L56 to L65 ecm change-heavy black smoke?

[matt-max]

99 tahoe 6.5td w/L56 program stock except kennedy diesel 3.5" exhaust

had dealership service dept reprogram ecm to 2001 6.5td 3500hd spec via VIN and dealer's computer.

now i've got very heavy black smoke (unburnt fuel) with more than half throttle.

full throttle from dead stop produced thick smoke and very sluggish acceleration followed by much better acceleration than stock program once rolling.

have not messed with egr yet.

any ideas on what is up or what to do next?

thanks,
matt

[ucdavis]

The HD intake manifolds of my year have a plug in between #3/5 and #4/6, and the rig has no EGR. Standard EGR engines have an open port in this position.
You probably have some sort of variance between programming & hardware for your year that you need to ferret out. The GM dealer gave me the wrong gaskets (non-HD) so I had to R&R the plug from the old gaskets; don't rely on the dealer to know all the differences.

[diesel65]

Unplug the MAF sensor, Of the three solenoids on the intake manifold unplug the two that are NOT connected to the wastegate and unplug the baro sensor on the firewall next to the hydro-boost.
Now you should be good to go.

[matt-max]

thanks guys

tried your tips today william and must not have done it right as i have less power and more smoke than before

MAF is left of air intake with 3 wires in 1 plug, correct? unplugged it first.

baro is just right of hydro boost pump on firewall, correct? unplugged it next.

not sure, which is wastegate?

removed turbo power cover and pulled plug off brass colored solenoid exiting manifold vertically at front of intake next.

unplugged 3"x1"ish black 'box' on top of intake. looks a bit like fsd or pmd....correct or incorrect other item to unplug?

if incorrect, which is correct?

i'm trying to do this with 2 broken elbows, 1 boken wrist and 1 broken arm so it is a bit tough on me!

do you then just leave them unplugged and zip-tie/tape them?

thanks
matt

[whatnot]

I am not sure where the MAF sensor is since I don't have one but make sure you didn't unplug the boost sensor or the IAT sensor. I think you need the baro sensor too since the computer uses it to adjust boost.
Their should be a strip of 3 solenoids on the driver side. the front one is the wastegate solenoid on mine.

[diesel65]

Matt,
Reconnect the two devices that you disconnected on top of the intake manifold....the brass colored sensor is the intake air temp sensor and the black box next to it is the boost sensor.
As Whatnot said the waste gate solenoid is most likely the first one on the strip, I am running the L65 program and I have looked at the 97's and 99's and they do not use a seperate baro sensor, I think GM uses the boost sensor as a baro sensor on startup....I have mine disconnected and it is running just fine...
I would disconnect the two batteries to clear the codes and retry again, also after you get it running correctly you need to check your TDC learn with the Tech II.

[charliepeterson]

I have the OBD I L65 "Hot Chip" in my truck which should be the L56 light duty.
One thing I know for sure about these two programs is the amount of fuel delivered to the Injectors. The "F" program with a #9 PMD resistor will deliver 80mm of fuel at WOT. My stock fuel delivery at WOT is only 63mm.
After you deliver all this fuel you must increase the boost level somehow.
I don't believe the reflash alone will increase your boost levels high enough to handle the extra fuel rate.
You will need a modified boost sensor. I believe JK and Bill Heath both sell what you need.

[matt-max]

already got one from john but have notnstalled yet, trying to do one change at a time to keep it simple.

no instructions with it either.

i'll keep at it.

i found where wastegate is now, too.

keep posting help if you have it.

thanks,
matt

[Turbine Doc]

Matt
I've been running as a L65 hybrid for almost 2 years by swapping my L56 PCM for a later model L65 PCM (Only when operating off road of course ;) , as tampering with emissions equip. is a violation on many laws but you knew that), if your reflash was successful the L65 program does not look for the L56 sensors, but I would leave them connected electrically as open ended electrical devices on a system designed with them, sets up a potential for electrical interference source to the PCM if not terminated as designed.

That said you can disconnect them mechanically (see caveat/warning) above, in my conversion I found I lost vaccuum across the L65PCM unpowered solenoids to the EGR/Baro system which caused the EGR to dump, if you have not properly disabled EGR this can cause the problem you are describing. The only solenoid I run with mechanically connected is the WG control, I reroute the hoses to WG sol only but retain electrical connection to preclude any EMI (electro magnetic interference)loops I might set up to the PCM.

Are you running a L56 intake still? If so you also need to know that your engine can unseat the EGR dump valve in some instances, mine did cuasing some problems, a solution there was to put a sheet metal blank off shim between EGR valve and intake EGR port, best solution is a L65 intake no EGR ports. Do you have proper vacuum should be 24"+, check on main line from vac pump, if that is okay, check WG sol output to WG actuator it should change with demand.

As far as the MAF sensor goes, when I off road mine ;) the MAF is disconnected mechanically and resides under the turbo intake tube and a piece of 3" PVC goes in it's place I shim it to proper sealing diameter with application of requisite amount of self adhesive ventilation joint material(okay duct-tape)

[matt-max]

thanks

you are correct, egr was problem

modified L56 intake today with grinder and jigsaw and installed kustom kut egr blockoff

runs and sounds much better

tons of black snot in intake to remove!

disconnected maf by airbox, left all others intact

can't drive myself due to injury, but with girlfriend driving it seems to pick up much better.

was still smoking some so added boost controller. no smoke now.

how do you adjust boost controller?

finally saw where you guys were talking about strip of solenoids on intake. duh. kinda slow i guess.

like your idea of keeping them hooked up. will try that.

anything to gain now with L65 upper intake?

will g-tech soon. stock it put out 1/3 of my dmax power. pathetic 127hp.

looking for 200+ if possible without intercooler or major internal mods.

seems to scoot pretty well now for light truck

thanks to all for past and future help!
matt

[triggerman]

Matt,
If your lookin for 200 RW HP with out a intercooler, You WILL be sadly disapionted with the life span of your 6.5. Just yesterday on a 70% day with only 1000+ lbs on the back, I watched the IAT's climb to 160 degrees and the EGT go to 900 degrees on a basic hill holding only 55mph at 8 lbs boost. Its almost scary how fast these engines build heat! And this is with a open 3 1/2 exhaust, stock L56 fueling and program. If these trucks could talk, they'd cry a river for a intercooler! On top of all that, there was a guy on here not long ago that pushed his 99 or 98 early oil spray block toward 300 hp. Here he posted a number of photos on the cracks that developed off the spray holes at the bottom of the jugs. He also posted photos of the NEW replacement block with the much smaller oil ports for comparison. And it was amasing how BIG a difference there was in those two blocks. If raw power is what your after, I personaly would eliminate the possibility of future block failure and go for a new AMG upgraded block,18 to 1 pistons and all the rest of the goodies. If you still want to play with the 99 block, Cooling is the FIRST place to start! By the way, If you have a late 99 block , there is a chance you already have the upgraded smaller spray ports. Finding out if it is or isn't is one of the more interesting problems you'll face. :cool:

[matt-max]

awwww prairie poop. :eek:

why can't a guy get a little fun out of his 6.5 without it all going pear-shaped?

thanks for the heads up trigerman

i will take your caution seriously and tread carefully. it just seems like not that much to ask out of this motor to get the advertised hp punched out at the rear tires.

do tell....do i find out via casting date or info on block or build date of truck or by open surgery? maybe a call to psychic holine?

thanks again, sincerely, to all who post and help their fellow disel-scented buddies. you (we) are what make this page so great!

matt

intercooler $$$$ and hassle seems pretty intense to me. anybody running one on a tahoe that you know of?

i know its the right thing to do though. just a cheapskate i guess.

i will install egt and boost next week. i know should be in already, but made last minute decision to go with a-pillar instead of overhead console for ease of viewing.

[triggerman]

Don't you know, it would be a case of self incrimination to release build date/casting# on boo-boo design.... Clearly they pleed the fifth your honor.... Now if there was enough Federal money goeing to the GM RnD dept. We could sue under the freedom of information act?? Naww, I think I like the idea of the phsyco or a phsycic better. WE Americans spend more on health care than anyone in the world, So I think surgery is the customary rout....Don't mind me, my butt's still sore from the last mechanical surgery I had performed. redface.gif

[Turbine Doc]

Matt I was off the circuit for a while computer crash, I'm using my new one now anyway missed the thread on how to adjust boost, do you have a controller module ala JK, then it is easy, once you have gauges hint hint, turn the brass screw CW if I remember correctly. for longevity on turn up enough boost only that to what you need especially if non IC, limit to 10psi boost sustained hard pull, you can peak to above 10 12-14 but without IC your engine won't bear up to it as Triggerman says.