the solitaire

ok, Iīm fairly new to TBI, or engines for that matter.

I have a 1989 RS with stock 305 TBI engine and itīs running somewhat rich.

I had some electric problems, but those were solved by now. Did not get a new ALDL reading however since I do not have the required equipment.

WinALDL says following:



As I understand it, Block Learn Multiplier should be at 128. It currently reads 117. So, how would I go about solving that problem?

I know this might be rather basic stuff for most of the more experienced of you, but for me itīs pretty much new.

Any help is appreciated.

EDIT: some additional info:
Checked all vac lines and hoses and they are all fitted correctly and not leaking.
Replaced air filter assembly and exhaust. The cat still seemed fine.
Did not get any warning LED's and no errors through ALDL
Spark timing set to 0 (I believe that's correct for TBI)

UnderCover89TBI

iTrader: (25)

These cars factory timing is supposed to be 0 for sure. But have you tried advancing it? That could help some. Maybe give you a more complete fuller burn

the solitaire

thnx, that might be worth a try. The oddest thing is that winALDL tells me itīs running lean but BLM says rich and the exhaust fumes smell like itīs running rich as well

RedneckNo4

maybe its your O2 sensor then

the solitaire

Not sure if itīs that.
The O2 sensor shows 735īish mV. That should be ok, right?

Damon

I've run into this quite a few times with stock TBI engines. The block learn always seems to settlle down to a low-ish number. 115-118. Had one that ran pretty close to 128 but it didn't run right. Found a split in the PCV line, fixed it and it ran much better, but the BLMs went down into the 112-115 range. In every case a new O2 sensor made little or no difference.

I think they run them fat in the chip programming and then rely on the O2 sensor to dial it back to stoich in closed loop, personally.

the solitaire

Thanks. That would make sense. The engine does run fine, but exhaust smells rich compared to TPI engines.

The only bit Iīm somewhat confused about is the running lean entry in winALDL

AvantiHall

I read scan data every day, the data displayed on the screen is a snapshot or freeze frame that is happening live very fast. It is about every fifth frame that most scantools displays. The "Fuel Mixture Status" is not something I would be concerned with on that data log, I look at the LTFT (long term fuel trim) or block learn to inform me rich or lean condition. The O2 sensor is moving rich and lean quickly, that is moving the STFT (short ~~~) or intergrator quickly rich or lean. If the STFT continually is moving and stay on the lean side of 128 or 0, [note: block learn 128 is the center of 0 to 255, LTFT 0 is the center of +30 0 -30 fuel trim] If the STFT is say -15 then the LTFT will shift maybe -3 and again watch the STFT. If the STFT now is switching back and forth evenly rich and lean it will stay at LTFT= -3. Most vehicles are +or- 7 and thats ok. Another example is when the PCV hose splits and causes a major vacuum leak. The PCM/ECM will start adding fuel, the first thing that happens is the STFT shift to say STFT +15, now the LTFT will move to about +5. It will continue to see the STFT in a plus condition, and move to LTFT +10. Again it sees the STFT adding fuel lets say the STFT is +18 again the LTFT will move more rich, LTFT + 15. Finally when it get to the limits of the program it will add as much as the program allows, maybe LTFT + 25 and then turn on the check engine light. Items to check would be vacuum leaks, low fuel pressure, CTS reading to hot, etc. On the older vehicles I look at the block learn and cross counts, also, the O2 to see if it's moving. On newer vehicle I would look for vacuum leaks and the BARO to be out of spec. Now, Back to the "Fuel Mixture Status", don't use it.

O2 sensors can drive you nuts, the good ones can be driven to there limits.

Buy a $50.00 digital volt meter from sears, unplug the O2 from computer and hook up to the output wire. Now pull the brake booster hose loose. Put your thumb over the end and creat a major vacuum leak, the meter should go to (0.100 volts or lower). Now get some propane and drive the O2 as rich as it will go (0.900 or higher) if the sensor goes above 1.0 or below 0.0 volts, its bias and no good. The last test to do is its speed, with the vacuum leak and at or near 0.0 volts, stop the vaccum leak and snap open the throttle. It should hit (0.900) or higher volts and be very very fast. On a DSO is 30ms, really fast when new. Only replace when bad.

Schurkey

SMELLS rich, INDICATES lean???

First guess: Misfire. The whole cylinderful of hydrocarbon mix goes out the tailpipe, along with all the air. The oxygen in the air drives the O2 sensor to show "false" lean mixture; the hydrocarbons tell your nose that the mixture is "rich".

A fuel mixture that is genuinely rich will be high in CO and low in CO2. CO is colorless and odorless.

ninetyone

iTrader: (2)

You will almost never get the BLM to 128. That is a fact. 117 is not bad at all. This indicates your car is a little on the richer side. Which is fine.

ninetyone

iTrader: (2)

Winaldl is telling you it is running rich. Lean is anything over 128. Meaning it is adding fuel. Any numbers below 128 mean it is pulling out fuel.