FTo2 goes to 100% when TPS reads 38-42% and Maf hertz reading is about 380hrtz

[And_44]

Ok, now I've gotten the o2 sensor fixed and reading now. Done a few pulls and logs with my logger. Its 1.8g MMCD, mods to car are 3" GM maf and translator, 1990 ePROM ECU in a 1992.

Question is. While logging when my TPS reading hits about 38-42% and the MAF hertz reading is about 380hrtz my o2-ft drops or raises to 100% from what ever it was at. Is that normal?

The injector duty keeps same pace as my MAF hertz after this happens. O2 voltage on MMcD stays between .79 and .83. Only raises above that when letting off the gas and clutch. Have no knock during acceleration only knock at low rpm's (assuming engine noise) I've looked into the low o2 reading and apperently the 1990 ecu "can" read it up to .1 off. So assuming that reading can be .89 - .93. Fuel trims most of time are right in between 90-110. Though my FTLT are at 118%, FTMT are 100% and FTST are 102%.

 

[MY1GDSM]

You going outside of closed loop... .

You should be tuning off a wide band not a narrow band... .

 

[And_44]

Ahhh, okie. Well wideband is getting ordered within the next month. But running stock boost until I get larger injectors, wideband, 190 fuel pump, AFPR. Just trying to figure out if that reading is accurate at those levels. Not having a whole lot of luck with searches on standard operation and readings from the logger.

Trying to nail down problems and fix them. Have a wierd loss of power feels like timing getting pulled or spark blow out but timing advance stays constant in high teens and low 20's when accelerating. Boost leak is very minimal, 1-4 counts of knock only once and a while at idle or low rpm's. While accelerating see maybe 1 count at rpm's higher then 4k.

Giving myself a week of tinkerin to figure out or bringing it into Pina or Boss for some diagnostic work.

But yes, not using to o2 voltage from mmcd to tune with to increase performance and boost. Just curious if it was normal for it to drop or raise to 100%. When it does that the ECU raises fuel by the reading from MaF.

 

[steve]

It does sound like your going into open loop, the question is why.
fueltrimupdatepoints [ECMTuning - wiki]

These are based on steady state, if you just hit the gas, you'll go open loop while in acceleration enrichment. It's not just the current TPS value but the rate of change of the TPS value.

 

[MY1GDSM]

With stock code in the ECU any time you go above 4k or about 35% to 55% throttle depending on the Rpm below that the car is going to figure its Target ARF from the Fuel Table instead of targeting 14.7 since it is no longer in Closed loop... .

Edit: as Steve said there more factors involved but that's the basics in the link he posted

Some kind of log would tell more then you describing what is happening... .

 

[And_44]

Ohh, that explains alot then. When car is in open loop when this happens is when it runs weirdly. Think my Translator setting still need to be tweeked for open loop.

"sigh" I've been trying to find a way to sync my Palm with my laptop but apparently Windows 7 doesn't like Palm products. Going to try to get it to work with my XP OS this next week.

 

[MY1GDSM]

Another Option for logging No Palm!

 

[And_44]

Went to install fuel pump rewire kit. Started to access fuel pump and found its the stock pump. I've had a few AWD's before and none whined like this so guessing pump is on way out and probally why it runs the way it does under load because fuel pump can't keep up. Ordering a 190 walbro this week.

Sticking with the 190 because I don't plan on more then 350ish HP. And don't wanna spend another $200 for an AFPR.