Getting started with Chrome. n00b questions.

[fast_eddie_72]

Hey all,

We were having issues with our '91 Stealth RT/TT. I didn't fully diagnose the problem because it sounded really likely that we were dealing with a bad ECU. Since I figured it needed to be taken care of anyway, I ordered the plug and play Jester Chrome ECU from 3SX. I really just wanted a reliable replacement ECU, but I did get the Tactrix flash module as well so we could start learning about flash tuning. The car is completely stock.

Got the ECU and hooked it up as directed with the included instructions. I ran the two wires and pins to the OBDI port and plugged everything in. The car fired up first try and runs better than ever. The issues we were having are completely gone. But after driving for a day or two, we got a check engine light.

So, I think I've figured this out and just want to run it by someone. I assumed that something must be wrong and we'd have to track it down and reflash the ECU. But then it occurred to me that we replaced an OBDI computer with an OBDII computer that may have found an actual fault OBDI didn't see. After confirming in the instructions that I could use an OBDII scan tool, I hooked it up and pulled the code. Sure enough, it showed a TPS fault. I cleared the fault and the CEL went off just as it should. That was last night. We've driven the car a couple of times and so far the CEL hasn't returned. But if it does, I'm kind of thinking the ECU is right and the TPS is probably giving it an unexpected signal. My plan for now is to replace the TPS if we get another code for it.

Does it sound like I'm thinking about this right? The car is running great, so it's hard to imagine there's any real problem with the ECU.

Sorry for the stupid question. I'm reading a ton and pretty soon will feel like I'm just getting to a novice level understanding of all this.

And, let me say, if this is all correct, this thing is amazing. Without cutting a single wire, and with 30 minutes of installation work, I have a 1991 car with OBDII. It might be one of those things that seems like magic just because I don't really understand it, but I'm kind of amazed by all of this.

Thanks,

Ed

[fast_eddie_72]

CEL came back this evening. Once again P0120 - Throttle Position Sensor A Circuit Malfunction.

[TwIzTeD_3kGt]

Did you setup your peripheries correctly? When I didn't have mine setup correctly, it would throw a false CEL. May want to PM Greg E., he's the mastermind who's willing to look at your config.

[fast_eddie_72]

I haven't even plugged the Tactrix into the car. I'm a little nervous I'll mess something up, but I read a LOT today and feel a little more comfortable. I may have a little time tomorrow to play with it. I know I have seen reference to turning off some things in the peripheries for the early cars. I think this was supposed to be flashed for that already, but it might be worth verifying. I can't mess anything up just reading the flash that's on it, can I?

[fast_eddie_72]

The "How To" thread says "After EVOScan is installed, you'll need to install the 2.0 cable drivers. There are instructions on the EVOScan website for this." I'm really trying, but I can't find this anywhere on the EVOScan site. I'm sure it's there.

Sorry, don't know what else to do but keep asking for help until I figure it out.

[Unlogic]

If you download EcuFlash from the Tactrix website it comes bundled with the drivers you need:

https://www.tactrix.com/index.php?op...d=36&Itemid=58

[Keyan]

you said its a 91. try unplugging our ECS computer in the trunk. its known to go bad and send poor signals down the throttle position wire and mess up the engine ecu

[Greg E]

Did you setup your peripheries correctly? When I didn't have mine setup correctly, it would throw a false CEL. May want to PM Greg E., he's the mastermind who's willing to look at your config.

Please no PMs...

Eddie, how are you reading the codes?

[fast_eddie_72]

Thanks for the input.

I'm reading the codes with an OBDLink scan tool. It works with my laptop.

http://www.scantool.net/obdlink.html

Keyan, the ECS computer is already disconnected. We pulled it when we put KYB struts on the car. Thanks, though.

[Greg E]

I can't remember all the test conditions for the TPS but one of them is if the sensor reads no voltage while the RPMs are increasing. A quick log will show if the sensor is working. You don't even need the engine to be running. Just turn on be ignition and check the TPS ID.

Thing is though, not all OBD2 readers are created equal. You mentioned that you haven't even plugged in the tactrix so that tells me you haven't flashed the ECU with the correct periphery setup. I wouldn't be surprised if there is nothing wrong with the TPS and CEL is on for a bunch of OBD2 faults which your scan tool isn't reading correctly.