wi3000gt
Probationary Member
- 2
- 0
- Nov 7, 2011
-
Glenwood City,
Wisconsin
First off sorry for the long post. I thought I would post a few lessons learned to hopefully help other newbies. These were all done in an effort to solve a nagging P0170 fuel trim malfunction. Keep in mind some of these issues are specific to the Eclipse Spyder 2.4 N/T. That is the main reason for the post since most the threads discuss other motors. My issue started as nuisance and then turned into a driveability issue coming off of idle.
1.) Step 1 was to retrieve the code. In my case the vehicle thought it was running lean. The long term fuel trim was maxed out at +12.5%.
2.) Reviewed the manual which stated the following possible causes:
-Volume air flow sensor output frequency
-Injector
-Fuel pressure
-Intake air leaks
-Engine coolant temperature sensor
-Intake air temperature sensor
-Barometric pressure sensor
-02 Sensor
-Exhaust manifold cracks
3.) Educational only - I had done exhaust work on the car and suspected that an exhaust leak was the culprit. It wasn't the problem but using sea-foam is a good way to detect exhaust leaks. By the way the reason an exhaust leak can cause a problem is because the O2 sensor is a differential sensor. Meaning it is measuring the difference between the oxygen outside the sensor and the oxygen in the exhaust pipe. An exhaust leak near the sensor reduces the measured difference and falsely indicates a rich condition (not enough oxygen in exhaust stream).
4.) Cleaned my injectors. Took them off the car, soaked the over night in chemtool b12, then using compressed air I forced cleaner through them. Note the 2.4 uses a higher resistance coil. I understand that the lower resistance injectors used in other DSM's can be damaged if you are not careful manually powering them. This made a slight improvement.
5.) Cleared code and minor improvements were made. I tested further and fuel pressure appeared to be the culprit. Using the test connector to power the pump I could not get above 40psi. After removing the pump and comparing pressure with the new one, I confirmed it was bad.
6.) Problem got worse. Driveability was consistently poor. Especially coming off idle and accellerating from a stop. Note: I believe this is specific to the 2.4. In the process of troubleshooting my fuel pump I used the test connector. This vehicle has a two terminal test connector. The documentation is a bit sketchy on the connector and I believe that I connected it backwards and damaged the "Fuel Consumption Unit". I was fortunate enough to find this post on a Montero site that help me find the problem.
7.) Car ran good for a while and then P0170 came back. I found another useful site on diagnosing the MAS: Part 1 -MAF Sensor Test. 2.4L, 3.0L Mitsubishi, Chrysler, Dodge
Between this procedure and data from my OBD scanner everything seemed OK. After driving a couple weeks I noticed the MIL light seemed to come and go based on air temperature. I retested and found that the MAS IAT (intake air temperature) sensor seemed to be reading about 20 degrees F higher than it should. Warmer air is less dense and so the ECU would incorrectly assume less air mass was entering the engine and create a lean condition. Slight driveability issues occured in cold weather. I searched this site and found the following post: http://www.dsmtuners.com/forums/tuning-engine-management/367614-datalogging-intake-temps-too-high.html#post152176844
I removed the MAS and tested the resistance between terminals 5 & 6. About 2.1 K Ohms. Using a brush and CRC MAF cleaner I carefully but thoroughly cleaned the thermistor only (CRC advises against cleaning Karman Vortex style sensors). After letting it dry I retested the resistance and it was 2.6 K Ohms.
I don't want to get into a big debate but I will throw out a word of caution: This car came with a K&N filter. I bought the K&N recharge kit. Cleaned it exactly as described, used the exact amount of oil and applied it as specified. Despite my attention to detail, it is my belief that the oil in the filter is the cause of my contamination on the thermistor. My son is a Ford mechanic and he also see's failures related to oil contamination on the diesel trucks. His biggest gripe though is that his customers brag about the lifetime high flow K&N filter but NEVER clean them!
In summary all three of my issues resulted in a lean condtion. Low fuel pressure due to fuel pump failing. Low fuel pressure due to damaged fuel consumption unit after entering closed loop (unique to spyder 2.4L). Lean condition due to inaccurate intake air temperature resulting in improper air mass calculation.
I hope this post can help a fellow DSM'er.
1.) Step 1 was to retrieve the code. In my case the vehicle thought it was running lean. The long term fuel trim was maxed out at +12.5%.
2.) Reviewed the manual which stated the following possible causes:
-Volume air flow sensor output frequency
-Injector
-Fuel pressure
-Intake air leaks
-Engine coolant temperature sensor
-Intake air temperature sensor
-Barometric pressure sensor
-02 Sensor
-Exhaust manifold cracks
3.) Educational only - I had done exhaust work on the car and suspected that an exhaust leak was the culprit. It wasn't the problem but using sea-foam is a good way to detect exhaust leaks. By the way the reason an exhaust leak can cause a problem is because the O2 sensor is a differential sensor. Meaning it is measuring the difference between the oxygen outside the sensor and the oxygen in the exhaust pipe. An exhaust leak near the sensor reduces the measured difference and falsely indicates a rich condition (not enough oxygen in exhaust stream).
4.) Cleaned my injectors. Took them off the car, soaked the over night in chemtool b12, then using compressed air I forced cleaner through them. Note the 2.4 uses a higher resistance coil. I understand that the lower resistance injectors used in other DSM's can be damaged if you are not careful manually powering them. This made a slight improvement.
5.) Cleared code and minor improvements were made. I tested further and fuel pressure appeared to be the culprit. Using the test connector to power the pump I could not get above 40psi. After removing the pump and comparing pressure with the new one, I confirmed it was bad.
6.) Problem got worse. Driveability was consistently poor. Especially coming off idle and accellerating from a stop. Note: I believe this is specific to the 2.4. In the process of troubleshooting my fuel pump I used the test connector. This vehicle has a two terminal test connector. The documentation is a bit sketchy on the connector and I believe that I connected it backwards and damaged the "Fuel Consumption Unit". I was fortunate enough to find this post on a Montero site that help me find the problem.
In my similar experience, my son left lights on and drained battery of 2000 Mitsubishi Montero Sport (3.0)
He must have reversed leads initially when he went to charge battery. This must be common scenario that may burn open the 100 amp fuse link and burns out the Fuel Consumption Unit, Mits part# MR239764.
Car goes into rough stall after warming up. For detailed people, when the car goes into closed loop after hitting certain temp (150F I believe) the computer calls for fuel increase (~25%) since car goes lean but no reponse from car. Checked out many things but couldn't ID problem.
Saw similar symptoms in this email thankfully and replaced Fuel Consumption unit. Fixed the problem.
Part is located inside car behind right most panel cover near passenger's feet. 2 plastic black "screws" hold it in place. Fuel Consumption Unit has chrome/silver cover.
1st clue was this part was very hot to the touch. Next to several wires so it didn't make sense why it could run so hot. Looked it up on internet and ran into this site. Best thing I did.
Relacement part did not run hot, warm at best.
One last thing, dealer wanted $260+ for replacement part but we went to nearby junk yard and picked up used part for $2.20! Part is same for several year models 1997+ apparently.
Hope this site helps others like it did myself.
Montero Sport Online Forum - Stalling problem fixed. Thanks Joel!!!
The symptoms in this post described my problem exactly. I found the part for $60 at a yard (including shipping and warranty). I used CAPS to determine what models use this part and contacted several yards. I had to be very specific with them about the description and location of the part because it isn't in their systems. Mine came out of a Montero.He must have reversed leads initially when he went to charge battery. This must be common scenario that may burn open the 100 amp fuse link and burns out the Fuel Consumption Unit, Mits part# MR239764.
Car goes into rough stall after warming up. For detailed people, when the car goes into closed loop after hitting certain temp (150F I believe) the computer calls for fuel increase (~25%) since car goes lean but no reponse from car. Checked out many things but couldn't ID problem.
Saw similar symptoms in this email thankfully and replaced Fuel Consumption unit. Fixed the problem.
Part is located inside car behind right most panel cover near passenger's feet. 2 plastic black "screws" hold it in place. Fuel Consumption Unit has chrome/silver cover.
1st clue was this part was very hot to the touch. Next to several wires so it didn't make sense why it could run so hot. Looked it up on internet and ran into this site. Best thing I did.
Relacement part did not run hot, warm at best.
One last thing, dealer wanted $260+ for replacement part but we went to nearby junk yard and picked up used part for $2.20! Part is same for several year models 1997+ apparently.
Hope this site helps others like it did myself.
Montero Sport Online Forum - Stalling problem fixed. Thanks Joel!!!
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7.) Car ran good for a while and then P0170 came back. I found another useful site on diagnosing the MAS: Part 1 -MAF Sensor Test. 2.4L, 3.0L Mitsubishi, Chrysler, Dodge
Between this procedure and data from my OBD scanner everything seemed OK. After driving a couple weeks I noticed the MIL light seemed to come and go based on air temperature. I retested and found that the MAS IAT (intake air temperature) sensor seemed to be reading about 20 degrees F higher than it should. Warmer air is less dense and so the ECU would incorrectly assume less air mass was entering the engine and create a lean condition. Slight driveability issues occured in cold weather. I searched this site and found the following post: http://www.dsmtuners.com/forums/tuning-engine-management/367614-datalogging-intake-temps-too-high.html#post152176844
I removed the MAS and tested the resistance between terminals 5 & 6. About 2.1 K Ohms. Using a brush and CRC MAF cleaner I carefully but thoroughly cleaned the thermistor only (CRC advises against cleaning Karman Vortex style sensors). After letting it dry I retested the resistance and it was 2.6 K Ohms.
I don't want to get into a big debate but I will throw out a word of caution: This car came with a K&N filter. I bought the K&N recharge kit. Cleaned it exactly as described, used the exact amount of oil and applied it as specified. Despite my attention to detail, it is my belief that the oil in the filter is the cause of my contamination on the thermistor. My son is a Ford mechanic and he also see's failures related to oil contamination on the diesel trucks. His biggest gripe though is that his customers brag about the lifetime high flow K&N filter but NEVER clean them!
In summary all three of my issues resulted in a lean condtion. Low fuel pressure due to fuel pump failing. Low fuel pressure due to damaged fuel consumption unit after entering closed loop (unique to spyder 2.4L). Lean condition due to inaccurate intake air temperature resulting in improper air mass calculation.
I hope this post can help a fellow DSM'er.
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