help with some DTCs and stall
03-07-2007, 06:06 PM
#1
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help with some DTCs and stall
My car has had a problem with running for about 3 months now(winter time, it is a DD but i have a backup) so i have been trying to fix it gradually.
The car runs good for a little while(5-10) minutes, and then randomly the car will give out. Pretty much what happens is the car loses power and slows down untill stall. Gas pedal does nothing at all, not even a little power if its floored. Now sometimes it will come back after a few seconds and the gas pedal will work and it will drive away fine. Since the car is standard, when it does this its running off the transmission, what im saying is if i press the clutch down while its lost the power, the car will shut off immediately. I have no SES light on nor have i ever. This happens randomly, every 1-10 minutes after its warmed up. It also happens any time at all, whether im stopped at a light or doing 80 on the highway. The problem is worse in the cold, like today it was 8 degrees and it was awful. But once the weather goes above 50-60 the car will not stall at all and wont give me any problems. Now i just got my autoxray 5000 in today and i pulled these 2 codes.
34 MAP signal too low
48 MAF sensor circuit
Now the MAF is new as of less than a year ago. Since it is a circuit fault im not sure where to go from here. I can tell the pigtail on the MAF was replaced by the previous owner because it has been cut and rewired together. Now i checked the voltage readings on the connector about a month ago and they were correct.
When running in operational data mode on the scanner, it shows the MAP sensor at 0.01 V. That isnt correct is it? Someone had posted what that value should be a while back but i dont remember it being that low. The connector here too looks old and weared. Wires seem to be in decent shape but the connector has seen its better days(locking clips broke off).
Any idea on what i can do to fix these 2 codes? and do these 2 make any sense on why my car is acting the way it is?
The car runs good for a little while(5-10) minutes, and then randomly the car will give out. Pretty much what happens is the car loses power and slows down untill stall. Gas pedal does nothing at all, not even a little power if its floored. Now sometimes it will come back after a few seconds and the gas pedal will work and it will drive away fine. Since the car is standard, when it does this its running off the transmission, what im saying is if i press the clutch down while its lost the power, the car will shut off immediately. I have no SES light on nor have i ever. This happens randomly, every 1-10 minutes after its warmed up. It also happens any time at all, whether im stopped at a light or doing 80 on the highway. The problem is worse in the cold, like today it was 8 degrees and it was awful. But once the weather goes above 50-60 the car will not stall at all and wont give me any problems. Now i just got my autoxray 5000 in today and i pulled these 2 codes.
34 MAP signal too low
48 MAF sensor circuit
Now the MAF is new as of less than a year ago. Since it is a circuit fault im not sure where to go from here. I can tell the pigtail on the MAF was replaced by the previous owner because it has been cut and rewired together. Now i checked the voltage readings on the connector about a month ago and they were correct.
When running in operational data mode on the scanner, it shows the MAP sensor at 0.01 V. That isnt correct is it? Someone had posted what that value should be a while back but i dont remember it being that low. The connector here too looks old and weared. Wires seem to be in decent shape but the connector has seen its better days(locking clips broke off).
Any idea on what i can do to fix these 2 codes? and do these 2 make any sense on why my car is acting the way it is?
03-08-2007, 03:23 PM
#3
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You have more than just a 34 & 48
Does your SES cycle on and off at key on? Both DTC's will set the SES. So you have another problem. If it were a simple matter of the light out, you would get a DTC 11.
The next thing you want to do after checking the function of the SES light is to remove the map sensor connector and jump the grey to the light green wire at the connector. Now see if the map voltage reading is over 4.7 volts. If it is not, measure the grey to the black wire to see if you have 5 volts.
Coincidentally, both signals go to the PCM on the black connector. May want to look at B29 and B19 at the PCM for any problems. Anyone remove the connector at the PCM lately?
The next thing you want to do after checking the function of the SES light is to remove the map sensor connector and jump the grey to the light green wire at the connector. Now see if the map voltage reading is over 4.7 volts. If it is not, measure the grey to the black wire to see if you have 5 volts.
Coincidentally, both signals go to the PCM on the black connector. May want to look at B29 and B19 at the PCM for any problems. Anyone remove the connector at the PCM lately?
Last edited by Guest47904; 03-08-2007 at 03:34 PM.
03-08-2007, 04:16 PM
#4
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SES light never comes on, not even at the turn of key. I didnt get dtc 11 when i pulled my codes with this scanner. but i have gotten dtc 11 two times when having two different shops pull them. Im not sure why it didnt pull 11 this time.
ill have to wait till tomorrow to bring my multimeter home from school and check the measurings.
And yes i removed my PCM to check connections, but this was after i got these codes. b29 and b19 are connection pins right? should i be looking for just bad connections?
ill have to wait till tomorrow to bring my multimeter home from school and check the measurings.
And yes i removed my PCM to check connections, but this was after i got these codes. b29 and b19 are connection pins right? should i be looking for just bad connections?
03-10-2007, 07:19 AM
#5
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Check the SES lamp circuit
To test the SES lamp circuit, pull the blue connector off the PCM. on the 9th pin there is a brown/white wire. Jump that 9th pin to ground with the key on. If the light comes on, the PCM is bad. If it doesn't, the circuit is bad. First check the I/p fuse box, a 10amp fuse number 9.
If the fuse is ok, move over to the RH kick panel. Find the blue 10 pin connector and jump ground to the brown/white wire while the key is on. If the light comes on now, you know the problem is between the blue PCM connector and the 10pin connector behind the RH kick panel.
If it still doesn't come on, you have to get to the bulb and confirm 12 volts is getting to it with key on.
I suspect the PCM is defective since you have no SES and a MAP and a MAF code but you need to prove me wrong by checking the wiring FIRST.
If the fuse is ok, move over to the RH kick panel. Find the blue 10 pin connector and jump ground to the brown/white wire while the key is on. If the light comes on now, you know the problem is between the blue PCM connector and the 10pin connector behind the RH kick panel.
If it still doesn't come on, you have to get to the bulb and confirm 12 volts is getting to it with key on.
I suspect the PCM is defective since you have no SES and a MAP and a MAF code but you need to prove me wrong by checking the wiring FIRST.
03-11-2007, 02:56 PM
#6
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alright back with some results
MAP volt readings
grey to light green: 4.99 V
grey to black: 5.02 V
Checked pins and connections on the black connector to the PCM, they look fine.
I jumped the 9th pin on the Blue connector to ground and the SES light did NOT come on.
Gauge fuse #9 10 amp, OK
I didnt know where to look exactly when you said to check the 10 pin connector in the RH kick panel, i gotta remove the panel to get to this no?
After i did some checks i ran my car again, removed the DTCS and checked for new ones. No trouble codes came up, however MAF is showing up in history.
I went into operational data on my scanner while the car was running and watched some readings. Map sensor reading is 1.2 v (the other day it was reading 0.01 V). MAF is reading 471 gr/sec. I waited for the car to go into closed loop to see if it would change(because the car seems to stall after it goes into closed loop) but it did not change and the readings stayed the same.
To add to this my car was stalling all last week and up until friday it was in the single digits. Yesterday and today the weather is in the 50-60s and the car is running beautiful with no stall. Does this prove my suspicion of my car having problems only in the cold? I do not get trouble codes for the MAP when it is warm and the voltage readings seem alot more accurate to what they should be when it is warm out. Again that voltage reading of the MAP at 0.01 volts was in single digit weather.
MAP volt readings
grey to light green: 4.99 V
grey to black: 5.02 V
Checked pins and connections on the black connector to the PCM, they look fine.
I jumped the 9th pin on the Blue connector to ground and the SES light did NOT come on.
Gauge fuse #9 10 amp, OK
I didnt know where to look exactly when you said to check the 10 pin connector in the RH kick panel, i gotta remove the panel to get to this no?
After i did some checks i ran my car again, removed the DTCS and checked for new ones. No trouble codes came up, however MAF is showing up in history.
I went into operational data on my scanner while the car was running and watched some readings. Map sensor reading is 1.2 v (the other day it was reading 0.01 V). MAF is reading 471 gr/sec. I waited for the car to go into closed loop to see if it would change(because the car seems to stall after it goes into closed loop) but it did not change and the readings stayed the same.
To add to this my car was stalling all last week and up until friday it was in the single digits. Yesterday and today the weather is in the 50-60s and the car is running beautiful with no stall. Does this prove my suspicion of my car having problems only in the cold? I do not get trouble codes for the MAP when it is warm and the voltage readings seem alot more accurate to what they should be when it is warm out. Again that voltage reading of the MAP at 0.01 volts was in single digit weather.
Last edited by dfa_crunch; 03-11-2007 at 03:02 PM.
03-11-2007, 03:10 PM
#7
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Check the harness connector for the MAP sensor. They dry out and crumble, causing intermittent MAP sensor readings. 1.2V corresponds to the MAP reading you would expect to see on a stock LT1... something in the range of 9.5"Hg. The 0.01V reading would indicate that there is a full vacuum (30"Hg) in the manifold, and that't not possible. Jiggle the connector while watching your scanner.
471gps is the reading you will get from the PCM when the MAF sensor is not connected. Its an open circuit. Check the harness connector for the MAF sensor, looking for damaged pins. Check for +12V on the pink wire in the connector, with the key on.
471gps is the reading you will get from the PCM when the MAF sensor is not connected. Its an open circuit. Check the harness connector for the MAF sensor, looking for damaged pins. Check for +12V on the pink wire in the connector, with the key on.
03-11-2007, 06:16 PM
#8
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well the connector on for the MAP sensor looks to be in very bad shape, clip on the connector is broke, and pretty much dryed and old like you said. ill have to check the readings again tomorrow. As for the MAF sensor, it looks to me that the pigtail was changed out because the wires are snipped and a new one is wired back on(maybe last owner tryed to change the pigtail to fix it). But when i checked the voltage readings on that connector they were correct. It was a little while ago though so I will check again tomorrow to be absolutely sure. The MAF is new as of 8 months ago, when i replaced it pretty much every pin was broken off of it.
03-12-2007, 02:51 PM
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i moved the connector on the MAP around while running in operational mode, no change to the voltage reading at all. Checked the MAF pins look brand new still, checked voltage reading on the connector, 12 volts on pink and 5 volts on the other side.
btw, The car is still not throwing the DTC 34, and is only throwing dtc 48 as a history code and not a current code. 471gps still there though
btw, The car is still not throwing the DTC 34, and is only throwing dtc 48 as a history code and not a current code. 471gps still there though
03-12-2007, 03:47 PM
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i have, ive been clearing them periodically to see if anything changes. cleared them while moving the MAP sensor connector around. only results were the Fans shut off for about 3-5 seconds and then came back on. 48 stays in history codes. clearing all codes would clear history and current right?
03-14-2007, 07:12 AM
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That would be an active code. While this code is active, the PCM will default to speed density mode. At this point you have to be sure the MAF is responding properly.
1) You need to check the signal from the MAF with a DVM that reads frequency. When checking the yellow wire to ground, engine running, snap the throttle and be sure you get a reading over 7KHz on the meter.
2) Check to see if the PCM is showing the proper reading from the MAF.
3) Ohm the wiring from the MAF to the PCM. IF the MAF checks out ok and the wiring ohms out ok but the PCM does not report the proper readings, the PCM is bad.
1) You need to check the signal from the MAF with a DVM that reads frequency. When checking the yellow wire to ground, engine running, snap the throttle and be sure you get a reading over 7KHz on the meter.
2) Check to see if the PCM is showing the proper reading from the MAF.
3) Ohm the wiring from the MAF to the PCM. IF the MAF checks out ok and the wiring ohms out ok but the PCM does not report the proper readings, the PCM is bad.
03-14-2007, 09:29 AM
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Ill have to make the measurements this evening, my meter is in my lab going to get it later.
To see if the PCM is showing the proper reading, is that the grs im getting from my scanner? or must i check it another way.
as for 3, are you talking about disconnecting a connector to the PCM and measuring the resistance through the wire to the MAF? if so do you know which pin on which connector it is? also what measurement am i looking for?
To see if the PCM is showing the proper reading, is that the grs im getting from my scanner? or must i check it another way.
as for 3, are you talking about disconnecting a connector to the PCM and measuring the resistance through the wire to the MAF? if so do you know which pin on which connector it is? also what measurement am i looking for?