94 850T check engine light while accelerating

henrysin44 · Post by **henrysin44** » 05 Jun 2020, 15:28

Well the air filter was quite dirty and filled with derbies even though I cleaned it 2K ago, cleaned that and swapped the TCV and now the check engine light only comes on briefly under WOT. Also the inter-cooler hoses seem very soft with hairline cracks all over them, soft enough to be collapsing under load, ordered a RIP-kit to replace it all and really hoping that will finish off this pesky CEL.

240gator · Post by **240gator** » 08 Jun 2020, 17:49

As someone stated previously, the flashing occasional CEL is to indicate knock. I think it is to help fine tune (pun intended) using a wideband, data logs, etc. This is used on those custom tunes assuming you used one from the wiki or the massive VS thread. I have the same thing going on with mine. If you put a 4.3 ECU back in, I bet it doesn't flash.

Post by **RickHaleParker** » 08 Jun 2020, 23:10

henrysin44 wrote: 31 May 2020, 01:32 Just got back from a 10 day road trip and the CEL is still doing its thing.

What is the octane rating of the petrol you are burning?

You might try running the tank empty then top of with high octane straight Petrol, no Ethanol. Run it long enough to purge the fuel lines. Then see if it makes a difference.

henrysin44 · Post by **henrysin44** » 10 Jun 2020, 20:02

240gator wrote: 08 Jun 2020, 17:49 As someone stated previously, the flashing occasional CEL is to indicate knock. I think it is to help fine tune (pun intended) using a wideband, data logs, etc. This is used on those custom tunes assuming you used one from the wiki or the massive VS thread. I have the same thing going on with mine. If you put a 4.3 ECU back in, I bet it doesn't flash.

Yep little did I know the flashing check engine CEL is programmed in the .BIN to tell the user when your running lean. Screen recorded while data logging and was able to see that the second the CEL came on ignition was pulled back and knock enrichment was set. The AFRs say 14.8 but that value is really N/A because I don't have a wideband sensor hooked up. I was under the impression that the O2 sensor was wideband in these cars....guess not, after the run I did (pic below) I added a AFR readings for the front O2 on tunerpro but the readings are all over the place so I doubt reading from a O2 sensor is the best.

RickHaleParker wrote: 08 Jun 2020, 23:10
henrysin44 wrote: 31 May 2020, 01:32 Just got back from a 10 day road trip and the CEL is still doing its thing.
What is the octane rating of the petrol you are burning?

You might try running the tank empty then top of with high octane straight Petrol, no Ethanol. Run it long enough to purge the fuel lines. Then see if it makes a difference.

94 with 10% ethanol, I'm in the tri-state area and have yet to find a gas station that doesn't cut their fuel with 10% of ethanol up here

Post by **abscate** » 11 Jun 2020, 03:02

I really hope you are not running 32 psi of boost at 5500 rpm?

henrysin44 · Post by **henrysin44** » 11 Jun 2020, 08:18

abscate wrote: 11 Jun 2020, 03:02 I really hope you are not running 32 psi of boost at 5500 rpm?

Ha! I max out at 12psi, its not getting a correct signal