: Reduced engine power, P0120 P0220 P1516 and P2101 (search is not working)



Brackets
06-21-12, 12:55 PM
So I've been getting "reduced engine power" mode for a while now. It started intermittently and has increased to the point where it goes into this mode as soon as I turn the key. The V is is a Maggied '05 LS6 so the first thing that I tried was replacing the TPS on the throttle body, no change. I wanted to eventually swap to an LS2 90mm TB so now seemed a good time for that. Swapped in a 90, new snout, and wiring harness, no change. Spoke with some local GM guys and figured it had to be the accelerator pedal so new pedal assembly ordered and installed, no change. One other thing to note here is that I tried a TB relearn after this and the engine started, it's my understanding that it should NOT. I also removed the ground wire from the back of the drivers side head, it was still shiny but I cleaned it anyway. Other than that I've visually checked and continuity tested what wiring and connectors that I could. Any other ideas before I take it into the dealership? We don't have a Caddy dealership locally so it's going to GM for a tech II read if I can't figure it out. Thanks for reading.

danrob0123
06-21-12, 03:16 PM
If you've already replaced all the parts that would have to do with the codes you are getting, I would check and re-check all the wiring/electrical connections. I read that the most common cause for these group of codes is a crimped wire near the throttle body. If all the wiring/connections look good then I would either wait for someone else to chime in on here or take it to the dealer.

darkman
06-21-12, 05:44 PM
So I've been getting "reduced engine power" mode for a while now. It started intermittently and has increased to the point where it goes into this mode as soon as I turn the key. The V is is a Maggied '05 LS6 so the first thing that I tried was replacing the TPS on the throttle body, no change. I wanted to eventually swap to an LS2 90mm TB so now seemed a good time for that. Swapped in a 90, new snout, and wiring harness, no change. Spoke with some local GM guys and figured it had to be the accelerator pedal so new pedal assembly ordered and installed, no change. One other thing to note here is that I tried a TB relearn after this and the engine started, it's my understanding that it should NOT. I also removed the ground wire from the back of the drivers side head, it was still shiny but I cleaned it anyway. Other than that I've visually checked and continuity tested what wiring and connectors that I could. Any other ideas before I take it into the dealership? We don't have a Caddy dealership locally so it's going to GM for a tech II read if I can't figure it out. Thanks for reading.

Read this thread and the attachments thereto: http://www.cadillacforums.com/forums/2004-2007-cadillac-cts-v-general/245357-darkman-got-one-you-throttle-body.html

See also attached.

Brackets
06-22-12, 01:52 AM
Okay thanks for the replies. Darkman, that thread that you linked looks like a possibility although mine isn't hunting like that. Hopefully post a resolution tomorrow.

Brackets
06-24-12, 02:20 AM
Well $300.00 later I get a call from the dealership "we were able to clear all your codes" so I go in to pick up the car and they tell me I now have a new code P0068, a mass air flow code and still in "Reduced engine power". What did you do to fix it I ask? "I swapped the green and purple wires in the harness" he tells me. "Which harness" I ask already starting to get a bad feeling. "The throttle body harness" (Katech LS6 to LS2 adapter harness). "Really?, those guys make a lot of those harnesses I really doubt that they would mix up those wires like that". "Maybe you should put your old throttle body back on and then the mass air code will go away". Great! I limp the car home again, swap snout, throttle body and remove the Katech harness and I'm back in the same boat, P0120, P0220 and P1516 "reduced engine power". So basically I guess I paid to have my codes read for me and for the "GM tech" to surf the web, very little real trouble shooting by following the service manual procedures. My fault I guess, shouldn't have confused them with an LS2 TB on an LS6. The weird thing is the codes were gone and I could do a proper TB relearn (no start). Before, and now again that I've put the old TB back on, it was starting on a relearn which I understand it should not do. One other thing, I didn't think that there would be a problem (codes, reduced engine power) putting the LS2 TB on. I knew that I would have to get it retuned of course but I was told by the tuner that I should be able to drive it.

crankedupforit
06-24-12, 10:12 AM
The TB scalar in the tune program knows the size of the TB. When switching from a 78 to a 90 this has to be reset into the tune. You have you gone into the ETC Area Scalar and appropriately increased the values for the increase in TB size?
Although the car may run, it certainly has the TB flow confused. That may be the issue since the amount of air flowing does not match the tables that are set in the tune.

darkman
06-24-12, 10:42 AM
I believe, based on the codes and the associated informatation that basic issue is the PCM's inability to determine (or perhaps use if the PCM is bad) the indicated throttle position. The other thread I referenced does contain a list of the wires colors, including the correction of a mistake in the Service Manual. It sounds to me like the dealer got caught up in the throttebody change and wiring and did not run the rest of the troubleshooting chart to eliminate stuff like the TAC module.

(I am skeptical that this problem relates to the change in throttlebody size and its affect on the tune. I ran an LS2 90mm throttlebody on an LS6 78mm throttleboyd tune for months and got no DTCs, experienced no reduction in fuel economy, and performance was improved. I understand, based in part on a detailed explanation by CTSVmapper, that the tune was "suboptimal" but I think the error involved "air flow" as opposed to the mechanically determined position of the throttle.)

Brackets
06-24-12, 01:32 PM
Thanks for chiming in crankedupforit but I'm leaning towards darkmans thinking on this. The first thing that puzzles me is why the tech should have to switch those wires (which I make out to be purple, 5v reference on TP sensor 1 and green, low reference TP sensor 2) in the brand new Katech TB converter harness PN: KAT-4752 http://store.katechengines.com/throttle-body-adapter-harness-p20.aspx . I mean, it's not even like those wires are even beside or above and below each other so I just don't see how they could have been inadvertently mixed up at Katech. The other thing is that I do know and had expected to have to retune but I just don't think that I've ever seen anyone throwing mass air flow codes after an LS6 to LS2 swap. That wire swap just doesn't sit right with me. And yes, I think the tech got very sidetracked in his diagnosis by the LS6-LS2 issue. Also does anyone know for sure if a mass air flow code will put the car in "Reduced power mode"?

crankedupforit
06-24-12, 03:54 PM
Darkman knows his stuff and his approach is a good one. The only reason I mentioned the scalar values was I am having the same problem but only on the track when the car gets warmed up it throws P2101s and goes into limp mode. I bought a new Katech harness and a new TB just in case but several corvette vendors at the track keep mentioning the scalar values and other tuning aspects to this problem. The problem with these codes is they can take a lot of trial and error to solve ($) from the TAC module to the PCM to the TB to the harness to the tune etc. I just don't know where to begin.

Brackets
06-24-12, 04:19 PM
Yup, I hear you man, thanks again.

darkman
06-24-12, 07:08 PM
Well Darkman is guessing on this one. As I understand it though the problem existed with the old throttebody and wiring harness - is that correct?

Brackets
06-24-12, 07:41 PM
Yes, Darkman you are correct sir.

darkman
06-24-12, 08:03 PM
If it were mine, I think I would put the stock wiring and throttle body on it and have a shop with a GM TechII scanner (the local Chevy dealer maybe better than the Caddy dealer when it comes to LS engines) run through the diagnostics shown in the DTC-related pdfs. If the troubleshooting procedure came to the "replace throttlebody" instruction I would have them put the new throttlebody. In the mean time, I would verfiy with Katech and/or a multi-meter that their harness is not somehow assembled incorrectly.

Brackets
06-24-12, 08:48 PM
Yup, that's where I am right now pard. As soon as I got the car home from the GM dealership the 90mm TB came off along with the harness and it's back to the stock wiring and TB now. Of course once I did that the P0068 was gone but I got back the P0110, P0220 and P1516.

RoverGuy7
06-24-12, 10:49 PM
The P0068 isn't a MAFS code, it's a correlation code between MAFS and TPS. With the Maggie and the 90mm TB, you're pulling in more air at a given throttle position, then your ECM expects.
Given the timeline and what you have going on, I'd be thinking the P0068 is tune related, and your old TB was bad. I'm sure someone can post up what wires should be in what pins in your adapter harness, to make sure that's correct.

Brackets
06-25-12, 02:24 AM
I'm not ruling anything out RoverGuy. Thanks for posting.

RADEoN
06-25-12, 10:21 PM
i actually agree entirely with roverguy, and that was going through my head as well. P0068 Is Throttle Body Airflow Performance... so it's possible your new throttle body might not be any good either?

I'm assuming you've tried replacing the MAF at this point?

Brackets
06-26-12, 10:58 PM
No RADEoN I haven't replaced the MAF. I'm not even confident that that P0068 is a real or valid code as it never showed up until the GM tech switched wires around in my brand new Katech harness. The car has the old LS6 TB on it again and is throwing the old P0120, P0220 and P1516 codes. The LS2 TB was throwing these same codes with NO P0068 until he switched wires around.

RADEoN
06-26-12, 11:02 PM
try a stock ls6 throttle body if you can get one.

carlson_mn
07-30-12, 11:09 PM
first thing I thought was change that MAF. Any resolution to this?

etcts-v
07-31-12, 06:41 AM
Yeah any resolution? I'm having the exact same problem!

crankedupforit
07-31-12, 04:46 PM
Check the wiring harness. Here's what I found on mine. Looks like a rat chewed it. Needless to say this caused some P2101 and P1516 issues. The car also drives much better at low speeds. See blurry phone pic below.

http://i1073.photobucket.com/albums/w382/mikesummers/Trailerpics003.jpg

etcts-v
07-31-12, 10:41 PM
Wow the stealership missed that! Thanks for The pics I'll check mine out thoroughly!

Brackets
12-07-12, 07:49 PM
So thought i'd post an update. The saga continues with no resolution yet. The mechanic (ex GM, retired) who I had working on the car replaced the tac module. That would have been the next thing that I would have suspected and replaced. No change, so he spent countless hours (his words) chasing all the related wiring and found no problems until he got to the ecm. Upon removal of the wiring connectors from the ecm he found significant corrosion on the lower section of pins. Much cleaning of pins and connector didn't help so he figured the ecm was shot. I ordered a ecm from Jesse at wait4me because I needed one with a tune for the Maggie. After installation of the ecm from Jesse all the trouble codes went away but still reduced engine power and service stability system come up on the dic. At this point the mechanic I had working on it threw in the towel and I limped it home to my father in laws. I tried swapping my old ecm back in and got the P0120 P0220 P1516 codes back as well as Reduced Engine Power. Swapped the ecm from Jesse back in and the trouble codes are gone but Reduced Engine Power and Service Stability System come up on the dic as well as Service Vehicle Soon. Did a relearn and Service Theft System went away but still had Reduced Engine Power and Service Stability System with no trouble codes or check engine light. Put my old tac module in and I got Service Vehicle Soon along with the old Reduced Engine Power, no check engine or Service Stability System . One thing that I question somewhat and that I haven't spoken to Jesse about yet is the fact that my ecm was part #12589462 and the one he sent me was #12576106. I realize that some of these ecm's are similar but from reading on a listing from an eBay vendor some are not. Can anyone shed any light on this or have any other ideas to add? Thanks for reading.

crankedupforit
12-07-12, 08:20 PM
Consider removing the faults from the tune. You can adjust the milleseconds which the throttle blade and the accelerator pedal position can be out of sync. Even with mine opened up to the max I still got the codes. I had the tuner remove the faults from the software. Worse case scenario is if the throttle sticks open you'll have to shut off the engine.

darkman
12-07-12, 08:46 PM
I found a couple TSB involving electrical "ghosts."

Crankedupforit's approach has some appeal.

Brackets
12-08-12, 01:48 PM
Thanks for the comments. Crankedupforit, do you mean to have the specific faults removed or can you have just the reduced engine power mode removed? I only get the codes with my original ecm, the ecm that I bought from wait4me doesn't throw codes but they both put the car into reduced power mode.

crankedupforit
12-08-12, 04:29 PM
Yes, you would remove from the tune the fault trigger when the commanded throttle position from the gas pedal is different from the actual throttle body blade position. It's probably not even off but the ECM thinks it is. One of those faults throws the car into limp mode. I'm not sure why your new ECM doesn't set up a code when it goes into limp. Doesn't make sense since it is definitely a fault and should record an event. I'll email my tuner and ask specifically what tables he worked on for you.

Brackets
12-10-12, 04:33 AM
Appreciate that pard. Here are a couple of pics of the corrosion that was in my original ecm.
100991100992100993
Click on pic for more detail.

Brackets
12-12-12, 04:20 AM
Darkman, if you're still watching this thread would you have any info available on the grounding locations? I've only checked the one on the rear of the engine block drivers side and it looked brand new. I'm sure there are others too? That's the only other possibility I can think of causing this issue.

darkman
12-12-12, 07:54 AM
Darkman, if you're still watching this thread would you have any info available on the grounding locations? I've only checked the one on the rear of the engine block drivers side and it looked brand new. I'm sure there are others too? That's the only other possibility I can think of causing this issue.

See attached.

Bad grounds on this car may appear okay because: (a) the deterioration can consist solely of a thin coating of oxidation; and (b) they may still work well for high voltages but fail as a low voltage reference. So it is a good idea to freshen the grounds with a small file, emery paper, or the like. Also star washers are your friend.

crankedupforit
12-12-12, 10:28 AM
Brackets
I've PMed you with the fix for certain DTC process enablers not to report. This should fix your issues but be aware that in the unlikely event the throttle blade should ever jam open, the engine will bounce off the rev limiter and you will need to shut down the motor by turning off the key. Good luck.

barrok69
12-12-12, 10:42 AM
Yup, that's where I am right now pard. As soon as I got the car home from the GM dealership the 90mm TB came off along with the harness and it's back to the stock wiring and TB now. Of course once I did that the P0068 was gone but I got back the P0110, P0220 and P1516.

Replace Throttle Body or Pedal assembly. All your problems should be solved.

Given that you have already replaced a bunch of things I would do a control test and put your LS6 hardware back on and swap out the pedal. I had the same issue with my car when I first got it. I've done alot of research on the topic of those codes and basically narrowed the issue down to 4 items. Throttlebody is bad, Pedal is bad, Bad grounds, or TAC module is bad. I had a tech2 hooked up and cycled the pedal and it was tracking normal, so that eliminated that. I noticed with the TB that the commanded position was off slightly from actual and that's what was triggering the fault. It will never fix itself. I replaced the TB and everything has been fine since.

Since you've already replaced or at least have a replacement TB, we can probably eliminate that, unless you bought it in "unknown" used condition. You've replaced the TAc module with no change. You've checked the grounds. The last thing that is associated with the P codes is the actual pedal assembly. They are available on rockauto for $120.

Hope that helps you a bit. And I would probably change your katech harness back to normal if you are going to use the 90mm.

Brackets
12-12-12, 01:49 PM
Thanks for the pm pard. Do you think by eliminating these that there would be any reduced functionality of the tc or stability systems? Darkman, as always, appreciate the attachments man, you're an awesome asset to this site.

----------

Barrok69, thank you for taking an interest. That's the thing that's so frustrating about this whole thing for me is that all this stuff has been replaced. The throttle pedal assembly was one of the first so unless I got a bad one from GM I think I can rule that out. The tac module was a GM rebuild put in by the mechanic who I had looking at the car to the tune of $415.00 for just the part. The 90mm throttle body was a brand new take off that I bought off a reputable forum member and had come from Katech along with the Maggie snout and wiring harness so I think that I can rule that out as well. Since this mechanic has had my car the problem has actually gotten worse. When I took it to him I did have a little throttle response and now I have absolutely none. Another thing that troubles me is that when I do the throttle body relearn by putting the pedal to the floor and cranking the engine, its not supposed to fire and it always does. I sure wish I had access to a tech 2.

Brackets
12-15-12, 11:46 PM
Got a call in to Jesse and asked about deleting the codes out of the computer. He told me that he already had done that and always does that just so guys don't have problems after doing engine mods then having to send their computers back in to be adjusted. I guess that would explain why my old ecm was throwing codes and the one from Jesse wasn't. Back to checking wiring and grounds.

crankedupforit
12-16-12, 10:55 AM
Sorry to hear that. Hope you find the issue. Maybe Jesse's tune wasn't throwing codes but it was/is enabling the limp mode when an event occurs..... no? Maybe I'm confused but I always assumed reduced engine power is a command from the tune and can always be added, changed or deleted.

dedeaux89
06-16-13, 12:49 PM
Was there any solution to this, I'm in a quite similar situation with my FAST 102 set up that I just put on