Weird TPS readings/Chipped ecu problems?? (LONG)
 

Ok, this might be a little long.....go grab a beverage and come back and read :-*

I am working on an 89 CRX Si that has an LS/VTEC swap using a b18a1 block and a b16 head and it is OBD0. Have both PR3 and PW0.

Guy brought me the car and said it would start, but you could not rev it and the check engine light and charge light were on.
I checked the codes and there were two, 7 and 14....TPS and IACV. He had told me he changed the TPS so I assumed it was not adjusted properly, checked the voltage and it was off. I set it, it was at .504 closed throttle and 4.34 at WOT. I reset the ecu, started the car, no code for TPS and I could rev it up now, altough it still seemed rough. He had the wrong plug hooked up to the IACV, so moving that cleared up that code. Upon further investigation, I found the problem with the charge light...the owner had hooked up the output of the alternator to chassis ground :o I connected that wire to the proper place and started the car and the charge light went away.

Ok, this is where it starts to get strange. The next day, that car was acting all fucked up again (it just sat overnight, never drove it) and I measured the TPS voltage again, it was now like 1.3v with the throttle closed and when I started the car, the meter went negative :S I did some looking around and found that the guy had a couple of other sensors hooked up wrong, he had the 02 sensor input hooked to the temp sensor and vice versa. At this point I was thinking that he fried the ecu with the incorrect alternator hookup, so I swap ecu's from the pr3 to the pw0 and I get the same thing. I grab a complete throttle body and plug the tps connector to it just to make a measurement and it acts the same way.

I had a PM6 ecu laying around, so I chipped it so I could put a DOHC map on it even though I wouldn't have vtec control, I just wanted to start the car and check the TPS reading with another different ecu. Well, I get a solid ecu light when the key is on with a 27sf512 chip with a stock pr3 map burned onto it, but the ecu seems fine if I put the oem chip back in the zif socket. With the PM6 chip in the zif, I do get a code 20 which doesn't suprise me because of the alternator snafu and IIRC pr3 doesn't check the ELD which is why it probably didn't show before. I check the voltage at the ELD between black and black/yellow and there is batter voltage present, but the is NO voltage present between the green/red and black wires.

Ok, so WTF do you guys think is wrong. I am installing a new alternator on tuesday. I don't have another underhood fusebox to swap the ELD, but I am not sure that is what is wrong. I am really stumped as to why I cannot get/keep the tps voltage correct and why it actually switches over to a negative voltage reading when the car is started.

All sensor grounds are attached and yes the hex address was correct when I was burning the 27sf512.

HELP!!!

Re: Weird TPS readings/Chipped ecu problems?? (LONG)
 

You can throw a PR3 Program into a PM6 and expect anything BUT a Solid CEL...

Plain and simple he has MASSIVE wiring problems...you will fix one at a time, it will be pain staking but you will prevail.

Lots of sensors share common grounds, if he fucked ---- up and is feeding voltage into a shared ground you will pull your hair out until you either find the stray voltage or run new wires.

Re: Weird TPS readings/Chipped ecu problems?? (LONG)
 

I know, I figured by using the chipped PM6 I could at least eliminate the ecu as the culprit. I even tried burning two different 512's and I had the same result with both. I don't understand why it appears to function normally when the actual factory PM6 chip is in the ZIF :S Is there any part of the ELD system that is actually in the alternator? I checked a number of the green/wht sensor grounds and they appear to have continuity between each other and to the ecu, although I didn't check every single one. I am going to replace the alternator on tuesday when I go back to work and go from there. I am HOPING that maybe that along with replacing the ELD will put things back to normal, but I forgot to mention this is a Y49 car and I probably should have told the dude your car is cursed, take it back home >:D

One last thing that I didn't mention on the original post. As far as the TPS goes, although the voltage is off(around 1.3v with no more adjustment available) at closed throttle when the key is on and engine off, it still operates somewhat normally, i.e. it gives me a positive voltage as I rotate the TB, but when you reach a certain point, the DMM will flash O.L. (overload) and then go back to a voltage reading. Yea, I even tried a different multi-meter :S

Re: Weird TPS readings/Chipped ecu problems?? (LONG)
 

Whoops...I meant cant.

PM6 and PR3 code are VERY different and will not run in each others ECUs.

Throw PM6 code (or NG60 using TurboEdit) into the PM6, but I bet you will come across the same wiring issues.