Porblems with a Ported TB, This is on my 01 z06, it's been a long run but to recap: I Bought a Stock ported TB from ebay, installed, ran for about 3 miles very well full throttle, light throttle everything untill.... "Reduced Engine Power" came on, Turned car off and back on and it was fine untill I gave any more than 1/4 throttle and it would go back into the reduced power mode. Try my original TB on there everything works fine drove for about 20 miles light, hard throttle everything is great, Bad TB right, send back the ported TB they send me out another ported TB with a new TPS sensor. This time is even worse goes into the reduced power mode even faster with about 1/8 throttle bieng pressed. Say screw it send it all back get my refund but I forgot to do one thing before sending it back, check my original TB to see if everything works as it did. Go to put it on and as soon as the car starts now it immediatly goes into "Reduced Engine Power" As soon as I turn the key to the on position without even turning the car on this is displayed. Cleared codes and again same problem. I get code (1221 TP sensor 1, 2 performance) and after the car is started I get code (1515 command Vs Actual Throttle Position Performance PCM)

This problem has just gotten worse and worse since installing this throttle body from bieng able to drive on light throttle, to very light throttle, to not even being able to idle without it going into the reduced power mode. I took the TPS sensor off very gently, didnt even disconect the wire harness just unbolted the 2 bolts that hold it on set it aside and then back on the new one, all wires look good. I can't seem to find a TPS sensor at a resonable price other than buying a whole new TB from the dealer, if that even is the problem i'd hate to put all that money out on a guess... I am really at a loss here, any help would be greatly appriciated.

 

Your situation sounds odd...
Do you have anything that might be inhibiting the movement of the TB blade ( like a Vararam velocity stack)
check the C5 parts for sale section. I picked up a used TB for $75 that I used as the core when bought a ported TB....

 

Nothing blocking the TB plate, checked that plate moves nicely, all the way open then closes on its own. It's almost as if the other TB damaged the TPS sensor, I dont know how it could but it has just seemed to get worse and worse. At first the car drove good with the ported TB Took it out went through 1st and 2nd pretty hard no problem it wasnt untill about 5-10 minutes later that this all started and it all went down hill from there. The thing that gets me is even the new TPS that I tried with the new ported TB gave me the same results... Witcdh is why im hesitant on purchasing another tps/throttlebody.

 

Bump up C6101 ETC Predicted Airflow. Bump all cells by 20% and you should be fine!

 

Bump up C6101 ETC Predicted Airflow. Bump all cells by 20% and you should be fine!

__________________
Chalky

99 Black FRC SOLD
01 Silver Z06 SOLD
04 Black Z06 SOLD
02 Silver Z06 SOLD
08 Black Z06 SOLD
07 Silver Z06

I predict 2009 ZR1 Black

Only makes sense.......

Sorry back on topic

 

Your issue is most likely due to a poor connection in the TPS connector.

Examine the female pins and make sure that there not deformed. Sounds like one or more are spread open and not making a good connection with the male pin inside the TPS sensor. Its either that or one of the wires inside the connector has broken and no longer electrically connected to the connector pin.

Take the TPS harness connector apart and examine all the wires and make sure that they are properly crimped to the female pins.

BC

 

I've actually seen the 1st part of your issue happen to me last week while tuning - my TB is stock by the way. During WOT runs, I'd get P1516 code and Reduced Engine Power. There is a table in the PCM that governs the max MAP pressure that should be entering the cylinders. If the table in the values is exceeded by the actual pressure going in, then the code is thrown. So, I'd suggest that you get a tuner to adjust that table for you, and see how you make out.

 

I will attempt to take apart the conector that goes to the TPS tonight to see if I see anything wrong with any of the pins, as for increasing the values go, I do not have a tuner nor have I ever done this, is it difficult to do and what tunner would you recommend for this. This is actually the solution the person I bought the TB from came to but i didn't want to go through all of this trouble, but if I can't even drive the car with a stock TB I guess I have no choice.

 

In my opinion,,,,,,theres nothing wrong with your tune. You put the STOCK TB back on and it did the same thing. I have installed several ported TB and they have never needed any immediate tuning. Sure tuning helps any MOD but,,,never seen an air flow issue cause that DTC. Unless you have done something wrong and the TB isnt installed properly but,,,thats difficult to do.



Your having a Throttle Position Sensor or wiring issue.

 

Couple of thoughts. After re-reading your OP to the end, I believe I may have to defer to Bill Curlee. Reduced power mode is common when the engine starts seeing more air than normal. A cam would do this, a new intake possible, heads for sure. That is when you would need to increase values. The fact that you are getting codes with a stock TB leads me to believe that the TPS may be the issue and not table C6101. Bill Curlee may be one of the best on the forum when it comes to electronic issues.

As far as tuning options, not sure where you live. Maybe find someone amatuer tuner locally with the EFILive of HPTuner that might be willing to help if needed. Post up on one of the forums and ask for local assistance.

 

Bill:

Didn't see your post until after I posted.

 

CUTE KID!!

No problem bud. Just trying to get the OP on the road.

 

Just checked the car all over, all wires, pulled the wiring harness apart and connectors cleaned them with electrical connection cleaner, no problems found Pulled the intake off with a flash light checled the tb blade moves freely goes back into position on its own. The strange thing is I am getting this code 1221 without turning the car on. As soon as I go to the on position I get reduced ewngine power, plug my obd2 scanner in and I get this code I clear the codes without turning the car on and immediatly after clearing I scan again and its right back again. the 1515 doesnt come on until the car is started. I've done entire engine rebuilds, installs before i'm not new at all to automotive work although I am new to the corvette, i've never had so many problems with a car.

One thing I did notice is I pulled the TPS off of the throttle body and laid it down with my scanner in hand I turned the TPS to several different spots and I noticed that if it was a hair from bieng closed all the way the code would clear, Reduced Engine Power would still be displayed on the dash though so I dont know what thats telling me.

 

Time to break out the meter. Check the sensor for proper resistance. Run it thru its full sweep and make SURE theres no dead spots. One sode of the sensor will have max resistance at rest aand the the other will have minimum at rest.

Make sure that you have the full 5 VDC reference voltage

BC