Hi all --

I have a TRD supercharged '02 T4R w/ the AEM FIC-6 and Supra injectors. The truck has worked well with this setup for the past 4-5 years but recently after driving for ~30 mins it suddenly starts running ridiculously rich -- pegged at 10 AFR on the wideband with black puffs coming out of the tailpipe. This often happens on the highway and around 50 MPH the truck starts bucking violently until I let off the gas. When throttle is added it pops back down to 10 AFR but when coasting it is around 11-12 AFR. Once it gets to this point, it will stall down at lower speeds (like at the end of the the offramp), sitting at traffic lights, for example, and becomes hard to start. After letting it sit for a bit it will restart and run normal again until it goes through all of the above, once again.

Any ideas on where to start here? I cleaned the MAF sensor but am suspicious of it, the oxygen sensor and perhaps the AEM FIC-6 itself. Code P1130 has been triggered and this phenomena is happening earlier and more frequently by the day; feels sensor related. Your advice is appreciated!

Thank you!
-Steve

I would start with checking all the spark plugs, spark plug wiring, and verify you are getting spark

Check the temp sensor at the front of the block. Make sure its reporting the correct temp.

The temp sensor on the rear of the block is for the temp gauge at the cluster.

Umm, unless things changed my 97 front sensor is for the Puter and the single wire rear sensor is for the dash.

OP:

Does your PCM read 10AFR or do you have a stand alone AFR sensor reading 10?

That code is the pcm telling you there is something with the pre cat sensor or it’s wiring. Which makes sense based on what you’re describing.

Do a once over on your wiring and if nothing is frayed or melted I’d replace the pre cat O2 sensor.


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Thanks guys. It's my UEGO / aftermarket wideband AFR gauge that is pegged down at AFR 10 when the truck goes into this mode. I just started it up and within 5 mins it was doing this again -- it used to happen after ~30 mins but now it's happening much more quickly. The dash temp gauge appears to work properly as does the temperature reading I'm getting with the ScanGauge II. It's as if the truck thinks it needs to add a lot more fuel than it really needs and keep in mind it has oversized injectors and the AEM FIC-6 which left unaltered by the AEM would run the truck super rich, too.

Doh, thanks for pointing out my confusion. I corrected my post.

Yeah, something is wrong! The larger injectors would not cause the engine to run rich as the stock ECU even with no piggyback will adjust for fueling without throwing a code and keep a 14.6 AFR in closed loop driving. I would scratch the injectors off the list of things to check. That leaves the AEM unit, the wiring, or the front A/F Ratio sensor. I have had wiring go bad on me before even though I soldered and protected it so I would take out your wiring harness for the AEM and resolder your O2 sensor wires and see if that fixes the problem. If it does not, your last option would be to replace the front A/F Ratio sensor which costs around $150 or replace the AEM unit - which is no longer in production.