So last week the TA decides to not start. The issue was at the racetronix relay ground. The shop that installed it (I won't mention it in hopes that that shop is still in business). The relay was bolted down with a sheet metal screw and was loose (ya think?) So I relocated it and bolted it down with a nut, bolt and lock washer as well as cable tied things up nicely.

Here's the weirdness - It fired right up and was running ok .... but then the next time I went to crank it up, it wouldn't start as I had to push the throttle pedal some - but it wouldn't run. Long story short, my tuner states that it seems to be running richer than before. I don't see that my fuel pressure is any different. OK - so once it warmed up a little it was running fine, but then started chopping heavily. The timing was up and down more than normal.

Anyhow - moving and bolting the relay was the right thing to do and clearly an improvement over a sheet metal screw that wouldn't even tighten down. But why in the world would it have those issues?

 

Maybe moving around had some sort of bad connection to where it didn't completely close the circuit and now it's working right since it's secured better.

 

I figured this was worth a picture. Here's a representation on what's going on. This was a very short drive in the neighborhood.
I've got a set of injectors on the way. Fuel pressures are 56. Nothing changed there.

 

Your PCM is still trying to add that "extra" fuel it thought was needed, but now the pump is already supplying enough. This results in the engine actually receiving too much fuel (a genuinely rich condition) until the computer can relearn the correct settings.

 

Correct. This thread should actually be rephrased to "What would effect both banks suddenly causing such a rich condition when nothing changed?" The tune didn't change. What would start dumping fuel even though the fuel pressure also didn't change? It's at 56 psi. I'm looking at the fuel regulator and a possible internal fuel leak to the vacuum hose.

 

I wanted to send an update on this. As it turns out - it was related. When I relocated the ground point of the relay, it popped the O2 sensor fuse. That was causing the pig richness.

 

I'm going to add to this thread. It's not resolved. It doesn't start on cold cranks as it's pig rich and doesn't run right until closed loop which replacing the ECM SEN fuse took care of the O2 sensors voltage.

 

Hook a fuel pressure gauge up, start the car and shut it off after a minute. It should hold fuel pressure, less one or two pounds, for at least 10-15 mins. Just something to verify, so you eliminate injector leaks, etc. When it's in open loop, it's relying on the values in the PCM to run the engine, so if those haven't changed, fuel is being allowed in elsewhere. I would be removing the EVAP purge solenoid hose from the intake and make sure that you didn't somehow saturate the canister and are drawing in raw fuel through it.

 

Unfortunately she's sitting and been forgotten about but I wouldn't mind getting her running before Spring. The fuel pressure holds solid at 56 PSI for several minutes after shutting off. When looking at logs, the pulse width on a cold crank is 45 ms - I'd say that's a bit much. Nothing has changed with the tune.

 

I removed the hose from the intake and it ran perfectly. I think that just means that that unmetered air helped to correct the rich condition, right?

 

Yes. Have you cleaned your MAF yet? Take the screens off ( if they're still there ) and use a Q-tip with alcohol to clean the MAF wires. This has happened to me previously and causes all kinds of driveability problems.

 

I've sprayed it with MAF cleaner but not used a q-tip with alcohol. This is an SD tune so the MAF isn't used.

 

That changes things. If allowing unmetered air in "fixes" the issue, it would seem like something is going on either with the TPS, the IAC, or the TB itself. I'm not well versed enough with tuning to really be able to say exactly what to look for, unfortunately.

 

Exactly. As you said - it was the IAC. The clue was absence of air and ran perfectly with the vacuum leak. That's the job of the IAC and even though the ECM is commanding the steps, there's no feedback that it's actually opening up. Anyhow - I swapped it and it fired right up.

 

Awesome, sometimes my schooling does come in handy. Lol.

 

And it is much appreciated!