Cars having a problem, need some log advice.

[93RedSE-R]

Recently I have been having problems with my '92 Talon TSi, I've been testing/replacing many things on it and have yet to find/fix the main problem so I figured I would post here to see if anyone could think of something I have not. The car is mostly stock with only a boost gauge and a K&N air filter.

After logging the car I have noticed that the O2 sensor voltage starts to act funny by basically dropping off mid pull, as if the car thinks its decelerating, at this point the car is hesitating horribly on and off and making it next to impossible to get to redline. This only happens during wide open throttle no matter if the car is stationary in neutral revving it or during a pull, in any gear and always in the same rpm area. This is my most recent log (which I will include a .jpg picture of the graph and seperate data from the log, if the file is needed as well just ask). Sorry that there is no TPS parameter logged but I think by looking at the Timing and Airflow parameters on the graph its pretty clear where the pull starts and stops.

Basically I am looking for a reason as to why it would be doing this and any help would be much appreciated. When I get a chance I'll try to come up with a basic list of things replaced/tested.

Thanks in advance.

Log Graph,
http://img.photobucket.com/albums/v215/93RedSE-R/3-21-08.jpg

Log Data,

Time,		RPM,	Knock,	Timing,	O2,	Airflow

00:00.10,	2156.0,	0.0,	35.0,	0.1,	126.0

00:00.20,	2156.0,	0.0,	35.0,	0.31,	126.0

00:00.29,	2156.0,	0.0,	35.0,	0.69,	126.0

00:00.39,	2156.0,	0.0,	35.0,	0.8,	126.0

00:00.50,	2188.0,	0.0,	35.0,	0.71,	126.0

00:00.58,	2188.0,	0.0,	35.0,	0.24,	126.0

00:00.69,	2188.0,	0.0,	35.0,	0.1,	126.0

00:00.79,	2188.0,	0.0,	35.0,	0.18,	126.0

00:00.89,	2188.0,	0.0,	35.0,	0.63,	126.0

00:00.99,	2219.0,	0.0,	35.0,	0.75,	126.0

00:01.09,	2219.0,	0.0,	35.0,	0.73,	126.0

00:01.19,	2219.0,	0.0,	35.0,	0.69,	126.0

00:01.29,	2219.0,	0.0,	34.0,	0.24,	246.0

00:01.40,	2281.0,	0.0,	26.0,	0.02,	353.0

00:01.51,	2313.0,	0.0,	25.0,	0.12,	372.0

00:01.62,	2344.0,	0.0,	25.0,	0.67,	403.0

00:01.73,	2406.0,	0.0,	25.0,	0.9,	422.0

00:01.83,	2469.0,	0.0,	24.0,	0.92,	454.0

00:01.95,	2531.0,	0.0,	22.0,	0.92,	479.0

00:02.05,	2594.0,	0.0,	21.0,	0.92,	517.0

00:02.17,	2656.0,	0.0,	21.0,	0.94,	555.0

00:02.27,	2750.0,	0.0,	20.0,	0.94,	599.0

00:02.38,	2813.0,	0.0,	19.0,	0.94,	643.0

00:02.51,	2906.0,	0.0,	18.0,	0.96,	706.0

00:02.61,	3031.0,	0.0,	14.0,	0.96,	756.0

00:02.74,	3094.0,	4.0,	14.0,	0.96,	832.0

00:02.86,	3219.0,	4.0,	14.0,	0.96,	895.0

00:02.98,	3313.0,	4.0,	14.0,	0.96,	939.0

00:03.09,	3406.0,	4.0,	14.0,	0.96,	958.0

00:03.22,	3531.0,	3.0,	15.0,	0.96,	977.0

00:03.33,	3656.0,	3.0,	16.0,	0.96,	1008.0

00:03.46,	3719.0,	3.0,	16.0,	0.96,	1052.0

00:03.58,	3875.0,	3.0,	16.0,	0.96,	1103.0

00:03.71,	3969.0,	3.0,	17.0,	0.96,	1128.0

00:03.82,	4156.0,	2.0,	17.0,	0.96,	1172.0

00:03.95,	4188.0,	2.0,	17.0,	0.96,	1235.0

00:04.07,	4406.0,	2.0,	17.0,	0.96,	1273.0

00:04.17,	4469.0,	2.0,	17.0,	0.96,	1305.0

00:04.30,	4625.0,	2.0,	17.0,	0.96,	1342.0

00:04.40,	4625.0,	1.0,	17.0,	0.96,	1361.0

00:04.52,	4750.0,	1.0,	18.0,	0.96,	1405.0

00:04.63,	4875.0,	1.0,	18.0,	0.96,	1418.0

00:04.77,	5000.0,	1.0,	18.0,	0.96,	1494.0

00:04.88,	5094.0,	1.0,	20.0,	0.94,	1512.0

00:04.94,	5250.0,	0.0,	21.0,	0.92,	1512.0

00:05.05,	5250.0,	0.0,	21.0,	0.88,	1563.0

00:05.15,	5313.0,	0.0,	21.0,	0.67,	1582.0

00:05.26,	5438.0,	0.0,	21.0,	0.06,	1582.0

00:05.36,	5438.0,	0.0,	22.0,	0.06,	1588.0

00:05.44,	5594.0,	1.0,	22.0,	0.04,	1582.0

00:05.52,	5625.0,	0.0,	22.0,	0.04,	1582.0

00:05.63,	5656.0,	0.0,	24.0,	0.06,	1588.0

00:05.73,	5719.0,	0.0,	23.0,	0.06,	1607.0

00:05.80,	5688.0,	0.0,	23.0,	0.06,	1607.0

00:05.90,	5656.0,	0.0,	23.0,	0.04,	1607.0

00:06.00,	5844.0,	0.0,	24.0,	0.06,	1594.0

00:06.09,	5781.0,	1.0,	23.0,	0.04,	1607.0

00:06.19,	5781.0,	0.0,	24.0,	0.06,	1569.0

00:06.28,	5875.0,	0.0,	25.0,	0.06,	1601.0

00:06.36,	5719.0,	0.0,	24.0,	0.06,	1607.0

00:06.44,	5875.0,	0.0,	24.0,	0.04,	1607.0

00:06.52,	5938.0,	0.0,	24.0,	0.04,	1607.0

00:06.61,	5844.0,	0.0,	25.0,	0.06,	1607.0

00:06.71,	6063.0,	0.0,	26.0,	0.06,	1601.0

00:06.82,	6000.0,	0.0,	26.0,	0.06,	1607.0

00:06.92,	6063.0,	0.0,	25.0,	0.06,	1607.0

00:07.01,	5969.0,	0.0,	25.0,	0.04,	1607.0

00:07.09,	6094.0,	0.0,	25.0,	0.04,	1607.0

00:07.15,	6063.0,	0.0,	24.0,	0.06,	1607.0

00:07.26,	6000.0,	0.0,	26.0,	0.06,	1607.0

00:07.34,	6156.0,	0.0,	27.0,	0.06,	1512.0

00:07.44,	6125.0,	1.0,	24.0,	0.47,	1601.0

00:07.52,	6094.0,	1.0,	25.0,	0.04,	1607.0

00:07.61,	6125.0,	1.0,	24.0,	0.04,	1487.0

00:07.71,	6375.0,	5.0,	24.0,	0.2,	1607.0

00:07.80,	6375.0,	5.0,	24.0,	0.0,	1607.0

00:07.90,	6188.0,	5.0,	22.0,	0.02,	1607.0

00:07.98,	6188.0,	4.0,	27.0,	0.0,	1582.0

00:08.06,	6500.0,	4.0,	23.0,	0.04,	1569.0

00:08.14,	6094.0,	4.0,	24.0,	0.02,	1607.0

00:08.22,	6281.0,	4.0,	23.0,	0.02,	1456.0

00:08.31,	6313.0,	4.0,	24.0,	0.29,	1601.0

00:08.39,	6719.0,	4.0,	24.0,	0.06,	1594.0

00:08.47,	6219.0,	4.0,	22.0,	0.02,	1607.0

00:08.55,	6344.0,	3.0,	26.0,	0.02,	1525.0

00:08.63,	6531.0,	4.0,	22.0,	0.47,	1582.0

00:08.71,	6500.0,	4.0,	24.0,	0.02,	1607.0

00:08.79,	6344.0,	4.0,	21.0,	0.0,	1582.0

00:08.89,	6375.0,	4.0,	24.0,	0.02,	1607.0

00:08.97,	6813.0,	4.0,	21.0,	0.0,	1594.0

00:09.06,	6313.0,	4.0,	21.0,	0.0,	1544.0

00:09.18,	6594.0,	3.0,	37.0,	0.88,	239.0

00:09.31,	6500.0,	0.0,	45.0,	0.8,	221.0

00:09.43,	6125.0,	0.0,	45.0,	0.71,	126.0

00:09.56,	5844.0,	0.0,	45.0,	0.75,	82.0

00:09.68,	5625.0,	0.0,	45.0,	0.69,	57.0

00:09.80,	5375.0,	0.0,	45.0,	0.78,	44.0

00:09.93,	5125.0,	0.0,	45.0,	0.69,	57.0

00:10.05,	4906.0,	0.0,	45.0,	0.73,	50.0

00:10.15,	4688.0,	0.0,	44.0,	0.67,	50.0

00:10.27,	4469.0,	0.0,	30.0,	0.71,	50.0

00:10.38,	4219.0,	0.0,	29.0,	0.63,	50.0

00:10.47,	4063.0,	0.0,	28.0,	0.08,	44.0

00:10.57,	3875.0,	0.0,	28.0,	0.02,	50.0

00:10.68,	3688.0,	0.0,	27.0,	0.02,	50.0

00:10.77,	3500.0,	0.0,	27.0,	0.02,	44.0

00:10.89,	3344.0,	0.0,	27.0,	0.02,	44.0

00:10.98,	3188.0,	0.0,	26.0,	0.0,	50.0

00:11.09,	3031.0,	0.0,	26.0,	0.0,	44.0

00:11.18,	2875.0,	0.0,	26.0,	0.0,	44.0

00:11.27,	2719.0,	0.0,	25.0,	0.0,	50.0

00:11.38,	2594.0,	0.0,	25.0,	0.0,	50.0

00:11.47,	2438.0,	0.0,	25.0,	0.0,	50.0

00:11.56,	2313.0,	0.0,	25.0,	0.0,	50.0

00:11.65,	2156.0,	0.0,	24.0,	0.0,	50.0

00:11.75,	2031.0,	0.0,	24.0,	0.0,	50.0

00:11.85,	1906.0,	0.0,	20.0,	0.0,	44.0

00:11.94,	1750.0,	0.0,	16.0,	0.0,	44.0

00:12.03,	1625.0,	0.0,	14.0,	0.0,	44.0

00:12.13,	1531.0,	0.0,	11.0,	0.0,	44.0

00:12.22,	1375.0,	0.0,	8.0,	0.0,	44.0

00:12.31,	1250.0,	0.0,	8.0,	0.0,	44.0

00:12.39,	1156.0,	0.0,	16.0,	0.0,	44.0

00:12.48,	1063.0,	0.0,	16.0,	0.0,	44.0

00:12.57,	1000.0,	0.0,	19.0,	0.0,	44.0

00:12.67,	1031.0,	0.0,	22.0,	0.0,	50.0

00:12.76,	1125.0,	0.0,	20.0,	0.0,	57.0

00:12.86,	1188.0,	0.0,	14.0,	0.02,	57.0

00:12.96,	1250.0,	0.0,	12.0,	0.29,	57.0

 

[2gGSX]

Dying O2 sensor would be a first guess. If you decide to replace it, make sure you go with an OEM 4-wire one. That doesn't explain why you can't make a pull to redline though, since the ECU doesn't use O2 values during open loop anyways.

Have you checked for boost leaks? That could do this. Have you checked your ignition components? Spark plugs gapped to .028", wires in good order, etc.

 

[93RedSE-R]

Thanks for the reply.

The O2 sensor was replaced with a brand new OEM one 2000 miles ago, this problem was still happening with the old one. There are no boost leaks, pressure tested the entire system up to 15psi which I'm sure is more then enough for stock boost levels. I also pulled off the intercooler piping and intercooler and pressure tested them seperately up to 20psi. As for ignition components, coil packs were replaced with a brand new OEM one a little over 2000 miles ago, problem was still there with the old one. Ignitor module was tested with a multimeter and tested fine. The spark plug wires were just replaced with new NGK wires, this problem was still there with 2 other sets. Spark plugs have been changed out 8-9 different times, all using NGK BPR6ES each set I gapped differently to see if it helped, anywhere from 0.021 all the way up to 0.034, current set is at 0.028. Base timing was reset by me, it was at 2* and I bumped it up to 5*, again this problem was still there before I bumped the timing back up to be in spec.

One thing I forgot to mention in my original post was that when I pulled the spark plugs they were white (all 4 of them), but I can not for the life of me understand how it could go that lean and the knock count only go up to 5 at most and have practically no knock during the almost the whole time the O2 voltage drops off.


While I am on things I have replaced/tested here is a quick list for now on top of the things posted above, everything that has been replaced the problem has been there with the old part,

-MAF with a known working one from a friends car. (lower honeycomb removed on his, mine is NOT hacked)
-CAS (bought used)(with the old one the problem was still there, however the old CAS died on me and I could not get the car started, this replacement one allowed the car to start again)
-BOV (replaced with brand new OEM one)
-PCV valve (brand new OEM one)
-Fuel filter (brand new OEM one)

Things tested with a digital multimeter that tested fine,
-Fuel Injectors tested with a multimeter, as well as the harness side. (they are also all firing)
-MAF harness plug.
-CAS harness plug.


If I come up with more stuff I forgot I will post it up. Also if there is anything else that you could think of please let me know, as again any help would be much appreciated.

 

[2gGSX]

Your symptoms are very close to whats wrong with my friend's car as well, and he hasn't figured it out yet. He posts under Whiteshadow on here and has a thread up--it may be worthwhile to look at http://www.dsmtuners.com/forums/tuning-engine-management/287783-4k-miss-wot-only.html

 

[93RedSE-R]

Hmm. Yeah it does sound very similar, because I too can go part throttle all the way to redline. I just put on a Hallman Pro RX MBC and eliminated the stock boost control solenoid thinking it might be bad but it didn't help. It is still set for stock boost though. I also just tried replacing my fuel pump with a Walbro 190lph and got rid of the fuel pressure solenoid and nothing changed. I have tried changing out my ECU with another one out of a 91 GSX (manual trans.) that was said to be working fine when it was pulled out of it and it did not fix my problem, but when I get the chance I will try swapping in my friends ECU that is currently known to be good to see if it fixes it.

Another thing I should mention is that I did a compression test, 165 across (give or take 1 psi) (this is the original motor, it has 102k miles on it).

 

[Whiteshadow]

Check your CAS sensor...There is no reason your timing should be advancing above 21, also do the basics check for boost leaks by spraying everything down with soapy water..also if you can clean your MAF as well.

Something is fishy with the timing though

 

[93RedSE-R]

CAS was replaced, this one did fix my no start issues the bad one had, but the same problem has been there with the old one vs the new (used, but known good). Boost leak test came back fine at 15psi which is more then enough for stock boost levels. Tried changing MAF with a known good one from a running car, didnt help.

I really do appreciate the help.

 

[Whiteshadow]

what is your base timing set at?

 

[93RedSE-R]

I set it to 5* btdc as when I checked it with a timing light it was at 2* btdc, problem was there at both settings.