So here's the deal, I have a 2012 Yukon Denali. It has had a lifter and cam swap, head studs, and long tube headers. I bought it like that and don't know the owner that done the mods. I bought it from a friend of mine that owns a used auto lot and he had the issue looked at by several garages and I to have tried to solve the issue. It runs great, strong, and pretty fast. But anytime, or most of the time when you floor it from a stop like your gonna race or pull out strong it will go into reduced engine power. And it doesn't throw a check engine code. The traction control mod been replaced, the ECU, throttle body and poison sensor, accelerator pedal, and more that I can't think of right now. Any body have a clue. Surely someone had ran into this other than me...... Thanks in advance
Reduced engine power no DTC code
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How do you know that the truck goes into reduced engine power mode? Are you getting a dashboard warning? If yes, then there is a trouble code that is being generated. If you have a quality bi-directional scanner, it should be able to access the trouble code.
If there is no dashboard warning, what leads you to your observation?
If there is no dashboard warning, what leads you to your observation?
^^^ This. You may need to read the code before turning off the engine (while the DIC message is displayed, if you're getting that). Then, if there is freeze frame data, look at that to see what condition may have caused it to trigger.
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I had a similar issue.ine was at idle at stop light. Bang into limp mode but not codes. Did that several times I would pull over plug in the reader and nothing but I will still go through clearing the codes not there, start up and on my way for another week or two. Finally found my throttle body plug had a broken wire. But never threw a code. The light works still don't know why.
I know it's been awhile, but still have the same issue. Yes, it says reduced engine power on the dash, and traction control and stability lights come on. Still no codes to be found.
I have used a snap on scanner and checked it before turning off. Still no code.
mikez71
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NVM I see you said new ECU/ECM..
Inspect the throttle body wiring real good? Same with accel pedal? (Pull the conduit back as far as possible)
I seen one post where the accel pedal wiring was pinched on inside firewall, behind the MBEC..
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I wouldn't think so, I get misfire code when I've burnt a plug wire, so that worked
When you're reading the scanner, is it reading generic OBD or is it identifying the VIN and using manufacturer-specific software?
I've used my smaller obd reader that does identify the vin and I've also use a snap on from where I work and it definitely has way more options. It's bi directional and scans things I didn't know could even be scanned..... Not sure about the manufacturer specific software but the snap on model I used stays updated. It's used by full time garage. And the vehicle has been to couple different dealers, they couldn't tell me anything other than it would have to be returned to completely stock before they could figure anything out.......
I can drive the vehicle and do daily and have gotten used to it. I can drive it to where it will not go into limp mode unless I want to make it happen or I forget and decide I'm gonna pull out in front of traffic fast like and yeah it's goes to reduced engine power. Never does it when I'm not pulling out aggressive.
I'd probably try to view/record live data while making it do that. A good scanner can graph the various throttle and pedal position sensors, transmission pids, as well as others to see if you can catch it in the act.
kbuskill
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Sounds like you need to read the ECU with something like HP Tuners. With it having a cam and lifter swap and LT headers there is no telling what was tuned in the ECU, but I bet something would show up. With HP tuners you can turn individual codes off without affecting others, so saying that the ECU shows misfire codes doesn't really mean much.
Using my little scanner/reader
there is several pedal position, throttle position, and similar parameters that I can view. Any thoughts on what I should look at and how much variance there can be. I've looked at those several times and I too think that is the place to start. I know the guys that worked on it before I got it said that they had put something like 3 different pedal ass. in it trying to fix it.
mikez71
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That's what I was thinking, but he said he replaced the ECM, throttle body and accel pedal..
Hopefully replaced with STOCK throttle body and pedal?
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To me, it looks like you're going to have to throw money at it, one way or the other, if you want a resolution. You say that you've had it looked at by several shops, and I have assumed that these shops were repair shops. Maybe, I'm wrong here. Have you had a local tuning shop look at your truck?
mikez71
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Since you get REP without a code, I've heard it can be the computer freaking out because airflow calcs are off..
Might check your MAP sensor values also.. (another part of the airflow calculation along with MAF and throttle position)
I wonder about RobertRN's post about the broken TPS wire..(also REP with no code)
Since you mention it happens when you gun it from a stop, motor movement could be pulling on the harness somewhere..
Regarding what to look for in the TPS/APP signals, @Fless gives a good explanation here..
www.tahoeyukonforum.com
Might check your MAP sensor values also.. (another part of the airflow calculation along with MAF and throttle position)
I wonder about RobertRN's post about the broken TPS wire..(also REP with no code)
Since you mention it happens when you gun it from a stop, motor movement could be pulling on the harness somewhere..
Regarding what to look for in the TPS/APP signals, @Fless gives a good explanation here..
Problematic P2135 code
All right, so I'll lay on my issue as plainly as I can. As the title states, I'm having a p2135 on our 2003 Denali XL. As I initially started to diagnose this issue, I started with the obvious things like throttle body and then eventually throttle pedal position sensor. While changing these...
www.tahoeyukonforum.com
Right, since you're cammed, a tuner *might* be able to kill two birds with one stone.. Fix the REP and tune your motor..
Driver's side engine mount good? Or is it allowing the block to move too far?
