Help with Maft Pro

[90mkiiisupra400hp]

Hey guys, I hate to ask questions but I am pretty much stumped. I just got my Maft Pro V5.22 all wired up with speed density and have had a couple problems getting it to idle right. First off I will say I have checked the ISCV per TSRM and replaced all the vacuum lines so I am confidant I can rule out a vacuum leak.

Now my problem is the idle will fluctuate from say 600rpm with a AFR of 18+ then go up to 1400rpm with a AFR of 10-13 then back down to around 600rpm and it will do this continually until finally it leans way out and stays between 900-1100rpm.If I hit the gas and it will go way rich as the rpm's go up then right back to lean as soon as I let off the throttle. I tried lowering the idle by lowering the fuel pressure but it just goes right back up and I have raised the fuel pressure to try to richen the AFR up but it seems to work its way back to the lean side, I have adjusted the main scale from +5% all the way to -40% with hardly any change in the AFR or idle.

I was thinking that maybe it was the ecu fighting in closed loop but when I checked my codes I got 21 and 24. I know 24 is normal with the Maft Pro but 21 is o2 sensor which is a newer unit so I figured it was in open loop but unplugged the o2 sensor just to be sure that way I could give PTT a try. I set up PTT around my high idle to see if I could at least a steady AFR but I have had no luck with that either.

I am VERY new to tuning and haven't stopped reading for the last 2 months but I I haven't been able to figure out if this is a Maft Pro problem or a Supra problem but it is very frustrating to say the least. If anyone has had this problem or can give me any pointers as to what I should try next I would really appreciate it. I am going to try to post a log file but I really have no idea how to do it. I will also post up all my settings in the Maft Pro below.

I have a 1990 turbo 5spd
Mods.
BIC d/p
Full 3in exhaust
RC550 injectors
Aeromotive AFPR
AEM UEGO
That should be all the relevant mods

This is what I got out of tunerpro
View attachment idleleanstall.zip

 

[JimR]

The first thing to note here is that since you are running speed density, vacuum leaks no longer matter. So you can definitely stop worrying about that one. ;-)

Here is how I would go about this.... most of this centres around getting rid of possible variables and simplifying:

1. Turn off / unplug all accessory electrical loads. That means AC, subwoofer, 12v power adapters for your laptop, etc.
2. Plug your stock O2 sensor back in and set your PTT idle tps to a good high value (4.0) so it does not get used, then verify that 'AF Tracking Enable' is listed as 'Disabled' in the ALDL Flags section in Tunerpro when you're running.
3. Pull your EFI fuse to reset the ECU (to clear any learned fuel trim values).
4. Log your idle and pay particular attention to your VF voltage on Aux input 1 (assuming you have wired that in). If you haven't, watch it from the diag block with a voltmeter.

Your maftpro settings look good.... I couldn't find anything really amiss there that would have this kind of effect. The only thing I would probably adjust is the mainscale which I would set to approx -20% to accommodate your RC 550's, and then play with other variables while leaving that value constant. It's also probably a good idea to set your fuel pressure to 37psi or so (vacuum hose off) at idle until we get the idle figured out.

I hope this helps narrow things down... let us know how things go.

 

[90mkiiisupra400hp]

Thanks for replying. OK the only additional electrical load I have is a turbo timer, I don't believe that would cause any problem but I suppose it wouldn't hurt to try unhooking it and see what happens, I guess if there is a bad connection where I tapped the rpm wire in that could be causing some issues, I will definitely check that out asap.

I will let you know as soon as I get enough time to do some more trouble shooting, I will give everything you said a try. I forgot to mention that I do have the Vf signal wired in and it reads like 4.8 no matter how long the car is running. I don't know we'll see what happens. Thanks again.

 

[ifyouaint1sturlast]

I really wouldn't mess with PTT until you get everything running right. You're right to suspect that your ECU is fighting closed loop which is why your adjustments to the main scale aren't taking affect. I would recommend checking your wiring and making sure that your ECU is seeing the o2 reading..

 

[90mkiiisupra400hp]

Hey guys just figured I would let you guys know my egr was leaking so I fixed that and now it won't idle at all unless I rest my foot on the gas pedal and VERY slowly take it off then it will idle around 400rpm. Throttle response isn't to bad but if I rev it up and let off it will stall out. I am assuming the vacuum leak was causing the high idle but now that it's fixed it won't idle at all. I don't know but I still have code 21, I have tried changing o2 sensors and resetting the codes but it keeps coming back. I read something about coolent temp sensor so I will try that next. Here is a log taken after the egr was fixed.
View attachment log9142011.zip

 

[JimR]

That zipfile contains a link to the file, not the file itself... ;-)