93 confusion

[PVSLS400]

Hey All
I got a 93 with a mech 6.5 td from what the vin tells me, now I am sure it mech due to a throttle cable to IP. It has a GM 8 turbo due to the fact that it has a vertical wastegate opposed to a mechanical one, and no ecu behind glove box and no ses light. Now i have plenty of power from 1st through 3rd and can hear turbo boosting, no smoke at all, not even at start up and its real cold in colorado now, but it seems to lag out in 4th gear in a mild incline
no power above 2k rpm's and i have to beg it to get any close to 3400 rpm's so i can shift to 5th and then issue arises again but can never get it above 2400 rpm's in 5th. It has a new nv4500 and 410 4x4, removed soot collector on exhaust and snorkel in fender, new af and fuel filter, wastegate seems to operate properly. was told that gm 8 will work on the L56 but requires modification? assuming requiring a vac pump and solenoid which it has, just hooked up to a hot connection always on. thats where i get stumped on the problem. city driving perfect no issues, highway or towing have to take frontage road. fuel economy is excelent so im baffled
Thanks

[JohnC]

The '93 had no catalytic converter and a mechanical wastegate, so, who knows what you have...

If it doesn't smoke then the problem is likely fuel, not boost. Do you have a boost gauge? Is the lift pump working?

[PVSLS400]

thank for the reply! i think you are right i have 2 other 6.5's with the electronic junk in them and they smoke and have power when needed. boost, egt, down pipe are all on there way from ss diesel. took it to shop and they said it was runnung lean. i bought the truck at sea level and now its a mile high so they re timed ip and seemed to help a little. I realy think its a issue with the wastegate so i guess ill yank off the vacume system and go mech on that item. its like it gets warm and under a load and loses vacume.


Can i leave vac pump alone if i go mech since vac line goes from turbo to solenoid to vac pump and nothing else? and i am sure this is a 96 coverted to mechanical 6.5, so did the 96 have the upgraded water pump 130gpm or the old 70gpm since that item is on my list to upgrade as well, if it is not the 130gpm
Thanks

[DmaxMaverick]

thank for the reply! i think you are right i have 2 other 6.5's with the electronic junk in them and they smoke and have power when needed. boost, egt, down pipe are all on there way from ss diesel. took it to shop and they said it was runnung lean. i bought the truck at sea level and now its a mile high so they re timed ip and seemed to help a little. I realy think its a issue with the wastegate so i guess ill yank off the vacume system and go mech on that item. its like it gets warm and under a load and loses vacume.


Can i leave vac pump alone if i go mech since vac line goes from turbo to solenoid to vac pump and nothing else? and i am sure this is a 96 coverted to mechanical 6.5, so did the 96 have the upgraded water pump 130gpm or the old 70gpm since that item is on my list to upgrade as well, if it is not the 130gpm
Thanks

Find a shop that knows how to find their butt with both hands. A Diesel engine CAN NOT run lean. If a Diesel is "too lean", it quits. Period. There is no fuel/air mixture, such as with gassers.

It is possible you are not getting enough air (plugged filter, restrictive intake, bad EGR, wastegate not closing under boost/load, etc.), or too much fuel for the air available (NOT called "rich"), usually indicated by an abnormal amount of black smoke during acceleration or sustained load.

If you convert to mechanical WG, and don't have/need an EGR, the vacuum system is excess baggage. If you have PCM issues removing it, get an aftermarket prom (chip) to address it. If you don't have EGT and Boost gages, get them...In that order. Tampering with the fuel and air supplies w/o them can be catastrophic unless you track the results in real time.

[DaveBr]

If you have a GM-8 turbo with a vertical vac controlled wastegate actuator you can wire the waste gate fully closed and test drive your rig to see if you have the power you should have.

WARNING Use this only to test. Do not leave like this or you will cause Damage to your rig. It is meant to help you determine if waste gate is your issue only!!!

[JohnC]

You said you have a vacuum solenoid. Problem is the '93 has no electronics to drive the solenoid. Get a Turbomaster wastegate control. Problem solved.

Sounds like someone who didn't know what they were doing threw a 94 or later engine into a 93.

Ditto the shop recommendation. The solution to altitude for a Diesel is more boost. If anything, engines get richer at altitude, not leaner.

[rameye]

I had a plugged fuel filter...did the same thing...simple stuff first.

[PVSLS400]

If you have a GM-8 turbo with a vertical vac controlled wastegate actuator you can wire the waste gate fully closed and test drive your rig to see if you have the power you should have.

WARNING Use this only to test. Do not leave like this or you will cause Damage to your rig. It is meant to help you determine if waste gate is your issue only!!!

wired wastegate closed, no improvement so..... i guess ill have to wait to the gauges get here to diag more

[PVSLS400]

I had a plugged fuel filter...did the same thing...simple stuff first.

did fuel filter a week ago with air filter

[PVSLS400]

How do i find out exactly which block I have? i know it is a electronic block due to finding a cam sensor, boost sensor, and some other unexplained wires not pluged in, and having to re wire both sides of harness on engine last summer due to a hack job, no gauges working ect... which i fixed. It needs a water pump but there were 3 made for the 6.5 and cant put right one on till i know which one i have!


Thanks Much