Hey all,
I have been gone from this site for about 2 years, been busy. It is good to see a some of the of old names and a lot of new ones. I have spent about as much time maintaining my 90Q as I have reading this site during that time. You can imagine the mechanical shape my Q is in. It is a statement to the engineers at Infiniti that my car still runs. But now it is time to get her back in shape. Here are some details.
1990 Q45150,000 milesChain guides doneTranny replaced @ 40,000 (before I owned it)Location Orlando, FL
A few weeks ago I ran into some problems (rough idle, stalling, excessive gas smell in exhaust) and took it to the dealer. They Dx the problem as a faulty MAF ground and fixed. The car ran fine for a couple of days and then the exact problem came back. Took it back to the dealer and was told that the O2 sensors were now out and it would cost about 650.00 to fix. Well this was enough to send me back to the church of the Q and here I am. I have replaced the O2 sensors (NKL? from Sparkplug.com) and the car runs great. My question now is I got the following readout from the dealer and don't know what it means? Could someone help? Thanks. BTW I have been told the Knock Sensor also needs to be replaced but I am not noticing any apparent problems directly related to that. All of the above symptoms are gone except there is still a very slight gas smell in the exhaust. Plugs replaced about 30-35000 miles ago.
Consult-IISystem EngineP/# 23710-64U05PWR BALANCE DIAG RESULTNGNo.1 -29 RPMNo.2 -17 RPMNo.3 83 RPMNo.4 305 RPMNo.5 -176 RPMNo.6 31 RPMNo.7 STALLNo.8 -217 RPM
BASE DATACMPS-RPM(POS) 825rpmCOLLAN TEMP/S 176F
MIXTURE RATIO TEST RESULTS
NG
REFERENCE DATA CMPS-RPM(POS) 1999rpmMAS AIR/FL SE 2.0V
Chris
Help with Consultant printout
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Since all 8 cylinders add vectorally to create the power [once ever 90 degrees or 4 cylinders per rpm and between the power pulse there is a drain of power caused by exhaust pumping losses and friction from the other non firing cylinders............ideally all cylinders should produce the exact same peak psi [they don't because of variations in air flow and injector flow plus differential wear of the rings [compression pressure].Brand new the engine cylinders were probably with 3-5%......therefore ALL the power balance rpm drops would have been within 3-5% of the average drop or the highest drop.
On the Consult I the rpm drop is averaged in 12-15 rpm steps [resolution], Consult II has a finer resolution.
The higher the test rpm the higher the drop [better resolution]
The numbers you provided are all over the place {??????}
I am use to seeing 50-100 rpm drops for each cylinder as the fuel and ignition is shut off.
I consider if all are 50-65 or 65-75 or 75-87 or 87-100 to be perfect. I always repeat the test once or twice and average the average results.
After a complete cleaning of injectors, TB, and plenum and a 15 mile blow out of the resulting gunk.........I have been able to achieve a perfect 65 or 75 rpm drop on each cylinder after my engine has gone 228,000 miles.
Obviously ring wear comes into play but if EACH compression is within the 14 psi variation range things should be perfect.
As long as the rings wear evenly [the same amount] the compression should drop evenly from new 185 to minimum 154 with age.
When you change plugs have the compression tested in minute detail with a peak reading [storage] compression tester so you can log the 1st and 4th rev [puff] reading.
Valve and valve seat/stem and stem seal wear [unintentional leak down] are other things to measure on low compression reading cylinders.
Unfortunately I didn't learn about all this stuff until my Q had over 100,000 miles so I don't have base readings new.
But we see 250,000 mile Q still running some shake rattle and roll and can't be cleaned up but most respond to cleaning to create a decent idle [not perfect but good enough].
Obviously a totally dead cylinder or 7 cylinder V8 would/could still produce at least 75% of rated full power if you could stand the vibration.
On the Consult I the rpm drop is averaged in 12-15 rpm steps [resolution], Consult II has a finer resolution.
The higher the test rpm the higher the drop [better resolution]
The numbers you provided are all over the place {??????}
I am use to seeing 50-100 rpm drops for each cylinder as the fuel and ignition is shut off.
I consider if all are 50-65 or 65-75 or 75-87 or 87-100 to be perfect. I always repeat the test once or twice and average the average results.
After a complete cleaning of injectors, TB, and plenum and a 15 mile blow out of the resulting gunk.........I have been able to achieve a perfect 65 or 75 rpm drop on each cylinder after my engine has gone 228,000 miles.
Obviously ring wear comes into play but if EACH compression is within the 14 psi variation range things should be perfect.
As long as the rings wear evenly [the same amount] the compression should drop evenly from new 185 to minimum 154 with age.
When you change plugs have the compression tested in minute detail with a peak reading [storage] compression tester so you can log the 1st and 4th rev [puff] reading.
Valve and valve seat/stem and stem seal wear [unintentional leak down] are other things to measure on low compression reading cylinders.
Unfortunately I didn't learn about all this stuff until my Q had over 100,000 miles so I don't have base readings new.
But we see 250,000 mile Q still running some shake rattle and roll and can't be cleaned up but most respond to cleaning to create a decent idle [not perfect but good enough].
Obviously a totally dead cylinder or 7 cylinder V8 would/could still produce at least 75% of rated full power if you could stand the vibration.
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rice_burner
- Posts: 4
- Joined: Sat Apr 19, 2003 4:06 pm
Thanks for the quick responce. Here is what I think you are saying.
1. Cylinder 7 is fouled out (I hope and not the injector) and not running.2. It is time to change the plugs.3. It is time to clean the injectors, TB and plenum.
I checked the numbers again and they are exactly what is on the slip.
There are still some things I don't understand.
1. What exactly is this testing? Are they running the car at 825 rpm and killing the injector on one cylinder at a time?
2. What does a negative vs. a positive rpm mean? If the previous is correct, as they cut off the injector to a cylinder is this the change in overall engine rpm. example, when #4 was killed, the rpm went up to 1130?
3. "I consider if all are 50-65 or 65-75 or 75-87 or 87-100 to be perfect. I always repeat the test once or twice and average the average results." If I read this right, you would like to see all the cylinders read -50 to -65, just to use one of your examples, is this correct?
4. "Obviously a totally dead cylinder or 7 cylinder V8 would/could still produce at least 75% of rated full power if you could stand the vibration." If I have a dead cylinder my Q is giving none of these indications. It really does idle very smooth at about 750 and there is no vibrations at any rpm.
5. Finally, this test was done after the MAF reground and before the O2 sensors being replaced. So this test was done on bad O2 sensors. (Sorry, after reading my post again I see that I did not get that in there.)
1. Cylinder 7 is fouled out (I hope and not the injector) and not running.2. It is time to change the plugs.3. It is time to clean the injectors, TB and plenum.
I checked the numbers again and they are exactly what is on the slip.
There are still some things I don't understand.
1. What exactly is this testing? Are they running the car at 825 rpm and killing the injector on one cylinder at a time?
2. What does a negative vs. a positive rpm mean? If the previous is correct, as they cut off the injector to a cylinder is this the change in overall engine rpm. example, when #4 was killed, the rpm went up to 1130?
3. "I consider if all are 50-65 or 65-75 or 75-87 or 87-100 to be perfect. I always repeat the test once or twice and average the average results." If I read this right, you would like to see all the cylinders read -50 to -65, just to use one of your examples, is this correct?
4. "Obviously a totally dead cylinder or 7 cylinder V8 would/could still produce at least 75% of rated full power if you could stand the vibration." If I have a dead cylinder my Q is giving none of these indications. It really does idle very smooth at about 750 and there is no vibrations at any rpm.
5. Finally, this test was done after the MAF reground and before the O2 sensors being replaced. So this test was done on bad O2 sensors. (Sorry, after reading my post again I see that I did not get that in there.)
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Normally the ecu looks at the coolant sensor temperature and the TPS voltage and separate closed throttle switch and selects an appropriate idle rpm.............lets say 650 rpm.
The ecu can change the injector time [1.9-2.3 milliseconds in 0.01 millisec steps], or change the ignition advance [+- from the static 15 deg] or command the IAC to add or subtract TB BYPASS AIR. ALL these things to keep the idle RPM constant at 650 rpm.
When the Consult does the Power Balance test, the IAC is commanded wide open 100% vs the more normal 10-20% thus the rpm goes up to 1000-1400 rpm [reason for variance between engines is exact amount of air and compression, fuel BTU and temperature]. The timing and injector pulse width is locked so O2 doesn't matter!
If a cylinder is not firing it is creating a frictional drag on the whole engine, worse raw fuel is injected that must be compressed with the air so a non firing cylinder in a power balance will create negative numbers.....the rpm actually goes up when the fuel is shut off to that cylinder! Less work to move the piston up and down.
We don'y have a Consult II only 3 Consult I , it seems from your description that the technican is not using the automatic POWER BALANCE TEST MODE but the manual test mode which I don't like, the automatic is much more accurate........
825 rpms is too low to be doing the power balance test for precise accuracy........of course if everything is so dirty that thats the rpm you get, clean everything untill you get at least 1,000 rpms.
Am I mising something what is the Master Techs recommendation or are you doing the testing.
Are you sure you know the correct engine vibration level? A perfect engine cannot be felt running [at 650 rpm idle] with your hand on the plenum centor top......no vibration period not a drop...........the injector clacking sounds sometimes confuse.
Motor mounts need changing around 120k to minimize vibration.
There is a thousand page 5" thick manual for the Consult system please read twice before using the device.
The ecu can change the injector time [1.9-2.3 milliseconds in 0.01 millisec steps], or change the ignition advance [+- from the static 15 deg] or command the IAC to add or subtract TB BYPASS AIR. ALL these things to keep the idle RPM constant at 650 rpm.
When the Consult does the Power Balance test, the IAC is commanded wide open 100% vs the more normal 10-20% thus the rpm goes up to 1000-1400 rpm [reason for variance between engines is exact amount of air and compression, fuel BTU and temperature]. The timing and injector pulse width is locked so O2 doesn't matter!
If a cylinder is not firing it is creating a frictional drag on the whole engine, worse raw fuel is injected that must be compressed with the air so a non firing cylinder in a power balance will create negative numbers.....the rpm actually goes up when the fuel is shut off to that cylinder! Less work to move the piston up and down.
We don'y have a Consult II only 3 Consult I , it seems from your description that the technican is not using the automatic POWER BALANCE TEST MODE but the manual test mode which I don't like, the automatic is much more accurate........
825 rpms is too low to be doing the power balance test for precise accuracy........of course if everything is so dirty that thats the rpm you get, clean everything untill you get at least 1,000 rpms.
Am I mising something what is the Master Techs recommendation or are you doing the testing.
Are you sure you know the correct engine vibration level? A perfect engine cannot be felt running [at 650 rpm idle] with your hand on the plenum centor top......no vibration period not a drop...........the injector clacking sounds sometimes confuse.
Motor mounts need changing around 120k to minimize vibration.
There is a thousand page 5" thick manual for the Consult system please read twice before using the device.