I'm stumped. open loop issue.

[crzycav86]

On my kat, I have 370cc injectors, adjustable fpr, n60(maxima) maf, and I'm using an safc for fuel management with base timing retarded to 16*.

After doing some highway pulls with some friends, the car suddenly lost power, and it would accelerate and decelerate sporadically(at a constant throttle, the car would lose power and regain it). I pulled over. The car would not idle, and it would rev with a lot of difficulty.

That was about 2 months ago. I've only checked on the car twice since then.

My first troubleshoot was to unplug the maf and see how it responded. I turned the fuel pressure down to about 22psi since the safc would not be able to lean out the a/f. After this, the car would be able to idle, free-rev, and hold revs pretty well(considering that the injectors are uncorrected). So I thought it must be a problem with the maf. I bought another n60 maf, and came home a month later to try it out.

Unfortunately, the new maf gave the same problem.... So I switched back to the stock maf - still the same problem.

I tried playing with the safc in/out settings for the n60 maf, I tried adjusting the fuel correction. i did a lot of messing around with the safc, and it didn't help. when I go back home for thanksgiving, i'm going to try reconnecting the maf without having it go through the safc. If that doesn't work, I think it might be a computer problem. If that doesn't work, I will have no more ideas.

One thing I must confess is that I have not checked the spark plugs because I was convinced that it was a maf issue. I will do that next time because spark plugs is pretty much standard procedure.

So to recap, I'm convinced that this is an open loop issue. My question is are there any sensors other than the maf that are not being used under closed loop operation?

Let me know if you guys have any advice on what to check. Remember that the car runs okay with the maf unplugged, so that narrows down the problem down quite a bit, but obviously not enough for me to take care of on my own. I am stumped. Thanks for your help.

[180fan]

pull the mafs and see if it idles ok. if it idles ok with no maf, the chance of two mafs being bad is pretty slim. I'd check out the AFC settings again.

[crzycav86]

yeah, the first thing i did was unplug the mafs. it idles and revs fine(as i stated in the post). the safc and vacuum leak are the next things to be checked. do you recommend anything else?

[180fan]

has your problem been resolved? have you pulled the plugs yet? I'd still suggest pulling the AFC from the loop, yours may have kicked the bucket.