. I think I'll be better off coughing up the money...

[Koldkut]

Nice to know someone is doing this swap. but I am curious to find out how to reverse engineer this swap back to a chevy setup or either wiring harnesses will work. I have a 3.4 out of a rolled isuzu that I am going to put in my jeep and I need to know what vehicle I need to rob a wiring harness out of to make it work.....How much of the isuzu stuff will fit on that engine? I have the isuzu stuff on it and I need to know what will come off or if the chevy wiring will adapt to the isuzu plugs.

[Canyonero]

A rolled Isuzu? I've never heard of such a thing! :P

What engine do you have in your Jeep? If it's the 2.8L, you already have the same ECU and wiring that the Trooper is using (assuming the Trooper is using the TBI setup, not SFI - in that case I would be disappointed, I thought I was going to be the first to do it). Otherwise, I can give you more insight once I actually start pulling my Trooper apart.

I'm not totally clear what you're doing with the wiring. You said you wanted to swap it "back to a chevy setup" - but in a jeep? The 2.8L is a Chevy engine - period. It just shipped in an Isuzu. The "Isuzu" wiring connects to the 2.8/3.4 TBI engine just as a real chevy's wiring would connect.

That sounds kinda weird - taking a Chevy engine out of an Isuzu to install in a Jeep...

In my experimentation: Just for kicks, I unplugged my ECU and powered up the Trooper. Everything seems to work fine sans-ECU (except for the engine actually firing of course). My ventilation fans only work when the engine is running, so I cranked the engine over and they came on. I don't know what triggers them, vacuum or what, but it's not the ECU. According to the wiring diagram, the A/C actually connects to the Cruise Control (to increase the idle speed when AC is on?). That sounds a little odd too, but easier for me!

[Koldkut]

Here is some background on the engine, I got it for free from a guy who needed it out of his garage, he took it from a rolled isuzu that had the 3.4 swapped into it from the origional 2.8l. What I have is the engine and some of the associated wiring that goes onto the engine. I have no way of telling what the deal with this engine is, has the isuzu intake, MPI setup, and a custom welded oil pan that holds more oil. Should I take some pictures of this beast?

What I want to do is find a wiring harness and ECU that will work with this thing. The jeep is gutted, the old t-case and trans had to go for sure. I have a SM465 and a Dana 300 that is going to be mated to this engine. I would perfer to get an entire chassis and engine harness to mate to the jeep. I've done swaps like this before and I know I have a lot of work ahead of me, I just need to know where to start....

[Ed_Mc.]

The EFI components on a stock 2.8 Trooper's motor are virtually identical to that of '86-and-up S-10 2.8's, so you should have no trouble finding anything you need, wiring wise, from the junkyard. The Trooper ECU is located in a different place than on an S-10, but I think the EFI wiring would have all the same functions in the harness whether it's from and S-10 or an Isuzu. When you say your 3.4 has the Isuzu intake (which is just an S-10 TBI intake) and 'MPI" setup, do you mean 'TBI' rather than 'MPI'?

If you really have Multi-Port than it's not stock and might be the Camaro SFI system. Does it have a 2-bbl TBI sitting on top of the intake or a myriad of intake plumbing with the big single-throated throttle body out front? If it's got the throttle body out front the former owner may have retained the Camaro SFI. Lots of good discussions in this thread about that too!

BTW Free is great! I thought I got a good deal last month on a core 3.4 (complete, was a runner but had bad rod brg) for $100 but Free is Way Better

P.S. on the Isuzu HVAC blower relay, I believe it's triggered by voltage i.e. alternator output. There's a fuel pump/oil pressure interlock/relay system too which chops the fuel pump if the engine dies (as in a rollover I suppose!).

P.S.S. I've driven my Troop like a Bat out of You-Know-What on the street, and never come close to rolling it! 'Course, anything's possible in extreme and they are a bit tall and 'tippy' but maybe it happened off-road. Having the wider tire/wheel combination definitely adds stability.

[Koldkut]

The EFI components on a stock 2.8 Trooper's motor are virtually identical to that of '86-and-up S-10 2.8's, so you should have no trouble finding anything you need, wiring wise, from the junkyard. The Trooper ECU is located in a different place than on an S-10, but I think the EFI wiring would have all the same functions in the harness whether it's from and S-10 or an Isuzu. When you say your 3.4 has the Isuzu intake (which is just an S-10 TBI intake) and 'MPI" setup, do you mean 'TBI' rather than 'MPI'?

If you really have Multi-Port than it's not stock and might be the Camaro SFI system. Does it have a 2-bbl TBI sitting on top of the intake or a myriad of intake plumbing with the big single-throated throttle body out front? If it's got the throttle body out front the former owner may have retained the Camaro SFI. Lots of good discussions in this thread about that too!

BTW Free is great! I thought I got a good deal last month on a core 3.4 (complete, was a runner but had bad rod brg) for $100 but Free is Way Better

P.S. on the Isuzu HVAC blower relay, I believe it's triggered by voltage i.e. alternator output. There's a fuel pump/oil pressure interlock/relay system too which chops the fuel pump if the engine dies (as in a rollover I suppose!).

P.S.S. I've driven my Troop like a Bat out of You-Know-What on the street, and never come close to rolling it! 'Course, anything's possible in extreme and they are a bit tall and 'tippy' but maybe it happened off-road. Having the wider tire/wheel combination definitely adds stability.

Ya know ed, I need to get some pics of this thing so I can get it all clarifed. It has injectors located on the isuzu intake and the throttle body appears to be a single barrel with what I would imagine to be an IAC and TPS on it. Does this engine sit in the trooper like most front wheel drive applications or does it sit like a RWD vehicle with everything in-line heading towards the rear. I'm not sure how familiar you are with colorado but a trooper rolling out here is a highly possible occruance with the number of difficult 4 wheeling trails that we have here. The jeep does not and most likely will not have A/C so I won't have to deal with it. This is going into a 68 jeepster commando and will have an engine/tranny combo that possibly has not been done before with the SM465 and Dana 300 combo...

[Koldkut]

sry for the double post, my post didn't come up with a few refreshes and now its there. I'll start my own post with pics of this beast, sorry for the hijack.

[Canyonero]

Attached are pictures of my new 3.4L on the pallet, and the 2.8L installed. Probably would have been more useful to remove the air cleaner for identification, but I didn't take these pictures special for you. As mentioned, it's just a 2-bl throttle body under there.

[Koldkut]

pics to come, very little of that 3.4 looks familiar and the air intake on the 2.8 doesn't look right either....

[Canyonero]

Well... those were your two options...

Maybe he put an Isuzu 3.2L in there? Aftermarket manifold on the 3.4L? I don't know...

[Ed_Mc.]

Well, the pic on the left shows a 3.4 which looks like it's right out of a Camaro, with the SFI injection and all. If you zoom in you can even see the "3.4 SFI" cast into the intake.

The pic on the right, with the motor installed, looks like a garden-variety 2.8 (or whatever variant of displacement) with TBI that you'd find in any '89-'91 V6 Trooper. Someone has even done the 'flipped lid' trick on the air cleaner, to gain more flow.

Works well, but is quite noisy. I spliced another snorkel (taken from an old S-10) onto the other side of the air cleaner housing, and also 'teed' the vacuum line to the original heat stove, so that after it warms up both heat stove flappers open up to admit air.

It's virtually as quiet as stock and flows plenty for the 3.4. If you were to pull the air cleaner lidon your Trooper, you'd see a 2-bbl downdraft TBI with one injecter per bbl.

At any rate, as you can see the Trooper 2.8 is just a standard RWD layout, but GM must have had some extra FWD-style blocks kicking around in '89, so it got Morphodited into RWD with FWD starter! Other than the starter layout, the bell housing bolt pattern is identical and any RWD 2.8/3.1/3.4 will bolt up. Of course unless that motor's got the starter on the left side you're drilling new holes.

BTW the earlier Rodeo's & P'ups that have the GM-built 3.1 are potential donors for a Trooper engine swap, if anyone were to have a hankering for a 3.1 upgrade. You just have to find one out of a 4WD. The 2WD Rodeo had the starter on the pssgr's side and used a Borg-Warner clutch and tranny, unlike all the 4WD 60-deg Isuzu-GM V6's which used their "MUA" Isuzu-built tranny/xfer case. Also early-90's GM minivans with cast-iron heads and TBI, as they have their starter on the same side as the Trooper's.

HTH...........ed

[Canyonero]

Yes, both those engines are mine. 3.4L pulled from a Firebird, and my flipped-lid 2.8L.

I went over my harness with some masking tape, a sharpie, and a copy of the wiring diagram. Everything (important) is ID'd and labeled. My engine most definitely came from an automatic equipped car. I'm crossing my fingers and hoping the ECU doesn't mind not having the transmission connected.

Just a matter of waiting for the rest of my parts to show up before I can finish up with the 3.4L prep and start yanking hoses and wires. In the meantime I need to go over my finances and see if I have enough money to buy food. These Trooper parts are adding up...

I'll still need to fasion some sort of intake for the 3.4L too, I'll stop by the ricer store someday and see what they have.

[Ed_Mc.]

Since your 3.4 came from an auto-trans Camaro, be sure and check the crank for a pilot bushing. Likely the auto-trans motor won't have one. Just pick up a new bushing (cheap) and drive/press it in.

Be sure to use no grease on the tranny input shaft when you slap 'er together, this is an Oilite-type of bushing; the bronze alloy is impregnated with lubricant, and grease will only plug up the pores in the bushing and cause premature failure.

Cheers.........ed

[Canyonero]

That's some good info to have. I'm so glad I signed up here, these are the little things that would stop me mid-project and frustrate the hell out of me if I didn't know ahead of time.

[Canyonero]

Since your 3.4 came from an auto-trans Camaro, be sure and check the crank for a pilot bushing. Likely the auto-trans motor won't have one. Just pick up a new bushing (cheap) and drive/press it in.

My clutch kit came with a new bushing. Looks to be a tight fit into the crankshaft, suppose I should wire-brush the hole a bit with the dremmel since it's been vacant for the last 13 years? Clean out some of the grit?

In addition to my clutch kit, I also recieved my electric fan (Flexlite Black Magic 150) and starter relocation jig. And might I comment on the jig - I haven't used it yet, but it looks pretty much foolproof. I think it's definitely the way to go for anyone feeling slightly uneasy about drilling into their new engine.