Just this week after the track I have started to get a stumble in the car on take off and have a lack of power. Ive had a bit of a stumble at around 2000rpm or lower while just cruising and it seems like its getting worse, along with this stumble while take off it first, it almost wants to die if i dont give it more gas on take off. I thought it was my rockers but I just adjusted them perfectly last night. I had two codes, code 16 and code 41, but I am sure they are from my opti since it quit on me and i just replaced it last week. I cleared the codes before I logged it this morning and I have no new codes. The plugs and wires have about 8,000 miles on them. Just replaced the fuel filter. Does everything look normal on the log?

the first 1300 seconds is of the car idling and warming up, after that i took a little drive stopped a couple of times and cruised a couple of times.

http://www.mediafire.com/?m4hmjm00mpx

 

Here's a picture of one of the plugs.. none of the wires are burnt

 

I tried to open the file in excel but it's very cluttered. What program are you using to read the .csv file?

 

Its in excel.. its in the 2007 edition maybe if i save it in the 2003 format it will work better

this is saved in the 2003 format maybe that will help

http://www.mediafire.com/?mkzymmdmgyn

 

anyone able to take a peak? can a moderator maybe move this thread into the tuning section, maybe it will get some responces there?

This is the first time I'm trying to interpret these readings from the freescan, but it looks like my IAC might be sticking because the values never dropped below 130 counts, even at idle. I read in another forum that the counts should be 20-40 at idle and a touch more with a cam. Any opinions?

 

anyone..? just a quick peak, or maybe even a link to somewhere that can help me understand the log more

 

The first version is a .csv and it opened fine in Excel.... no problem with it, and no clutter.

It will take a while to look at it, its a large file. I've already looked at a file for you on 9/16. This appears to be a different file. Were both of them run to track down the same problem?

 

Thank you very much I appreciate it. The first file on 9/16 still had the low rpm stumble when cruising, but would not hesitate and stumble at take off, it seems the stumble got worse. The first one was because the car would randomly shut off and not turn back on, but I found out I had a bad oil leak in the water pump drive shaft seal and it got in the opti, ruining it and causing the car not to start at all.

So the second one is with a brand new AC Delco opti and i replaced the coil as well. Now I have a loss of power, the low rpm stumble, and it sputters and almost stalls when trying to take off from a dead stop. So the first problem is fixed, now i'm just trying to track down this stumble.

 

Coolant temp is low, never more than 153*F. Adding a lot of fuel at idle. Right side BLM's are always higher than the left side. At one point while idling (just before you shut it off), the right O2 sensor seems to stay in the range of 300-400mV for an extended period of time, even though its in closed loop. Where is your IAT sensor? Appears to stay close to 70*F all of the time.

 

My IAT sensor is in the stock location just like in this photo from shoebox
http://shbox.com/1/iat.jpg

I can hear whatever is going on on the right side. Its a slight woosh noise almost like a little bit of fuel may be hitting the header. Its real hard to pick out but noticable when im really paying attention. The picture of the plug is from cylinder #4 on the passenger side. I just looked under the hood in the dark and do not see any arching in the dark. I had to replace the left O2 sensor last year, but the right was functioning fine at the time. Do you think the right O2 is starting to kick?

 

It seems as though the right o2 is roughly .100 lower than the left while cruising below 2000 rpms and it seems that gap only becomes larger as the rpms decrease almost .400 lower than the left at some points. Do you think that at least narrows it down to the right side?

 

You can't compare the left and right O2 values in a single frame of data. The two banks of the engine are controlled indpendantly, and one side could be at 0xxmV while the other one can be at 9xxmV in the same frame. You've got a sampling rate of about 13 frames/sec, which is fairly high. I'm wondering if sometime at idle the O2 sensors are running cold, because of the low coolant temp. Do you have any idea why the engine runs so cold? With a 160*F t'stat (if that's what you have) it would still be closed at that temperature. Almost looks like it might be stuck open. Its just barely warm enough (135.5*) to allow it to kick into closed loop at 206 seconds.

Also unusual for the IAT to show so little movement. Was the ambient air temp about 70* when you did the data log?

 

Ok i found out that my coolant level was a bit low and topped it off and a touch of the stumble went away but the stumble is still there. The temp went up to 198 degrees and the air intake temp went from 75 to 102 when the car was warmed up. It seems the IAC has evened out a little more as well. From what I saw at idle the right O2 was sticking around .400 at idled but would fluctuate once given gas. Here is a short clip of driving with the coolent filled. still no codes.

http://www.mediafire.com/?wkkeyndm1jb