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Discussion Starter #1
Well Got the IP put in and fired up everything was good at idle the tdco was at -1.3 and the pump timing was at 8.4 actual and desired........... and then I thought it was a good idea to do a RELEARN FOR THE TDCO .......... Bad IDEA! It sent my tdco to -2.5 and through a tdco code........ I tried to adjust the pump the other direction and it went to +2.5 and my actual and desired up in the +10.0 degrees for timing...... Is there a sweet spot in the middle I should have not done the relearn at all I read somewhere if you change the pump you should. Well its quiet now throttle is like crazy touchy at highway speeds well before it went +2.5 on the last adjustment I have not drove it since I adjusted it. ANY HELP WOULD REALLY BE APPRECIATED!
 

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1995 GMC Suburban
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So you probably need to go the other direction.

Most people said to have it between -1.50 (most people) to -1.94 (performance).
So the -1.30 is probably closer.

So, you need to move it towards where it was, may be slightly less.
The FAQ have some instruction, IIRC, 1mm is 1 degree so it is not much to screw it up.
 

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Wound up leaving mine a -1.41 after screwing with it for an hour trying to achieve -1.94 and im quite content with the performance and fuel economy, so dont think its necisarry to fall in the 'performance' range of -1.50 - -1.94

The slightest turn will make a large difference. What year truck is this? What scanner are you using?
 

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Discussion Starter #4
The truck is a 1996 I am using a OTC Genisys scanner its the same as a matco determinator..... Yea Its just kinda confusing on the actual vs Desired timing it doesnt seem to change much at all with like a 1/4" movement?
 

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Hm, i really wish i knew more on the OBD2 6.5's. But if recall, the scanners can sometimes throw odd readout's that are different to understand. May have been a snapon, im truely not sure, but Racer55 should. Shoot him a PM, eventually he will probably see this lol.
 

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Just make sure you do it when the engine is hot.
 

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Forget about actual and desired timing-the ECM is constantly trying to correct for that-TDCO is the value you need to lock in via the KOKO relearn and IP movement.

Very small movements of the IP make big changes to the TDCO value eg: 1mm of movement is enough to get it inline or out of line depending where you start.

As stated there can be no codes and engine temp must be 170F + to peoperly do the relearn.
 

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Discussion Starter #9
Well got the timing part corrected seems to run well until 55 mph....... It starts bucking and kicking from 1500 rpm - 2500 rpm back and forth if I touch the throttle it goes all the way to 2500 pulling hard for a second or two then drops FAST to 1500 and surges back and forth very bad and violent and if I am hard on the throttle BLOWS BLACK BAD........... What a deal................ any ideas on this ..... I have good vacuum at the wastegate but I have no idea what it is doing when I am at highway speeds ( thinking maybe the solenoid ) IDK......
 

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Which solenoid???

Have you make sure LP is pumping enough fuel to the IP?

IIRC, this is a used IP also, so there is always that possibility.
 

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Hm, i really wish i knew more on the OBD2 6.5's. But if recall, the scanners can sometimes throw odd readout's that are different to understand. May have been a snapon, im truely not sure, but Racer55 should. Shoot him a PM, eventually he will probably see this lol.
the snap on mt2500/mtg2500 will give a odd reading if you use a to 99 domestic cartridge, if you use a to 2000 or the 2001 cartridge it reads properly
 

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the snap on mt2500/mtg2500 will give a odd reading if you use a to 99 domestic cartridge, if you use a to 2000 or the 2001 cartridge it reads properly
My findings as well-no matter the year of the truck (96+),if entered into the MT 2500 as a 2000 the TDCO readings will jive with other scan tools and specs to 1 decimail point eg:-1.9 vs the -1.94 shown on more current scan tools.
 

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My findings as well-no matter the year of the truck (96+),if entered into the MT 2500 as a 2000 the TDCO readings will jive with other scan tools and specs to 1 decimail point eg:-1.9 vs the -1.94 shown on more current scan tools.
i found with the earlier cartridge if i enter mine as a 98 it will read wrong but if i enter it as a 98 on the 2000 or 2001 cartridge it reads correctly, i have the mtg2500, i could have sworn it also shows the extra decimal point too, i'll have to check that again tomorrow
 

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Mine is the basic mt2500,can't say about the mtg version?
i found my buddies mt2500 is the same deal with the earlier cartridge vs the newer one

only difference between the mt2500 and the mtg2500 is the graphing capability and nicer display
 

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Discussion Starter #16
waste gate solenoid is what I was thinking but I am not thinking that is the problem the bucking and jerking got way worse today anything over 25mph the rpms act like I am stomping the throttle and letting all the way off over and over............
 

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Wastegate solenoid will not cause what you describe.

It will just a little sluggish during high speed driving but most won't feel it.
 

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Discussion Starter #20
Well everyone after 1 Reman IP and 2 used IP'S I finally got this pig back on the road! The first 2 IP's were bad the reman came off ebay......... 500 bucks wasted..... second was a 2 month old reman guy broke is crank another 350 wasted......... and finally as a last resort found one that was 3 years old the guy was parting out the truck I gave 100 bucks for it runs like a top................. What a deal I guess next time I will just spend the 1000 and save all my Time......... Thanks to everyone that had helped me with the truck you guys really helped me learned to DIAG the notorious 6.5 that No One really know what to do with lol! Thanks again Tom
 
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