Hello,

About a month ago I finally got my rebuilt motor back into my 94 A4 trans am. I put in a comp cams 503 cam 224/230 112 LSA, and supporting lifters, springs. For the past month it has been driving real nice and causing me no issues. A few days ago as i was stopped at a light and the car was idling in drive and it threw a SES light. a scan resulted in a lean left bank condition. This led me to start researching and trying to figure out what would cause this. I picked up a cable from akm and did some freescan data logging. After reading many many posts and trying to compare symptoms i have noticed there is lots wrong with my scan. From IAC readings to 02 readings and split blm's in cells 16 and 18. some times the left goes to 108 and sometimes the right goes to 108.

Since the cam install i have not tuned the car. Could this all be from just a bad tune?

The problem is i really don't understand what these numbers really mean and how they correspond to each other. I am running out of driving season to fix this issue and would like some help from those that have time to spend on my csv file.

http://rapidshare.com/files/28819646...parameters.csv

 

The lack of proper tuning is a problem but with some sudden symtoms I would look for an exhaust leak which will make the O2 read lean.

 

A 108 BLM tells you the O2 sensors are seeing a rich condition, and in response the PCM is reducing the injector pulse width to reduce the fuel supplied by about 15%. That's the limit to how much fuel a stock tune can pull out in response to a rich condition (real of false rich). At that point, the short term corrections may be pulling additional fuel.

108 BLM's are not consistant with a "lean left bank" code. What was the exact code you got when you scanned it? If you had a lean condition, the PCM would start adding extra fuel, and the BLM's would head north from 128, with an upper limit of 160.

Read this to help understand your scan data:

http://www.injuneer.com/ScanMast.html

 

the code that it threw was code 44

edit...

after reading your write up I understand how the numbers should increase decrease and what its trying to accomplish.
here is a snap shot of my cell 16

left 02 right 02 cell Lblm Rblm LIR RIR
0.83 0.169 16 129 108 127 124
0.36 0.679 16 129 108 127 122
0.36 0.679 16 129 108 127 122
0.16 0.107 16 129 108 129 124
0.16 0.107 16 129 108 129 124
0.777 0.058 16 129 108 127 124
0.777 0.058 16 129 108 127 124


it also seems that both cell 16 and cell 18 have split blms. the left being higher than the right by at least 8 or more

half way through the data log. cell 18 equals out to 108 108

0.062 0.737 18 108 108 125 123
0.062 0.737 18 108 108 125 123
0.737 0.062 18 108 108 115 133
0.737 0.062 18 108 108 115 133
0.049 0.098 18 108 108 125 133


0.768 0.093 18 121 108 128 135
0.768 0.093 18 121 108 128 135
0.253 0.093 18 121 108 138 135
0.253 0.093 18 121 108 138 135
0.799 0.089 18 121 108 128 135
0.799 0.089 18 121 108 128 135

at this point the integrators go up significantly on the left side and raise the blms on the left to 129 but the rights stay at 108 and it repeats this cycle. I am having trouble what this implicates. It seems as if its trying to correct it but its not responding or reading the sensors right? does this tell me to replace the 02s? and go from there. Once again i have not tuned this yet and have a comp cams 503 cam. through other peoples posts there was a suggestion that valves are not adjusted right and staying open. could this be it?

 

96capricemgr even with a proper tune i still dont understand why when the computer is dumping more fuel to increase the blms the right does not respond in cell 16 or 18 but the left responds and moves up and down.

edit....

I will replace the header gasket on the left side as it is still the metal style and not the same as the felpro on the right to eliminate the possibility of a leak at the header. I do have a leak after the y pipe but again it is after the 02's.

Most importantly. can i drive this car or am i risking some major damage to a rebuilt motor?

 

DTC 44 is for low readings from the left bank O2 sensor. But you don't have low readings for the left sensor in the limited data you published. The right O2 sensor spends most of its time in the low 0xx mV range, but that's not setting a right bank code, and low O2 sensor readings don't cause a 108 BLM. They would elevate the BLM. Something is screwed up.

I'll try and review you data file tomorrow.

Try swapping the O2 sensors side to side. If the problem (108 BLM) follows the O2 sensor to the other side of the engine, its a faulty sensor. If it stays on the right side, its a wiring problem, the exhaust leak or misfires.

Cell 18 is mathematically calculated from the other operating cells (01 - 16). When is it using Cell 18? If it is using at at part-load conditions, that would indicate the PCM is dropping out of closed loop. When its in closed loop, it will only use Cell 18 when you go WOT, and usually only when the PCM has BLM's below 128.

Is that data from actually driving the car, or are you letting it idle and blipping the throttle to put it into Cell 18?

 

Most of the time it enters cell 18 at idle but I noticed it also under 10 percent throttle

 

It should never be in Cell 18 at idle. Is your closed throttle TPS voltage above 1.0V?

I tried a download, but it said the site was busy serving "premium members".

 

here is another link you can try

http://www.mediafire.com/download.php?ymzjo3wtlh2

The tps volts stay at .7 - .75 when tps is at 0

 

Has anyone else ever experienced these symptoms and remember what they did to remedy the problem?

 

Chasing a similar split BLM down with my cam-only car right now.

Tried adjusting the TB Blade Set Screw, cleaning the IAC, checked plug wires for arching...

Now I am awaiting new MSD wires and AC Delco O2's to replace my one AC Delco and one Bosch currently in the car. Will reply if either fixes my current condition. Replacing wires because they are about (4) years old, maybe more? They are from Elite Spark Plug who (at the time) had unlimited lifetime warrenties on all their ****. Then they went under ... After researching it, I found (2) member on here who had wires fail (breaks in the wire, not arching though) and started to develop Split BLM's ...

Joe

It is very ... very ... gay.

 

ya im running brand new out of the box taylor 8 mm wires and brand new ngk platinum plugs gapped .050 .

 

Downloaded it. I'll look it over.

 

thanks in advance injuneer

 

It idling in Cell 18 because your throttle blades are not closing all the way after the engine heats up. The closed throttle TPS is under 0.70V when the engine starts. The PCM baselines that voltage as 0% throttle. Later on, when the engine warms up, the closed throttle TPS voltage is typically 0.75V and the PCM interprets that as 1% open throttle, assumes its no longer at idle, and switches to Cell 18.

That's not what's causing your problem, but it explains why you got the Cell 18 idle.

Its a huge file, more than 35 minutes and almost 30,000 lines of data. It will take a while to review in detail.

Who tuned it? At idle, its showing 10 GPS air flow, but 5mSec injector pulse widths. Almost seems like someone put the wrong injector size in the program. Usually at idle you would expect a much lower pulse width.

The MAP looks a bit on the high side for the 503 cam. Are the valves adjusted correctly?

I didn't see anything in the log that would suggest its running lean. There are a couple higher load cells where its adding a little bit of fuel with BLM's above 128. But the big problem is in the low load cells, where its pulling out a lot of fuel with BLM's lower than 128. The "lean" code may have set due to an intermittent wiring problem producing a static O2 voltage below 0.20V for more than 50 seconds. I didn't see any evidence of that in the log, but its got a lot to review. There's really no point in letting it sit and idle for minutes on end.

I did take about 4 minutes to warm up and get into closed loop. That about a minute longer than I would expect.

You have almost constant small amount (0.4-deg) of knock retard it idle.

I'll look it over some more.