Engine is running really rich @ 10.0 AFR

[Richard Le]

My check engine light came on earlier today, and the engine is running really rich at around 10.0 afr on my wideband O2. It was running fine yesterday. Attempting to jumper the A and B terminals on the ALDL port with a paper clip did not cause the check engine light to flash. I didn't even get Code 12. Maybe there is something wrong with my ALDL port? Anyhow, I tried a new wideband O2 sensor and MAP sensor to no avail. Timing is at 0-degree with the tan wire disconnected. Fuel pressure is correct with the vacuum line disconnected from the AFPR and plugged.

Any ideas on where to look next here? Ideally, I would like to pull the trouble code(s) from the ALDL port.

 

[dgoodhue]

Re: Engine is running really rich @ 10.0 AFR

I would make sure the memcal or chip adapter is properly seated in ECM.

 

[Richard Le]

Re: Engine is running really rich @ 10.0 AFR

Chip adapter is properly seated in the ECM. Maybe my coolant temperature sensor has failed. Which one sends info to the ECM, the one on the left side of the block or the one on top by the thermostat?

 

[JSM]

Re: Engine is running really rich @ 10.0 AFR

Got a spare ECM? Something has quickly changed obviously and no data through ALDL port tells me something is up.

Is this on a burnt chip or ostrich? Had a few ostrich randomly loose a tune.

 

[Jay92Ty]

Re: Engine is running really rich @ 10.0 AFR

Chip adapter is properly seated in the ECM. Maybe my coolant temperature sensor has failed. Which one sends info to the ECM, the one on the left side of the block or the one on top by the thermostat?

The one on the top (manifold) is to the ecm. The other I believe goes to the gauge.

 

[Richard Le]

Re: Engine is running really rich @ 10.0 AFR

Found the source of the issue. The burnt chip was not seated properly in the adapter as Dave hinted above. In fact, only the pins on one side of the chip were inserted into the adapter (my bad). I'm surprised the engine ran at all. Seems to run OK now but still rich at idle, around 12 AFR. I'm still going to replace the coolant sensor. Maybe the ECM is seeing cold coolant temps. Thanks.

 

[dgoodhue]

Re: Engine is running really rich @ 10.0 AFR

The burnt chip was not seated properly in the adapter as Dave hinted above. In fact, only the pins on one side of the chip were inserted into the adapter (my bad). I'm surprised the engine ran at all.

The PROM likely was not functioning at all. The memcal has a limp mode chip which basically is the backup if the PROM fails. I am glad I could point you in the right direction.

 

[JRoyPDX]

Glad I found this thread. Trying to help get a Sy with a TT chip working. This explains why I can't get it to show me any codes and why it idles super rich. Also explains why I can't get any of the dials or dip switches to respond (since its running on that limp mode chip).

What is the likelihood that the ECU might be the problem versus the TT chip?

UPDATE - I did end up testing another ECU and it was ok. I had the chip checked and it was ok as well. This one ended up being a really botched wiring of the AEM wideband into the ECU, causing a short.