Dyno'd Lean as Hell
 

I put my car on the dyno last night. It made 324/338. Seems low but it is running really lean. At 5400rpms it was at 15afr and caused the wideband to quit reading it as it was still getting leaner.

What could cause this? tune?

As far as I know right now my car has an exhaust leak from the header gasket and also needs new o2 sensors.

I'll post up dyno graph soon as they email it to me. I need suggestions and ideas to point me in the right direction to get my car making 350+ where it should be.
http://i878.photobucket.com/albums/a...o77/mydyno.jpg

the exhaust leak and the o2's being bad at the same time isnt a good thing. I would get them replaced and then do another pull. If its still leaning out then its got to be in the tune.

O2's and exhaust leak should be fixed. I bet that's your problem.

I was thinking it was the o2's but have bin told that it wont effect it under WOT. Is this correct? Would an exhaust leak really cause the car to be down on power 25hp.

o2's do not control wot fueling... Id start by checking your fuel pressure! Oh and fix your header gasket too. A tune is not majically goin to start running lean, something is causing it and I couldnt imagine a tuner leaving a tune at 15:1 afr @ wot... has the car been tuned since the cam install??

in sig. Mail order from PCMFORLESS and 255 walbro fuel pump.

could not imagine pcmforless being that far off with the tune, but I guess it could be a possibility... Again i would start by checking fuel pressure, just because you got a walbro upgrade means nothing, they have been known to have issues... when is the last time the fuel filter was changed?

I'm going to try and get a fuel pressure gauge asap if that reads fine that will cancel out the fuel filter and any other fuel related issues. Filter was changed at about 75k miles car is at 120k right now, might just change it for the hell of it.

On the dyno the af was prity high thru out the whole rpms but it wasn't picking up any knock.

I wouldn't even bother putting it on the dyno with exhaust leak/o2 issues.

Computer does not use 02 for WOT nor would an exhaust leak mess with the AFR under WOT but the exhaust leak and bad 02 would mess with the afr during normal driving & cruising.

I forgot about that. I thought I remember reading that your overall power enrichment mode could be effected by your long term learns eventually.

As close as you are to Mooresville, why not take it to PCMforless and let them fix their tune?

Thats my plan Gizmo. I want to fix all the bugs 1st.

WOT does not use O2s to determine fueling as said many times already. If the tune does not read O2's a leak won't effect the run. So you won't pickup hp from the exhaust leak BUT lack of fuel can and will cause you to lose HP.

The fuel pressure guage will be one indication of fuel system health. A clogged filter can still be a problem...you will need to watch the guage under WOT. You can get the guage set so a rider cn read the guage in second gear. Second to make sure you see when the engine is loaded!

K, Thx will double check my fuel pressure. What is it 43idle 53wot?

They gave him a tune that is for his setup if he made no changes since getting the tune chances are it is his setup NOT the tune. PCMforless won't work on the car WOT AFR >14.7 is not close and not likely the tunes fault.

I will bet it is in his fuel system, pump, filter, injectors, but lets also remember the O2's read oxygen so if the car is missing the AFR would show lean...

Leave no stone unturned it could be the tune but it is 1000:1 against it.

Good luck

I think it is 48 normal 52 wot. The absolute number is not that vital that it goes up WOT and stays at that number while pulling through second gear is what you need to focus on.

Usually a fuel problem will be obvious with guage pulling in second gear.

Good luck

Alvin is really easy to work with. I am sure that if the OP were to take a car that is in good order, he will be able to nail the tune. A mail order tune will never be as good as a dyno tune. There are way too many variables.

I don't know about Alvin on the chipped cars BUT I do know Herter has broke more than a few pistons with 14:1 and leaner at WOT and extreme spark advance so don't put blind faith in a vendor just because they are popular. Again this is a comment specifically about Bryan Herter not Alvin.

May well turn out to be a fuel filter issue but could just as easily be tuning, don't dismiss anything till you test it and double check.