PCM Diagnostics & Tuning - Wideband goin crazy after LTs.
02-22-2007, 08:54 AM
I just installed LTs on an otherwise stock engine. My A/F, prior to the LTs, with cats, reading from the tailpipe was 13.8.
Now, with the headers and my AEM wideband, I am reading anywhere from 14.5-15.5. I thought the A/F would go the OTHER way after headers! :jest:
Kinda worried about this. What do yall think?
Im wonderin if it will just take some time for the ECM to relearn the perameters, because my guage is really everywhere.
02-22-2007, 09:01 AM
Tailpipe readings are kind of iffy to start with. A slight exhaust leak and your readings are shot.
However, headers will lean out a car just like any other mod that increases the engines ability to breathe. The PCM can only learn at light~moderate throttle, which it would then use to make assumptions about heavy~wide-open throttle. Either way, fueling can be off up to 8~10% with the stock parameters still in the PCM on a bolt-ons car. I would seriously think about investing in a tune, tuning software, or at least a MAF translator to help bring your AFR in line. Just make sure you get a better reading than from the tailpipe.
02-22-2007, 09:04 AM
It is getting tuned Sat. Im just concerned about the meantime. The tailpipe reading was just offered as a "base" idea of what it was prior to the headers and on the dyno.
02-22-2007, 09:07 AM
It should be fine as long as you keep your foot out of it....in the mean time.
02-22-2007, 09:36 AM
are you reading 14.5-15.5 at wot or idle/part throttle...at part throttle those numbers are perfectly normal.
02-22-2007, 09:53 AM
That is just part throttle/idle. That makes sense. It never got a chance to really warm up this morning, and I WILL NOT run an engine hard untill it is warm enough. I will open her up on the way home then and see what she runs.
02-23-2007, 08:56 AM
Yup that was it. At WOT the A/Fs were high 13's to low 14's. Thanks guys!
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