Newb needs A/F troubleshooting advise

[kshoes]

Hello everyone
Sorry for the long post right off the bat. I'm a newb to tweaking my 4Runner, a computer nerd by trade so take it easy on me if I ask obvious / stupid questions.

Recently I supercharged and URD'd my 2001 4Runner as well as TRD headers, TRD CAT back exhaust and AFE cold air intake. The problem I'm having is with the tuning of the MAP tables. The original MAP loaded in the piggyback computer makes it run incredible but the ODB scan tool trims show very lean (+10 to +20 trims). I loaded a new MAP with all set to neutral (10) this brought the trims down but still average around +5. This also took away considerable performance.

What I have noticed that seems to be my problem is this – with the neutral MAP and while still not up to temp but after closed loop the trims appear to be correct (short term in the -10 to -20 range) telling me it's too rich. As soon as it gets to temperature the trims go to +1 to +5. I think the trims are lying to me after reaching operating temperature, is this possible? The other thing I've noticed is the voltage swing on the O2 sensor appears happy (.2 to .8 volts) when cold but after hot it either doesn't swing or changes very slowly (5 or more seconds between any voltage change. Is the O2 sensor bad or getting too hot to operate correctly? It is located right before the first CAT and right after the collection point of the headers. Thanks in advance for any help or advise you can give.

[corax]

how are you checking your O2 sensor? one problem I've run into many times is the "refresh rate" on most DVOM's is too slow to read an O2 (unless you have a good Fluke or equivalent, better yet is an o-scope or graphing meter). An O2 at off idle is jumping up and down too fast for the meter, so what the DVOM does is grab the voltage at specific time intervals, which mucks up the readings.

[kshoes]

how are you checking your O2 sensor? one problem I've run into many times is the "refresh rate" on most DVOM's is too slow to read an O2 (unless you have a good Fluke or equivalent, better yet is an o-scope or graphing meter). An O2 at off idle is jumping up and down too fast for the meter, so what the DVOM does is grab the voltage at specific time intervals, which mucks up the readings.

So far I've only used the OBD scanner readings of the O2 sensor voltage. My o-scope is mounted to an electronics workbench so that will be a last resort check. I'll go check with the Fluke now to see if the reading match the scanner, thanks.

[Stevo3]

Wish I could help you out with the whole URD thing. But it seems as I have similar issues as to you. Just too far inconsisant results for me. Blink on the boards here and myself would manage to get a decent tune out of my truck then days later things go haywire. And uhmm, what year truck do you got?

Hope you can figure things out. As I cannot. If you have something else you need help with just ask.

[kshoes]

Sorry for the delay in posting back (out of town). The 4Runner is an 01. At the moment my results are at least consistent, at least after it's up to temp - always thinks it's lean and adds too much fuel. A mechanic friend suggests against the lower temp thermostat but then this is the first he has dealt with the SC and URD fuel upgrade. I did get the chance to monitor my 02 sensor with a scope and it looks weak to me (.1V p-p and sometimes locks up high instead of swinging). I'm going to replace that sensor and will post back with the results.

With the original URD MAP it runs great but the short term trim shows way lean (+20). With a nuetral MAP performance is down the tubes but the short term trim get close to 0 at times.

[MTL_4runner]

I did get the chance to monitor my 02 sensor with a scope and it looks weak to me (.1V p-p and sometimes locks up high instead of swinging). I'm going to replace that sensor and will post back with the results.


That is normal operation for an A/F sensor.
....they don't give you a sine wave like the O2 sensors do.

[kshoes]

I finally got the chance to install my wideband sensor I got with the URD fuel kit. The only info I can add at this point is the A/F seems to swing to much. At idle 14.1 to 15.2. From idle to WOT it swings from 10.2 to 18.9. Any suggestions?

[mastacox]

I finally got the chance to install my wideband sensor I got with the URD fuel kit. The only info I can add at this point is the A/F seems to swing to much. At idle 14.1 to 15.2. From idle to WOT it swings from 10.2 to 18.9. Any suggestions?


Your AFR should never go above 12.0:1 at full throttle or you might be risking damage.

Have you followed Gadget's U-Tune Guide? http://www.gadgetonline.com/U-Tune.pdf