Car's first trip out, running rich at times and knock issue.

[czimpel]

I finally got a chance to get me car out today after all of my upgrades over the winter. Experiencing some intermittent rich conditions and knock issues.

Most of the rich condition is during cruising speeds, at times it will run perfect with o2 at 700-800, and my WB reading 14.5-14.8. But, every so often is gets into a mood and runs with the o2 at 39, yes 39, and the WB bottomed out at 10.0. Kick it down and it seems to come out of it until I go back to cruise speed. If I stop at a stop sign and take off again it may go back to running good.

I did about a 10 mile trip with lots of stops and it happened probably 4 or 5 times.

Also experiencing knock retard between .5 and 5.0 at about 8 pounds of boost.

Running 100 E85 with a TT E85 chip and 120's.

Sig should have all info for upgrades.

 

[87chrisss]

What's the BLM's looking like?

 

[HouTX87]

New 02 sensor?

 

[HouTX87]

Sounds like a false lean signal from the O2 causing it to go super rich. I'd try another sensor.

 

[czimpel]

I thought about a bad o2. Any particular brand to buy or stay away from?

FP is at 43 with vac off. Plugs are stock replacement AC gapped at what the book said. Can't remember all of the details.

Do I need to see BLMs when it's throwing it's fit, or will the BLMs be the same no matter what?

 

[87chrisss]

BLM's will show you if the computer is adding fuel or removing +or- 128 that can tell you if you have a cracked header/ possible vacuum leak other little things. How much boost you plan on running? I would use colder than stock plugs, and a tighter gap as well depending of boost levels. You should be able to run 15+ psi with E85 and have no knock issues. Do you run a 6.1 widebandchip?

 

[czimpel]

Plan to run close to 25 psi. I will look into colder plugs. What do you suggest? I'm not running the 6. chip, wish I was.

 

[HouTX87]

R43T

 

[czimpel]

Blms are at 140+/- when it's acting up. I'm going to try a new o2 sensor first.

Any idea on why I'm getting knock at 8 psi with e85?

 

[87chrisss]

Your car is adding fuel, BLM's should be near 128 + or - 10 . I like to keep it as close to 128 as i can. Swap out the o2 sensor throw a denso in and check for any vacuum leaks or an exhaust leak pre turbo header leak as well. Driver side header likes to crack.

 

[czimpel]

OK, thanks. Do you know the denso number off hand?

 

[87chrisss]

234-1001

 

[czimpel]

My cross counts stop counting when the issue arrises. Does this still point to an O2 issue?

 

[87chrisss]

If you have a chip that provides an Open Loop idle, it will probably show zero cross counts at idle and this is normal. Check the cross counts at cruise. Also, do not expect cross counts at wide open throttle. Just swap out the o2 for a new one, and see what happens.

 

[87chrisss]

Here i pulled this from Vortex Buicks

cc = Cross Counts
Cross Counts are the number of times that the factory O2 sensor has crossed from lean to rich across the stochiometric point (0.441v) during the sample rate of the scan tool. The more active the sensor is, the better job the ECM will do in keeping the A/F at the desired stochiometric ratio for idle and part throttle driving. At wide open throttle, it is not used. Many scan tools may show this number as a cumulative addition so that the first frame may be 10 and the second may be 30 which means the second frame was actually 20. When the total reaches 255, it resets to zero and starts over.
Given that a tool like the ScanMaster samples at approximately 1.4 second intervals and more sophisticated tools like PowerLogger may provide 20+ fps, one must take this into consideration when looking at the results.
Something like 10-40 cross counts per 1.5 seconds is probably normal. An O2 sensor that is sluggish and consistently is on the low end (count-wise) should be replaced. O2 sensors are cheap and it does not cost much to replace one periodically anyway. If you don't, gas mileage and drivability will soon go down hill.
As stated prior, leaded racing fuel will often drastically shorten the life of the O2 sensor. Symptoms are reduced output, sluggish cross counts, and/or a check engine light. Many believe the Denso sensors resist degradation much longer than do the factory AC sensors. When leaded gas has been used, even the Densos will show a sluggish cross count, but, will sometimes clean back up with use. Watch the counts, if they don't recover to a normal level, put another one in if you want optimum mileage and part throttle performance.


Here's a good writeup on BLM's

http://www.gnttype.org/techarea/faq/BLMINT.html

 

[czimpel]

O2 sensor did the trick, Thanks for the help Chris!

 

[czimpel]

Still getting some knock though. That will be the next trick. Sometimes none, sometimes while under boost, and sometimes just after letting off. Lots to learn!!

 

[HouTX87]

Sounds like a false lean signal from the O2 causing it to go super rich. I'd try another sensor.

Glad the o2 worked.

 

[czimpel]

Glad the o2 worked.

Sorry, thank you too houtx87!