Vortec MAX Posted September 19, 2008 Report Share Posted September 19, 2008 (edited) I am looking to buy a GM extended warranty. I was concerned about my mods voiding the warranty, making it a waste of money. I explained to the salesman that I had the usual bolt ons including headers. He said he didn't think GM could say much about that unless I had somehow modified the engine internally. He did mention jacking up the truck, chips, camshafts, nitrous, and superchargers as things that will void the powertrain portion of the warranty. I asked him more about the "chips." He said that the dealer could tell if the truck had been "chipped" (tuned), even if the chip was removed or the PCM swapped. Is this true? I still have the original PCM that I keep around in case I need warranty service. What is the advice of the all knowing members of this great forum? Mike Edited September 19, 2008 by Vortec MAX (see edit history) Quote Link to comment Share on other sites More sharing options...
benjaminh2 Posted September 19, 2008 Report Share Posted September 19, 2008 the only way a dealer can tell if you have a custom pcm calibration installed is if you show up there with the tuned pcm in it. if you put the stock one back in there is no way to tell, since our software would only read that pcm's calibration. dealers are paying more attention to programing mods, especially on diesel engines. plus, if you had a complaint or a problem that required the pcm software to be updated by the dealer, it would write right over your tuned program, basically erasing it, another reason to leave the tuned pcm out when it goes to the dealer. Quote Link to comment Share on other sites More sharing options...
misterp Posted September 19, 2008 Report Share Posted September 19, 2008 ... He said that the dealer could tell if the truck had been "chipped" (tuned), even if the ... PCM swapped. ... Life rule - never completely believe a used car salesman LOL. I can't see how; if you swapped out the original PCM for a 'play' PCM and then swapped back they'd have no way of knowing, not directly anyhow. However if you bring them a motor with busted valvesprings and dropped valve or two they can tell from the secondary damage that the engine was overrevved; or if there's a hole burned through a piston they can tell the spark tuning or AFR was way off; etc etc etc. Dealers are not stupid, they can usually tell from secondary damage if the PCM had been altered, but again that's not direct evidence. OTOH if you apply a pre-packaged aftermarket tuning product and then later remove it there will be telltale signs to a PCM engineer that the instruction or code segment on the computer was altered (or both). Even a 'clean' product that restores the PCM's memory back to a carbon copy of the original image (i.e. EFILive) will show an incrimented flash count, but that's pretty sketchy evidence for the dealer to get into a pissing match with. Mr. P. Quote Link to comment Share on other sites More sharing options...
zippy Posted September 19, 2008 Report Share Posted September 19, 2008 The dealer can identify a pcm as having been altered. The other side to that is almost no GM Tech is smart enough to tell the difference to even know to check for it. I've worked for the dealer I'm at for almost 12 years and have experienced it first hand. I agree with Mister P though in that unless you break the engine or something of that type they wouldn't even check for that. If they did you could just get someone to send you a stock pcm and then bring it in. Quote Link to comment Share on other sites More sharing options...
Vortec MAX Posted September 19, 2008 Author Report Share Posted September 19, 2008 The dealer can identify a pcm as having been altered. But can they tell that I just swapped in my stock PCM before it arrived at their dealership? If they did you could just get someone to send you a stock pcm and then bring it in. I have my stock PCM still. I "read" the stock tune and saved it as a file, but I have never changed the tune on the original PCM. I actually carry the stock PCM, a 5/16 wrench for the battery cable, and a 7mm nutdriver for the PCM harness in the truck. If I blew my tranny pulling my trailer (just an example), I would swap it out while waiting for a tow truck. Am I safe with this plan? Quote Link to comment Share on other sites More sharing options...
misterp Posted September 19, 2008 Report Share Posted September 19, 2008 (edited) ...Am I safe with this plan? In my judgement, yes. Mr. P. Just don't leave the modified one sitting on the seat when you take it in! Edited September 19, 2008 by Mr. P. (see edit history) Quote Link to comment Share on other sites More sharing options...
zippy Posted September 19, 2008 Report Share Posted September 19, 2008 I don't think they'd be able to pick up that you swapped pcm's before coming in, no. Quote Link to comment Share on other sites More sharing options...
Vortec MAX Posted September 19, 2008 Author Report Share Posted September 19, 2008 ...if you bring them a motor with busted valvesprings and dropped valve or two they can tell from the secondary damage that the engine was overrevved This may be off topic, but how far can it safely be revved? I noticed my tuning guy has that set higher than stock. What is safe? Just don't leave the modified one sitting on the seat when you take it in! That's what underseat storage is for. It's also inside a cardboard box just in case they are "snoopy." Thanks for your advice guys. Mike Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted September 19, 2008 Report Share Posted September 19, 2008 if you had a complaint or a problem that required the pcm software to be updated by the dealer, it would write right over your tuned program, basically erasing it, another reason to leave the tuned pcm out when it goes to the dealer. That is unless your PCM is locked so that the dealer cannot gain access to the program.......yes they'll know it's tuned since it's locked, but they cannot screw with it. Only and absolute Einstein with a Tech2 will be able to crack it(rare). This may be off topic, but how far can it safely be revved? I noticed my tuning guy has that set higher than stock. What is safe? These engines are somewhat rev happy.......I turn mine to 6100 in 1st and 6200 in 2nd. Quote Link to comment Share on other sites More sharing options...
chpspecial Posted September 20, 2008 Report Share Posted September 20, 2008 savvy techs can feel the difference. I know that some of my brothers coworkers can tell the difference in how a car drives tuned vs. untuned. However proving it is another story Quote Link to comment Share on other sites More sharing options...
Vortec MAX Posted September 21, 2008 Author Report Share Posted September 21, 2008 (edited) These engines are somewhat rev happy.......I turn mine to 6100 in 1st and 6200 in 2nd. Wow Dan! I am not revving mine quite that high. Stock settings are 5,600 on the 1-2 shift and 5,200 on the 2-3 shift. You are 500 over stock on the 1-2 shift, and a full 1,000 over on the 2-3 shift. I'm glad to hear you're not having any problems. Must mean these motors and transmissions are pretty stout. GM designed the 4L70E (M70) to be able to withstand 6,400 RPM shifts at both the 1-2 and 2-3 shifts. So I guess you are safe, as long as the engine can take it. GM listed the maximum engine RPM for the LQ9 engine as 5,600 rpm in their performance parts catalog. Just for reference, the designed maximum shift speed for the 4L65E is 6,400 at 1-2, and 6,200 at 2-3. For the 4L60E, it was 6,200 and 6,100 RPM. Mike Edited September 21, 2008 by Vortec MAX (see edit history) Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted September 21, 2008 Report Share Posted September 21, 2008 Wow Dan! I am not revving mine quite that high. Stock settings are 5,600 on the 1-2 shift and 5,200 on the 2-3 shift. You are 500 over stock on the 1-2 shift, and a full 1,000 over on the 2-3 shift. I'm glad to hear you're not having any problems. Must mean these motors and transmissions are pretty stout. These motors are very strong, the transmissions are another story. The LQ9 has cross bolted main bearings making it very strong....there are several guys here running 11s and 12s on the stock lower half. You are shifting out of 2nd at 5200? Thats right around peak horsepower, way too low IMO. I think someone here said a while back that the LQ9 is good all the way up to 6500rpm. Quote Link to comment Share on other sites More sharing options...
Vortec MAX Posted September 21, 2008 Author Report Share Posted September 21, 2008 I think someone here said a while back that the LQ9 is good all the way up to 6500rpm. Really? On stock springs? Mike Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted September 22, 2008 Report Share Posted September 22, 2008 Really? On stock springs? Mike I guess so, but I would never chance that. I don't ever plan on turning higher then I do now even when my cam/springs/rods eventually go in. Quote Link to comment Share on other sites More sharing options...
Vortec MAX Posted September 22, 2008 Author Report Share Posted September 22, 2008 (edited) Even at what you are turning, that calculates to 50.7 MPH in 1st gear and 96.8 MPH in second, assuming you are running 3.73 gears and 275/55R20 tires. That's pretty good. Mine shifts at 44.2 MPH and 80.2 MPH. I would imagine yours never needs third gear through a quarter, but mine sure will. The difference is mostly in my 4.10 gearing, although I do shift at lower points. There is another table in the tuning software that will tell the transmission to shift at a certain MPH. I am not sure but I believe that it will shift at whatever is higher. This means that if the 1-2 shift MPH was set at 34, but the 1-2 shift RPM was set at 5,600, it would wait until 5,600 RPM were achieved, even though it is now going 42 MPH. Mike Edited September 22, 2008 by Vortec MAX (see edit history) Quote Link to comment Share on other sites More sharing options...
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