Hi everyone,I was hoping some of the forum members could help me out with an issue I'm having. The car is. 95 nsxt with a sos supercharger with an aem fic.As of recently I noticed the vehicle running extremely rich and would often not start the following day. So I would have to change the spark plugs in order to get the car to start again. However, the other day the vehicle was idling in the garage getting ready to take her out for a spin and the car just shut off and would not crank again.Since then I have changed the spark plugs (ngk bkr7e), new main relay, new ignition switch and new igniter all with no luck. The car has fuel, fuel pump is working. I have no spark to any of the coils.So I figured maybe it's the FIC so I disconnected the harness to fic and plugged it back into just the factory Ecu. Still nothing.Mechanic mentioned maybe cam or crank sensor not sure if that makes sense though. Anyone have input?Thanks,
HELP!! Car won't start - supercharged
- Thread starter Bigren
- Start date
You said the car 'would not crank again'. Most people understand the word 'crank' to mean the starter motor engaging and turning the engine crankshaft. So, do you mean that the starter motor won't crank the engine or do you mean that the starter is engaging; but, the engine is failing to start running on its own? Its an important distinction because the causes of the problem are typically different.
Based upon your description of the things you have tried, I am going to guess that the motor is cranking; but, not starting. On that basis, you have hit just about all of my suggestions as likely candidates, in particular the FIC since there was a recent case on Prime where the problem was a failed FIC on a comptech installation. If you have by-passed the FIC and nothing is happening, then you have addressed that issue.
You said the fuel pump is working. Did you do this by testing the fuel pump or did you hear the fuel pump go through its 2 second prime cycle when you first turned the ignition key to the run position (not start). If you confirmed this by listening for the fuel pump prime, that is good because it confirms that the fuel pump is running and the ECU is getting powered up and is at least partially alive (the part that controls the pump). If you did a separate fuel pump test, do the 'turn to start' test and listen for the fuel pump to prime. You will probably need to open the driver door and listen down by the driver side rear wheel. Unless your pump is getting old, an OEM pump can be hard to hear particularly with a full tank of gas. If the pump does not go through the 2 second prime, check to see if the MIL light comes on briefly when you first turn the key to the run position. The MIL light coming on is part of the ECUs self check procedure. If the MIL light does not come on, the ECU is not powering up or there is a problem with the ECU - that would be rare.
If the ECU seems to be working, the next thing I would do is to check for stored error codes in the ECU. Your car is '95 so it should be OBDII so you can use a code scanner or you can use the service check connector and count the flashes to determine the error code. A failed crank / cam position sensor would certainly leave you dead in the water with no ignition and no injector pulses. A failed crank / cam position sensor should generate the appropriate error code. NSX crank / cam positioners always seem to look like they are ready to die because they ooze gooey potting compound; but, they don't die from that. They seem to be very reliable. What does kill them is somebody pinching the wires from the sensor after some maintenance has been done. Again, that should show up as an error code.
If you have no spark when cranking the engine, check to make sure that you are getting 12 v at each coil connector when the ignition is switched to run. No voltage could indicate a blown fuse for the coils or a wiring problem. You will need to get a service manual to find the appropriate terminal in each coil connector to test for voltage.
Do all your testing with the FIC disconnected just so that you can eliminate it as a possible cause.
You talked about the car running extremely rich. Normally that would trigger error codes - mixture out of range. Do any of those codes show up on a scanner or when you use the service check connector? One cause of running really rich is fuel pressure that is too high. If the fuel pressure is really high, you can be dumping too much fuel in during the start cycle which would make starting difficult. If this were happening you would typically smell the fuel in the exhaust system. If this is the case, then I suggest a static fuel pressure test (has to be static since the engine isn't operational) to see if the fuel pressure is even in the right range. If the fuel pressure is really out of spec I suggest doing an oil change because you may have seriously contaminated the oil with fuel in addition to washing all the oil off the cylinder walls. Seven years ago at 65,000 miles the spark plugs on my car came out pretty much sparkly clean. Any fuel mixture issue that so contaminates the spark plugs on an NSX that you are having to change them regularly to get the car to start is a sign of a serious underlying issue - or a really bad set-up on the FIC. That said, high fuel pressure would not cause an ignition failure so you may have multiple factors contributing to your problems.
Based upon your description of the things you have tried, I am going to guess that the motor is cranking; but, not starting. On that basis, you have hit just about all of my suggestions as likely candidates, in particular the FIC since there was a recent case on Prime where the problem was a failed FIC on a comptech installation. If you have by-passed the FIC and nothing is happening, then you have addressed that issue.
You said the fuel pump is working. Did you do this by testing the fuel pump or did you hear the fuel pump go through its 2 second prime cycle when you first turned the ignition key to the run position (not start). If you confirmed this by listening for the fuel pump prime, that is good because it confirms that the fuel pump is running and the ECU is getting powered up and is at least partially alive (the part that controls the pump). If you did a separate fuel pump test, do the 'turn to start' test and listen for the fuel pump to prime. You will probably need to open the driver door and listen down by the driver side rear wheel. Unless your pump is getting old, an OEM pump can be hard to hear particularly with a full tank of gas. If the pump does not go through the 2 second prime, check to see if the MIL light comes on briefly when you first turn the key to the run position. The MIL light coming on is part of the ECUs self check procedure. If the MIL light does not come on, the ECU is not powering up or there is a problem with the ECU - that would be rare.
If the ECU seems to be working, the next thing I would do is to check for stored error codes in the ECU. Your car is '95 so it should be OBDII so you can use a code scanner or you can use the service check connector and count the flashes to determine the error code. A failed crank / cam position sensor would certainly leave you dead in the water with no ignition and no injector pulses. A failed crank / cam position sensor should generate the appropriate error code. NSX crank / cam positioners always seem to look like they are ready to die because they ooze gooey potting compound; but, they don't die from that. They seem to be very reliable. What does kill them is somebody pinching the wires from the sensor after some maintenance has been done. Again, that should show up as an error code.
If you have no spark when cranking the engine, check to make sure that you are getting 12 v at each coil connector when the ignition is switched to run. No voltage could indicate a blown fuse for the coils or a wiring problem. You will need to get a service manual to find the appropriate terminal in each coil connector to test for voltage.
Do all your testing with the FIC disconnected just so that you can eliminate it as a possible cause.
You talked about the car running extremely rich. Normally that would trigger error codes - mixture out of range. Do any of those codes show up on a scanner or when you use the service check connector? One cause of running really rich is fuel pressure that is too high. If the fuel pressure is really high, you can be dumping too much fuel in during the start cycle which would make starting difficult. If this were happening you would typically smell the fuel in the exhaust system. If this is the case, then I suggest a static fuel pressure test (has to be static since the engine isn't operational) to see if the fuel pressure is even in the right range. If the fuel pressure is really out of spec I suggest doing an oil change because you may have seriously contaminated the oil with fuel in addition to washing all the oil off the cylinder walls. Seven years ago at 65,000 miles the spark plugs on my car came out pretty much sparkly clean. Any fuel mixture issue that so contaminates the spark plugs on an NSX that you are having to change them regularly to get the car to start is a sign of a serious underlying issue - or a really bad set-up on the FIC. That said, high fuel pressure would not cause an ignition failure so you may have multiple factors contributing to your problems.
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Hi old guy,
appreciate your post, was extremely helpful in diagnosing the issue at hand.
the car was indeed cranking but not firing up as you stated. The issue has now been resolved. It seems to have been a bad ground. The mechanic said that whomever installed the supercharger did not ground the unit. Do to the relocation of the ignitor on top of the supercharger it seems that unit was lent grounded properly causing issues.
i'm hoping this is also the reason the car was running rich all the time perhaps not enough spark. Anyhow time will tell I suppose. Love nsx prime.
Old guy any thoughts as to whether a bad ground could possibly instill all the issues I was having?
Thanks
appreciate your post, was extremely helpful in diagnosing the issue at hand.
the car was indeed cranking but not firing up as you stated. The issue has now been resolved. It seems to have been a bad ground. The mechanic said that whomever installed the supercharger did not ground the unit. Do to the relocation of the ignitor on top of the supercharger it seems that unit was lent grounded properly causing issues.
i'm hoping this is also the reason the car was running rich all the time perhaps not enough spark. Anyhow time will tell I suppose. Love nsx prime.
Old guy any thoughts as to whether a bad ground could possibly instill all the issues I was having?
Thanks
95 ecu
Old guy,
The 1995 has an ODB2 ECU but no J1962 connector. The dealer is supposed to have areader/harness adapter but they didn't when I needed it. I know, had to wire one in to "talk" to the ECU. It only uses 4 of the 16 pins: Chassis ground, digital ground, 12+ and Data. Honda has their own choice of pins in the J1962 connector. SAE conection uses different pins. See http://www.nsxprime.com/photopost/g1233-anything-electrical.html
Oh dup, it's not there, will upload it when I get home
Stephen
Old guy,
The 1995 has an ODB2 ECU but no J1962 connector. The dealer is supposed to have areader/harness adapter but they didn't when I needed it. I know, had to wire one in to "talk" to the ECU. It only uses 4 of the 16 pins: Chassis ground, digital ground, 12+ and Data. Honda has their own choice of pins in the J1962 connector. SAE conection uses different pins. See http://www.nsxprime.com/photopost/g1233-anything-electrical.html
Oh dup, it's not there, will upload it when I get home
Stephen
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There are numerous ground points. Both on the engine and also from engine to chassis so it would be necessary to know which ground(s) got fixed. A bad ground can certainly cause a no start problem or misfires (corrosion on the grounds on the ignitor module is a classic case on the NSX). A poor quality ground can cause voltage offsets that could screw up a sensor reading leading to mixture problems. However, as far as I can remember all of the sensors on the NSX ECU have individual isolated ground returns so it should be relatively immune to that sort of problem. However, if the 'ground' fix makes the problem go away - embrace the love. That is probably a relatively inexpensive fix.
As an observation. I have never been super keen about washing the engine and front compartment. Once a year max. No point in introducing a bunch of moisture to support corrosion which can mess up those grounds. I read a lot of Kaz's blogs about the repairs that he does on cars in England and I am always amazed by the amount of surface corrosion that I see in his photos. Seems like those guys must be driving in a perpetual fog bank.
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