First off is the TPS %, when I first started the car it was showing around .35 in the TPS % box in TTS Data Masters. I attempted to elongate the holes so I could adjust the sensor to the recommended .50, well the plastic was brittle and sensor broke to pieces. Got another sensor (Delphi), made the necessary adjustments to the mounting holes to be able to adjust the sensor but no matter what, I see 0% on the TPS sensor % in Data Masters, thus triggering a code 22, low TPS voltage. IAC count is 160 and the TPS volts is 5.5. The car has all sorts of throttle issues, basically the throttle response is, ok I'll rev for you, no what is stumble and back fire Alex for $500, or my favorite I'll try to die when you give me gas. Right now I'm largely attributing these fun features to the TPS sensor being whack. The brakes were also funny, well death defying would be a better phrase, I guess they aren't a problem unless you want to try and stop. Using TTS Data Masters, the MAP reads 72-76KPA at what it likes to call an idle 700-900 (RPM). As you increase throttle these numbers drop, I have triple checked my vacuum fittings, line and brake booster hose. The car is tuned, has a mail order tune from ION, which actually the first time we started it up and ran the valves correctly, car ran well. Also putting an LS1 in it is not an option, cursing and throwing tools how ever has become my specialty.

 

To start with, .35v is perfectly fine for the TPS at closed throttle (anythng from .2v-.9v is acceptable). You did not need to mess with that. It is correct that you should see 0% throttle with it closed. Are you saying that it never changes when you open the throttle?

With your IAC counts so huge, you should try cracking the stop screw on the TB blades just a touch, so that the counts come down. You would have to check the TPS voltage again after doing that.

 

Correct, right now I see a steady zero no matter what the throttle, the only thing that changed was messing the sensor. The set screw is screwed all the way back, so it isn't touching the throttle linkage at all.

 

Rob,

I think I got the wrong sensor from NAPA got another one from A-zone, installed it out of the box voltage showed .49 closed, started the car, no ses light, idled steady and reved up with no problems or hesitations.

 

The right sensor would help, eh?

 

This isn't the first time it's happen, I usually have to double check serpentine belt part numbers because the box will say one thing and the part number on the belt will say another, thats happened to me twice before.

 

Just so no one reading this gets confused - 0.35 (and 0.50) is the TPS voltage, not the TPS %. TPS % is a number between 0% and 100% representing the throttle physical position (a translation from the TPS voltage).

There is no reason to believe the engine will run any better with the TPS voltage set at 0.50V. That just happens to be the factory spec for the pre-LT1 engines, because the ECM's used prior to the LT1 did not have the capability to baseline the 0% throttle position from the TPS voltage at key on.

You indicate you have a cam, but don't indicate what one it is.... a large cam gives you high MAP (low vacuum) at idle.

 

Sorry for the confusion, I have a CC306 in the car, I was going off this link, http://www.golenengineservice.com/html/tps.html and a book I have on GM EFI, both recommended .50 for closed voltage for modified motors. The new sensor installed was .49 volts which is perfectly in range, it seems fairly sensitive. I also checked the vacuum today with a gauge, I'm at 10" at 900 RPM (idle) and that number increases with throttle, was using the linkage on the motor so I don't have the RPM to correspond the vacuum readings.

 

You don't need to put a vacuum gauge on it. You can calculate vacuum from your data log. Vacuum = BAR - MAP. That's the good thing about using the DataMaster
"export as .csv" function, set the data up in an Excel spreadsheet, and add a new column for BAR - MAP. Now you have vacuum under all engine operating conditions.

Are you referencing the book "Chevrolet Fuel Injection" by Ben Watson for your TPS voltage? That book is based almost totally on the 3rd Gen ECM? I note that in the review of the book on my website.

 

Thanks Fred, yep thats who wrote the book.