NEED HELP 2000 century custom

[MelsRegal]

when i check the fuel pressure do i need to start it or just key on? let it stand on the gauge for how long to see if it drops? what is good pressure?

Thanks

AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Fuel Pressure Tests for Hard Start

AGCO provides overall lowest costs of vehicle ownership. We do this by providing extremely high quality automotive service, following the theories and practices of Dr. W. Edwards Deming., why car takes too long to start

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[mike nich]

AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Fuel Pressure Tests for Hard Start

AGCO provides overall lowest costs of vehicle ownership. We do this by providing extremely high quality automotive service, following the theories and practices of Dr. W. Edwards Deming., why car takes too long to start

www.agcoauto.com

thanks

 

[mike nich]

UPDATE
Took fuel pressures today, they are as follows--Key on 46psi dropped to 41 in ten minutes
cleared gauge and fuel pressure
Engine on 56psi went up to 58psi in ten minutes
so that tells me no injector leak, or fuel pump problems--RIGHT?
changed fuel pressure regulator just for the heck of it, the old one --no fuel in vacuum line or coming out of the regulator-- but it still hesitates on take-off like it is not getting enough fuel (is the only way I can explain it) like it is falling on its face. if I lift off the accelerator and push back down it catches and goes, then when shifting it hesitates in shifting, I drive in the overdrive position, and it wants to down shift to regular drive at the slightest little incline witch it has never done before, if I floor it, it is like it does not want to change gears by itself I have to lift to get it to go into the next gear. Is there a vacuum line or something that I could have knocked loose when I changed the transmission filter? As I do not remember anything under there that was in the way of getting the pan off, did not unplug anything either. Rechecked the fluid and it is between the marks when hot and in park I used Dextron lll fluid, did not flush, just pan drop and filter and it really was not that dirty, this is weird and driving me CRAZY!!! So far, I have changed the ITA sensor, mass sensor, O2 sensor bank1, fuel pressure regulator, Fuel pump, fuel filter, engine oil and filter, air filter, trans. fluid and filter.
Any suggestions will be greatly appreciated.
Thanks in advance---Mike

 

[chem_man]

OK on the fuel pressure being good. Factory spec is 41 - 47 psi. We can rule that out.

I see that you changed your spark plugs and wires about 2 years ago. Did you use ACDelco 41-902 platinum spark plugs? I know that some engines are really sensitive to which spark plugs are used (such as my 2004 TrailBlazer with the 4.2L I6 engine).

I think you should test the ignition coils with a digital multi-meter (DMM) and make sure that the resistance of the primary side and secondary side of each coil are in spec. The Primary Side resistance specification is 0.50 - 0.90 ohms, and the Secondary side resistance specification is 5000 - 9000 ohms. The Primary side of the ignition coils is the flat portion of the coil that plugs into the Ignition Control Module. The Secondary side are the where the spark plug wires go onto (coil tower).

If the resistance of either side of the ignition coil is out of specification, replace it. Please do not use cheap, no-name coils or coils that sell for an unbelievably low price regardless of brand. My recommendation for coils are as follows ACDelco/GM Genuine, Delphi, Standard Motor Products/Blue Streak (non T series), NAPA Echlin, and BWD Select (non P series). You can get decent coils on rockauto.com for ~$25 - $40 each. Expect to pay more at a brick and mortar parts store for obvious reasons.

I went through something similar to this 4 years ago and all 3 of the ignition coils in our 99 Buick Century were bad. Caused all kinds of trouble that mimicked transmission and fuel problems

Good Luck!

 

[mike nich]

OK on the fuel pressure being good. Factory spec is 41 - 47 psi. We can rule that out.

I see that you changed your spark plugs and wires about 2 years ago. Did you use ACDelco 41-902 platinum spark plugs? I know that some engines are really sensitive to which spark plugs are used (such as my 2004 TrailBlazer with the 4.2L I6 engine).

I think you should test the ignition coils with a digital multi-meter (DMM) and make sure that the resistance of the primary side and secondary side of each coil are in spec. The Primary Side resistance specification is 0.50 - 0.90 ohms, and the Secondary side resistance specification is 5000 - 9000 ohms. The Primary side of the ignition coils is the flat portion of the coil that plugs into the Ignition Control Module. The Secondary side are the where the spark plug wires go onto (coil tower).

If the resistance of either side of the ignition coil is out of specification, replace it. Please do not use cheap, no-name coils or coils that sell for an unbelievably low price regardless of brand. My recommendation for coils are as follows ACDelco/GM Genuine, Delphi, Standard Motor Products/Blue Streak (non T series), NAPA Echlin, and BWD Select (non P series). You can get decent coils on rockauto.com for ~$25 - $40 each. Expect to pay more at a brick and mortar parts store for obvious reasons.

I went through something similar to this 4 years ago and all 3 of the ignition coils in our 99 Buick Century were bad. Caused all kinds of trouble that mimicked transmission and fuel problems

Good Luck!

thanks, i have a meter but do not really know how it is done. do i just put the NEG. AND POS. leads to the place where the plug wires attach on the SEC, side? where on the flat on the PRIM. side do i put the leads?

Thanks

 

[chem_man]

On the bottom of the ignition coils there are 2 slots where the contacts from the ignition control module go in. Place the test leads there - one for black, one for red, and have your DMM on the lowest ohms range if it is not auto-ranging. For the secondary side, go across the tower terminals and have the meter on the X10 or X100 range.

 

[mike nich]

On the bottom of the ignition coils there are 2 slots where the contacts from the ignition control module go in. Place the test leads there - one for black, one for red, and have your DMM on the lowest ohms range if it is not auto-ranging. For the secondary side, go across the tower terminals and have the meter on the X10 or X100 range.

cool Thanks again was just watching it on u tube, i will check them tomorrow, Thanks. can i check the sec. side with it on the car or does it have to be disconnected all the way off of the bottom contacts, on u tube the coils being tested were all the way off of the car.

 

[chem_man]

You should be able to check the secondary while they are on the car. Primary side tests require the coil to be removed.

 

[mike nich]

On the bottom of the ignition coils there are 2 slots where the contacts from the ignition control module go in. Place the test leads there - one for black, one for red, and have your DMM on the lowest ohms range if it is not auto-ranging. For the secondary side, go across the tower terminals and have the meter on the X10 or X100 range.

ok all coils tested low on the sec. side like 0.1 on 20k scale, did not bother testing the bottom, replaced all three coil packs still had hesitation, pull plugs ( back 3 are a bitch) loosened dog bones pulled engine froward got it done. they were densos replaced with the delco pt# 41-902 it is a lot better but still has that hesitation, but runs better, when I used to floor it in park it would hit the rev. limiter now it does not do that if that helps, I think that has something to do with the power loss and the hesitation on takeoff, but do not know where to look for that, no codes, no engine light. engine runs good no misses or misfires, has quick response in the driveway in park or neutral. Any other thoughts would be appreciated. I know it is something little I just cannot find it. Looked underneath around trans. no vacuum lines, plugs or anything loose there, looked at all vacuum lines (sprayed a little either no RPM change so no vacuum leak). any help will be appreciated once again THANKS

 

[chem_man]

OK on replacing the three ignition coils, and glad to hear the engine is running better.

I normally do not replace parts that are not proven defective but in the case of our 99 Buick Century, I went ahead and installed a new Ignition Control Module (ICM) for a couple of reasons. One, because all three of the ignition coils were bad I was worried that they might have damaged the ICM, and two, there was a fair amount of corrosion on the coil towers due to moisture intrusion from where the ICM and coil packs are located, I was concerned about moisture intrusion into the ICM as well.

I used a BWD Select (non P series) ICM that I got for a decent price at Advance Auto Parts. Just as an FYI, BWD is a brand name owned by Standard Motor Products (SMP) and except for the color of some of the cases used, are the same as the Standard Motor Products (non T series) parts. Also, most NAPA Echlin engine management parts are also manufactured by SMP and are the same as the SMP non T series and BWD Select parts. SMP has been around for over 100 years and their top tier parts are generally regarded as being very good.

So, you might want to think about replacing the ICM as well - just in case. If you do, rockauto.com has ACDelco/GM Genuine, Delphi, and Standard Motor Products (non T series) parts for pretty decent prices.

You also should check to make sure the MAF and MAP sensors are functioning properly. Here are a couple of websites on how to test them:

How To Test The GM MAF Sensor (3.1L, 3.4L, 4.3L, 5.0L And 5.7L)

GM 4.3L, 5.0L, 5.7L Index of Articles

easyautodiagnostics.com

How To Test The MAP Sensor (3.1L V6 Buick, Oldsmobile)

GM 3.1L Index of Articles

troubleshootmyvehicle.com

Good Luck!

 

[Buickguy123]

ok all coils tested low on the sec. side like 0.1 on 20k scale, did not bother testing the bottom, replaced all three coil packs still had hesitation, pull plugs ( back 3 are a bitch) loosened dog bones pulled engine froward got it done. they were densos replaced with the delco pt# 41-902 it is a lot better but still has that hesitation, but runs better, when I used to floor it in park it would hit the rev. limiter now it does not do that if that helps, I think that has something to do with the power loss and the hesitation on takeoff, but do not know where to look for that, no codes, no engine light. engine runs good no misses or misfires, has quick response in the driveway in park or neutral. Any other thoughts would be appreciated. I know it is something little I just cannot find it. Looked underneath around trans. no vacuum lines, plugs or anything loose there, looked at all vacuum lines (sprayed a little either no RPM change so no vacuum leak). any help will be appreciated once again THANKS

WOW! You have gone the distance on your car!

 

[mike nich]

WOW! You have gone the distance on your car!

yes sir and drove it to work today and it feel the same way as when i started this mess, done dumped a lot of money in this in the last week and still is not right i am lost. Things replaced chasing this problem::

INTAK AIR SENSOR--- DO NOT REMEMBER THE CODE THAT CAME UP
PO172-- MASS AIR FLOW, O2 SENSOR BANK 1, 3 COILS, 6 PLUGS, FUEL FILTER, FUEL PUMP, FUEL PRESSURE SOLENIOD, AIR FILTER, OIL AND FILTER, TRANS. OIL AND FILTER, (DROP PAN CHANGE NO FLUSH) AND IT STILL RUNS LIKE SHIT.
all ways been a reliable car do not know what to do next.
This morning the RT. Window won't work so there goes a regulator will do that tomorrow.
HELP ME GUYS AS I AM LOST NOW

 

[mike nich]

OK on replacing the three ignition coils, and glad to hear the engine is running better.

I normally do not replace parts that are not proven defective but in the case of our 99 Buick Century, I went ahead and installed a new Ignition Control Module (ICM) for a couple of reasons. One, because all three of the ignition coils were bad I was worried that they might have damaged the ICM, and two, there was a fair amount of corrosion on the coil towers due to moisture intrusion from where the ICM and coil packs are located, I was concerned about moisture intrusion into the ICM as well.

I used a BWD Select (non P series) ICM that I got for a decent price at Advance Auto Parts. Just as an FYI, BWD is a brand name owned by Standard Motor Products (SMP) and except for the color of some of the cases used, are the same as the Standard Motor Products (non T series) parts. Also, most NAPA Echlin engine management parts are also manufactured by SMP and are the same as the SMP non T series and BWD Select parts. SMP has been around for over 100 years and their top tier parts are generally regarded as being very good.

So, you might want to think about replacing the ICM as well - just in case. If you do, rockauto.com has ACDelco/GM Genuine, Delphi, and Standard Motor Products (non T series) parts for pretty decent prices.

You also should check to make sure the MAF and MAP sensors are functioning properly. Here are a couple of websites on how to test them:

How To Test The GM MAF Sensor (3.1L, 3.4L, 4.3L, 5.0L And 5.7L)

GM 4.3L, 5.0L, 5.7L Index of Articles

easyautodiagnostics.com

How To Test The MAP Sensor (3.1L V6 Buick, Oldsmobile)

GM 3.1L Index of Articles

troubleshootmyvehicle.com

Good Luck!

ok I tested the map sensor all is good there good GRND. 12V AND DECREASES WITH VACUUM APPLIED
the maf got 12v and ground my meter does not have HZ but it has a setting kinda looKs like a right arrow connecting to a + sign
>+
do not know what it is but the frequency increases with the throttle applied and decreases back down at idle (in that setting)
The MAF i bought was NEW not a REMAN. so i am sure it is good

 

[chem_man]

OK Mike, lets step back for a minute, take a breather and relax.

OK, break is over. If you go out and start your Buick, is the Check Engine Light illuminated? If you plug in a code reader, what codes are present, and what codes are pending?

Now, is your code reader/scanner capable of monitoring various engine/emission systems in real time (things like oxygen sensor voltage, MAF data (grams per second), Long Term and Short Term Fuel Trim Values? I ask because we need some data to see what is and is not behaving normally.

 

[mike nich]

OK Mike, lets step back for a minute, take a breather and relax.

OK, break is over. If you go out and start your Buick, is the Check Engine Light illuminated? If you plug in a code reader, what codes are present, and what codes are pending?

Now, is your code reader/scanner capable of monitoring various engine/emission systems in real time (things like oxygen sensor voltage, MAF data (grams per second), Long Term and Short Term Fuel Trim Values? I ask because we need some data to see what is and is not behaving normally.

no check eng. light, no codes, no codes pending
i erased the one for the Iat sensor (do not remember the #
then got p0172 for the other stuff that i replaced.
the reader i have is ACTRON CP9125
eng. & i/m used for emissions, not in real time just get the codes read them find out what they mean fix the problem and erase the code and hope it does not come back. does not do 02 sensor voltage or real time that i know of, just got the book out and do not see anything like that in there.

could an egr valve cause any of these issues, just curious
Thanks

 

[chem_man]

OK on the Actron CP9125, and there not being any codes or a check engine light - thanks!

Just a reminder that the P0172 code is telling you that the engine is running rich - getting too much fuel in the exhaust stream.

At this point, you do not need to worry about the EGR valve. If there was a problem with a restriction in the exhaust flow through it, or if something else was up with it, you would get an ODBII code that is specific for the EGR valve.

Check the PCV hose that goes across the top of the engine from the PCV valve to where it goes into the block. Make sure that the flexible (or rubber) part that goes over the PCV valve is intact and completely covers the top of the PCV valve. Also, make sure that the rigid part of the tubing is not cracked. A leak in the PCV hose can cause a P0172 code to be set.

Also, I am wondering if there might be a leaky fuel injector. Now before you go replacing the injectors do the following. Get two 20 ounce bottles of Techron Complete Fuel System Cleaner, and right before you next fill up with gas, pour both of them into the gas tank and then fill up with a Top Tier brand (BP, Amoco, Chevron, Exxon, Mobil, Sunoco, etc.) of 87 Octane gas and then go for 100 - 200 mile or so drive on the interstate and let the detergents in the gas tank do their job on the fuel injectors. If there are an deposits on the injectors, a decent drive on the interstate can do wonders at cleaning up dirty injectors.

By the way, Autozone has Techron on sale - buy one get one free.

Good Luck!

 

[mike nich]

OK on the Actron CP9125, and there not being any codes or a check engine light - thanks!

Just a reminder that the P0172 code is telling you that the engine is running rich - getting too much fuel in the exhaust stream.

At this point, you do not need to worry about the EGR valve. If there was a problem with a restriction in the exhaust flow through it, or if something else was up with it, you would get an ODBII code that is specific for the EGR valve.

Check the PCV hose that goes across the top of the engine from the PCV valve to where it goes into the block. Make sure that the flexible (or rubber) part that goes over the PCV valve is intact and completely covers the top of the PCV valve. Also, make sure that the rigid part of the tubing is not cracked. A leak in the PCV hose can cause a P0172 code to be set.

Also, I am wondering if there might be a leaky fuel injector. Now before you go replacing the injectors do the following. Get two 20 ounce bottles of Techron Complete Fuel System Cleaner, and right before you next fill up with gas, pour both of them into the gas tank and then fill up with a Top Tier brand (BP, Amoco, Chevron, Exxon, Mobil, Sunoco, etc.) of 87 Octane gas and then go for 100 - 200 mile or so drive on the interstate and let the detergents in the gas tank do their job on the fuel injectors. If there are an deposits on the injectors, a decent drive on the interstate can do wonders at cleaning up dirty injectors.

By the way, Autozone has Techron on sale - buy one get one free.

Good Luck!

will check the PCV this morn. got some of that yesterday and put both of them in, not empty but we will see, also put some catalytic converter cleaner in there, just do not know where to look next and really tired of putting $ in it, not that i would not spend more if i could find the problem! just would like to find the issue.
thanks

 

[mike nich]

OK on the Actron CP9125, and there not being any codes or a check engine light - thanks!

Just a reminder that the P0172 code is telling you that the engine is running rich - getting too much fuel in the exhaust stream.

At this point, you do not need to worry about the EGR valve. If there was a problem with a restriction in the exhaust flow through it, or if something else was up with it, you would get an ODBII code that is specific for the EGR valve.

Check the PCV hose that goes across the top of the engine from the PCV valve to where it goes into the block. Make sure that the flexible (or rubber) part that goes over the PCV valve is intact and completely covers the top of the PCV valve. Also, make sure that the rigid part of the tubing is not cracked. A leak in the PCV hose can cause a P0172 code to be set.

Also, I am wondering if there might be a leaky fuel injector. Now before you go replacing the injectors do the following. Get two 20 ounce bottles of Techron Complete Fuel System Cleaner, and right before you next fill up with gas, pour both of them into the gas tank and then fill up with a Top Tier brand (BP, Amoco, Chevron, Exxon, Mobil, Sunoco, etc.) of 87 Octane gas and then go for 100 - 200 mile or so drive on the interstate and let the detergents in the gas tank do their job on the fuel injectors. If there are an deposits on the injectors, a decent drive on the interstate can do wonders at cleaning up dirty injectors.

By the way, Autozone has Techron on sale - buy one get one free.

Good Luck!

checked pcv all good there. did the fuel pressure check the other day, all pressures held so that tells me no internal injector leak right?
drove close to 100 mi today 2 BOTTLES TECHRON, CAT CLEANER, still no change. it is something stupid I know just cannot pinpoint it, driving me NUTS. any other suggestions before i burn it!
Thanks again

 

[chem_man]

OK on checking the PCV hoses and on doing the Techron. Without live data it's going to be difficult to nail down the cause.

Regarding the fuel injector issue and the fuel pressure question, yes it is generally true that if pressure holds after turning the engine off, then injectors are seating properly and sealing.

If you want to invest another $25 in something that will allow you to monitor live data for various systems, is user configurable, stores data for analysis away from the car, AND you have an android device, let me introduce you to this Bluetooth ODBII dongle from Amazon and the Torque Pro app from the Google Play Store:

https://www.amazon.com/gp/product/B011NSX27A/?tag=elightbars-20

I use this setup all the time. I will monitor virtually every system on the vehicle and store the data. You can simultaneously monitor Short and Long Term Fuel Trims (useful for tracking down lean and rich conditions), MAF data, MAP data, throttle position data, Engine Load, Oxygen Sensor voltages, engine coolant temperature, current and historical misfires by cylinder, etc.

In the case of your P0172, it would let you see what is going on with the Oxygen Sensors in real time as well as seeing if the MAF and MAP sensors are supplying accurate information to the ECM.

Something else just popped into my mind. When you purchase gasoline, do you continue to add gasoline after the pump stops the flow of gas into the gas tank in order to get a full tank? If you do then you might have an EVAP charcoal canister that is literally flooded with liquid gasoline and that could well be the source of the extra fuel that is causing the P0172 code.

I was one who would always keep adding gas after the pump tripped off in order to make sure I got a full tank of gas. While I did not get a P0172 code, I did find that the engine was running really rich over 50% of the time because I was monitoring the Short Term and Long Term Fuel Trim values on our 99 Buick Century. What was happening is that when the EVAP purge solenoid would open to allow trapped gasoline fumes to out gas from the charcoal canister, there was more fuel going into the engine than was anticipated by the ECM so the engine would run rich for 20 to 40 seconds at a time. Then the EVAP solenoid would close and the fuel trims went normal.

With the help of a retired pro on another forum, I monitored several other engine functions to rule other things out, and by ruling them out over the course of a couple of weeks, we were able to "condemn" the charcoal canister. I went ahead and replaced it and the new canister weighed a whole lot less than the old one (indicating the old one was indeed full of gas) and the 20 - 40 second periods of the engine running rich went away.

Hope this helps.

Let me know what you are going to do.

 

[mike nich]

OK on checking the PCV hoses and on doing the Techron. Without live data it's going to be difficult to nail down the cause.

Regarding the fuel injector issue and the fuel pressure question, yes it is generally true that if pressure holds after turning the engine off, then injectors are seating properly and sealing.

If you want to invest another $25 in something that will allow you to monitor live data for various systems, is user configurable, stores data for analysis away from the car, AND you have an android device, let me introduce you to this Bluetooth ODBII dongle from Amazon and the Torque Pro app from the Google Play Store:

https://www.amazon.com/gp/product/B011NSX27A/?tag=elightbars-20

I use this setup all the time. I will monitor virtually every system on the vehicle and store the data. You can simultaneously monitor Short and Long Term Fuel Trims (useful for tracking down lean and rich conditions), MAF data, MAP data, throttle position data, Engine Load, Oxygen Sensor voltages, engine coolant temperature, current and historical misfires by cylinder, etc.

In the case of your P0172, it would let you see what is going on with the Oxygen Sensors in real time as well as seeing if the MAF and MAP sensors are supplying accurate information to the ECM.

Something else just popped into my mind. When you purchase gasoline, do you continue to add gasoline after the pump stops the flow of gas into the gas tank in order to get a full tank? If you do then you might have an EVAP charcoal canister that is literally flooded with liquid gasoline and that could well be the source of the extra fuel that is causing the P0172 code.

I was one who would always keep adding gas after the pump tripped off in order to make sure I got a full tank of gas. While I did not get a P0172 code, I did find that the engine was running really rich over 50% of the time because I was monitoring the Short Term and Long Term Fuel Trim values on our 99 Buick Century. What was happening is that when the EVAP purge solenoid would open to allow trapped gasoline fumes to out gas from the charcoal canister, there was more fuel going into the engine than was anticipated by the ECM so the engine would run rich for 20 to 40 seconds at a time. Then the EVAP solenoid would close and the fuel trims went normal.

With the help of a retired pro on another forum, I monitored several other engine functions to rule other things out, and by ruling them out over the course of a couple of weeks, we were able to "condemn" the charcoal canister. I went ahead and replaced it and the new canister weighed a whole lot less than the old one (indicating the old one was indeed full of gas) and the 20 - 40 second periods of the engine running rich went away.

Hope this helps.

Let me know what you are going to do.

how does thing work? does it plug into a laptop? can i buy it other than amazon? kind of want to get this problem resolved sooner than the shipping time. i do not see a charcoal filter under the hood.
Thanks