I recently purchased an 89 si hatch with an lsvtec swap converted to obd1 and running on a chipped p28. Whenever it hit over 5k rpm it would throw a cel and not crossover to vtec. I pulled the code and it was a code 7 (TPS). Reference voltage with the connector unplugged and the key on is just under 5v using both the ecu ground and body ground. With the connector plugged in back probing for signal voltage (pins 2 and 3), however, the voltage with the throttle closed is 1.9v. With it open all the way, it is a little over 4.5v as it should be. I replaced the sensor with a dorman tps part#911-753 because of the closed throttle voltage, however the new sensor I cant seem to get even close to calibrated properly. No matter how I position the sensor, it gets very low volts in the closed position (~0.003v) and at WOT it only sees around 3.5v.

Is this possibly the wrong sensor? And as far as the original issue goes, am I approaching this the right way or does it sound like a separate issue entirely?

 

Congrats on actually diagnosing your CEL code and proceeding to troubleshoot it. That is refreshing actually.

That is the right TPS from what I have seen.

https://honda-tech.com/honda-crx-ef-...hread-2830131/

Check that thread for more info.

Make sure it was wired correctly and not backwards.

 

I believe I had the prong on the inside of the sensor positioned incorrectly. Reinstalled the sensor, but now the lowest i can adjust closed throttle voltage to is 1.78v and wot is 4.994v. I believe it is wired correctly. The wire colors are different from what they are supposed to be, but it seems that pin 1=vref, pin2=vsignal, and pin3=ground.

Edit: I believe both sensors were installed incorrectly and I had it right the first time. It seems that one of the prongs that form a slot for the prong on the sensor to fall into on the throttle body is bent abnormally. Idk if reading my description will provide a full understanding of what I am talking about. It is difficult to get a good picture of this as the tb sits rather close to the firewall in these cars, but the upper prong that forms the slot is bent upwards away from the lower one. Here is a crappy picture that I was able to get compared to the picture in this post. http://i88.photobucket.com/albums/k1...8/IMG_0765.jpg

FIXED. I simply straightened out the bent prong as well as I could with a pair of needle nose and got the tps adjusted perfectly. I've never seen this problem before and can't think of any way it could've gotten bent like that without someone physically damaging it, but I guess anything is possible.