Idle problems....

[radioman310]

My car was lumpy and lacking low down power, worse when warm so replaced the CTS, no difference. I also removed the EGR, blanked it off and added the EGR cheater... no difference. Was not getting any EML so looked at throttle body, it was filthy as was the inlet manifold. Removed both and cleaned with carb cleaner. All looking good so fitted back on. Now have worse issues. OK when cold but after a short time as it warms up the idle is too high, it throws up this code:

P0507 - Idle Control System RPM Higher Than Expected
(00) - Present

When that happens the revs rise and drop like blipping the pedal, clear the code and the idle speed rises again to around 1400 rpm and after 30 seconds or so the EML come on again with the same code. I didn't have this issue when the throttle body was dirty. I have checked all connections, there are no inlet or vacuum leaks so am now puzzled, another problem I can do without.
Attached is the latest live data and below is the measuring blocks info when the engine was warm with the EML on.
Any help on this appreciated.

Measuring blocks information:

Battery Voltage 14.0 V
Main Relay Active
Fuel Pump Relay Active
APP Sensor 1 (Accelerator Pedal Position) 0.98 V
APP Sensor 2 (Accelerator Pedal Position) 4.51 V
Calculated Pedal Position 0%
APP at Idle Position (Accelerator Pedal Position) Active
TP Sensor 1 (Throttle Position) 4.37 V
TP Sensor 2 (Throttle Position) 0.65 V
Calculated Throttle Position 1%
Throttle Position Idle
Engine Speed 1.420 RPM
MAP Sensor (Manifold Absolute Pressure) 0.90 V
MAP Sensor (Manifold Absolute Pressure) 27 kPa
Coolant Temperature 1.89 V
Coolant Temperature 93 °C
Intake Air Temperature 1.82 V
Intake Air Temperature 30 °C
A/C Information Switch (Air Conditioning) Inactive
Brake Switch 1 Inactive
Brake Switch 2 Inactive
Clutch Switch Inactive
Vehicle Speed 0 km/h
Cruise Control Tip Switch Not Programmed
Cruise Control Not Programmed
Vehicle Speed in Cruise Control Range Inactive
EGR Valve (Exhaust-Gas Recirculation) Inactive
EGR Position Command (Exhaust- Gas Recirculation) 0%
EGR Position Feedback (Exhaust Gas Recirculation) 1.14 V
Fuel Tank Ventilation Valve 0%
Knock Control Inactive
B1S1 O2 Sensor Heater (Bank 1 Sensor 1) Active
B1S1 O2 Sensor (Bank 1 Sensor 1) 850 mV
B1S1 Air/Fuel Ratio (Bank 1 Sensor 1) Rich
B1S2 O2 Sensor Heater (Bank 1 Sensor 2) Active
B1S2 O2 Sensor (Bank 1 Sensor 2) 134 mV
B1S2 Air/Fuel Ratio (Bank 1 Sensor 2) Rich
B1 Long Term Fuel Trim (Bank 1) -1%
B1 Short Term Fuel Trim (Bank 1) 2%
Requested Torque (Traction Control) 400 Nm
A/C Relay (Air Conditioning) Inactive
A/C Cutoff Mode (Air Conditioning) System OK
Malfunction Indicator (MI) Off
Service Vehicle Soon (SVS) Indicator Off
Fan Relay 1 Inactive
Fan Relay 2 Inactive
Idle Speed Offset Inactive
Ignition Dwell Angle 0.2 ms
Ignition Spark Angle 11.7 °CA
B1 Knock Sensor Signal (Bank 1) 0.96 V
Knock Retard Cylinder 1 0 °CA
Knock Retard Cylinder 2 0 °CA
Knock Retard Cylinder 3 0 °CA
Knock Retard Cylinder 4 0 °CA
Ignition Status On 12V
ETC Limp Home Mode (Electronic Throttle Control) Inactive
Total Misfire 0
Crank Angle Sensing Error Learn Attempts 0
Fuel Tank Ventilation Valve Inactive
Tank Sensor 0.00 V
Tank Sensor 1 L

 

[MikeS]

either you have a massive airleak inside the inlet manifold or a faulty throttle body

your throttle position at idle should be closer to 7% at 800 rpm not 1% at 1400rpm

try another throttle bodyif that does not work and you are 100% sure no air leaks then move onto wiring / pedal position sensor / ecu

looks as if ecu is compensating rpm by trying reduce angle on throttle body as much as poss

try planting the accelerator pedal and watch the measuring blocks for throttle position sensor % - should hit 100% around 20% for 2500 rpm

obvious things to check are leaks where the brake vacuum hose enters the manifold and also the fuel vent pump is working correctly and not stuck open - hose running from airbox to side of throttle body

 

[radioman310]

OK thanks. I am convinced there are no air leaks so have another albeit used throttle body coming to see what happens. It is just annoying as cleaning the throttle body is supposed to make it idle and run better but this is definitely worse. I will try what you posted tomorrow regarding the the throttle position sensor and check again all of the air pipes, vacuum pipes etc... how do I check the fuel vent pump, is there a test on OPCOM I have missed or another way?
Thanks for your help so far, it is appreciated.

 

[radioman310]

Still could not find any leaks, I tried choking the throttle body with steel over the top, the idle did reduce but not by a great deal but it kept running, I then tried to rev it and it would not. I checked the measuring blocks and the pedal position moved as expected and measured with engine off also. Here are the snippets of data:

With engine on "as normal":

APP Sensor 1 (Accelerator Pedal Position) 0.98 V

APP Sensor 2 (Accelerator Pedal Position) 4.51 V

Calculated Pedal Position 0%

APP at Idle Position (Accelerator Pedal Position) Active

TP Sensor 1 (Throttle Position) 4.35 V

TP Sensor 2 (Throttle Position) 0.65 V

Calculated Throttle Position 1%

Throttle Position Idle

Engine Speed 1.231 RPM

At times the Throttle Position went from "Idle" to "partially open" even though I did not touch the pedal.

With engine off:

APP Sensor 1 (Accelerator Pedal Position) 0.98 V
APP Sensor 2 (Accelerator Pedal Position) 4.51 V
Calculated Pedal Position 0%
APP at Idle Position (Accelerator Pedal Position) Active
TP Sensor 1 (Throttle Position) 3.10 V
TP Sensor 2 (Throttle Position) 1.90 V
Calculated Throttle Position 21%
Throttle Position Idle
Engine Speed 0 RPM

I found one I did a week ago before cleaning the throttle body and this is it:

APP Sensor 1 (Accelerator Pedal Position) 0.98 V
APP Sensor 2 (Accelerator Pedal Position) 4.51 V
Calculated Pedal Position 0%
APP at Idle Position (Accelerator Pedal Position) Active
TP Sensor 1 (Throttle Position) 4.12 V
TP Sensor 2 (Throttle Position) 0.88 V
Calculated Throttle Position 7%
Throttle Position Idle
Engine Speed 815 RPM

See the 7% Calculated Throttle Position?
I can't see how cleaning this would have caused this problem but it seems to have.
I also noticed with the engine off and throttle fully open at 99 and 100% the measuring block went to "Invalid" on the screen, would that be normal?

 

[MikeS]

looks like you have buggered the throttle body


APP Sensor 1 (Accelerator Pedal Position) 0.98 V
APP Sensor 2 (Accelerator Pedal Position) 4.51 V
Calculated Pedal Position 0%
APP at Idle Position (Accelerator Pedal Position) Active
TP Sensor 1 (Throttle Position) 4.12 V
TP Sensor 2 (Throttle Position) 0.88 V
Calculated Throttle Position 7%
Throttle Position Idle
Engine Speed 815 RPM

this is spot on imo

you pedal is not being touched so zero but at idle it needs to allow air in so ecu adjust throttle position to obtain 800rpm

if you choke the engine of air then it will cut out so i dont know how well u stopped it from having air

 

[radioman310]

Yes the first readings are pretty good. I have no idea how it got buggered then, I took it off and cleaned it carefully with carb cleaner, just like I have with ones off the X20XEV engines I have had before. I have a second hand replacement on the way so see what that does. I cleaned this one since the idle was a little uneven as posted in my other thread and had a flat spot at low revs but now it is so much worse. Don't think I will clean the replacement, if it works I'll leave it be.

 

[MikeS]

if it works leave it alone m8

x20xev was funny - use to breath heavy as fark

 

[radioman310]

Oh yes, when it arrives I will fit it as is and hope for the best. Will update here when done. My wife's car is a 99 vec sri 140, I do like those engines.

 

[radioman310]

Well I found what was wrong and it seems my cleaning skills are OK after all, just my observation skills are poor..!
When I stripped it all down to clean the small "O" ring or gasket that goes on the EGR pipe that fits into the inlet manifold came off when I removed it and I missed that it was not on there. It was only after I did the test of choking the throttle body with steel (as you said MikeS) and it did not stall that I realised something is definitely amiss. After a quick search of the ground where I stripped it down I found the rubber gasket and fitted it back on the EGR pipe and it idles as normal now. Not done a reading yet but it is definitely better and how it should be.

Note to self: Must be more observant when stripping parts to ensure things don't fall off and get forgotten!

 

[MikeS]

good result m8

hasn't cost you an arm and leg to get fixed

 

[radioman310]

Absolutely not and it is better for that clean so all's well that ends well. Thanks for your help, it made me realise what happened in the end.

 

[MikeS]

no problem m8

have a look in the 'how to' section for my piece on permanently blanking off inlet manifold port for EGR

obviously you need to do the egr cheat & plate as well