2G 99 Eclipse GSX idle problems

[PheonixDSM]

I have a 99 Eclipse GSX with a 6 bolt swapped 2.3L stroker motor running on DSMlink V2.

I noticed for some reason after driving it for a while, whether I'm doing hard pulls or just casual driving for extended periods, the idle will act up a lot. If I’m driving and I have to stop at a light or if I’m coming home etc and I’m off the gas and in neutral, the idle will rev up like I’m tapping my foot on the pedal consistently, or if I’m cruising and come to a stop, and the car is in neutral, the rpms will sit at 1500-1900 rpms and just stay there.

Sometimes if I actually tap the gas pedal, I can get the rpms to drop and idle at around 1050-1200 rpms (normal for this car) and stay there,but sometime they’ll drop momentarily and climb back up to 1500-1900 rpms, occasionally fluttering on its own as I mentioned earlier. The car only does this after its been driving at operating temperature for a while, not on startup or when it’s only been at operating temp for a little bit, just when it’s been driven a lot/hard.

I have reason to believe I don’t have boost/vacuum leak so all I have changed on the car so far is the IAC Valve, O2 sensor, MAP sensor, and IAT sensor (my car runs Speed Density instead of stock MAF). I tested my TPS sensor with an ohmmeter and everything seemed to check out fine but It’s the only thing I can think of I just don’t know at this point.

IDK if it matters but when the car was doing it’s weird idle, I unplugged the TPS and tried plugging it back in and it didn’t seem to do a whole lot of a difference. I noticed very small differences with it unplugged vs plugged in but sometimes it didn’t seem like it did anything whether it was plugged in or not.

Unfortunately, the guy I bought the car from did not have his DSMlink V2 cable or I would try seeing what I could find there but apparently no one has a DSMLink v2 cable, everyone is DSMLink v3/ECMLink now so I feel SOL.

DSM Wisemen, your help would be greatly appreciated

 

[steve]

DSMlink V2 without the cable is one step above useless. In V2 it was the cable that was the proof of purchase just like a dongle for software and without it you can't log, check or change anything unless you have a good friend with a cable.

Time to start saving to buy V3. But first let's make sure you don't have V3 because I don't remember V2 supporting SD. Pull the ECU, open it and take a picture of the PCB. If it is V3 you can buy a replacement cable.

Make sure your throttle cable is loose at idle. It needs a little slack.

 

[PheonixDSM]

DSMlink V2 without the cable is one step above useless. In V2 it was the cable that was the proof of purchase just like a dongle for software and without it you can't log, check or change anything unless you have a good friend with a cable.

Time to start saving to buy V3. But first let's make sure you don't have V3 because I don't remember V2 supporting SD. Pull the ECU, open it and take a picture of the PCB. If it is V3 you can buy a replacement cable.

Make sure your throttle cable is loose at idle. It needs a little slack.

Well you were correct, I just pulled the ECU and opened it up, it has a 2G DSM ECMLink chip in it. Throttle cable was fine. Just goes to show not to believe everything the PO claims, even though he had the car for 10+ years, he gave me a spare dsmlink v2 ecu (which I opened and verified is actually a v2) with the car swearing up and down that’s what was identical to what’s in the car in case anything ever happened to the current ecu. Anyways, this is great news, I’m glad I have ECMlink and that I can get a replacement cable for it and maybe see what’s going on

 

[steve]

Just goes to show not to believe everything the PO claims, even though he had the car for 10+ years

After years of watching here it best not to believe anything a PO says without verifying yourself.

 

[PheonixDSM]

After years of watching here it best not to believe anything a PO says without verifying yourself.

Absolutely true, I’m just glad in this case the error was more in my favor, I’ll try to figure out how to work ECMLink and see what I can find, I guess worst case scenario I can take it to a tuner shop and see what they can help me find