Too rich?

[Clayman]

Ok so my 5.3 swap into my 94 silvy is great except for this... i took it for a decent drive in the mountains today and it seems like it is running too rich because if you keep it at half throttle for a while it just keeps bogging down and feels like its losing power but if you let off completely and then give it throttle again then it feels fine. Its like its running too rich or something. Any ideas? And also on interstate i couldnt get it to pick up speed going downhill in overdrive at like 75 mph.. but then 10 minutes later (after i had let off) it would pick up speed going uphill.. either somethings wrong or i had a hellacious headwind trying to go downhill.

[Clayman]

Also im not getting any check engine codes or anything.

[kerrige]

Do you have a wideband? Not much to go on. Your part throttle air/fuel tables may need some fine tuning. Definitely need more info tho.

[Clayman]

Yeah i dont have a wideband... how much trouble would it be to install? and i just got a mail order tune from Nelson when i did the swap.. im pretty sure its too rich tho cuz i can wash my truck one weekend and by the next weekend there is a black sooty residue on the fender over the exhaust

[kerrige]

Yeah i dont have a wideband... how much trouble would it be to install? and i just got a mail order tune from Nelson when i did the swap.. im pretty sure its too rich tho cuz i can wash my truck one weekend and by the next weekend there is a black sooty residue on the fender over the exhaust

Sounds like you have a rich condition caused by an exhaust leak causing the O2s to miss calibrate your fuel trims. This would make sense because at wot your O2s are ignored and no rich condition would occur. However, at part throttle this wouldn't always be the case. Check for exhaust leaks above the O2s. Also might be a bad 02.

[Clayman]

Ok.. ill buy that. Not trying to be a smartass but wouldnt a bad o2 give me a check engine light?

[pl4yboy]

Ok.. ill buy that. Not trying to be a smartass but wouldnt a bad o2 give me a check engine light?

It may be in the code history, but hasn't caused a cel yet.

[Clayman]

So how do you test o2 sensors? Or do you just have to get a reader and see what codes are thrown?

[pl4yboy]

So how do you test o2 sensors? Or do you just have to get a reader and see what codes are thrown?

Hook them to a scanner and watch them cycle.

[Clayman]

Ok ill have to get around to that.. or i may just try to test them on the bench. Do you guys know of anywhere i can get an obdII port to hook into my harness?