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Old 09-09-2011, 11:18 PM   #1
98tadriver
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Default Recieved the Infamous "REDUCED ENGINE POWER" message :/

It threw a few codes

most recent-
P1514 Throttlebody performance
C1278 TCS Temporarily Inhibited by PCM


DTC P1515 Control Module Throttle Actuator Position Performance
DTC P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance

This has been doing this on/off for a while. It was actually fine for a few months. So I didnt bother messing with it.


It stalled on me a few times when driving at low speeds, also it feels like it surges/bogs a little on its own when idling/driving. that usually happens a few mins before it sets the codes and then the REP light comes on

Could this be a TAC module going bad? From what I've read, this reduced engine power crap seems to be a common problem.

Any ideas on what I should do?

I figured this weekend I'll-

Check ground wires- front ones had a lil corrosion. I cleaned those up.
Check connection at TAC module
check to see if throttle blade is sticking- Checked and it's not sticking

Any other ideas? All help is appreciated

Last edited by 98tadriver; 09-12-2011 at 11:02 PM.
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Old 09-11-2011, 05:05 PM   #2
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Last night it threw a P1120 code as soon as i started it and went into REP mode

today it threw a P1515 and a P1293

just did some more searching and came across an interesting thread. THis should be helpful http://forums.corvetteforum.com/c5-t...tion-long.html

Last edited by 98tadriver; 09-11-2011 at 05:11 PM.
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Old 09-12-2011, 02:53 PM   #3
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It may be because the year, but there's a table in your ECM, that governs the density of year entering the motor. Its more like a threshold amount, and can happen with intake + exhaust boltons at the least. I've gotten it a few times before I found the table I needed to change. Ever since I did that, these codes have never come up again.
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Old 09-12-2011, 08:50 PM   #4
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What are your mods? Any chance you've got a tune and or data log?
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Old 09-12-2011, 11:01 PM   #5
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Very interesting info. I didnt know about that

mods- 2001 vette, auto, Fast 90mm intake and tb, vararam, 25% UD pulley, longtubes, off road x pipe, staight pipes for an axleback, 3400 converter, 3.42 gears.

UPDATE- I cleaned up those ground connectors up front in the lil plastic cases. also switched out my TPS for one that I had from another TB. So far so good But then again, it was ok for a few weeks when i didnt do anything to it lol. Only time will tell

I have hp tuners, but my laptop is broken. looking to get a replacement very soon
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Old 09-13-2011, 11:05 AM   #6
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I think the table is in the Eng Diag section of HP Tuners. For me, the code only showed up when I went WOT.
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Old 09-15-2011, 12:53 PM   #7
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Hi---don't panic easy fix---Its a common isssue on modded LS's
NOTHING is wrong with your throtttle body or communucation or your Tracttion Control or ABS
The P1514 is the root cause of all of the codes and "reduecd power mode "
When modding-- you eng's airflow will become greater than the "predicted airflow " in your tune --All you have to to is to go to the
"Predited Airflow table" (in EFILIVE table C6101") and ADD about
30-40% to the ENTIRE table--It does require use or either HP or EFILIVE to make these changes- Once changed it won't go into red. power mode--- In the mean time -all you have to do is start your car and turn it off 3 times and the red. power will be turned off and reset
Simply turning off the DTC permanently or deleting the codes won't do it either---
The reduced power mode uses the ABS and TC systems to redsuce the power--hence all the ABS and TC codes--They should disappear after the correction-----
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Old 09-23-2011, 09:04 AM   #8
SoDak 04' Vette
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Default Another Question about Reduced Engine Power

I'm sure this is a dumb question; but, I Ned to ask anyway before I spend a lot of time and money troubleshooting my problem.

The car was wrecked (not by me). The air bags deployed and have not been reset. There is a wire to the drivers side front brakes missing ( I assume this is the ABS lead)...

Will this cause the Reduced Engine Power message? I cannot reset no matter what I try. Cleaned all the engine area grounds, etc.

Please help.

Thanks
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Old 10-02-2011, 08:53 PM   #9
98tadriver
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Quote:
Originally Posted by tblu92 View Post
Hi---don't panic easy fix---Its a common isssue on modded LS's
NOTHING is wrong with your throtttle body or communucation or your Tracttion Control or ABS
The P1514 is the root cause of all of the codes and "reduecd power mode "
When modding-- you eng's airflow will become greater than the "predicted airflow " in your tune --All you have to to is to go to the
"Predited Airflow table" (in EFILIVE table C6101") and ADD about
30-40% to the ENTIRE table--It does require use or either HP or EFILIVE to make these changes- Once changed it won't go into red. power mode--- In the mean time -all you have to do is start your car and turn it off 3 times and the red. power will be turned off and reset
Simply turning off the DTC permanently or deleting the codes won't do it either---
The reduced power mode uses the ABS and TC systems to redsuce the power--hence all the ABS and TC codes--They should disappear after the correction-----
I forgot to check back here lol. I have HP tuners. I'll definately look into that. big thanks!
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Old 11-03-2011, 08:41 AM   #10
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98tadriver; I had the same issues as you listed. I did a lot of research and ended up replacing my ignition and the car has been great since. The brass pins that make contact with the metal tabs inside begin to arc and wear down due to the high current that runs through the ignitiion. Once I popped open the old part sure enough 3 of the pins were bad which would reduce a clear flow and throw out codes of all kind and cripple the performance of the car overall.
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Old 11-03-2011, 09:23 AM   #11
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Quote:
Originally Posted by chipscvettec5 View Post
98tadriver; I had the same issues as you listed. I did a lot of research and ended up replacing my ignition and the car has been great since. The brass pins that make contact with the metal tabs inside begin to arc and wear down due to the high current that runs through the ignitiion. Once I popped open the old part sure enough 3 of the pins were bad which would reduce a clear flow and throw out codes of all kind and cripple the performance of the car overall.
no kidding? Luckily all has been well with my car. just out of curiosity,what part of he ignition did you replace?
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Old 11-03-2011, 09:23 AM
 
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