Isuzu SUV Forum banner
21 - 36 of 36 Posts

·
Registered
Joined
·
4,003 Posts
Discussion Starter · #21 ·
Another update.
And no I didn't buy another truck :D but yes there is another trooper at the house.
Not mine though. There was a fella up the road from me that wants the 2.8 I got from Choppy to replace his 2.8.
I tested his first and had no compression on two cylinders so at least Choppy's heart now has a home.
I'm half way done with the swap and good thing too, I'll treat this as a practice run on the black LS.
Automotive parking light Tire Wheel Land vehicle Vehicle

Someone used stop-leak in the white trooper so I took both my black LS radiator and his to a radiator guy to get cleaned out and repaired.
Both are original copper rads, not the slightly thinner new plastic aluminum rads that you get aftermarket.

I did also find a 3.1 computer! @Ed Mc. didn't you say that I needed the 3.1 ? Hope those numbers match and are legit!
One more question Ed. How many teeth and how large is the 3.1 flywheel? I remember you saying to run the 3.1 or can I run the 3.4 flywheel?
Rockauto is showing the same flywheels for the 2.8 as the 3.1 so I'm stumped here.
Handwriting Font Gas Writing Art


@geoffinbc I sent you a msg on getting the intake bored out. Do you need just the upper intake or the tbi bottom half? Help me out and I'll get that knocked out.

I also grabbed some whole knuckle outer hub assemblies from a Rodeo for the Big Brake conversion. What's just as important as going? Stopping!!
Not positive I will run those junkyard rotors though. For the money, I think a complete front end rotor and caliper package from rockauto is going to look real good and stop real good too for the coin.
Automotive tire Motor vehicle Rim Metal Circle


As for the white and gold/bronze 88 Trooper. It is almost done. I sent the pwr steering pump off to rebuilt only to get denied and now need to find a replacement for it, pulley and all.
It seems the 88 is a cutover year where Isuzu switched to a spline drive pulley and cardone won't rebuild mine for whatever reason. So I'm hoping to switch to the new style with a spline pulley.
Last tidbit on the 88 I did was upgrade the front disc and caliper to the dynamicFriction special rockauto has right now. Ceramic pads too. Repacked the bearings and am going to put gold painted Aisins on it. Need to put the new clutch line in place with a new master and slave. Seems she bled out when I was on vacation. Once that is done, then she is for sale. I'll post a pic of the beauty when I'm done.
Automotive tire Motor vehicle Alloy wheel Rim Automotive wheel system


last little teaser.... I have an awesome surprise coming out of Atlanta for wheels. Just you wait!
I will get on the Black LS here soon!
 

·
Registered
Joined
·
2,131 Posts
I used a 1991 pickup 3.1 flywheel (same part no as 2.8, so either/or is fine) and 3.1 clutch kit on my 3.4 (just checked my rockauto receipt from 2015).

Regarding ECUs and injectors in a 3.4:

2.8 ECU + 2.8 injectors = fine at idle, lean at WOT
3.1 ECU + 2.8 injectors = fine at idle, may need fuel pressure turnt up to keep up at WOT (heavier spring for an additional psi is available)

2.8 ECU + 4.3 injectors = can be rich at idle, fine at WOT
3.1 ECU + 4.3 injectors = likely to overfuel at idle and WOT

It will likely depend on how hopped up the motor is. An untouched essentially stock 3.4 may do fine with just the 3.1 ECU and the 2.8 injectors. Cam upgrade and some other stuff may require adjustment or jump to the 4.3 injectors + 2.8 ECU combo plus additional fine tuning.
 

·
Registered
Joined
·
4,668 Posts
What Paul said, if you order the flywheel and clutch kit for a 1991 3.1 4WD pickup, you can't go wrong. The 3.4 should run better with the 3.1 ECU. I've been running my 3.4 LS for years with the OE 2.8 ECU and a Holley Big-Bore TBI, which does pretty much the same as a GM 4.3 TBI. Haven't had any big issues with it, although I do have a spare 3.1 ECU ready to go if need be.

Each swap is gonna be a bit different on tune, depends on what you do for exhaust, how you build the engine. As Paul was saying a heavier spring (14 psi spring) in the fuel pressure regulator will fix most ills with the swap. If you use 2.8 injectors you're definitely gonna have to increase fuel pressure; a 3.4 on 2.8 injectors will "lean surge" when cold. Having more fuel pressure/fuel injected will cure the lean surge, and when the ECU goes into Closed Loop it's regulating with input from the O2 sensor and should be OK except as Paul mentioned might be lean at WOT.

Conversely, you may run rich with the 4.3 TBI and bored-out intake, depending on the build. In that case you might need to reduce fuel pressure. Just a tuning thing. The stock regulator can be made adjustable within a few-psi range, and that could be enough to make the engine happy. I tweaked on the FPR when I did a "3.2 Stroker" build back in 2005 and it was just right, killed the lean surge and had good fueling all-around.

Use the stock 2.8 intake manifold, that's what you'd need to ship off to have bored to fit a larger TBI. The best mod (besides exhaust) that you can do to these engines. They respond well to increased airflow.

You've been busy, have fun!..........edc
 

·
Registered
Joined
·
2,131 Posts
One other thing that will likely help in any condition is swapping to a heated o2 sensor. Geoff had a writeup on his site. I know mine will not go into closed loop at idle no matter how long I let it sit, even with the o2 sensor sitting in the cat directly where the 2 exhaust downpipes enter. I have to actually drive it for that thing to heat up enough to go into closed loop. If I end up keeping my motor longer term it will definitely be on the to do list.
 

·
Registered
Joined
·
4,003 Posts
Discussion Starter · #25 ·
Both you guys are super immensely helpful. Thank you.
So after your message @Ed Mc. I looked around some yards and there are tons of Astro 4.3 TBs.
I got one for $50 complete.
I think what you were saying too is the throttle plate on that ebay one looks identical or similar to the 2.8.
Well check this out. yeah its dirty but little elbow grease and she's new again.
Art Machine Gas Engineering Auto part
Bicycle part Tool Art Machine Auto part
Wood Bicycle part Art Machine Gas
 

·
Registered
Joined
·
2,131 Posts
Duder where's another Astro TB?? I am thinking of swapping back to the GM TB and huckin' the Holley and it's sticky injectors.
 

·
Registered
Joined
·
4,668 Posts
Paul, maybe that's the problem with mine. On rare occasion it gets cranky, won't idle well, seems like it's running on half power. If I rev it up, the problem clears. I can't think of anything else but what you describe as "sticky injector" would do that. I drove it this week and it ran perfectly. But the time before, after the engine had already been fully warmed, it did it once. Revved up to get going, problem went away, didn't come back. Very strange indeed.

I think we may have covered this a while back, but you can modify the Holley TBI base by drilling a hole for an offset air cleaner lid hold-down stud. Then install a GM injector pod. Plus rewire the injector plugs. You'll lose the adjustable fuel pressure regulator, but you can always modify the GM F.P.R. to be adjustable.

Here are some informative links that I bookmarked a while back:


 

·
Registered
Joined
·
2,131 Posts
Paul, maybe that's the problem with mine. On rare occasion it gets cranky, won't idle well, seems like it's running on half power. If I rev it up, the problem clears. I can't think of anything else but what you describe as "sticky injector" would do that. I drove it this week and it ran perfectly. But the time before, after the engine had already been fully warmed, it did it once. Revved up to get going, problem went away, didn't come back. Very strange indeed.

I think we may have covered this a while back, but you can modify the Holley TBI base by drilling a hole for an offset air cleaner lid hold-down stud. Then install a GM injector pod. Plus rewire the injector plugs. You'll lose the adjustable fuel pressure regulator, but you can always modify the GM F.P.R. to be adjustable.

Here are some informative links that I bookmarked a while back:


Yeah Ed, it may be the injectors. My holley was new old stock and sitting for probably 20 years, so the injectors were gummed slam shut when I first got it, and it took 2 trips to a nearby injector shop to get them cleaned up (they did ultrasonic cleaning). And I don't drive it super often, so it's entirely possible that they got gunky again. My problem, I think, is that it overfuels, so I think they are sticking open. Could be my tune, could be something else out of order.
 

·
Registered
Joined
·
4,668 Posts
Hey, Paul, you may have noted we had some really cold and snowy weather here in the PNW a while back. Well, the ol' gal was acting up again, but only did it one evening and the next morning. After that, it cleared out and ran perfectly in the snow and cold for over a week.

In the late fall I dumped 2 bottles of Regane Hi-Miles in a full tank. I'm thinking the powerful cleaning action and top-end lube did the trick.

It also helped to block off part of the grille. Looking at it later, I see there are 2 pretty big rectangular inlets below bumper height, I hadn't noticed them before. Looks to me like when it's 20 deg F outside, that's all the cooling one would need. I've got a piece of about 1/4" wooden veneer that would make a really nice grille cover, so I'm going to fab that up before next Winter.

I plan on using a couple of spring-loaded metal hook-style bolts, such that you'd push them in and twist then release, to hold the cover to the grille structure. Should make quite a diff in how fast she warms up, and heater output too. These really need some help, there's a lot of cast-iron to warm up to temp.

Thankfully, we're pretty much done with that unless there's a freak storm. Temps are getting up to low 50's some days and hi-30's to 40's at night. Although last week we had a low of 28! Brrr!! 52.2 today on my outside porch temp sensor. Come on, Spring! 🌞
 
  • Like
Reactions: lorenzo816

·
Registered
Joined
·
2,131 Posts
I was actually tinkering on mine the other day trying to get it to idle smoothly. Didn't notice any vacuum lines out of place. I decided to play with the fuel pressure, which adjusts easily from the top on the Holley. I had to crank it up to max pressure to smooth out the idle, but I am sure it is way more than needed. I'll be sending the injectors out for a good cleaning again, replacing plugs, wires, etc (just because it's been years and it's not too expensive), checking timing, all that. I need to go ahead and do the heated O2 sensor as well. Hopefully I'll get her dialed in.

Funny, I was just telling Lorenzo about this yesterday and he remembered he needs to get his @SS in gear on this rig!
 

·
Registered
Joined
·
4,668 Posts
Yeah, Lorenzo, wazzup with dat? Gotta get with the program, Spring is on its way!! 😸
 

·
Registered
Joined
·
4,003 Posts
Discussion Starter · #32 ·
Y’all killing me. I did finish a motor swap and refreshed the gold 88 entirely. And I got a red scout 800 to finish up. Oh yeah the house… the floor… now the laundry room. Yea she added that too.
I promise I’ll get on the 3.4 asap. I did tear down one motor and I have another to tear down for parts and scrap.
Btw Ed someone on Facebook in our isuzu group just did a 3.4 swap but kept the mpfi and intake. If you’re still saying to go with the 4.3 tbi and bore the intake and it’s gonna be more hp. Then I’m game!
I also got some mixup on the cams to get. Read somewhere that another 3.4 swap dude regrets getting a specific cam. I think he ran 31s and 4.56 so I’m wondering which one he’d be sad over.
any idea?
 

·
Registered
Joined
·
4,668 Posts
The MPFI is nice n' smooth, but you can make more power more cheaply with the TBI setup. It's all airflow. The engine management on the MPFI is probably better, but the TBI is simpler and when you pop the hood for a smog inspection (if you have one of those), they won't be able to even tell that anything's been done.

Plus there's a lot of wiring to do for the MPFI and if you're not into that, could be daunting. You also need a VATS (Vehicle Anti Theft System) delete and that's more $$$ to buy. The Camaro SFI is only rated at 160hp stock. I'd imagine you'd have to buy a bigger throttle body and do other stuff to get much above that. A bored 2.8 intake and 4.3 TBI gets you more than enough airflow.

A TBI 3.4 in an S10, similarly equipped plus headers, pulled 187 RWHP on a dyno. Something like 205 at the crankshaft. That's not too shabby for Stone-Age bolt-on equipment!

Geoff put a Comp Cams "252" kit into his "3.2" (a 3.1 with an overbore), and he really likes it. That grind was pretty much what GM used for the Goodwrench Crate 3.4. Plenty of low-end torque, runs out of steam somewhere past 4000 IIRC. He also used the Comp Cams Magnum 1.6:1 roller-tipped rocker arms, which add a bit of lift and duration, making the cam seem "hotter".

If you're doing high-speed highway work, you might like the Comp Cams "260" grind better. The stock Camaro cam doesn't have much torque below 2000. It really starts to pull when you get up near 3000 and beyond. It'll rev past 5000 if I push it, and still making power. I noticed a decent jump in performance with improved exhaust. The stock system is terribly restrictive.

Just depends on how you're gonna drive it. If you're gonna trail, you'll appreciate the "252" torque grind.

Don't forget some sort of performance exhaust, the cam won't help much if the engine isn't flowing air. Better exhaust will also make the TBI mod (bored intake, 4.3 TBI) more effective.

We can speak in depth about exhaust mods when you're ready for that............ed
 

·
Registered
Joined
·
4,003 Posts
Discussion Starter · #34 · (Edited)
Okay long overdue delayed update but I got a great update!!

well in between working on resto-ing a 68 scout 800, I swapped Choppy’s 2.8 into another guy’s Trooper, replaced the entire front end suspension on another trooper, I fixed up Goldie really good and sold her! Here’s the listing in case ya missed it.
FS: 1988 trooper LS

I’m talking she was mint. I didn’t want to see her go but I didn’t need another trooper. I needed to get back on the LS project!

So this guy Greg flew out from Utah and I picked him up from the airport and he drove it all the way back! I gave him a fresh fuel pump just in case.
woo hoo! Here’s the pics of the journey.
1988 isuzu trooper - Goldie
I was actually in Moab the week after he got back. I tried to get him to come down but didn’t happen. Next time!! Here’s pics of the Moab trip. Moab isuzu 2022

hopefully you’re still with me here on this long delayed much needed post!

Anyhow back on the LS!
Oh and I got most of my floor done in the house! Talking about getting **** done

Now seriously back to the LS. :ROFLMAO:

I got some 15” snowflakes polished and mounted some general grabbers 31” to them.
Tire Wheel Automotive tire Motor vehicle Light


they look gorgeous. And just last month I found some chrome 16” snowflakes! Omg so many choices!! Let me see if I can find a pic of the chrome and I’ll add it here.

Anyhow I am not sure if I mentioned I got a 4.3 tbi and a 3.1 computer and a 3.1 tensioner to delete the smog pump from the accessories. I also got a big brake setup for the front. Debating going mid track arms but I got new CVs already soooo eh.

Last weekend and today I got the body bolts all pulled loose. Disconnected all the hard lines, gas lines and electrical along with the steering shaft.

I got boards ready to pull the body off and yanked the gas tank out today.
this sucker is rolling now! It is finally happening.
PROGRESS!!!


I’m going to get the frame shot and sprayed while I get on the engine.
I ordered a pair of old man emu dakar springs for the rear. I already have a drop diff ready for when i I service the front along with some oem isuzu rebuilt CV axles.

Tomorrow is mothers day or I’d be back on it trying to pull the body off and roll the frame out. Next weekend more progress.Today is the first day she’s been on rubber in more than a year and off jackstands!

Wheel Tire Automotive parking light Land vehicle Vehicle
 

·
Registered
Joined
·
1,885 Posts
Those polished wheels look great.

I'm going to look through that Moab album tonight when I have time. I just got back from Moab as well! Looks like you have a bunch of Colorado photos. The second picture, the Argo Mine is in Idaho Springs. My very first job was at Beau Jo's Pizza in Idaho Springs. If you're ever through here again, you should eat there at least once.
 

·
Registered
Joined
·
2,131 Posts
You need some centercaps for those bling wheels homie!
 
21 - 36 of 36 Posts
Top