I just thought I would throw out some details of my experience with this truck over the last year.
Injector pump timing:
No gains to be made there, with either fuel mileage or power. Advancing increases the noise/rattle and increases bearing wear (confirmed by oil analysis), and retarding shoots the EGT too high.
Injector pump max fuel adj:
Didnt notice much, but there was slight improvement in power. Fuel efficiency dropped slightly, also.
Transmission:
I have concluded that the torque converter is the culprit to the higher engine RPM's and the problems shifting. Stock TV cable adjustment settings are best. I have found a torque converter for this transmission from BD, but the bolt pattern is listed as "Dodge" pattern. If anyone has any info (or reference material that shows) that this is the same bolt pattern as the Isuzu 6bg1t, I would appreciate it.
And last, but not least, a very strange issue that I thought sharing would help someone else diagnose without spending several hours figuring out.
(terms listed for search engine tags) Isuzu NRR 6bg1t or 6bg1 engine fails to shut down with key turned off:
In a nutshell: when you turn the key OFF, it disconnects the 12v system from the battery, yet the fuel shutoff valve requires power to run the little electric motor to cycle the valve OFF. The power used to run this motor comes from the alternator output circuit (which is disconnected from the battery when the key is OFF). So....if your alternator is bad, the engine will not shut down. Oh, the hours I spent disassembling the dash to test all the little components in the fuel shutoff circuit....
On the bright side, this alternator is very stout. It has over 250k miles on it and the bearings and (steel-looking) armature are in excellent condition. It also uses VERY long brushes, so they last a very long time. The brushes (installed by SAS) cost less than $50.
Tool truck project
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- mattawajeep
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I think I may have to regear the rear axle.
This truck is not quite what I was expected. This 6.0 has variable cam timing (RPO code L96), which GM seems to have installed to "make up" for the larger intake they installed on this engine. It seems down on power in the lower revs than the older 6.0's. Also, the 6-speed transmission has double-overdrives (5th and 6th gear), so she is pulling about 2200 rpm at 70mph. The combo does not work real well for a truck that is over 11k lbs.
I hear a tune will do wonders with engine, since the trans is completely electronically controlled, and so is the cam timing. Just not sure whether I should go with a setup like HP Tuners or just buy a canned tune. Dale, have any insight on tuning hardware/software?
This truck is not quite what I was expected. This 6.0 has variable cam timing (RPO code L96), which GM seems to have installed to "make up" for the larger intake they installed on this engine. It seems down on power in the lower revs than the older 6.0's. Also, the 6-speed transmission has double-overdrives (5th and 6th gear), so she is pulling about 2200 rpm at 70mph. The combo does not work real well for a truck that is over 11k lbs.
I hear a tune will do wonders with engine, since the trans is completely electronically controlled, and so is the cam timing. Just not sure whether I should go with a setup like HP Tuners or just buy a canned tune. Dale, have any insight on tuning hardware/software?
Paul
'84 XJ, '19JL
'84 XJ, '19JL
- mattawajeep
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- Joined: Wed May 19, 2010 6:18 pm
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Wrench wrote:I hear a tune will do wonders with engine, since the trans is completely electronically controlled, and so is the cam timing. Just not sure whether I should go with a setup like HP Tuners or just buy a canned tune. Dale, have any insight on tuning hardware/software?
It's been a very long time since I've looked at software tuners and things have changed. It looks like HP Tuners will do just about everything, including your truck, but it's not cheap. A lot of this stuff used to be free, but it seems like the free stuff hasn't kept up with the new models.
Is there anyplace in tri-cities that does dyno tuning? You'd probably get the best tune that way with a minimum of effort, and actual numbers makes things easier feeling it. Of course that may not be as fun as tuning it yourself on the fly.
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