Those look terrible lol. I'm curious to see how the car does now that they are clean.
-
Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.
Cranks but won't start
- Thread starter e9coupe
- Start date
I was glad to see bad numbers. I have plans tonight and almost feel like canceling just to test the injectors in the car.
Got the injectors in. Still runs like shite! Yippee. I have a fuel pressure gauge on the way to check pressure but... WTH.
Check the pressure to rule it out; but, sad to say it is probably time to revisit the valve timing.
I'm with @Old Guy. It really doesn't sound like a fuel issue, it is possible though unlikely.
Despite your leak down results I'd check the indexing of the crank and cams. Make double sure the crank is not 180 out of phase.
You can keep your gauge hooked up to the port on the fuel filter. Depending on tool config, if it has a long hose, you might consider taping it to the back window so you can watch what is going on from inside the car.
Verify your crank angle sensor. You might have to get "middle school" on it and get a data logging setup. MotorMouth has published a way to get/watch real time data.
Despite your leak down results I'd check the indexing of the crank and cams. Make double sure the crank is not 180 out of phase.
You can keep your gauge hooked up to the port on the fuel filter. Depending on tool config, if it has a long hose, you might consider taping it to the back window so you can watch what is going on from inside the car.
Verify your crank angle sensor. You might have to get "middle school" on it and get a data logging setup. MotorMouth has published a way to get/watch real time data.
To recap recent events... the motor was running decent but had the roughness that kind of showed in the video. I took it for a drive up and down the street and it ran the same in first gear and not under load. The first time I accelerated hard the motor misfired way worse, like it does now, and now misfires badly with or without load.
Since then I've rechecked timing marks, done a leak down, compression test (since I was already there), had the injectors cleaned/calibrated and made sure the battery cables were clean and connected well.
Heavy misfiring after a load could be fuel but I usually go to ignition first. There are six new coils and plugs, ignitor has been replaced and a friend probed the signals from the ECU on his hand scope and said it looked good. I'll look into the crank angle sensor procedure.
Since then I've rechecked timing marks, done a leak down, compression test (since I was already there), had the injectors cleaned/calibrated and made sure the battery cables were clean and connected well.
Heavy misfiring after a load could be fuel but I usually go to ignition first. There are six new coils and plugs, ignitor has been replaced and a friend probed the signals from the ECU on his hand scope and said it looked good. I'll look into the crank angle sensor procedure.
Last edited:
If you are absolutely 100% confident that the valve timing is not an issue then I would check the base ignition timing as per the service manual.
You can get tail pipe adapters for O2 sensors which allow you to sample on the go with a wide band sensor. Doing that might give you some idea as to whether you are having a fueling issue of some kind. You can also measure the voltage that that your existing narrow band sensors are reading; but, narrow band sensors are so no linear that it pretty much just tells you that you are above 14.7 or you are below 14.7. It would point out differences between the front and rear banks and would probably tell you whether you were really really lean.
You can get tail pipe adapters for O2 sensors which allow you to sample on the go with a wide band sensor. Doing that might give you some idea as to whether you are having a fueling issue of some kind. You can also measure the voltage that that your existing narrow band sensors are reading; but, narrow band sensors are so no linear that it pretty much just tells you that you are above 14.7 or you are below 14.7. It would point out differences between the front and rear banks and would probably tell you whether you were really really lean.
I have test pipes with an O2 sensor bung and a LM-1 for situations like this. This [prior to having kids] was part of my test rig for my CTSC.
This looks to be modern version as all my tools are now vintage.
www.innovatemotorsports.com
FYI, Legend injectors look the same as NSX but run super lean. I tried them initially when getting my original injectors cleaned and the NSX was my daily driver. I didn't get past the idle stage and just borrowed until my original injectors came back from RC.
This looks to be modern version as all my tools are now vintage.
LM-2: Handheld Digital Wideband Air/Fuel Ratio Meter & Datalogger, Single O2, Complete Kit
LM-2 AFR Kit w/case
www.innovatemotorsports.com
FYI, Legend injectors look the same as NSX but run super lean. I tried them initially when getting my original injectors cleaned and the NSX was my daily driver. I didn't get past the idle stage and just borrowed until my original injectors came back from RC.
This was the tail pipe adapter thing that I was thinking of which allows you to use any wide band sensor for tail pipe AFR measurements. Some of the tips on the NSX exhaust system that really flare out wide may render the adapter ineffective.
Fuel pressure is good so fuel is eliminated as the problem. I couldn't get an inductive timing light to work on the service loop yesterday. Any trick to it? I guess I should test the timing light on another motor just to make sure it's working.
I wonder if your ECU is bad?
The list is getting really short and that's on it.
If the engine is running, the ECU is definitely not 100% bad. If you have probed the injector and ignition outputs from the ECU and they all appear to be switching when the engine is running (no dead cylinders) then the probability weights on the side that the ECU is OK.
The ignition testing service loop is low voltage (12v) between the negative terminal of the #1 coil and the switching transistor in the ignitor. If you look at some inductive timing lights, specifically those meant to work by clamping the inductive pick up over the #1 high voltage lead between the distributor and spark plug, they will have an arrow on the pick up indicating that it should be pointed at the spark plug. The triggering circuit in some timing lights is sensitive to the orientation of how the pick up is aligned. If incorrectly aligned some will not work at all, some give flakey results and some are insensitive to the orientation of the pick up. It is a good idea to check your timing light on a running engine to confirm that it is not defective. If it tests out OK, try flipping the orientation of the pick up back and forth to see if that resolves the problem. Also, the loop is not huge and if you have a large pick up the jaws of the pick up may not be closing completely. If the jaws of the pick up are not closing completely around the service loop that will make for a weak trigger signal which may not fire the timing light.
Since you were messing with the ignitor, check the grounding connector G103 which connects to the 8 pin connector on the ignitor. Check the actual grounding lug (G103) and check the continuity of the pins in the C123 8 pin connector which connect to the lug. In fact, check all the terminals on the ignitor for signs of corrosion. 10 years ago it was not unheard of for people to have ignition problems because of flakey electrical problems with the ignitor connections / grounding. This problem seemed to be more common on owners who obsessed about having a clean engine.
There is a condenser on the ignition coil +12 supply for radio noise suppression. If the condenser becomes iffy, it can cause problems for the ignition system. Unfortunately, testing the condenser requires a rather uncommon tool. The connector for the condenser gives you access to the 12v supply to the coils so you can probe at that connection to confirm that the coils have a healthy 12v supply.
I will note that none of this really jives with your circumstances where the engine was running fine and then wasn't running fine. However, you now seem to be in the process of eliminating all possible causes so this would be part of the process of ruling out an ignition problem.
If you can get the ignition timing light working, you can do the basic test in the service manual which is checking the timing at idle which should be 15+/- 2 deg. The service manual gives no guidance for checking the timing at any other engine operating condition.
The ignition testing service loop is low voltage (12v) between the negative terminal of the #1 coil and the switching transistor in the ignitor. If you look at some inductive timing lights, specifically those meant to work by clamping the inductive pick up over the #1 high voltage lead between the distributor and spark plug, they will have an arrow on the pick up indicating that it should be pointed at the spark plug. The triggering circuit in some timing lights is sensitive to the orientation of how the pick up is aligned. If incorrectly aligned some will not work at all, some give flakey results and some are insensitive to the orientation of the pick up. It is a good idea to check your timing light on a running engine to confirm that it is not defective. If it tests out OK, try flipping the orientation of the pick up back and forth to see if that resolves the problem. Also, the loop is not huge and if you have a large pick up the jaws of the pick up may not be closing completely. If the jaws of the pick up are not closing completely around the service loop that will make for a weak trigger signal which may not fire the timing light.
Since you were messing with the ignitor, check the grounding connector G103 which connects to the 8 pin connector on the ignitor. Check the actual grounding lug (G103) and check the continuity of the pins in the C123 8 pin connector which connect to the lug. In fact, check all the terminals on the ignitor for signs of corrosion. 10 years ago it was not unheard of for people to have ignition problems because of flakey electrical problems with the ignitor connections / grounding. This problem seemed to be more common on owners who obsessed about having a clean engine.
There is a condenser on the ignition coil +12 supply for radio noise suppression. If the condenser becomes iffy, it can cause problems for the ignition system. Unfortunately, testing the condenser requires a rather uncommon tool. The connector for the condenser gives you access to the 12v supply to the coils so you can probe at that connection to confirm that the coils have a healthy 12v supply.
I will note that none of this really jives with your circumstances where the engine was running fine and then wasn't running fine. However, you now seem to be in the process of eliminating all possible causes so this would be part of the process of ruling out an ignition problem.
If you can get the ignition timing light working, you can do the basic test in the service manual which is checking the timing at idle which should be 15+/- 2 deg. The service manual gives no guidance for checking the timing at any other engine operating condition.
