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Go fast bits

Getting the best performance from your Isuzu, the in's and out's

Re: Go fast bits

Postby geeves » Tue Mar 14, 2017 6:18 pm

that butterfly is for overboost protection not qws. You can remove it and seal the holes but then oil will just seep through the rubber hose at each end of that pipe. You could dismantle and clean inside which will keep it at bay a few months and maybe fit a catch can as well
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Go fast bits

Postby MuZILLA » Tue Mar 14, 2017 6:31 pm

Oh right. Cheers for the clarification. Any idea what boost pressure activates the butterfly or what conditions must be met for it to start choking boost.
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Re: Go fast bits

Postby geeves » Wed Mar 15, 2017 4:55 am

The pressure release valve (blow off valve if you were younger and had your hat on the wrong way) operates at 16psi as does the waste gate I imagine that the rest of the system works around that pressure
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Go fast bits

Postby MuZILLA » Thu Mar 16, 2017 2:41 pm

Cheers for that mate. I finished the install thanks to your great information. Unfortunately I have hit a new problem before I could test it. :(

I started the car as I was about to go for a test drive to set my duty cycle and so on. Just before I reversed it out of the garage I notice fluid on the floor. Went around to the front and there is deisel dripping constantly from under the injector pump while the engine is running. Not sure why it decided to start leaking today. Possibly due to lots of vibrations from going out for a fourby on its last drive. Such a pissy way to end a job done on the truck. :oops:
Here are some pics if anyones got suggestions of where it could be leaking from out of experience or knowledge. I'm pretty sure the part it's dripping off is the ignition timing advance. But not sure whether it's leaking from that or just running down to it. Seems to be dry right above this part.
First pic taken from under vehicle.
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Unfortunately it's not quite possible for me to take the injector pump to a deisel specialist for a regular seal. I know that would be the best option. Any advice would be great. Let me know if I should post this in another thread instead of continuing this one. Cheers.
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Re: Go fast bits

Postby geeves » Fri Mar 17, 2017 4:57 am

Im not the expert on this but there is a seal on the back of the pump between the bock and pump that might be the culprit. Not easy to do with the pump in place but Rob says it can be done. Hopefully he will have part numbers etc
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Go fast bits

Postby isuzurob » Fri Mar 17, 2017 9:23 am

Behind those side plates are o rings just undo the 10mm head bolts, do 1 side at a time, the inner one can be done in place just patience is needed
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Re: Go fast bits

Postby stardog » Fri Mar 17, 2017 12:28 pm

I had the same problem last year I just undone the 10mm bolts and reused the o rings dried everything off and put some gasket goo on the outer side of the o rings let it set for about a hour and put it back together that fixed it.
Then the front seal went diesel seeped into the engine oil so it was pump out and new seal in I have a gear drive 4jb1t engine out of a rodeo I got the seal kit from freewai I think from china no problems since.
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Re: Go fast bits

Postby MuZILLA » Fri Mar 17, 2017 1:58 pm

Thank you guys. I'm going to have a crack at it now. Hopefully it is just those o-rings and I can do it with the pump in place. I have found a seal kit locally for $34. Does anyone know if those o-rings are usually included in the general rebuild/seal kits? And if the front seal is gone, will it almost always seep into the engine oil? I was about to remove the pump and do a whole pump re-seal, but I think I'll try your suggestions first. I will keep you posted. Thank you again. :)
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Re: Go fast bits

Postby stardog » Fri Mar 17, 2017 2:06 pm

The set up on a belt drive pump is different to the gear drive if the front seal leaks it leaks fuel onto the timing belt instead if im not mistaken.
I check my oil level every week that's how I found it the oil level had risen up on the stick I was lucky I could of had a run away engine and gone boom.
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Re: Go fast bits

Postby MuZILLA » Fri Mar 17, 2017 3:13 pm

Cheers. Yeah no deisel on timing belt or engine oil. I am waiting now for gasket goo to dry for the outer plate. I am leaning more toward the inner plate being the culprit. Either that or a crack on the pump housing which I don't really think is likely. Now there is a spring inside the outer plate. Do you know if I'm going to be surprised by any parts falling out once I remove the inner plate? Being such a hard area to reach and being so dirty around it(Running out of degreaser :( ), not really wanting to drop anything.
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Re: Go fast bits

Postby MuZILLA » Fri Mar 17, 2017 5:06 pm

Outer plate was not the problem. Still leaking. Can't even seem to loosen the bolts for the inner plate. I have been trying for quite some time. Getting a spanner on the bolts is proving harder than I thought. So much blood and swearing happening in my garage right now. I think my patience level is down today. :evil:
Going to take 5 and maybe try again before I end up removing the pump.
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Re: Go fast bits

Postby stardog » Fri Mar 17, 2017 5:34 pm

Welcome to the world of working on Isuzu's if you aint swearing and loosing skin and blood your not trying hard enough just joking but its true.
Do you have a set of 1/4" socket kit because spanners are a bit hard to get in there to do anything.
Easy way is take the pump off and do it that way but remember to put it in TDC number1 piston and put 8mm bolt in the cam sprocket and mark things for the timing also you will have static time the pump with a dial gauge plenty of info on the forums on this site to help you out.
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Re: Go fast bits

Postby MuZILLA » Fri Mar 17, 2017 6:34 pm

Haha. Too true. It's a love hate relationship with my mu truck. Love it to bits even though I'm swearing at the thing every few days.

After a few more cuts, and a bunch of French. I have just gotten the bolts, inner plate and o-ring out. The o-ring does seem to have some miniscule cracks in it. Going to cover it in gasket goo and give it a shot. If it's a no go, I'll make the hour long trip tomorrow morning and grab the seal kit. Hopefully there is no need. The plate has some scoring on it. Do you think it's worth flipping it over?

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Re: Go fast bits

Postby MuZILLA » Fri Mar 17, 2017 6:52 pm

All good. Disregard last question. I just ended up resurfacing the plate.
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Re: Go fast bits

Postby geeves » Sat Mar 18, 2017 5:38 am

I hope you got it flat.
As for the blood and french think what the cars saying every time you take it on an untracked adventure
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Go fast bits

Postby MuZILLA » Sat Mar 18, 2017 11:24 am

Yes flat as a piece of glass. As that's what I did it on. Yeah everytime I spurt a new fluid leak. That's the car bleeding from what I put it through.

Anyway I got that plate and o-ring back in last night with great difficulty and as Rob said, a heap of patience. By the time I finished I couldn't get my hand out from behind the pump due to it swelling up from all the cuts. (Excess metal head gasket sticking out was very very sharp)

All in all, it sealed perfectly and I was jumping up and down with joy. Honestly all credits to you guys. I literally couldn't have done it without you. I probably wouldn't have even attempted that rear plate with the pump in place. Until you guys said it is slightly possible.

I finally got to do that test drive and on stock boost I was reading 9.5psi peak and stable around 9.3psi in 3rd or 4th gear. Set the duty cycle gradually up to 80% and started getting around 11. 4psi peak 10.9 Stable.
If I remove the vac line from the overboost protection will that stop its function? Next I'll be turning the boost compensator diaphragm and adjust the fuel screw a tad. Any other tips on sucking a bit more boost through the engine? Or any more restrictive factors that are easy enough to overcome?
Once again I really appreciate all the help you guys gave me. Absolute life savers.
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Re: Go fast bits

Postby geeves » Sat Mar 18, 2017 12:49 pm

The device on the inlet manifold is preset to 16psi. All you can do is block the hose between this and the inlet pipe to the turbo. Before doing that though block the hose between the turbo and wasetgate That will pretty much give you all the boost it can.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Go fast bits

Postby Jackmate » Sun May 28, 2017 7:03 pm

Hey guys, I've got a bighorn with the 4jg2 in it, currently boosting at 16psi. I've wound the diesel pump up heaps. Still looking to get more juice out of it. Really lacks top end power, feels like it runs out of boost past 3100rpm. Has plenty of midend though. Has anyone experemented with putting a bigger turbo on, and if so, which turbo. I'd prefer one that bolts straight on but if anyone sells adaptors I'll use one.
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Re: Go fast bits

Postby isuzurob » Mon May 29, 2017 7:05 pm

Remember its not a petrol engine, can run a hybrid turbo with a 12 or 15r exhaust housing with a vf10 core with a 1kz compressor wheel, compressor housing needs machining, or run a vf8 with vf10 or 4jb1-t turbine wheel and shaft, there are lots of options, bigger turbo to get better top end with make it smoke lots and be laggy
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Re: Go fast bits

Postby geeves » Mon May 29, 2017 7:59 pm

If its still boosting 16psi then a bigger turbo isnt going to help much. If it drops away at higher revs you could get some gains but unless you get into the black art of variable vane turbos any gain at the top will be matched by a lag at the bottom. Before doing anything get the rest of the induction right. ie free flowing filter bigger exhaust etc. Also look at timing sometimes a sight advance can help but not so much that it knocks. Also read up on ve fuel pumps. Unless its electronic there are a few other tweaks apart from just fuel. Also have a good cooling system
As a rule of thumb on adjusting the fuel screw wind it up a little at a time until it smokes on full throttle then wind back till it stops smoking
Sanding your knuckles before starting work can help. That way you cant skin them
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