TOPIC: Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope!

Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 10 Jan 2020 07:37 #1

  • neil
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Hi everyone,
I have been driving diesels for some time and haven't had time to keep up with these forums last couple years. Anyway I now have an interest in improving a 3.2 litre Isuzu V6 petrol. Its heavy on fuel, at around 14 litres per 100kms. Apparently this is normal enough, the motor seems to run very nice, after about 3000kms traveled,since grooving the throttle body.
In 2013 I purchased a set of the three "grooving" cutters and although my attempts are limited I haven't really had any success with improving fuel economy....a couple vehicles were LPG too!.
Anyway! Here we go. This little ute weighs only 1.5t and is a 5 speed manual so im giving it another go. This is what I have done, 1. Blocked off idle speed control with a 3/8bsp threaded plug, 2. Grooved the throttle body with middle sized bit (couldn't find the large one at the time), 3. disconnected the PCV valve. 4. Disconnected the manifold port used for the petrol vapor, now it goes in the air cleaner housing.
A few things not done yet 1. Valve clearance adjustment. 2. disconnect brake booster vacuum take-off. 3. maybe re-cut the throttle body with the largest bit? 4. Have not fixed a fault code showing "vehicle speed sensor" but runs fine, must be electrical as the speedo still works fine, from the same sensor (i think). 5. Planning to corrupt the air-flow meter next to make it run leaner.
I really would like to know if others have had success, and how much success! on this or similar motors. I am not shy to do lots of work but I need a bit more hope at the moment. It is geared very high, the motor does 3000rpm at highway speed, I noticed that the throttle barely needs to be opened to maintain highway speed. I think this means that it is running pretty rich. I just swapped out the airflow meter with one I cleaned from another vehicle. It runs off airflow meter and airflow temperature. There is no manifold absolute pressure sensor.
I have been following this forum since 2013 and feel privileged that all you guys keep this going...Ron! Good on you! I regret not having utilized things I have learnt and wanted to try, but I promise I have been gainfully busy and everyone's good input has not been lost on me.

Kind regards, Neil
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 10 Jan 2020 11:29 #2

  • GregK
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hello Neil -
It's a good sign you don't need to press the accelerator to maintain speed - it shows that manifold vacuum is deep (so it's not leaking!) and vapourizing fuel, and the groove is better mixing fuel and air than the factory designed it to. Once you get the computer open to learning by fixing the code, the injectors will respond and listen to the o2 sensor again as well, and you'll get a nice hot dryer vent exhaust (I'm guessing that it's pretty moist at the moment), and I'm predicting significant gains in mileage/reductions in consumption.

Yes, do re-groove with the largest bit. But Repair the engine code FIRST: That sensor tells the computer what range of injector pulse durations to reference for the oxygen sensor to trim to.
In other words, that light is causing the computer to default to factory injector pulse duration and PREVENTING it from learning what the groove is doing for it.
So, of course it's running rich; much richer than necessary.

these are just the beginning. You'll be able to fine tune your vehicle's fuel usage by following some of our other tricks, like tweaking your ignition system with low resistance spark plug wires and increasing your plug gap, bumping your tire pressure, (you've already cleaned your intake air sensor, it seems...awesome!)...well, just get your groove opened up and fix the computer code and then do the re-learn procedure. You'll be very glad you did. we can get to this other stuff after you see some gains, so that you can see more.
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 11 Jan 2020 03:38 #3

  • neil
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Great! Thanks Greg.
You inspired me to fix this code. Like an idiot I assumed the worst, read the entire troubleshooting procedure for vehicle speed sensor ....and then decided to just swap the sensor with a second hand one, disconnect and short battery terminals for a while...and presto...no light! (KISS Keep it simple stupid) Hopefully the light stays off, the speedo also works from it so guess the computer just wasn't happy with the signal;.
Anyway I will get the throttle body off again and use the biggest bit soon!... jumping ahead to the spark plugs. Can you give me some advice? It has coil over plugs, so I think thats a good thing. I would have just chosen non-resistor NGK plugs and gapped them wide...say 1.5mm and see what happens. I see you guys are talking about more fancy plugs, I'm in Australia so I guess I can order stuff from USA and wait for it.
I don't know if the same motor is used in the USA, or what the vehicle is called. In Australia it is sold as a Holden Rodeo. I think I might have heard Isuzu troopers were sold in USA but I have no idea if they used this 3.2 litre V6? I think about 2003 they upgraded from my 3.2 litre to a 3.5 litre motor, which is very similar in design/specs.
Kind regards, Neil
PS Is there any benefit in cutting another groove after the first one? I nearly did it last time and just thought of it again now....seems multiple grooves might have some benefit??
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 11 Jan 2020 08:18 #4

  • Ron Hatton
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Hey, Neil!
There is actually a DETRACTION from the benefits to add a second Groove. You have to start thinking in pressures and waves to become truly successful with The Groove.

Imagine a bread board. Cut slots in parallel across the board and then take a glass of water and pour it in a fashion perpendicular to the grooves. As the water crosses the grooves, each successive groove takes a little of the water away.

Same with the waves created by The Gadgetman Groove.

One interesting thing, though. The O2 sensor extenders we USED to have to make with an anti-fouler and a drill press are now being manufactured and are available in various lengths, usually right from your local parts house.

Adding an extender to your upstream O2 allows the highest concentration of exhaust to hit the sensor tip, convincing the ECU there's a higher level of raw fuel, encouraging a leaner mix. If you opt to gut your cat, reportedly you can use the same technique on the post-cat O2 to convince the ECU the cat's still functional.

I don't recommend gutting the cat, but many have done this, and used this technique to stop the check engine light.

Just sayin'...

Ron
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 11 Jan 2020 12:29 #5

  • GregK
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Neil - I'm happy my description inspired you to get on a seek and destroy mission for that engine code. the VSS might be there for traction control/antilock braking in addition to fuel delivery in the computer - I'd have to dig deeper - and the speedo is probably cabled to the final drive of the transmission, which is why it worked when the sensor code got thrown.

Isuzu and Holden both fall under the General Motors banner (along with Opel, and others, I'm sure), so my Buick and your Trooper may indeed have more than we know in common under the bonnet. (we did have Isuzu Troopers here in North America because...General Motors. Holdens were (are?) sister cars to our Pontiacs and Buicks and Oldsmobiles and Chevrolets...)
In your case with coil-on-plug ignition, you can probably open up the spark gap wider than you might think possible...but I'd be wary of resistorless plugs. Just put good Iridiums in there if you're going to swap them, and start with a 20% increase over stock gap, which I would guess is in the 40-46 thousdanths of an inch range (0.040-0.046"). There's an emissions control system sticker under my bonnet that tells me what mine is - you may have one too.

Glad you're going to put a full-depth groove in your TB...and if I may offer one other modification on it to consider while it's off, consider shaping the edge of the throttle plate across from the groove. Not the edge that passes over the groove, the one on the un-grooved side of the TB. (I'll find the old post on here that details TB shaping so you can get a better idea of what I'm talking about if you're confused) My belief is that it enhances the vortexes generated by the groove, or prolongs them as they travel down the intake runners to the valves. Further, I've added a bunch of golf ball-like dimples around the bore of my TB uptream of the butterfly to try to mobilize boundary layer air up into the airstream that the throttle plate itself hopefully directs at the groove. There's a bunch of posts about that in the forum's history as well I'll try to find for you. Dimples and Why dimples

Updates please!!

have you noticed a difference in your mileage/consumption since you changed the sensor? is it idling lower/slower? what about the sound of the exhaust note - is it deeper? that's the first indicator to me that it's running easier, that the mods have taken effect...a deeper rumble/resonance of the exhaust system. On mine, when I first grooved it, it was a definite large musical interval lower - and while the soundproofing of the cabin made it a quiet ride before groove, the engine was quieter than wind and tire noise as I rolled down the road post-groove. I rather like that I'm driving a near silent, stealthy, sleeper-ish car.
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Last edit: by GregK. Reason: linky linky

Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 11 Jan 2020 12:32 #6

  • GregK
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Ron Hatton wrote: The O2 sensor extenders we USED to have to make with an anti-fouler and a drill press are now being manufactured and are available in various lengths, usually right from your local parts house.

Adding an extender to your upstream O2 allows the highest concentration of exhaust to hit the sensor tip, convincing the ECU there's a higher level of raw fuel, encouraging a leaner mix.


Post #7 here for why to extend your o2 sensor's port depth with extenders

Ron - link to those extenders, please?

ALSO: there are small ports on the outside of the sensor for the sensor to compare what it's looking at inside the exhaust system to what the outside air is like. if those ports get blocked, the sensor can't do it's job. so get eyes on yours every so often, and if there's grunge/crud on the sensor, clean it off and get those ports open! I'm going to start paying attention to mine, and giving it a wipe and healthy blast of carb cleaner when the exhaust is cold.
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Last edit: by GregK. Reason: back to the future...

Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 11 Jan 2020 16:06 #7

  • Ron Hatton
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Come on, Greg.

Use Google for "O2 Extender".

Ron
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 11 Jan 2020 18:22 #8

  • neil
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G'day guys, Thanks so much for the advice!!
I never knew cleaning the outside of the oxygen sensor was important, I will pull it out and clean it. Also found some O2 extenders. There are all sorts available, some are quite long at 45mm and only have a small hole to the re-positioned sensor, Some even have mini catalytic converters in them. I think the sort I want are simply to back out the sensor a little bit. I liked one that is only 32mm (1 1/4 inch for you guys Lol) long and has a large 1/2 inch "through-hole".
I am surprised you guys like resistor plugs. Have you experienced issues with non-resistor plugs? I know interference is supposed to be a problem...
Next, My experience is limited on free-flowing exhausts on petrol engines but I think free flowing doesn't help with petrol (does with diesel) so I wasn't planning any exhaust modifications or catalytic converter removal. I once saw that Landrover recommended 2 PSI back pressure in an exhaust system, and I know how critical back pressure is for two stroke motors too. Does anyone have good experience of increasing free-flow of petrol exhausts? And I am really only asking about fuel economy benefits.
Again, Many thanks
PS I left this until last....I also cut a grove at the top of the throttle body....I know the throttle plate doesn't direct a concentration of air past the gap at the top of the throttle plate ....but I just thought whatever air does make it over the top of the throttle plate might as well pass over another groove. Be honest...I do have a spare throttle body.

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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 11 Jan 2020 18:58 #9

  • GregK
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I’ll let Ron reply re: upper Groove; I want to talk o2 sensor:
It doesn’t need to be pulled. Just clean the outside, ensuring that the few holes around the circumference are clear. If you do pull it to decarbonize it when adding the (shorter 32mm) extender tube, it can’t hurt, unless you don’t use sensor-safe cleaner. Take care with what product you choose to use, or you might damage it.
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 12 Jan 2020 16:49 #10

  • kman
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Neil,
A couple of tips for using extenders.
I have tried a few with no success but have heard of others who used them to clear codes and even save gas by fooling the sensor.
One is to make sure you get a quality metal extender since the first one I tried actually collapsed a year later when I went to remove it to change the sensor. The metal was not rust resistant and too thin composure so it bent and fractured upon removal. Bummer getting this out when you are under the vehicle.
Second is to use a never seize product to prevent seizing of the threads inside your exhaust pipe.
That grease has saved me a few times from having seized threads on other applications on my vehicle.
Amazing how easy it was to remove the second extender when this was applied.
Just be careful on getting this on your hands or clothes since it seems to be difficult to remove, even with acetone
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 12 Jan 2020 18:12 #11

  • Tracy Gallaway
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Well I'm the latecomer to this thread...glad to see everyone else chiming in to help Neil. Greg mentioned tire pressure alrady. I usually say to inflate tires to their sidewall max press. specs. IF the truck is driven w/ no load, maybe a few pounds less in the rear. IF the tires are on good shape, and it drives OK at full sidewall recommended pressure, you can go over some, say 5 lbs.

Under-inflated tires are so common that the US Gubmint tells us to check the tire pressure often. I Check mine when cold for accurate #'s. Just don't go nuts w/ tire pressure, use common sense. Reducing rolling resistance is reducing parasitic losses, and that equals gains, even if small.

Tracy G
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Isuzu 2001 dualcab 2wd 3.2l V6 Petrol hungry. Need some hope! 13 Jan 2020 18:01 #12

  • kman
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Neil,
Adding to what Greg and Tracy are telling you about tire pressure, I remember a video I watched from years ago.
Mike Hollar is an expert when it comes to engine performance know how and I remember him stating that one can improve gas mileage by about 1MPG for every 4lbs of extra pressure above your tires recommendation.
Some of his videos may be on this site since Tracy introduced me to his videos shortly after I grooved my first vehicle.
This is why I am always at least 4-8 pounds above on my suggested tire pressure. Easy mod for a little extra gain.
Mike Hollar and Dan Merrik used to post here years ago.
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