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To ATT or not part II Technical Discussion Only ?

tazz said:
I am taking my milage from my GPS as my speedometer is off, for example when on the highway speedo reads 64mph and the GPS reads 70mph. By the way, how do I adjust that on an OBDII truck?

As far as the GM5 to ATT I think you hit the nail on the head and that is why I am asking to ATT or not. I have not had the pleasure of driving in a rig with an ATT so I don't really know how they perform. I am getting all of my info from this site and what other members say about it which is mostly towing larger trailers and such. I don't plan on hauling trailers for long distances maybe an occasional trip with a car trailer but that's about it. As I said before I have a dump insert in the truck and haul that way. As for the GM5 you are right it certainly does pull nicley off the line with or with out a load. Being that the cost for a new turbo be it an ATT or a GM is the same is the reason I am asking this question. As far as puttiing an HX35 on the truck I am not going to go that route so it is going to be between these two. I'm just looking for opnions.
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You won't be sorry, in fact, you'll be very impressed with the ATT, IMHO. You will notice that there is a difference, for me it was as if the truck feels a little "heavy" off the line (Slim's second definition of "LAG" but the ATT is definately not a #2 [pardon the poor humor] I very much enjoy mine) but at your altitudes, it will be minimal and depending on how old your tune is, you may be better served updating that. Give Bill a call, talk about what you've changed on the truck, what you need to do with it and he'll set you up for success.
 
I understand the difference between the two turbos that I am talking about as where the GM likes the lower rpm range (spools quicker) as to where the ATT is more for the mid to upper rpm range, please correct me if I'm wrong, but that is how I'm understanding them. As far as what everyone calls lag I also understand that and I know that from the time you depress the throttle to the time it takes the exhaust gas to spool up the turbo is what is cosidered lag but that is just part of owning a turbo charged vehicle.
 
maybe a minor point but it's not really about engine rpm it's about heat and volume which you have under a heavy load. You can have high rpm but no load
 
Slim, a week ago I was at 7800' elevation, essentially trying to parallel park at a trailhead. Wheels turned sharp, in 4 hi, trying to move forward. Burb would not/barely budge, blowing gobs of black smoke. I'd say in those specific conditions, there was tons of lag with the ATT. I could barely get out of there. The rest of the time, you're right. The lag is minimal.
 
Big T said:
Slim, a week ago I was at 7800' elevation, essentially trying to parallel park at a trailhead. Wheels turned sharp, in 4 hi, trying to move forward. Burb would not/barely budge, blowing gobs of black smoke. I'd say in those specific conditions, there was tons of lag with the ATT. I could barely get out of there. The rest of the time, you're right. The lag is minimal.
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Big T you may want to contact bill about that black smoke. Bill may have more fuel down low that is needed. I don't think much is goign to spool at just off of idle if that is where you were at. Sounds like a timing issue and fuel rate issue. My manual does not do that course I wasn't at 7800 either. Let me know

Slim
 
elevation plays a big factor into the smoking ability of all diesels. Unfortunately I do no think the Barometric Pressure sensor input works on these PCMs, I mean it does input it and you can read it on the scanner but whatever fuel trimming it is supposed to do is a a big fail. Our injection system, is fairly rudamentary, it doesnt measure air to fuel ratio and unless you get a code for boost it doesnt trim back the fuel at all. Fuel in per the pedal position, RPM and programmed amount.
 
So it's decided then.........an ATT it will be. As soon as the check book allows which it never seems to. I will also use two hump hoses with the four t-bolt clamps along with the cut out length of intake. Maybe Slim will have updated this setup by the time I decide to purchase. So until then thanks to everyone for the useful info.

Dan
 
So it's been awhile since I last posted on this but now since the turbo that is on there now is degrading more and more with time I just placed my order for an ATT with the new hose design, should be here around mid week. As far as this coming week goes I have my work cutout for me. On Monday I'll be starting my cooling system upgrade. Here's what I'll be doing and I now have all the parts on hand, 2000 water pump, Duramax fan, Hayden 2886 fan clutch for a Kodiack, Cloyes timing chain set for a 6.2, AC Delco t-stat, all new hoses, belt, heater hose quick disconnect mod (5/8 nipple x 1/2 pipe thread) and anything else that I might have not thought of along the way. the main reason for the cooling system upgrade is when it was 105 degrees here the truck started to run hot as a matter of fact I had to run the heater on high on my way home from work to keep the temps at or just below 210. I know that with the bad turbo on there now with it running higher than normal egt's is just enhancing my cooling system deficiencies so I might as well get it done. Seeing as the truck has 216,000 miles on her I might as well do the chain while I'm in there. If there is anything that I missed let me know. As soon as the bank account recovers I'll tackle the fuel system from the tank to the pump but that will be another thread.

Dan
 
Dan

The turbo will go out Monday, should be there by mid to the end of the week a the latest. Had a family emergency Wednesday.
 
tazz said:
So it's been awhile since I last posted on this but now since the turbo that is on there now is degrading more and more with time I just placed my order for an ATT with the new hose design, should be here around mid week. As far as this coming week goes I have my work cutout for me. On Monday I'll be starting my cooling system upgrade. Here's what I'll be doing and I now have all the parts on hand, 2000 water pump, Duramax fan, Hayden 2886 fan clutch for a Kodiack, Cloyes timing chain set for a 6.2, AC Delco t-stat, all new hoses, belt, heater hose quick disconnect mod (5/8 nipple x 1/2 pipe thread) and anything else that I might have not thought of along the way. the main reason for the cooling system upgrade is when it was 105 degrees here the truck started to run hot as a matter of fact I had to run the heater on high on my way home from work to keep the temps at or just below 210. I know that with the bad turbo on there now with it running higher than normal egt's is just enhancing my cooling system deficiencies so I might as well get it done. Seeing as the truck has 216,000 miles on her I might as well do the chain while I'm in there. If there is anything that I missed let me know. As soon as the bank account recovers I'll tackle the fuel system from the tank to the pump but that will be another thread.

Dan
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Speaking from experience, put a new CPS in there while you got it apart. $50 from Rock Auto.
 
Big T said:
Speaking from experience, put a new CPS in there while you got it apart. $50 from Rock Auto.
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X2 on the CPS! And it isn't even fun with the part off to get the old CPS out.

I find the A-Team likes the higher RPM's. You should think about when you shift and make adjustments. In fact you will love higher RPM's now for the rocket - tuned anyway.
 
Yes I a going to replace the CPS, I can pick one up at my local NAPA and with my discount it should be cheaper than RA. I know that my truck is pretty good off the line or was, now it's a dog with the failing turbo and being a 5spd I can pretty much shift where I want. As far as the upper rpm range, it would fall on its face above 2200 rpms so I can't wait to see the difference the ATT will give me. The only bummer that I foresee is I plan on starting this job on Monday the 15th and it looks like we'll be getting a bit of rain and I think you know where I'm going with this seeing as I don't have a garage, just the good ole trusty driveway. My two days off a week are Monday and Tuesday and I need the truck for work, we'll see.
 
tazz said:
Yes I know but I don't see a big problem with that unless the sprocket is totally shot.
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Although the chain stretches the sprockets also wear. It can be significant and also irrelevant. When the chain goes on they are tight - pluck a guitar string tight. 30K miles later they are sloppy. Thus the allowed slack makes wear almost irrelevant.
 
So I'm about half way done with the job, couldn't work on it Monday there was way too much rain all day. I got the front end torn down and cleaned up and pretty much buttoned back up. Just got to put the drivers side bracket back on but that will be tomorrow as I'm going to replace the power steering pump, it's leaking pretty good. But I have a question about the timing chain and the IP. The old chain was extremely loose, more than I thought it would have been and the new new chain went on nice and snug. So I marked the IP before I took the housing off and all that other good stuff and lined her back up on reassembly. Seeing as I have a nice tight chain in there now about how much will that throw off the timing if at all? I figure I'll have to do a TDCO again.

I made an IP turning tool today, can I tell you that I'm glad I have a spare IP and I got a horizontal band saw over the winter. I haven't really had a use for the saw until today and what a life saver it was. I found a pic on ebay of what the tool looks like and no problem. I had a piece of 1" square tubing and used a couple of old header bolts. I put the bolts through the front side of the flange and tacked them to the tube from the other side then I cut the heads off with a die grinder and finished welding what are now studs on then I cut another piece of tubing at about a 120 degree angle and welded that to the short piece with the studs, seeing as the tube is pretty short because I can put a 3/8 extension in there for some more leverage. Just thought I'd share that.
 
tazz said:
But I have a question about the timing chain and the IP. The old chain was extremely loose, more than I thought it would have been and the new new chain went on nice and snug. So I marked the IP before I took the housing off and all that other good stuff and lined her back up on reassembly. Seeing as I have a nice tight chain in there now about how much will that throw off the timing if at all? I figure I'll have to do a TDCO again.
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It's almost definately going to change now that your timing chain is tight again. I would check/reset it again anyway just so you know it's right.

I bet it's going to feel like a different truck when you're done..... with the timing being on the money and the ATT.
 
Old chain vs. new chain was a dime thickness difference in timing. Not that the marks are that accurate - they are not. Yes it will change and slowly drift back as the chain stretches.
 
I got the toughest part of the job done this morning and the truck fired up. Boy the older I get the harder the jobs become, seems like it took me forever and it whooped me. So new chain, water pump, fan and clutch, p/s pump, upper lower hoses, cp sensor, thermostat, heater hose nipple and a bunch of new clamps. I also switched from Dexcool to good ole green. I'm still waiting on the ATT to arrive but I figured I'd get her running to make sure everything else was OK and it is. I haven't taken her down the road yet just brought her up to operating temp and pressurized to make sure that end of the job is done. I haven't timed the pump yet as I have no means here to do that so if there is anyone near me that can help me with that I'd appreciate it. I did set the pump to the position that it was at which was set to -1.94, I don't know which way it would swing with the new chain but she fired right up, sounds good and no codes thrown so I'll see how she goes down the road till I can get her timed. I would have taken pics but that was one messy job. I also picked up a can of POR-15 in the spray bomb type and did my brackets and the radiator support as it was looking pretty rough so I bought it some more time. I hope the turbo shows up today, I'm waiting with anticipation.
 
So the turbo did show up on Thursday around 4:30pm and I ended up the install around 10:30pm, not too bad considering I had to pack everything up for a while for some thunderstorms that rolled through. I still have some final adjusting to do now that I have a couple of days driving on but nothing big. I'll post up some pics the first part of the week. As far as how the turbo works, I like it alot better than what was on there, I have power now in the upper rpm range as well as down low. I am still reserving further opinion on it till I get some more miles and adjust my driving style.

The one thing right now that I am not happy about is that my EGT'S are higher and seem to climb quicker than with the stock turbo that was on there. I am still going to reserve further comment on this as I still have to get the truck timed and I plan on sending the ECM to Heath and having him upgrade it for me for the new turbo. I know that the old turbo was well on its way out, there is alot of slop on the waste gate shaft and I figured that was the main cause of my EGT'S creeping up but now I'm begining to wonder if that problem is elswhere such as the timing.

All in all I am very happy with the new setup. With the new chain and turbo the truck runs much quieter and smoother up through the rpm range and with the new cooling system I can actually hear when the fan clutch is engaged but I've yet to have a hot day to really see the benefits.

One thing I forgot to mention was the boost thaty I am now running: normal crusing on the highway I'm at around 2psi, with the old turbo it waas around 6-8psi. WOT is around 6-7psi, now being limited by EGT, old turbo was 15psi WOT
 
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