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Old 07-15-2008, 12:39 AM   #1
t-wrex
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Member#: 74030
Join Date: Nov 2004
Location: Evergreen, CO
Vehicle:
02 WRX
WRB

Default maf sensor not reading @ low end

I am new to tuning and my logs are a mess. My maf volts never go below 1v and don't go above 3.2V. I am also getting a lot of knock in the engine load area of .40 - .86 X 1200 - 4400 RPM. I am thinking that this may be related. Can you look at my log and give me some advise? I cleaned the maf sensor and it seemed to work for a day, but now it doesn't. I have modified the maf scaling a bit, but not in the lower range where the trouble is. My maf housing is the same size as stock and the scalar in that low end is the same as stock.

Code:
AFc1	(AFR)	load	rpm	fbkc	flkc	iam	boost	maf	maf v	tps
-25	13.78	0.17	701	0	0	11	-6.67	1.99	1.08	0
-25	14.59	0.18	727	0	0	11	-6.96	2.15	1.1	0
-25	14.24	0.18	728	0	0	11	-6.96	2.13	1.1	0
-25	14.24	0.18	720	0	0	11	-6.96	2.13	1.1	0
-25	13.78	0.18	729	0	0	11	-6.96	2.13	1.1	0
-25	13.67	0.18	719	0	0	11	-6.96	2.16	1.1	0
-25	14.7	0.18	717	0	0	11	-6.96	2.13	1.1	0
-25	14.01	0.17	730	0	0	11	-6.96	2.11	1.1	0
-25	14.01	0.17	734	0	0	11	-6.96	2.07	1.1	0
-25	14.01	0.19	665	0	0	11	-6.82	2.07	1.1	0
-25	13.67	0.18	728	0	0	11	-6.96	2.15	1.1	0.78
-25	14.13	0.18	718	0	0	11	-6.96	2.16	1.1	0.78
-25	14.36	0.18	726	0	0	11	-6.96	2.16	1.1	0.78
-25	13.44	0.19	709	0	0	11	-6.82	2.21	1.12	0
-25	13.9	0.19	724	0	0	11	-6.82	2.23	1.12	0
-25	14.01	0.19	713	0	0	11	-6.82	2.27	1.12	0
-25	14.36	0.19	720	0	0	11	-6.67	2.28	1.12	0
-25	14.59	0.19	730	0	0	11	-6.82	2.27	1.12	0
-25	14.7	0.18	745	0	0	11	-6.82	2.23	1.12	0
-25	14.59	0.18	726	0	0	11	-6.82	2.2	1.12	0
-24.22	14.7	0.2	694	0	0	11	-6.67	2.21	1.12	0
-21.88	15.5	0.2	690	0	0	11	-6.67	2.27	1.12	0
-25	12.63	0.17	788	0	0	11	-7.11	2.27	1.12	0.78
-25	13.32	0.18	783	0	0	11	-6.96	2.27	1.12	0.78
-25	13.44	0.17	772	0	0	11	-6.96	2.23	1.12	0.78
-25	13.9	0.17	762	0	0	11	-6.96	2.21	1.12	0.78
-25	13.67	0.18	728	0	0	11	-6.96	2.18	1.12	0.78
-25	14.59	0.18	708	0	0	11	-6.82	2.2	1.12	0.78
-25	14.7	0.19	716	0	0	11	-6.82	2.23	1.12	0.78
-24.22	15.04	0.19	710	0	0	11	-6.67	2.23	1.12	0.78
-25	14.81	0.2	692	0	0	11	-6.67	2.32	1.12	0.78
-23.44	15.27	0.2	680	0	0	11	-6.53	2.34	1.12	0.78
-19.53	16.19	0.22	649	0	0	11	-6.53	2.4	1.14	0
-25	11.94	0.18	796	0	0	11	-6.96	2.38	1.14	0.78
-21.09	15.62	0.2	684	0	0	11	-6.53	2.4	1.14	0.78
-19.53	16.42	0.21	674	0	0	11	-6.38	2.44	1.14	0.78
-17.97	16.19	0.23	648	0	0	11	-5.95	2.45	1.16	0
-25	11.25	0.16	1007	0	0	11	-7.69	2.56	1.16	0.78
-25	11.25	0.17	926	0	0	11	-7.55	2.56	1.16	0.78
-25	11.14	0.18	859	0	0	11	-7.4	2.53	1.16	0.78
-25	11.37	0.19	804	0	0	11	-7.11	2.49	1.16	0.78
-14.84	17	0.22	672	0	0	11	-6.24	2.51	1.16	0.78
-11.72	17.46	0.24	646	0	0	11	-6.09	2.59	1.16	0.78
-13.28	17.11	0.24	640	0	0	11	-5.66	2.6	1.18	0
-25	11.02	0.15	1069	0	0	11	-7.69	2.59	1.18	0.78
-5.47	17.92	0.23	649	0	0	11	-5.95	2.59	1.18	0.78
7.81	18.26	0.21	740	0	0	11	-6.09	2.6	1.18	0.78
7.81	19.41	0.2	792	0	0	11	-5.8	2.62	1.2	0
-25	11.37	0.14	1129	0	0	11	-7.84	2.6	1.2	0.78
-0.78	18.6	0.22	678	0	0	11	-5.8	2.6	1.2	0.78
4.69	18.83	0.22	711	0	0	11	-5.8	2.6	1.2	0.78
8.59	17	0.22	765	0	0	11	-5.95	2.69	1.22	0.78
-21.09	11.71	0.14	1210	0	0	11	-7.84	2.71	1.22	0.78
3.91	20.56	0.24	711	0	0	11	-5.08	2.91	1.24	0
-14.84	11.71	0.14	1288	0	0	11	-7.84	2.94	1.24	0.78
-7.03	18.6	0.28	654	0	0	11	-5.22	3.02	1.26	0
-7.81	11.37	0.15	1346	0	0	11	-7.84	3.22	1.26	0.78
0.78	12.06	0.15	1460	0	0	11	-7.84	3.44	1.3	0.78
10.16	14.13	0.13	1653	0	0	11	-7.84	3.51	1.32	0.78
12.5	16.77	0.34	763	0	0	11	-5.22	4.1	1.4	1.96
13.28	14.47	0.17	1781	0	0	11	-7.4	4.96	1.42	1.18
19.53	14.81	0.17	1864	0	0	11	-7.11	5.16	1.46	2.75
20.31	14.81	0.17	1848	0	0	11	-7.25	5.16	1.46	2.75
18.75	14.47	0.17	1837	0	0	11	-7.4	5.16	1.46	2.75
17.19	14.47	0.17	1840	0	0	11	-7.4	5.11	1.46	2.75
14.06	14.24	0.17	1822	0	0	11	-7.4	5.09	1.46	2.75
19.53	17	0.28	1019	0	0	11	-4.35	5.41	1.48	2.75
19.53	15.16	0.18	1776	0	0	11	-6.67	5.31	1.48	2.75
17.97	15.39	0.21	1500	0	0	11	-5.66	5.54	1.5	2.75
-2.34	11.6	0.49	1642	0	0	11	-2.03	14.46	1.86	9.8
3.91	17.23	0.7	794	0	0	11	-2.32	9.88	1.9	13.73
2.34	14.36	0.38	2278	0	0	11	-4.06	14.53	1.9	8.63
-3.12	14.01	0.49	1931	0	0	11	-3.77	14.83	1.9	9.02
0.78	14.47	0.42	2171	0	0	11	-4.21	15.04	1.92	8.63

AFc1	(AFR)	load	rpm	fbkc	flkc	iam	boost	maf	maf v	tps
0.78	14.81	0.53	2440	0	0	11	-3.34	22.02	2.14	12.16
1.56	14.81	0.65	2034	0	-1.05	11	-1.74	21.61	2.14	14.51
0.78	14.59	0.59	2223	0	-0.7	11	-1.89	22.03	2.14	12.94
3.12	15.27	0.77	1658	0	0	11	0.44	21.69	2.14	32.94
0.78	14.81	0.6	2153	0	-0.35	11	-2.03	21.64	2.14	13.33
3.91	14.7	0.68	1888	0	0	11	-2.61	21.23	2.14	14.51
3.12	14.7	0.66	1931	0	0	11	-1.31	21.33	2.14	16.08
-3.12	15.39	0.77	1768	0	0	11	-0.44	22.2	2.14	25.1
-3.12	14.24	0.48	2692	0	0	11	-3.19	21.9	2.14	11.76
-1.56	14.93	0.47	2746	0	0	11	-3.48	21.73	2.14	11.37
5.47	15.16	0.5	2594	0	0	11	-3.92	21.78	2.14	11.76
2.34	14.59	0.5	2603	0	0	11	-3.63	21.63	2.14	10.98
-2.34	14.47	0.39	3350	0	0	11	-4.5	21.81	2.14	10.59
0	16.54	0.67	1452	0	0	11	-0.15	27.22	2.16	83.14
-7.03	14.59	0.53	2398	0	0	11	-2.47	21.98	2.16	13.73
-25	11.37	0.73	1807	0	1.05	11	0	21.95	2.16	24.71
-9.38	15.62	0.77	1746	0	0	11	0.58	22.54	2.16	61.18
-3.91	14.47	0.49	2842	0	0	11	-2.76	22.92	2.16	10.2
8.59	14.93	0.49	2804	0	0	11	-3.48	22.68	2.16	12.16
3.91	14.47	0.46	2940	0	0	11	-3.77	22.62	2.16	11.76
-6.25	14.7	0.53	2518	0	0	11	-3.34	22.21	2.16	12.55
3.12	14.59	0.64	2080	0	-1.05	11	-1.6	22.15	2.16	14.51
2.34	14.59	0.65	2108	0	-1.05	11	-1.6	22.43	2.16	14.9
2.34	14.7	0.63	2114	0	-0.7	11	-1.6	22.56	2.16	14.51
0.78	14.7	0.77	1732	0	0	11	0.29	22.12	2.16	28.63
0	14.24	0.6	2237	0	-0.35	11	-1.31	22.45	2.16	13.33
3.12	14.93	0.59	2231	0	-0.35	11	-2.03	22.14	2.16	13.33
0.78	14.47	0.53	2492	0	0	11	-2.9	22.27	2.16	11.76
4.69	14.81	0.66	1973	0	0	11	-1.31	22.09	2.16	16.08
0	14.36	0.49	2740	0	0	11	-3.63	22.4	2.16	11.37
-0.78	17.11	0.7	1900	0	1.05	11	0	22.63	2.18	29.41
-14.84	11.25	0.63	2112	0	0	11	-0.15	22.24	2.18	44.31
1.56	14.47	0.47	2944	0	0	11	-3.63	23.19	2.18	11.76
-25	11.02	0.74	1902	0	1.05	11	0.29	23.39	2.18	54.9
-3.91	14.59	0.53	2631	0	0	11	-3.34	22.98	2.18	12.94
-4.69	14.93	0.53	2588	0	0	11	-3.34	23.06	2.18	12.55
-6.25	14.13	0.47	2955	0	0	11	-3.92	23.04	2.18	11.76
0	14.81	0.54	2535	0	0	11	-3.19	22.71	2.18	12.55
-0.78	14.59	0.53	2624	0	0	11	-3.19	23.01	2.18	12.55
-5.47	14.59	0.43	3188	0	0	11	-4.35	22.5	2.18	11.37
1.56	14.47	0.63	2143	0	-0.7	11	-1.6	22.71	2.18	14.51
2.34	14.81	0.64	2210	0	-0.7	11	-1.6	23.16	2.18	14.51
1.56	14.7	0.77	1781	0	0	11	0.44	22.78	2.18	28.63
3.91	14.59	0.58	2341	0	0	11	-2.18	22.64	2.18	12.94
3.91	14.59	0.58	2374	0	0	11	-2.32	23.02	2.18	12.94
6.25	14.7	0.66	2030	0	0	11	-1.31	22.58	2.18	16.08
0	14.93	0.74	1806	0	-1.05	11	-0.29	22.75	2.18	25.49
-1.56	13.9	0.54	2622	0	0	11	-2.32	23.37	2.18	12.16
7.81	14.93	0.53	2582	0	0	11	-3.48	22.81	2.18	12.16
5.47	14.47	0.54	2613	0	0	11	-3.19	23.1	2.18	12.55
5.47	14.59	0.53	2587	0	0	11	-3.19	23.01	2.18	12.55
0.78	14.36	0.51	2724	0	0	11	-3.34	22.88	2.18	12.16
4.69	14.47	0.63	2266	0	0	11	-1.89	22.91	2.18	14.51
3.91	14.47	0.66	2098	0	0	11	0	23.54	2.2	22.35
-9.38	14.24	0.73	1912	0	1.05	11	0	23.39	2.2	20
-3.12	14.93	0.49	2926	0	0	11	-3.05	23.86	2.2	13.33
0.78	14.7	0.47	3060	0	0	11	-3.34	23.78	2.2	12.94
2.34	14.7	0.4	3493	0	0	11	-3.63	23.66	2.2	11.37
-0.78	14.36	0.43	3324	0	0	11	-3.63	23.95	2.2	11.76
-0.78	14.47	0.43	3327	0	0	11	-3.77	23.5	2.2	11.76
-0.78	14.59	0.44	3320	0	0	11	-3.77	23.87	2.2	11.76
0	14.7	0.43	3330	0	0	11	-3.63	23.95	2.2	12.16
0.78	14.59	0.44	3301	0	0	11	-3.63	24.11	2.2	12.16
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Old 07-15-2008, 12:44 AM   #2
reddevil
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Um..... Go to a tuner?

How do you know the MAF worked, then it didnt?
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Old 07-15-2008, 12:45 AM   #3
reddevil
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What MAF is it? Stock? AM?
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Old 07-15-2008, 01:05 AM   #4
t-wrex
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It is a stock maf sensor. I think that it worked for a bit because after I cleaned it, it was giving output voltage in the range of .94 - 4.18 and my afr correction was a lot less than it was before cleaning it. So...after reviewing my logs, you think all my trouble is in tuning. I don't want to waste $150 per hour to have a tuner tell me that he can't tune because my maf sensor is bad.
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Old 07-15-2008, 02:19 AM   #5
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First thing to do is to make sure the MAF sensor cable is plugged in properly.

Second thing to do is to flash it back to the stock ROM to see if it makes the problem go away.
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Old 07-15-2008, 11:16 AM   #6
t-wrex
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Quote:
Originally Posted by williaty View Post
First thing to do is to make sure the MAF sensor cable is plugged in properly.

Second thing to do is to flash it back to the stock ROM to see if it makes the problem go away.
The Maf is plugged in correctly.
I can't use a stock map because I have 830cc injectors. My MAF & Base Timing tables are the same as stock though.

Maybe we can simplify things here:
Is it right for my maf sensor voltage to be at 1.1v @ idle? It would seem that I would need a 1.5" maf housing to make that read true. My maf housing is the same size as stock. Is there something else that could make the sensor read that high @ idle? I really don't think that it is installed backwards. If you look at the word "Denso" on the sensor, the air enters the "D" and exits the "O".
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Old 07-15-2008, 11:54 AM   #7
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my maf sensor voltage @ idle is ~1.2v with an aps cai. i see as high as 4.6v @ wot.
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Old 07-15-2008, 07:10 PM   #8
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Quote:
Originally Posted by reddevil View Post
Um..... Go to a tuner?

How do you know the MAF worked, then it didnt?
I was working personally with him.

First off the the MAF sensor was reading really bad. It was reading only about 60% of actual airflow. causing it to run waaaaaaaay lean. Then after the cleaning, things straightened out. There does seem to be something wrong with the low end of scale. It is always running rich and maxes out corrections. The Injectors are running proper scalar and latency. The only difference between his cars set up and mine is the intake.

The reason we believe the sensor is getting worse is because the next day the readings were dramatically different from the day before.

This is the stock diameter intake and it appears to need serious scaling. Corrections around 50%. Has anyone else had to scale a intake this much.
Today(hopefully) we will swap MAF to see what happens.
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Old 07-16-2008, 02:32 AM   #9
t-wrex
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Quote:
Originally Posted by nhat View Post
my maf sensor voltage @ idle is ~1.2v with an aps cai. i see as high as 4.6v @ wot.
Thanks. I needed to know if that was normal or not. I swapped maf's w/ eminehart and it seems mine is ok. Problem was in latency's.

Big thank you to eminhart for all the work on my car.
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Old 07-16-2008, 02:59 AM   #10
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i think we got stuck on the maf thing because the original readings were way low. I hope all gets worked out.

I think im going to plug those latencies into my car and see how she runs. My guess is it won't change much but be proper. my cars voltage doesn't swing as much as yours did.
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Old 07-16-2008, 09:54 AM   #11
nhat
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who is tuning your car? harvey?
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Old 07-16-2008, 11:35 AM   #12
t-wrex
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Quote:
Originally Posted by nhat View Post
who is tuning your car? harvey?
Eric (eminehart)
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