Not holding idle

RXtacy · 08-09-2008, 12:08 PM

First a little background. The FD was running great after a PFC tune from Ray Wilson. I got a set of underdrive pullies, so I install them. While I am doing that I do some cleaning around the engine bay with simple green. I get them installed, start the car and It doesn't hold idle. So I think it's just due to eliminating the air pump, so I reinstall stock pullies and airpump. Same thing happens. So I think maybe the simple green deteriorated a vacuum hose or somthing, they are silicone by the way. I pull the UIM and check the vacuum lines, everything appears to be in good shape. Reinstall UIM and still have problem. When I start the car it will crank, and fire, but it doesnt sound right. I can rev it to about 3k rpm but it will not go higher. Then as soon as I let off the gas it will just die. When it dies there is a sound of escaping air. The only other thing I can possibly think could be the problem would be the gasket between the UIM and LIM? Oh one more thing the wiring connector to the air pump shorted briefly during this process, but I checked all fuses and they are ok. Any advice would be greatly appreciated.

Dr-Rotor · 08-10-2008, 02:31 AM

Hmmmm.....interesting problem.

Since you have a PFC...do you have a hand controller? We can start by checking your TPS is at the right voltage. If you have a hand controller, go to the ECT screen then sensors....top left in the list of sensors you will see 3 or 4 abreviated things....the 2nd one down is the 1st TPS. It dose not say TPS but it is. Next to it there will be a number. This number is the voltage & it needs to be between 0.75 & 1.0 with ignition on & the car at operating temp but not running. If your numbers are correct, push the throttle all the way in & check to see the number increases to a 4.??. If the number highlights your TPS is seeing to many volts at full throttle.

So you will need to adjust it a little. The TPS is located behinde the throttle body. Its a black thing with a plug going into it. 1 screw at the top & 1 at the bottom. You will need a 90deg ratchet setup with a flathead drive. Once you loosen the TPS it can rotate, this will adjust the voltage. Get your wife or a friend to sit in the car & tell you if the numbers go up or down. Depending on what your problem is. IE: If your numbers are to high or low at temp with just the ignition on then adjust till you are in the range of 0.74 to 1.00. After that check you max by pushing the throttle in all the way...if the number highlights then you will need to lower the voltage untill it dose not.

This TPS voltage thing is some times the reason for not holding an idle after backing off the gas. I dont know why your car will not rev past 3k. When you shorted the airpump wires you may have blown & sensor and put the car into one of its limp modes that are designed to protect it. You will need the manual to figure out what sensor you have blown.

If it makes the escaping air noise when you have the airpump in that will be because the air it is blowing dose not go to a cat like it used to. That will be the noise you hear when it shuts off. The pump works at idel speeds.

RXtacy · 08-10-2008, 03:11 PM

I do have the commander. I took a picture of the sensor screen with the ignition in th on position, but it was with a cell phone and is difficult to read. The car was not at operating temp as it is difficult to keep it running for more then a few seconds, but VTA1 was .52V and VTA2 was 1.11V. However the first value on the list was highlighted. Does this mean that it is out of spec? I believe it says PIM? I can't read the value from the picture so I will have to go back and check. Thank you for your help.

Dr-Rotor · 08-10-2008, 05:10 PM

ooo yes...your pim is out then. Wow I have no idea how the hell you did that. PIM is your Boost VS RPM. You may have stuffed you PIM sensor when you sparked the air pump plug. This will explain the 3000rpm limit. PIM voltage needs to be a certain value too.

I will take a look at the manual tonight to see what it needs to be.

RXtacy · 08-11-2008, 03:42 PM

Ok, new revelations. I went back to the car today to take another look. When I first put the key to on I got a PIM voltage of 4.85 and it was highlighted. The values read as follows:
PIM 4.85
VTA1 .52
VTA2 1.11
VMOP .91
WTRT 2.28
AIRT 2.23
FUEL 3.82
O2S .01
I then pushed the pedal to the floor and
PIM 4.98
VTA1 4.39
VTA2 4.97
Everything else stayed the same. So I turned the car back to off, and checked out the MAP sensor, it seemed to be plugged in correctly, but I unplugged the wiring connector and reattached. I then went back and turned the key to on. Now the PIM read 3.32 and was no longer highlighted. I tried to start the car. I started and reved freer then before (would rev past 3k) but was still very lumpy and pouring smoke out the tail pipe. I held it at 3k rpms for a while thinking it might just be deposits built up from sitting and it would clear out. Continually smoked, but after would hold idle between 100-600 rpms. It would vibrate and smoke incessantly the entire time it was running. I have no idea what is going on at this point?

Phoenix7 · 08-11-2008, 03:56 PM

compression check came back ok?

RXtacy · 08-11-2008, 03:59 PM

I haven't done a compression check, but its a fresh rebuild with less the 4k on it and it was running great untill i started to take things apart lol.

Dr-Rotor · 08-11-2008, 06:39 PM

your idel is too slow....adjust it back to 900-1100 depending on porting.

Dr-Rotor · 08-11-2008, 06:43 PM

O & yea your PIM....had the incorrect voltage thats why it was highlighted. You VTA seems fine...leav it. Adjust your idel...check to see if the smoke goes away.

Did you let the car warm right up? Let it go to 80c..then check to see if it smokes.
Do you still have the airpump on or off? If on..unplug it if you have no Cat.

Check that you did not bump your crank angle sensor when you were washing the car...thats a killer as it will loose its timing & run like shit.

dregg100 · 08-12-2008, 12:19 AM

make sure the vac line that goes to the map sensor is plugged in and not leaking. that is exactly what this sounds like.

RXtacy · 08-12-2008, 02:13 PM

The Idle is set to 900 rpms that hasn't changed, the car just will not stay at that rpm by itself. It got to around 77C before i turned it off, barely running and smoking the whole time. The vacuum line was plugged into the map sensor, but I will check for leaks. The air pump is on and plugged in, I still have my main cat. I will have to look into the crank angle sensor, do you have a picture of where it is located by any chance?

Regards
Mike

Dr-Rotor · 08-13-2008, 03:16 PM

Was your pim still highlighted? If so you have a faulty pim sensor. You may have damaged it during the engine bay cleaning or got it too wet or that sparking on the airpump fucked it. Crank angel sensor is behind the crank pully. I dont think its that.

I think your pim is out some how & you need to get it hooked up to a Datalogit to see if its still on value 1 and not any of ther others. Also if its seen to high a volt from that spark that will do it to.

Do you have a stock map sensor? That may also be poked. 2 things to try...get hold of a nother pim & map sensor. Plug them in 1 at a time to see what happens. If the problem goes away it was the sensor.

If this dose not work then Unplug your TPS and see if it idels. We had a car once that had a TPS that just jumped around all over the place randomly with the vault reading & the car would not idle properly. It never highlighted on the PFC either. So we unpluged it and it just smoothed out right away.

08-11-2008, 06:43 PM	#9
Dr-Rotor Rotary Fan in Training Join Date: Aug 2008 Location: Auckland iTrader: (0) Posts: 70 Rep Power: 17	O & yea your PIM....had the incorrect voltage thats why it was highlighted. You VTA seems fine...leav it. Adjust your idel...check to see if the smoke goes away. Did you let the car warm right up? Let it go to 80c..then check to see if it smokes. Do you still have the airpump on or off? If on..unplug it if you have no Cat. Check that you did not bump your crank angle sensor when you were washing the car...thats a killer as it will loose its timing & run like shit. Last edited by Dr-Rotor; 08-11-2008 at 06:49 PM.. Reason: adding

08-12-2008, 12:19 AM	#10
dregg100 Rotary Fanatic Join Date: Feb 2008 iTrader: (2) Posts: 432 Rep Power: 17	make sure the vac line that goes to the map sensor is plugged in and not leaking. that is exactly what this sounds like. __________________ '93 SSM Touring-S475... '87 Tii-LS1/T56

08-10-2008, 02:31 AM	#2
Dr-Rotor Rotary Fan in Training Join Date: Aug 2008 Location: Auckland iTrader: (0) Posts: 70 Rep Power: 17	Hmmmm.....interesting problem. Since you have a PFC...do you have a hand controller? We can start by checking your TPS is at the right voltage. If you have a hand controller, go to the ECT screen then sensors....top left in the list of sensors you will see 3 or 4 abreviated things....the 2nd one down is the 1st TPS. It dose not say TPS but it is. Next to it there will be a number. This number is the voltage & it needs to be between 0.75 & 1.0 with ignition on & the car at operating temp but not running. If your numbers are correct, push the throttle all the way in & check to see the number increases to a 4.??. If the number highlights your TPS is seeing to many volts at full throttle. So you will need to adjust it a little. The TPS is located behinde the throttle body. Its a black thing with a plug going into it. 1 screw at the top & 1 at the bottom. You will need a 90deg ratchet setup with a flathead drive. Once you loosen the TPS it can rotate, this will adjust the voltage. Get your wife or a friend to sit in the car & tell you if the numbers go up or down. Depending on what your problem is. IE: If your numbers are to high or low at temp with just the ignition on then adjust till you are in the range of 0.74 to 1.00. After that check you max by pushing the throttle in all the way...if the number highlights then you will need to lower the voltage untill it dose not. This TPS voltage thing is some times the reason for not holding an idle after backing off the gas. I dont know why your car will not rev past 3k. When you shorted the airpump wires you may have blown & sensor and put the car into one of its limp modes that are designed to protect it. You will need the manual to figure out what sensor you have blown. If it makes the escaping air noise when you have the airpump in that will be because the air it is blowing dose not go to a cat like it used to. That will be the noise you hear when it shuts off. The pump works at idel speeds.

08-10-2008, 05:10 PM	#4
Dr-Rotor Rotary Fan in Training Join Date: Aug 2008 Location: Auckland iTrader: (0) Posts: 70 Rep Power: 17	ooo yes...your pim is out then. Wow I have no idea how the hell you did that. PIM is your Boost VS RPM. You may have stuffed you PIM sensor when you sparked the air pump plug. This will explain the 3000rpm limit. PIM voltage needs to be a certain value too. I will take a look at the manual tonight to see what it needs to be.

08-11-2008, 06:39 PM	#8
Dr-Rotor Rotary Fan in Training Join Date: Aug 2008 Location: Auckland iTrader: (0) Posts: 70 Rep Power: 17	your idel is too slow....adjust it back to 900-1100 depending on porting.

08-13-2008, 03:16 PM	#12
Dr-Rotor Rotary Fan in Training Join Date: Aug 2008 Location: Auckland iTrader: (0) Posts: 70 Rep Power: 17	Was your pim still highlighted? If so you have a faulty pim sensor. You may have damaged it during the engine bay cleaning or got it too wet or that sparking on the airpump fucked it. Crank angel sensor is behind the crank pully. I dont think its that. I think your pim is out some how & you need to get it hooked up to a Datalogit to see if its still on value 1 and not any of ther others. Also if its seen to high a volt from that spark that will do it to. Do you have a stock map sensor? That may also be poked. 2 things to try...get hold of a nother pim & map sensor. Plug them in 1 at a time to see what happens. If the problem goes away it was the sensor. If this dose not work then Unplug your TPS and see if it idels. We had a car once that had a TPS that just jumped around all over the place randomly with the vault reading & the car would not idle properly. It never highlighted on the PFC either. So we unpluged it and it just smoothed out right away.