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Old 02-12-2014, 06:30 PM   #16
C Squared
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Quote:
Originally Posted by Wasser View Post
First red flag I see. That is if the readings are correct on the scan tool.

Heavy throttle should= lower number (less vacuum, closer to atmospheric pressure)

Closed throttle= higher number (high vacuum)

Normal engine is ~17-22 in. hg at idle. As the throttle plates open, the numbers should start dropping. It looks like yours are going higher. Especially at closed throttle down hill. You should have a very high vacuum reading.

I'd throw an old school vacuum gage on it just to compare readings.

Since your vehicle uses a MAP, it is a speed density system. MAP is a key input for a speed density system. It is used to calculate engine load.

Your readings seem totally out of wack. Could be the scan tool. That is why I would try a "old school" vacuum gage just to compare.
Yup. You need to figure this out. values seem wrong.
Any time you are double digits on STFT you have a problem. STFT is based mostly off the O2 sensor. It could be right and ECM is trying to correct.

? EGR valve. Maybe a part of the problem. But your data doesn't show this.
PCV valve ?

I'd need to have it in font of me to be a real help. With a scan tool I like and trust.
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Old 02-12-2014, 06:52 PM   #17
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Agreed, seemed backwards to me also. But I posted it because I thought well maybe I'm not seeing it correctly.

The software is OBD.com. It consists of a OBD connector X USB cable and software. I have it loaded on a laptop so I could take it into the car.

I glanced down several times while driving on the interstate. I lifted and values went down????? I nearly floored it and it went up high?????
I tried different sensors and came back to the MAP yet same results. The values are off the map sensor with the units " of mercury.

I'm going to e-mail the company this question.

The MAP is a combination intake air temp / MAP. It was replaced a few years ago when the CEL came on with a intake air temp. out of range error. Sensor replaced and all was fine.
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Old 02-13-2014, 02:56 AM   #18
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snip from this website: http://www.obd-codes.com/faq/fuel-trims.php



Quote:
Keep in mind that the computer has no idea if the o2 sensor is reading properly in some cases. For example if an o2 sensor was sticking rich, the computer would assume it was reading correctly and begin taking away fuel to compensate. This is referred to as a "false rich" condition. The computer would be leaning the engine and setting a possible P0172, P0175. The codes would indicate the engine was running rich but it ACTUALLY is running lean. If you use only the false rich codes to diagnose and don't observe all the fuel trim and o2 sensor data, you may make a false diagnosis.
dont over diagnose it. a bad O2 can cause the computer to compensate for a non-existant problem. if you can troubleshoot the O2 sensors, do that first.

depending on how many miles are on it, a new O2 sensor might be a good idea anyway. using fuel additives can also cause funky readings on some systems. (dodge neons were notorious for this)
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Old 02-13-2014, 04:40 AM   #19
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A lot of time the map reads backwards, not a vacuum sensor but a manifold absolute pressure sensor . Check map with koeo ( key on engine off) see what it reads then start car and see what it reads. Like 29 koeo and 11koer ( key on engine running) 29 - 11 = 18 in of vacuum good luck
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Old 02-13-2014, 06:29 AM   #20
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I'd guess vacuum leak. Can affect fuel trim and might account for the lag as well.


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Old 02-13-2014, 07:13 AM   #21
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Injectors.

Replace the fuel filter while you're at it...under the back seat.
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Old 02-13-2014, 10:24 AM   #22
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Quote:
Originally Posted by b1pig View Post
snip from this website: http://www.obd-codes.com/faq/fuel-trims.php





dont over diagnose it. a bad O2 can cause the computer to compensate for a non-existant problem. if you can troubleshoot the O2 sensors, do that first.

depending on how many miles are on it, a new O2 sensor might be a good idea anyway. using fuel additives can also cause funky readings on some systems. (dodge neons were notorious for this)
I did monitor the both O2 sensors I believe the outputs are acceptable.
(snipped from post #14)
Within I'd say a few minutes the O2 sensor very quickly began to oscillate between .85 v and .03 v. Values were slightly changing but the high and low centered around those numbers. It switches quickly, I'd guess like 2 cycles per sec.
also
Rear O2 sensor switched slowly from .8 (something) to .03 (something). Frequency was several seconds before a change.
I've owned the car since 22K miles (now 104K) and I've never added anything but regular fuel to the tank.
I was tempted to replace both sensors but I hate throwing parts at something. From what I have read the O2 sensors output values are normal.
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Old 02-13-2014, 10:45 AM   #23
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Quote:
Originally Posted by boasjohn View Post
A lot of time the map reads backwards, not a vacuum sensor but a manifold absolute pressure sensor . Check map with koeo ( key on engine off) see what it reads then start car and see what it reads. Like 29 koeo and 11koer ( key on engine running) 29 - 11 = 18 in of vacuum good luck
29 - 11 = 18 in of vacuum
I think you have it.

I did receive a reply (very quickly!) from the OBD software mfg. I snipped out most of the reply but below is the bulk of it.

MAP is manifold absolute pressure.
(Manifold Vacuum) = (Atmosphere) - (MAP)

I think I got it now.

So take a partly cloudy day, the barometric pressure is around 29". (not sure what it actually was yesterday)
Subtract it from the MAP sensors readings (in my case ~24 when hard on the throttle)
That = 5" of manifold vacuum at nearly WOT.

When going down hill closed throttle it was around 7, so 29 - 7 = 21" manifold vacuum.

It makes more sense now.
Understand all the numbers may be off a bit. I was driving to work with the laptop on the passenger seat. I thought I was recording data when in fact I forgot to click the button. So I glanced down at times to briefly watch the numbers. A few stuck in my head. like mid 20's with heavy throttle and single digits coasting.
None the less I now believe the MAP is providing correct numbers. But with a better understanding I will test it again.
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Old 02-13-2014, 11:21 AM   #24
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Who makes the obd test system? Try to make sure the canister system does not allow fuel vapor in the intake and cause a rich condition. Also a digital volt meter on the o2 sensor can read voltage moe accurately than a scanner . Cause a artificial enrichment and watch voltage or introduce a vac leak and watch voltage and will see if o2 is working properly. Also o2heater can show high voltage causing a false rich code. Scanner not fast enough to read actual o2 voltage changes ideally need a lab scope .
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Old 02-13-2014, 12:34 PM   #25
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Quote:
Originally Posted by boasjohn View Post
Who makes the obd test system? Try to make sure the canister system does not allow fuel vapor in the intake and cause a rich condition. Also a digital volt meter on the o2 sensor can read voltage moe accurately than a scanner . Cause a artificial enrichment and watch voltage or introduce a vac leak and watch voltage and will see if o2 is working properly. Also o2heater can show high voltage causing a false rich code. Scanner not fast enough to read actual o2 voltage changes ideally need a lab scope .
Test system:
OBD.com is the Mfg. of the software and cable.

Canister system:
Now there have been a few issues with the canister system. Early on the purge valve was replaced. Next the air pump that checks for (i guess gas cap and filler neck leaks) failed. Later one of the tubes in that system developed a leak from rust. Good thing the car had a long warranty.

O2 readings:
Yes there appears to be a slight lag when reading sensors. Easy one to see is the throttle position.
As b1pig posted it may be best to replace them. I did further Googling on Oxygen sensors and it seems as + 100K miles is a bit too long of a service life for them.
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Old 02-14-2014, 03:20 PM   #26
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Originally Posted by larryboy View Post
Injectors.

Replace the fuel filter while you're at it...under the back seat.
I'm in agreement with Larryboy. You have a power loss. The rich condition is caused because one cylinder is not getting enough fuel and misfires, so the unburned gas gets dumped into the exhaust.

You haven't mentioned any black smoke, or poor mileage, or the crappy suffocated feeling the engine gets with a too rich system.

I am not a big fan of fuel injector cleaners since I feel they do not do as thorough a cleaning as should be required but the Seafoam brand especially does make a noticeable difference usually, I'd suggest putting a can of that in and replacing the fuel filter is a good idea too.
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Old 02-14-2014, 04:45 PM   #27
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There are companies that clean fuel injectors off the car. They also put on new orings and filter screens. Cost is around 20 an injector. I have experience with an ASNU machine. It works very well.

Rod
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Old 02-15-2014, 12:56 PM   #28
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Quote:
Originally Posted by GreaseMonkey View Post
The rich condition is caused because one cylinder is not getting enough fuel and misfires, so the unburned gas gets dumped into the exhaust.
Unburned fuel/air mixture (misfire) would not cause this code to set and STFT & LTFT to go negative. If he had misfires, he should also see P03XX codes.

P0172 means that the average LTFT on bank 1 is below a predetermined threshold for too long. The ECM is subtracting (negative ST & LT fuel trim) because something is causing a rich condition. Or at least the B1S1 O2s to report a rich condition.

Vacuum leak (intake), leaking injector(s), plugged air intake/filter, incorrect MAP readings (looks like that is ruled out,) fuel pressure high (regulator stuck,) restricted exhaust, fuel contaminated crankcase oil, evap purge problems or, quite possibly even a O2s reading incorrectly.
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Old 02-15-2014, 07:49 PM   #29
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I would start with a fresh set of oxegen sensors . .yes,all of them. it's past due for new ones. Rest the fuel trims to default if you can or simply clear the memory by disconnecting the battery for a few min. Drive it & see what happens . . .

If the problem comes back. Test the injector spray patterns. maybe you have a leaky injector or two on that one bank.

These are the most likely things to cause a code for one bank running rich.
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Old 02-16-2014, 10:18 AM   #30
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Timing Belt. Check for missing teeth. DAMHINT.
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