Reduced engine power!!! Wtf! Help!!! Please
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Reduced engine power!!! Wtf! Help!!! Please So for the past two years ive been building this truck, 2000 gmc sierra rcsb(stepside) was a 4.3, has been converted to all 04 tech and 04 5.3 only 80,000miles on motor and a brand new trans, new drive shaft and rebuilt rear-end, Mechanically Everything is ready to go but , electronically its being a little bitch the computer and harness are driving me up a damn wall...I can start the truck and it run fine, runs at about 698-701rpms which is normal (correct me if im wrong). I can get the rpms all the way up to 6500(max) but feathering the pedal several times and making the rpms slowly climb, but if I try to give half throttle or full throttle I get reduced power message along with service brake booster message...Ive checked the brake booster holds vacuum and there no vacuum leaks at all ive personally checked the whole motor over 15times for vacuum leaks with several cans of carb cleaner and patients....If you have any idea on what can help me im all ears please, ive change throttle bodies( I have done a idle relearn) changed plugs and wires, fuel injectors, and even a new reflashed pcm(coded to my vin with the security relearn done) here are the codes im getting if it helps...p0522, p0300, c0265, p2101, p2175. the oil pressure code is due to a bad oil pressure sensor which will soon be replaced.
Circuit continuity between the dark blue wire at pin A on the alternator and the black/white wire at pin D on the pump?
Matching 2004 pedal, TAC module and PCM?
Don't see P2175 as a valid 04 5.3 code.
C0265- no communication with ABS module
P0300- The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.
P0121- throttle is not achieving commanded position
Matching 2004 pedal, TAC module and PCM?
Don't see P2175 as a valid 04 5.3 code.
C0265- no communication with ABS module
P0300- The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.
P0121- throttle is not achieving commanded position
Last edited by DrX; May 27, 2015 at 05:22 PM.
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Circuit continuity between the dark blue wire at pin A on the alternator and the black/white wire at pin D on the pump?
Matching 2004 pedal, TAC module and PCM?
Don't see P2175 as a valid 04 5.3 code.
C0265- no communication with ABS module
P0300- The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.
P0121- throttle is not achieving commanded position
Matching 2004 pedal, TAC module and PCM?
Don't see P2175 as a valid 04 5.3 code.
C0265- no communication with ABS module
P0300- The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.
P0121- throttle is not achieving commanded position
I believe the p2175 is Throttle Actuator Control System Low Airflow Detected yes the pedal TAC module and PCM are the same year, Ive been checking all possible causes and still no such luck I took it down the road it would only do about 35mph and the crazy thing was the trans was shifting very quickly for such slow speed but it was shifting smoothly
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its all 04, the harness ground is on the front of the block not the rear didn't think there was a difference in were it was in location?
Last edited by Brandon Tof Edwards1; May 28, 2015 at 05:29 PM.
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well I put the ground back in the factory location nice and snug still no change (didn't think it would but id try pissing on the tire at this point) all my grounds are good im thinking of just buying a new gas pedal harness and TAC. Do you advise that or should I look at replacing the brake booster since the gauge cluster keeps telling me to service brake booster and the code wont go away even when cleared?
well I put the ground back in the factory location nice and snug still no change (didn't think it would but id try pissing on the tire at this point) all my grounds are good im thinking of just buying a new gas pedal harness and TAC. Do you advise that or should I look at replacing the brake booster since the gauge cluster keeps telling me to service brake booster and the code wont go away even when cleared?
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Nope battery is a brand new optima red top battery not even a month old, no other brake codes are present abs is working and theres no indicator light, still haven't found the cause of the misfire, but the truck caught on fire awhile back and burned up the neutral safety switch was melted a good bit and I think that could be the cause of my problem. Any thoughts on that being a possibility? it still shows which gear I,m in but it idles kinda rough in park and neutral and smooth in reverse and drive. so maybe that could be it??
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ok ive replaced neutral safety switch no luck.... I also replaced map sensor seeing how I was get a maf performance code and know that a bad map sens can sometimes make it look like the maf sens is the culprit but still no luck.....I can unplug the maf and the engine idle doesn't change on throttle hesitation, now keep in mind that it still says reduced power With the ENGINE OFF AND KEY ON....I have yet had anyone explain how a sensor or what sensor could cause this....Im going to buy a new maf when I get paid but If anyone and I mean anyone can help with this I would greatly appreciate it. 
Reduced Power EOKO is normal when there is a throttle control system issue.
Are you seeing 5V on the grey and blue wires of the throttle connector? Also check the continuity/resistance to ground on the black and black/white wires. And check that the throttle blade does not rub or stick against the bore, and that the gears operate smoothly.
Check the grounds/low refs on the MAP and MAF connectors as well. ORN/BLK on MAP. Black and BLK/W on MAF.
Are you seeing 5V on the grey and blue wires of the throttle connector? Also check the continuity/resistance to ground on the black and black/white wires. And check that the throttle blade does not rub or stick against the bore, and that the gears operate smoothly.
Check the grounds/low refs on the MAP and MAF connectors as well. ORN/BLK on MAP. Black and BLK/W on MAF.
Last edited by DrX; Jun 6, 2015 at 10:24 AM.
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I live in Idabel Oklahoma small town but as far as voltage on the wires the last time I checked them they were getting the right voltage, but now the truck goes into reduced engine power as soon as it starts idles like crap I'm lost and don't understand why it would all of a sudden change