[Ed Mc.]

Matt, if you disconnect the battery for more than 60 seconds, the ECM should clear any trouble codes set.

Get the min idle speed (with IAC disabled) as close to 750rpm as you can. My 3.4 was really fussy until I got the idle speed and TPS voltage set to a Gnat's Ar$e. As close to .5V as you can.

It's possible the MAP sensor could be damaged from backfiring, so you should probably check that out.

Here's some good info on that:

Part 1 -How to Test the MAP Sensor with a Multimeter (GM 2.8L 3.1L, 3.4L)

Page 1 of 2: How to test the GM MAP Sensor (3.1L, 3.4L). Symptoms of a BAD MAP Sensor. Troubleshoot and test codes: P0108 (OBD II) or codes: 33, 34 (pre-95 OBD I). Testing the MAP Sensor. Testing the 5 Volt power supply. Testing the MAP's ground supply.

troubleshootmyvehicle.com

Also make sure the timing was adjusted with the ESC wire in the console unplugged from itself. The black wires with white stripe and a white connector. See attached pic. Note that the ALDL wires (white with blue stripe) are normally disconnected unless you're running a diagnostic or doing the IAC/TPS procedure to drive the IAC pintle all the way in. The other way to put the ECM in diagnostic mode is to jumper together the 2 pins in the corner of the ALDL plug.

How's the injector fuel spray look? With a 14psi spring, you should have more than enough fuel to make a stock 3.1 happy. Definitely check all the vacuum lines, a leak somewhere will mess things up royally.

Any more issues with the engine oil? That sounded scary.

 

[mattdk]

Thank you as always Ed. I will dial in the idle and TPS voltage as best as I can with the new TPS sensor (it might help if I had another person to help me unlike last time 😂) and I'm going to test the MAP sensor too. My vacuum pump just broke so ill have to grab another one at harbor freight. I did set the timing with that white ESC plug undone and I have identified the ALDL plug as well.

One thing I keep reading is that the timing and idle adjustments should be done with the engine warmed up and in closed loop. How am I supposed to know the engine is in closed loop besides seeing the coolant temp gauge hold steady in the middle of the readout?

Video of the engine reving up from idle and then stalling out when I try to accelerate:

Also, the injector spray seems pretty conical and even; I can see it pulsing and it does sputter a little after quickly opening the throttle. Although, it does looks like there might be excess fuel spraying from the injectors and it does occasionally spit fire out of the throttle body after opening the throttle abruptly. So maybe there is too much fuel? I've already checked the fuel pressure going into the throttle body and it measured an even 13psi (figured it should be 14psi..).

Video of the Injector spray and backfire:

Yeah I was planning on changing the engine oil and hoping it didn't turn creamy again, hopefully it is just a little bit of excess moisture and metal shavings in the engine from when we initially tore the engine down.

Thanks in advance.

Matt

Added a ton more photos to the thread!

 

[Ed Mc.]

Yeah, that's pretty strange how the Check Engine light comes on instantly when you give it some throttle. I'd say about the only things that could make it do that are TPS and MAP sensors. Nothing else on the 2.8 TBI system would respond that fast.

If you can't get it in Closed Loop to adjust timing, at least if it's warmed-up you can still get it done. But you do need to disconnect that ESC wire in the console, or you don't know what the setting is. Most times it's impossible to read the timing scale if Electronic Spark Control is disabled.

I think you'll find an issue with one of the sensors. Otherwise maybe the ECM's screwy. I'd definitely pull the trouble codes out and see what's happening.

 

[mattdk]

Figured it out...

The trooper lives again...

The ECM ground wire that goes to the engine block was loose.

There is not the same ground location on the 3.1L engine block as there is on the 2.8L (See picture). We used an oil pan stud to ground to and the nut must've came loose after the first 16 mile drive, giving us a weak/intermittent ground to the ECM. I tightened up the nut and it drives around great! I will definitely need to find a much more suitable ground location moving forward.

Now that the ECM is grounded correctly, we drove it around town a bit and the engine eventually threw codes 13 and 33 (O2 Sensor and MAP Sensor, voltage high). I was already planning on converting to the heated O2 Sensor, but I was reading Geoffinbc's heated sensor how-to document and wondered what the best 12v switched positive lead (hot in run) would be on the trooper? Could I use something out out of the fuse block?

The Heated O2 Sensor How-To:
https://9839f16c-3fad-4d37-89f6-38d...d/a62d6a_c81bf44980dc43159cdb64da7f582da0.pdf

Thanks in advance.

Matt

 

[Ed Mc.]

Yeah, that's a big ol' mess of ECM and engine control ground wires in one lug, that will cause a lot of pain if it's not connected or loose. Ask me how I know! When I did the engine swap I had pushed those wires into the fender well, out of the way. Took a while to figure out where to put them.

The 2.8 had a bolt hole in the pssgr's side of the block where you could fasten the ground wires. I used the crank sensor bolt on the 3.4 to do the same thing. If you can find a solid grounding point right on the block, it would be a better & more reliable connection than on the oil pan.

As I recall on the heated O2 sensor, there was a suggestion to tie into the power windows circuit at the fuse block. If your rig doesn't have power windows, then you could hook right into the empty PW relay socket. It's a high-amp, switched source of power. The heated sensor doesn't draw a lot, at any rate. I have mine all installed and the "hot" wire run up to the engine compt, haven't figured out what to hook it too yet. My LS has power windows. Will just have to find a convenient source of switched +12VDC and splice it in.

If the engine is running well, and the MAP sensor tests out, I'd ignore it. I get an occasional "check engine" light with EGR code on my 3.4. Probably 'cause the 2.8 computer is expecting a certain amount of exhaust flow/change of exhaust mixture when it opens the EGR valve when driving down the road to test how it's working. When the light goes on, if I turn the ign off then on again the light goes away. Just an irritation, it's not affecting how it runs.

Anyway, glad you finally got to the root of the problem. Now you can concentrate on other things!

 

[mattdk]

Yeah it was quite the discovery! I was dumbfounded when I figured out that was source of the problem. Anyways, I found a solid location for the ground wire, ended up using small bolt on the underside of the passenger side motor mount. Cleaned up/removed the paint off of the mount surface, bolt, ground washer at the end of the wire, and used battery terminal grease. Should be much better now.

I'll see if I can wire the positive 12V power lead for the O2 sensor into the power windows circuit (the trooper does have power windows).

Changed the oil and it looked absolutely terrible. It was a light milky brown/grey colored. I saw a lot of fine metal shavings in the oil and I'm pretty sure it was in there because of the metal work we (stupidly) did with the intake manifold off. At least, that's what I'm hoping its from. IIRC the oil that was in the 3.1L when we got it was not milky nor had any metal shavings in it, just dark oil. Fingers crossed it doesn't look like that again. Could coolant be leaking into the oil around the intake manifold gasket? I'm not too confident that was put on as well as it could've been. Is it common to have a leaky intake manifold?

I need to get the trooper registered and plated, and in my county I need to pass emissions, but the trooper didn't have a muffler when we bought it. About a 3ft section of exhaust is rusted out between the catalytic converter and the tail pipe; its almost as if the muffler rusted right off at some point 😂. I feel like this is a good time to upgrade to the larger free flowing exhaust if its not too much $$$. Given my current setup (3.1L, bored Intake and larger TBI), should I get a 2" or 2.25" diameter exhaust?
Do I need to replace everything up to the headers including the y-pipe or can I just replace the catalytic converter and do a cat-back exhaust?
I'm going to take it to a muffler shop, but I need to know what tp tell them to replace.
Recommendations on a budget free flowing cat and muffler?

Thanks in advance

Matt

 

[Ed Mc.]

Hi, Matt, yes, intake manifold sealing is critical. Use Permatex Ultra Grey RTV for sealing purposes.

https://www.permatex.com/products/gasketing/ultra-series-gasket-makers/permatex-ultra-grey-rigid-high-torque-rtv-silicone-gasket-maker-2/

You might want to put a very thin bead around every water port. And a bead of course at the front and rear, this manifold uses no gaskets there. Make sure you torque it down to specs, if you can't get at a bolt with your torque wrench, use your own good judgement to get it as tight as the others that you can torque.

Note that some bolts extend right into the cooling system, and you need to put a bit of RTV on the bolt threads to help seal them.

Here are some very good installation tips from Fel-Pro:

https://www.rockauto.com/genImages/6/1348(4-2).pdf

On the exhaust, you don't really need to replace the downpipes coming out of the exhaust manifolds; they are 2" which is plenty large for this engine.

You can, however, get rid of a big restriction in the system by having the muffler shop cut-out the exhaust wye.

I used a Walker dual-inlet cat on my 3.4 LS, but they're getting terribly expensive. This cat with dual 2" inlets is only around $55 shipped on eBay:

2" Inch Inlet 2.5" Inch Outlet Catalytic Converter Universal-Fit w/O2 Port EPA | eBay

O2 Sensor Port: 2. Inlet Quantity: 2. 1x Universal Catalytic Converter. Outlet Quantity: 1. Restricted States: California, New York, Colorado & Maine. Overall Length: 18". 5 Years or 50,000 Miles Manufacturer Warranty.

www.ebay.com

This cat has a bung for the O2 sensor built-in. So the sensor will run hotter and this will make the engine run even better.

On the pssgr's side, the downpipe comes down and has a 90-degree flange where it connects with one side of the wye. When we cut out the wye, we left a stub at that flange and welded a 90-degree elbow to the stub. The elbow was routed right to the cat, and was the 1st side welded. This helped locate the cat, and all that was needed to run the driver's side downpipe into the cat were some slight bends.

Any competent shop should be able to do this, easily. And a lot better than we did, laying in the driveway! If you get a mandrel-bent 2" 90-elbow, you'll have better flow. Or a shop that can do mandrel bends.

The rest of the exhaust is easy. Use a reducer on the 2.5" outlet side of the cat, down to 2.25", to the muffler and tailpipe. 2.25" a good size for mild performance build, and won't kill your low-end torque.

I used a Dynomax muffler, but there are any number of cheap 2.25" mufflers available on eBay and elsewhere. If they have a decent price on a generic turbo muffler, use that.

Here's a 2.25" P/N 17747 Dynomax Super Turbo "long body" muffler on eBay:

Dynomax 17747 Super Turbo Muffler For Jeep Grand Cherokee | eBay

Find many great new & used options and get the best deals for Dynomax 17747 Super Turbo Muffler For Jeep Grand Cherokee at the best online prices at eBay! Free shipping for many products!

www.ebay.com

These mufflers have a good tone, nice growl at lower speeds and idle, but don't drone on the hiway. That open-box one I linked is $56.06 shipped, a decent deal.

On mine, we hung the muffler temporarily so I could drive the rig to the local muffler shop. They bent up a new, larger tailpipe and properly hung the system. It made a huge difference on mine, over the terribly restrictive stock setup.

Anyway, there's a few thoughts. Hope you get your oil contamination issue under check..........ed

 

[mattdk]

Wow Ed, I can’t thank you enough. Your vast knowledge and research on these troopers and engine swaps continues to surprise me. Thank you.

That sounds like a super solid plan for the exhaust and I like it a lot. Thanks for explaining that out. That cat you linked seems to reconfigure the new exhaust system quite nicely, especially for the price. The 3.1L seems to have more power (than the worn out 2.8L) and revs up pretty fast for what it is, but I'm hoping the improved exhaust can give the trooper a little more grunt and torque.

On to the oil contamination, I am a little more convinced that coolant got into the oil via the intake manifold gaskets. I've decided I'm going to remove the manifold and replace the gaskets with new ones, RTV around the water passages, and reinstall the manifold with the right torque specs and sequence just to be sure.

I am also going to check the valve lash too while I’m in there. Is there any benefit or reason I wouldn’t want to replace the pushrods and lifters while I’m in there also?
I found a great price on new pushrods and hydraulic lifters from EngineTech on Rockauto ($8 and $21 respectively).

Any preference between intake manifold gaskets? I'm thinking on the Fel-Pro MS91022 (only $5 on Rockauto), but I've read that the Victor Reinz 111061501 is preferred from another thread that I read.

More Information for VICTOR REINZ 111061501

More Information for FEL-PRO MS91022

Thanks in advance.

Matt

 

[Ed Mc.]

Any progress? I have Fel-Pro gaskets in my 3.4 and the swap is almost 20 yrs old. Nothing wrong with the Victor Reinz gaskets, either. Be sure to use some Permatex Ultra-Grey sealer around water ports and at the front/rear of the intake where it seals against the block. DO NOT cut the new intake gaskets to get them to fit around the pushrods. Use a Lisle pushrod tool in that case, it'll make things a lot easier if you aren't replacing the lifters/pushrods.

48300 Push Rod Remover

Redesigned for Newer 3.5L and 3.6L GM Engines. Also Works on GM V6 2.8L, 3.1L and 3.4L.

www.lislecorp.com

Can't hurt to renew the lifters/pushrods but you will have to set the valve lash. Typically on stock engine it's about 1 turn CW on the locknut past the point when the pushrod stops "jiggling" up and down in your hand as you tighten the locknut. Keep a close eye on the lifter and if the top starts to move downwards, you're past Zero Lash. Soak the lifters in motor oil overnight and work them a bit, to purge air out of 'em.

Examine your cam lobes and the surfaces of the old lifters; the lifters should not be "dished" as they are normally convex; the cam lobes should look sharp and crisp, any wear on any lobe means it's time for a Comp Cams "252 Torquer" grind!

Cheers & have a Merry Christmas...........ed

 

[mattdk]

Finally got around to removing the intake manifold and sealing the water passages between the manifold and cylinder head. I used Permatex Ultra Grey on both sides of the gasket and waited until it got tacky before bolting it down. I also bought new pushrods (not lifters!) (accidentality ordered 8 instead of 12 so I had to reuse a few old ones ), installed those and set the valve lash while I was in there.


Now for the bad news...

My buddy who is a master mechanic at a dealership, helped me this time and he said the oil isn't/wasn't contaminated with coolant. After we reassembled the engine, we drained the old oil out to replace it and it was a mud color with metal shavings. Also, the oil didn't come out separated while draining as if it had coolant in it.
My buddy thought the cam looked worn down (pitted/scored) when we replaced the intake manifold, so we are under the impression that the cam and lifters got ground down when we first started the engine. We think it's been shaving metal since then as well.

If this is what has happened, how can this be? Was I supposed to follow a break-in procedure when it first started up?

I didn't remember reading anything in Ed's Engine swap packet or this thread.
I pre-oiled the engine with the valve covers off and made sure that oil flowed up through the pushrods and over the top of each rocker arm.
I used engine assembly lube on everything I was told to in this thread (new components I installed).
I'm pretty sure all lifters spun when I hand cranked the engine while on the stand.

I just researched the break in procedure for rebuilt flat tappet engines and found that there were a number of things I didn't do: use conventional oil and a ZDDP oil additive, lube the camshaft lobes, run the engine above 2,000 rpm for 20-30 mins upon the very first startup and drain and refill the oil after the initial startup and run. I guess I just figured since the cam and lifters were original to the engine and I didn't remove them, they didn't need and engine assembly lube or any extra care.

I know a lot of people have done this swap before, has anyone experienced shredded cam/lifters or mud colored oil with metal shavings in it after initial start up of their swapped engine?

Matt

 

[Ed Mc.]

Used cam and lifters in the engine? Still a good idea to pour some oil over them before startup, but doesn't require a break-in. Already broken-in! Unless you pulled the cam & lifters, and the lifters didn't go back in exactly where they were before. Mis-matched, worn lifters could ruin a cam.

And it goes without saying that a new cam and lifters require break-in as you stated above. This is common shop practice and I don't necessarily include every procedure for an engine rebuild, in my swap information.

You may recall, in my "Ed's 3.4 Swap Info" document, the following:

Obligatory Caveat: Note that the info in these files is oriented to provide additional info, hints, and tips on the things that are unique to adapting the 3.4 motor into an Isuzu application. These files are not meant to be a step-by step recitation on how to rebuild a GM V6. As there is a ton of info on that topic out there already, I’d highly recommend the purchase of a shop manual if you haven’t done an engine rebuild or R&R (Remove&Reinstall) before. This also assumes ‘normal’ skills and knowledge when it comes to using hand tools and pulling/reinstalling engines, trannies, replacing clutches, etc etc etc.

So that's that.

On use of zinc, it might help with new tappets/cam. I bought some but I haven't used it in the Trooper. Was more concerned about the extra zinc polluting my new cat. However, I've run it 20 years (although not a ton of miles) using quality synthetic oil, and it still runs flawlessly. Has a wee bit less oil pressure at idle than it used to, but still gets over 50 psi off idle. So I think it's gonna run for a bit longer.

Hard to say with your used 3.1. Ground-up bits don't sound so good, let-alone the discolored oil.

I'd be at minimum pulling the intake and lifters and inspect the bottoms of the lifters, and the cam lobes for wear. The lifters must be slightly convex (i.e. bulged out, not caved-in) or they wont rotate properly in their lifter bores.

Here are some more words regarding that, from "Ed's Swap Writeup":

BTW a lot of the Camaro used motors show cam wear. Do a very careful visual inspection on the cam lobes. After the valves are adjusted, rotate the engine thru several revolutions and watch the lifters. If the cam and lifter surfaces are in good condition, the lifters will actually rotate as they go up and down. This evens-out the wear on the cam and lifters. If the lifters do not rotate, the cam/lifters are worn and must be replaced. Otherwise wear is localized on the lifter/cam interface and eventually the cam lobe will go "flat".

If your cam is shot, replace cam/lifters as a set. Do not re-use old lifters on a new cam & vice-versa. The Goodwrench HT 3.4 crate motor cam is a good choice as it makes excellent torque, better than the Camaro cam. But you must use the HT’s valve springs and retainers if you use the HT cam. eam 11/30/04

Those comments about lifter rotation apply to the 2.8, 3.1, 3.4, and pretty much any other GM engine using flat-tappets. So after you pull your intake, turn the engine over and watch the lifters as they rise and fall. If you see one that just sits there and doesn't move, its cam lobe is flat. If any lifter doesn't rotate, then the entire cam assembly and lifters are probably shot.

In that case, if you can swing it, a Competition Cams "252" V6 cam kit would be a great addition and give you better performance. You'll need at minimum the cam, valve springs and retainers, as they are special and must be used with the cam. Plus new lifters of your choice, of course. Flush out all the pushrods if you re-use them.

Or, call up Delta Camshaft in Tacoma and ask for a "Torque" regrind for your 3.1. They work well and are cheap (well, used to be, haven't priced one lately!). I did a "3.1 Stroker" build on an '89 2.8 Trooper engine, using that cam. Broke it in per procedure and it's still running great after 17 years. My Nephew inherited it when my Stepdad passed in '11 and he loves it.

Hope that helps and Good Luck with troubleshooting. Put your Master Mechanic friend to good use!

 

[mattdk]

I didn't think I needed to break in the engine either since I never touched the cam/lifters, which is why I was wondering if I missed something obvious in the engine swap files/threads. As you mentioned though, it seems the Camaro cams show wear after time and maybe since this engine sat for nearly two years without being started it got worn out upon first starting. I am not mad at anyone or anything, I took on this endeavor knowing that I could mess something up royally. All the information I've received thus far has been immeasurably helpful.

I think the plan is to R&R the camshaft and lifters and use conventional oil with the ZDDP additive. I've considered putting in the Comp Cams "252" grind camshaft and lifters, but it sounds like I would need stronger valve springs among other items that I might as well replace while I'm in there. Also, at this point I just want to get the trooper up and running again considering how much time and money has already been put into it thus far.

I called up the guys at Delta Camshaft and they said they could do a "torque" grind of my 3.1 and lifters for $170 shipped and core charge, which sounds like a stellar deal! I asked what the cam specs were on this cam and they said it would be a 260 grind (212/212 duration) with about .440-.450" of lift. They said I could use the stock valve springs and shouldn't need to change anything with the fuel system/TBI to accommodate the hotter cam.

What is your take on that grind? Sounds a little too aggressive, but they did mention it should idle fine at about 800 rpm. And not needing stiffer valve springs? I'm a little confused as to how a less aggressive grind (252 grind) from Comp Cams needs stiffer valve springs, but this grind from delta doesn't need the stiffer springs.
Ed, what all did you replace alongside installing your Delta "torque" grind camshaft and did you have to change/adjust anything on the engine after putting it? More fuel pressure? 4.3L injectors? timing? or everything pretty much stock settings? I've read a couple threads on here that cam timing can be is a bit off/weird after installing these delta cams.

I think I am either gonna go with this "torque" grind camshaft/lifters from Delta or a stock replacement camshaft/lifters like this Melling kit:
Melling CL-MC1290

Thanks in advance.

Matt

 

[Ed Mc.]

The Comp Cams "252" grind is a new core, so hard to compare to the Delta regrind which will have material ground off the base circle, but it doesn't change the other characteristics of the cam. Not a cam expert but the "3.2 Stroker" drove great even with stock exhaust, stock valve springs & lifters, and a stock TBI. I didn't built that for high-end performance 'cause it was going to my Mom and Stepdad. It ran pretty good and got good mpg, better than a 2.8 trooper.

You'd have to examine all the specs of the 2 cams to begin to understand how each works. I can't speak for the valve springs, but from what I understand Comp Cams says that the stock valve springs will coil-bind with their cams. Never had any issues with combining a stock cam and 1.6:1 Magnum Roller-tipped lifters, or with the Delta regrind and otherwise-stock valvetrain.

You can buy the Comp camshaft separately, but you'd still have to get the springs, retainers, and keepers. Their springs & retainers are pretty much the same as early Z28 hardware. So if you have any good swap meets nearby, maybe you could pick up a killer deal on Z28 springs & retainers. Not that hard to change springs if the heads are off. Use an inexpensive valve spring compressor.

The "3.2" lean-surged when cold, with a 2.8 TBI. I defeated the spot-weld on the fuel pressure regulator adjustment nut and tweaked-up the fuel pressure a bit. That did the trick.

If you're running a stock 2.8 TBI, you can use a 14 PSI spring in the F.P.R. and that should raise pressure enough to get adequate spray. Check Amazon or eBay for deals on the spring. Sometimes called a "Yellow Spring".

If you planned on boring-out the intake, you'd use a GM 4.3 TBI and either 2.8 or 3.1 injectors. And you'll have to adjust pressure up/down to suit. You can buy some fuel test gauge adapters that go between the TBI and the fuel lines, and these adapters typically have a plugged test port, where you can pull the plug and hook up a test gauge. It'll help greatly if you need to fine-tune fuel pressure.

Last thought, be sure you understand what really happened to your engine before dumping a lot more $$$ into it. Hard to say where those metal chips have gone, have you considered pulling the engine and checking oil pan, oil pump, rod and main bearings, etc? Would hate to have the problem happen again. Yes a lot of work but it's a lot of labor and money working on the top end too, especially if you have more problems and have to pull it down again. Just a thought.

G'luck with the repairs/upgrades..............ed