- Joined
- Feb 18, 2006
need help interpreting PowerLogger data
- Thread starter at7we2
- Start date
thanks for the suggestions, but....
re: coils and modules - In the course of 3 years or so, I've had about 6 different coils on it (either new or known good ones) and at least 4 different modules (also new or known good ones) - didn't change anything.
re: grounds - my mechanic friend and I have chased potential ground issues extensively and beat that dead horse to oblivion. first we installed a Casper's ground relocator kit (no change) then we checked all other existing grounds and re-grounded everything. you really would have to have seen the extensive work that was done on this to believe it. my turbo Buick mechanic/friend spent several days checking grounds. at one point the car looked like some kind of Frankenstein experiment with all the sensors hanging loose and auxilliary ground wires strung everywhere. **as a side note to that, we have also checked several power and signal wires to things like the spark control module, coil module, knock sensor, etc.
been chasing this a long time and have gone through more than one round of just throwing money at it (new sensors, plugs, coils, chips, fuel pump, fp reg., plug wires, MAF sensor, the list is long) also done some parts swapping from other cars. In my mind, there's really not much I haven't checked, replaced or swapped, but *obviously* I've still missed *something* because the problem is still there and hasn't changed.
as of this post I haven't re-checked the crank sensor like was mentioned in a post above. hopefully I'll have an opportunity to do that later this week.
Rob
hmm.. I dont' have the PowerLogger software on this computer, but I'll look at it in the morning. I'm still learning how to interpret this stuff so I might not know what I was looking at anyway. what did you see? does the IDC drop out? I have no idea what would cause an anomaly in the IDC data stream, does anyone else?
hmm...I really don't have a clear idea of what a "normal" run would look like. What are you seeing that looks odd?
Thanks,
Rob
look at the RPM, when it spikes the ECM cuts off fuel (rev limiter)
It really looks like an crank sensor signal issue.
A couple things:
the crank sensor signal passes thru the ignition module on its way to the ECM.
Grounds and things connected to these signals (shift lights, tachs, etc) can mess the signal up.
I am wondering if crankshaft endplay or an out of spec balancer could make the signal funky at WOT.
Bob
(looking at file PwrLggrQuickSave.032909.dat)
TurboBob -
Thanks for the reply. What you've said there makes sense and is more inline with what my mechanic friend was saying the last time we talked about this car. He suggested I check the crankshaft endplay and noted that if the crank is walking back and forth too much, it could be messing with the crank sensor.
Now, you also mentioned:
"the crank sensor signal passes thru the ignition module on its way to the ECM. Grounds and things connected to these signals (shift lights, tachs, etc) can mess the signal up"
Wow!...This sentence really caught my attention. I stared at that sentence for a couple of minutes and thought back to the mods I've done to this car and when this problem surfaced. I have an Autometer 3" Street Tach tied into the tachometer signal under the dash. I've got the tach. tied directly into the factory signal wire under the dash *without* a Casper's tach. module - could this be the problem??? The tach. reads fine under normal conditoins, but it does jump around when the popping/misfire occurs.
I wish I had the car with me here at work, I'd go out there and yank the tach signal wire loose right now!
ok, so need to check the following ASAP:
1. Tach. signal wire (disconnect and test drive) ***
2. check crank sensor installation
3. check crankshaft endplay
can't wait to get home and test drive it with the tach. disconnected.
Rob
Thanks for the reply. What you've said there makes sense and is more inline with what my mechanic friend was saying the last time we talked about this car. He suggested I check the crankshaft endplay and noted that if the crank is walking back and forth too much, it could be messing with the crank sensor.
Now, you also mentioned:
"the crank sensor signal passes thru the ignition module on its way to the ECM. Grounds and things connected to these signals (shift lights, tachs, etc) can mess the signal up"
Wow!...This sentence really caught my attention. I stared at that sentence for a couple of minutes and thought back to the mods I've done to this car and when this problem surfaced. I have an Autometer 3" Street Tach tied into the tachometer signal under the dash. I've got the tach. tied directly into the factory signal wire under the dash *without* a Casper's tach. module - could this be the problem??? The tach. reads fine under normal conditoins, but it does jump around when the popping/misfire occurs.
I wish I had the car with me here at work, I'd go out there and yank the tach signal wire loose right now!
ok, so need to check the following ASAP:
1. Tach. signal wire (disconnect and test drive) ***
2. check crank sensor installation
3. check crankshaft endplay
can't wait to get home and test drive it with the tach. disconnected.
Rob
got it. I'll add that to the list of things to check.
Thanks for all this help. I think we're closing in on the problem!
does it sound anything like this?
DivX : http://85merk.com/stuff/rtp/mac_rpm_s.avi
WMV : http://85merk.com/stuff/rtp/mac_rpm_s.wmv
your problem sounds exactly!! like mine, except mine does 100% of the time.
DivX : http://85merk.com/stuff/rtp/mac_rpm_s.avi
WMV : http://85merk.com/stuff/rtp/mac_rpm_s.wmv
your problem sounds exactly!! like mine, except mine does 100% of the time.
well, actually no. I don't think my car sounds anything like that.
it's a little hard to tell on the audio, it sounds like you're running with a dump open and the exhaust note (sounds good btw) makes it hard to hear the ignition issue. It was hard to tell, but it sounds like your misfire was much more rapid than mine. thanks for posting those clips though, I've been thinking about doing the same - If the weather permits, I'll make some videos of my car's misfire problem and post them this weekend.
philosobrad
New Member
- Joined
- Apr 23, 2004
I have the Powerlogger software.........soooo, how do I review your .dat files? When windows prompts me to "open with?" what do I use?
You only need to put the .dat file in your powerlogger folder.
Open Powerlogger, press F3, L(load) and choose the file you want to monitor.
DO NOT TRY RUNNING THE .dat file by double clicking it.
Run it from within PL as described above.
philosobrad
New Member
- Joined
- Apr 23, 2004
Thank you, sir.
update...
Ok. I've had a couple more opportunities to check things and log some data. I believe I have a lot of information to post so I'll give everything in chronological order....
Last Saturday (4/4/09) I had the help of two good friends from our local Buick club. We checked, set and verified the cam sensor - it's 100% dead-on. That same weekend we also did a vacuum system check by pressurizing all the vaccum lines with compressed air and checking for leaks. Almost everything was leak-free except we did find two small leaks in the wastegate plumbing, these were small leaks but we replaced the leaking hoses and re-checked for leaks - no more leaks there. Took it for a test drive and there was no difference, still all the same symptoms as before.
Yesterday afternoon (Friday 4/10/09) I took the car back to my friend's shop and we spent a few hours checking things and logging data. We made some interesting observations, but didn't manage to fix it yet. One of the first things we checked was the crank shaft end-play but it checked out ok, within spec. Crank end-play was within spec. I've given a description of 5 data logs below:
Data log #10 and #11:
- Adjusted the wastegate actuator (lengthened) to what I *expected* to be about 12 lbs. It was previously running up to 15 lbs which is consistant with what I *thought* I set it at. (I've mentioned this because of what we discovered *after* all 5 data runs)
- Put transmission in 2nd to eliminate any possible disturbances the transmission might be inducing
- rolled into throttle somewhat slowly
Data log #12:
- No adjustments made
- Transmission in 2nd
- Stabbed throttle instead of rolling into throttle
Data log #13 and #14:
- Same conditions as data log #12
- data gets interesting this time!
So based on those five runs, it looks like I have 3 pretty clean runs and then things went haywire with no changes made. However, to me it looks like the last two runs point to a bad crank signal as was suggested previously.
Now, here's where things got really weird...
We wanted to see if the issue had anything at all to do with boost so we disconnected the wastegate actuator and took it for a test drive. Much to our surprise, the car still made 15 lbs. of boost!!! We figured the wastegate must have been binding up or something so we wired it open with a piece of steel wire. Nope, the wastegate wasn't binding - even with the wastegate wired *completely* open the car will *still* builds 15 lbs. of boost!!! It does take it a while to get there, but it does hit 15 lbs everytime. So, I believe it's logical to deduce the wastegate port is too small. I have not removed the downpipe to measure the port size, but I'm hoping to have a chance to do that this evening. The downpipe is an ATR 3". I purchased the turbo from another board member (don't remmeber who) and it's *supposed* to be a Limit TE-44.
I didn't log any data with the wastegate wired open because my laptop battery was dead by the time we discovered the boost issue. But, with the wastegate wired open and the boost coming on slowly, the popping/misfire seems to be *gone*! I don't know how that's possible if there is an issue with the crank signal.
So, thoughts???......
Ok. I've had a couple more opportunities to check things and log some data. I believe I have a lot of information to post so I'll give everything in chronological order....
Last Saturday (4/4/09) I had the help of two good friends from our local Buick club. We checked, set and verified the cam sensor - it's 100% dead-on. That same weekend we also did a vacuum system check by pressurizing all the vaccum lines with compressed air and checking for leaks. Almost everything was leak-free except we did find two small leaks in the wastegate plumbing, these were small leaks but we replaced the leaking hoses and re-checked for leaks - no more leaks there. Took it for a test drive and there was no difference, still all the same symptoms as before.
Yesterday afternoon (Friday 4/10/09) I took the car back to my friend's shop and we spent a few hours checking things and logging data. We made some interesting observations, but didn't manage to fix it yet. One of the first things we checked was the crank shaft end-play but it checked out ok, within spec. Crank end-play was within spec. I've given a description of 5 data logs below:
Data log #10 and #11:
- Adjusted the wastegate actuator (lengthened) to what I *expected* to be about 12 lbs. It was previously running up to 15 lbs which is consistant with what I *thought* I set it at. (I've mentioned this because of what we discovered *after* all 5 data runs)
- Put transmission in 2nd to eliminate any possible disturbances the transmission might be inducing
- rolled into throttle somewhat slowly
Data log #12:
- No adjustments made
- Transmission in 2nd
- Stabbed throttle instead of rolling into throttle
Data log #13 and #14:
- Same conditions as data log #12
- data gets interesting this time!
So based on those five runs, it looks like I have 3 pretty clean runs and then things went haywire with no changes made. However, to me it looks like the last two runs point to a bad crank signal as was suggested previously.
Now, here's where things got really weird...
We wanted to see if the issue had anything at all to do with boost so we disconnected the wastegate actuator and took it for a test drive. Much to our surprise, the car still made 15 lbs. of boost!!! We figured the wastegate must have been binding up or something so we wired it open with a piece of steel wire. Nope, the wastegate wasn't binding - even with the wastegate wired *completely* open the car will *still* builds 15 lbs. of boost!!!
It does take it a while to get there, but it does hit 15 lbs everytime. So, I believe it's logical to deduce the wastegate port is too small. I have not removed the downpipe to measure the port size, but I'm hoping to have a chance to do that this evening. The downpipe is an ATR 3". I purchased the turbo from another board member (don't remmeber who) and it's *supposed* to be a Limit TE-44.I didn't log any data with the wastegate wired open because my laptop battery was dead by the time we discovered the boost issue. But, with the wastegate wired open and the boost coming on slowly, the popping/misfire seems to be *gone*! I don't know how that's possible if there is an issue with the crank signal.
So, thoughts???......
I'm 'gonna go out on a limb here and ask... Are you sure you are not experiencing compressor surge ?
You said at WOT it runs fine, but acts funny at 5-10lbs boost...
That almost sounds like compressor surge to me...
I have a similar problem since installing a 70GTQ on my car...
At light/part throttle, building minor boost, it will buck and carry on like a wild Bronco. If I just run it balls-out, it runs like a scalded cat.
I have some ideas on how to correct it, but don't want to admit what I'm 'gonna try.
You said at WOT it runs fine, but acts funny at 5-10lbs boost...
That almost sounds like compressor surge to me...
I have a similar problem since installing a 70GTQ on my car...
At light/part throttle, building minor boost, it will buck and carry on like a wild Bronco. If I just run it balls-out, it runs like a scalded cat.
I have some ideas on how to correct it, but don't want to admit what I'm 'gonna try.
yullose -
thanks for the reply. I can't say it's definately *not* compressor surge, but based on the power logger data, I'm 99% convinced it's electrical/electronic -the PowerLogger data shows erratic spikes and dips in the RPM data. Some of the RPM spikes are up at well over 7k rpm. - I *know* my engine isn't capable of turning that fast without going BOOM!
Right now I suspect the popping problem may be a result of the engine torqeing over and either breaking a connection somewhere or shorting soemthing out. my next test will be to overtighten the engine tie-down strap and go for a test drive. I'm hoping this will make the popping go away - if it does then I'll know the problem is from the engine moving around and affecting the wiring somewhere. Then it will just be a matter of finding the loose connection or short.
thanks for the reply. I can't say it's definately *not* compressor surge, but based on the power logger data, I'm 99% convinced it's electrical/electronic -the PowerLogger data shows erratic spikes and dips in the RPM data. Some of the RPM spikes are up at well over 7k rpm. - I *know* my engine isn't capable of turning that fast without going BOOM!
Right now I suspect the popping problem may be a result of the engine torqeing over and either breaking a connection somewhere or shorting soemthing out. my next test will be to overtighten the engine tie-down strap and go for a test drive. I'm hoping this will make the popping go away - if it does then I'll know the problem is from the engine moving around and affecting the wiring somewhere. Then it will just be a matter of finding the loose connection or short.
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