tysparks81 Posted October 24, 2023 Share Posted October 24, 2023 Hey LGT people, I have a strange thing happening and I'm just looking for opinions on something happening with my car. It has been E-tuned for over a year now, and re-tuning is kind of out of the question, since I am on a Cobb AP. My cars AF on the AEM wideband on first start up is around 14, the Cobb AP is showing 14 as well on first startup. Once I start driving under partial throttle & full throttle AF is spot on between the Cobb AP & AEM wideband. But once I come to a stop sign or red light the AEM wideband jumps to 16.6-17 while the Cobb AP is still showing around 14 this only really happens after driving and coming to a stop with the car still idling, no hesitation, no bucking or bogging, no stuttering. I had changed the rear o2, and MAF previously when I was having hesitation and wide sweeping AF numbers earlier this year, which leads me to it believe that the Bosch LSU 4.9 Sensor is failing, but before I go spend money on the sensor it would be good to have someone else validate my logic. #LGTSTi is still cheaper and nicer then an equal year wrxsti Follow my 2007 Spec B. Build here Link to comment Share on other sites More sharing options...
subisubisu Posted October 24, 2023 Share Posted October 24, 2023 I am not authoritative enough to validate, but I have a replacement Bosch LSU 4.9 inbound from Summit as I type. Mine zooms up to 18.5 shortly after it completes its start-up routine of displaying codes and finally 14.5, and I mean in a few seconds. My internet searches led me to believe that sensor fouling is a frequent failure with the AEM system. I believed it enough to buy another sensor. I can let you know when I get mine installed whether it solves my problem. 1 Link to comment Share on other sites More sharing options...
subisubisu Posted October 26, 2023 Share Posted October 26, 2023 Replacement sensor arrived. Popped it in and idled the car briefly. It showed reasonable-looking values the whole time, rich and lean in response to throttle blips, and not the 14.5 to --- march it was doing previously. Couldn't take it for a drive this evening due to family obligations, but I expect to take it for a drive tomorrow. If anything changes, I will report back. 2 Link to comment Share on other sites More sharing options...
blackobxt Posted October 26, 2023 Share Posted October 26, 2023 When I had an aem wideband on my Sti I remember seeing exactly what you are noticing. The aem would read richer than the ap because it would only read so rich and coming to a stop the aem would read leaner than the ap. Link to comment Share on other sites More sharing options...
tysparks81 Posted October 26, 2023 Author Share Posted October 26, 2023 On 10/24/2023 at 4:09 PM, subisubisu said: I am not authoritative enough to validate, but I have a replacement Bosch LSU 4.9 inbound from Summit as I type. Mine zooms up to 18.5 shortly after it completes its start-up routine of displaying codes and finally 14.5, and I mean in a few seconds. My internet searches led me to believe that sensor fouling is a frequent failure with the AEM system. I believed it enough to buy another sensor. I can let you know when I get mine installed whether it solves my problem. Is the Bosch sensor less prone to the failures of the AEM sensor? #LGTSTi is still cheaper and nicer then an equal year wrxsti Follow my 2007 Spec B. Build here Link to comment Share on other sites More sharing options...
Haze Posted October 26, 2023 Share Posted October 26, 2023 FWIW, all these 4.9 wideband sensors are the same other than pigtail length and occasionally the wiring connector. I got a stock sensor for a 3.5 Ecoboost F-150 from Rockauto for the Innovate WB in my XT. I think it cost me about half of what getting one through Innovate would have. Ran it through the free air calibration sequence and it works fine. 1 Link to comment Share on other sites More sharing options...
subisubisu Posted October 27, 2023 Share Posted October 27, 2023 9 hours ago, tysparks81 said: Is the Bosch sensor less prone to the failures of the AEM sensor? I do not know. But I did go for a drive, and it does seem to be reporting credible values now, so I presume that the original sensor was fouled and a new one was the solution. Do I have confidence that I am not fouling this new one at the same rate? No, I do not. 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now