CEL codes 1 and 2, also lately when the car is hot it is hard to start.

[BrianB]

Just a few hours ago the CEL came on while acceleration into traffic. The car seemed to go into a sort of limp mode. Got it home, checked the code it flashed once then pause then twice over and over. So I determined its code 1 and 2 or maybe 12 but the first flash didn't seem too long. I had DC headers and comptech exhaust put on about 1k miles ago along with a full 90k service by a acura dealer if that matters. Also on a side note last weekend and this weekend after the NSX gets hot it seems like I have to crank the ignition more to get it to start. Sometimes cranking it twice to start. It did the hard to start thing awhile back but once the service work was done its been fine. I've got an idea that it might be a igniter? For the hard start.
But as far as the o2 sensor faults I'm not sure.
Any help would be appreciated.
Thanks,
Brian

 

[ftuhy]

If its two codes, 1 & 2, it means both your front and rear primary O2 sensors have failed with a low voltage. I kind of doubt that both primary O2 sensors failed simultaneously. A short in the wiring or a disconnected connector can cause that. Other likely causes per the manual, are fuel supply (eg, fuel pump or clogged filter) or the ECM.

It its code 12, that means insufficient EGR Vale lift detected. Probable causes (per the manual) include the EGR valve, the EGR valve lift sensor circuit, the EGR control solenoid valve or its circuit, the EGR line, or the ECM.

 

[BrianB]

Thanks, I've got the a/c on in the garage to help get the engine cooled down then I'm going to try to check the wiring. The dealer that did the work did tell me they had to re run the O2 wire for one of the sensors because of the headers. I'm thinking that's the place to start. I thought the cats could be bad but then thought no way both at the same time and they only have 74k miles on them. I don't think it was a 12 the first flash didn't seem long. From what I've found on prime and talking to a fellow NSX owner for the starting thing it's either a main relay or ignitor.

 

[BrianB]

I've been researching and getting ready to reset the CEL and test drive with the O2 sensors unplugged as I've seen LarryB recommend in other situations like this. But I am suspecting the fuel pump I've changed the fuel filter already. The start problem is still a mystery only happens when car is warm. So far I see igniter or main relay. I'm thinking of changing the O2 sensors and fuel pump I just have to decide on the pump. I'm going to CTSC the car later on for now it's headers exhaust and intake. So the warlboro 255 or 225 whichever it is seems like it would be enough flow. But I see some people have reliability issues with it. I will update tonight after some testing. Any other ideas please let me know, I have a trip with the NSX set up the 20th of July. Oh and I'm thinking the SOS O2 sensors instead of the Honda part since they are supposed to be the same anyway.

 

[docjohn]

As far as fueling goes I was tripping lean codes on my 96 with a 2000 motor. Larry B tested system fuel pressure first which was normal,so he sent my injectors to RC..well 2 were clogged,and the others partially blocked....after they were returned car runs better.

 

[BrianB]

I just got back from a drive, I decided to just reset the cel and see what happened... Well it came back on after about 5 miles of spirited start and stop and rolling accelerations. Came back and checked it. It flashed 2 times then pause then 1 time. Before I thought it was one time then the 2 times does that matter in which order the numbers flash? If it does and it's a 21 then it says its a vtec solenoid. The car didn't seem to have as much restriction after the CEL came on. But after getting home in the garage I let it idle and is was alittle bumpy of a rev and seemed maybe low? Like 5-600 rpm.
I'm letting the engine cool down then I can try the unplugging the O2 sensors. But the car runs fine with them plugged in so I'm not sure if unplugging them will matter? Debating on taking it to the dealer but is rather fix it myself worst case I guess I'll just start throwing parts at it. But the vtec solenoid possibility sucks.
thanks in advance for any advice!
Brian

 

[Larry Bastanza]

First thing to do is MAKE SURE the front and rear sensors are wired correctly to the respective front/rear connections on the engine. Since the header will reposition the "front" sensor at the rear of the oil pan, it is likely the front/rear 02 sensors are plugged into the wrong harness connector, Ask me how I know.....

Remember the front 02 sensor, now located at the rear, by the oil pan, must connect to the plug on the top of the FRONT VALVE COVER.

The result of this will be that the ECU is confused as to which bank it is adjusting fuel for, and the code 1,2 can be the result.

Regards,
LarryB

 

[BrianB]

LarryB,
Thanks for the info! I will check this evening when I get home. The car has drove around 1000 miles with no issues other than the occasional hard to start when warm. The hard issue to start has became more frequent lately. Would the car run ok for a 1000 miles with the sensors backwards? And would the O2 sensors make me have to crank the car more than once to get it to start once warm?
I will update once I check the plugs and positions of the o2 sensors.
Thanks
Brian

- - - Updated - - -

I jacked the NSX up and checked. They are going to the proper plugs as far as front and rear bank. I was thinking of jumping out the fuel pump resistor to see if that keeps the light off?

- - - Updated - - -

I just got back from a 20 minute drive with the fuel pump resistor jumped out with a 12ga wire. No CEL came on. The car seems to be running ok. I ordered o2 sensors from SOS last night so looks like I have them anyway... But can the fuel pump resistor cause those codes? And does that mean I need just the resistor or a new pump also? I'm sitting in my drive way now starting and turning off the car every 5 minutes to see if it stoops the hard start issue. What rpm ranges should the car idle in? And does the a/c on effect them. When I pulled in and shifted to park the car bobbled for a second and smoothed out around what looks like 500.

 

[Larry Bastanza]

What you are doing is allowing more fuel in. So you really need to do a fuel pressure test, per the service manual to determine what in the fuel system is the issue. If the pressure is good after all tests, you should consider having the fuel injectors cleaned and balanced. RC Engineering in Cali does the really great service. I had a 1996 that was very intermittently throwing a "lean" code. Very illusive. Had the injectors balanced and cleaned, and although it is too early to tell about the actual code, immediately the car ran significantly better/smoother. I was so impressed I am removing mine and sending them out, after 22 years.

Regards,
LarryB

 

[BrianB]

What you are doing is allowing more fuel in. So you really need to do a fuel pressure test, per the service manual to determine what in the fuel system is the issue. If the pressure is good after all tests, you should consider having the fuel injectors cleaned and balanced. RC Engineering in Cali does the really great service. I had a 1996 that was very intermittently throwing a "lean" code. Very illusive. Had the injectors balanced and cleaned, and although it is too early to tell about the actual code, immediately the car ran significantly better/smoother. I was so impressed I am removing mine and sending them out, after 22 years.

Regards,
LarryB

LarryB,
Thanks for the explanation, I have a event on the 20th I wonder if they could have it done by then. Is it safe to drive with this jumper in? Possibly a small road trip?
I will look for a fuel pressure test kit, what pressure should I look for? And should I check it with the old resistor plugged in, or order a new resistor before the test?

 

[BrianB]

I have got a fuel pressure test kit from autozone loan a tool program. It's a fancy digital one. I says 47 psi is what I should look for. I have to take the banjo fitting loose and replace the bolt with their banjo bolt. Anything else I should test with this? Just idle pressure,or rev it? Do I plug back in the resistor first?

- - - Updated - - -

The book says it should be 47 I haven't tested it yet

 

[Larry Bastanza]

I have got a fuel pressure test kit from autozone loan a tool program. It's a fancy digital one. I says 47 psi is what I should look for. I have to take the banjo fitting loose and replace the bolt with their banjo bolt. Anything else I should test with this? Just idle pressure,or rev it? Do I plug back in the resistor first?

- - - Updated - - -

The book says it should be 47 I haven't tested it yet

range is 36-44 psi with vacuum regulator hose connected
range is 46-53 psi with vacuum regulator hose disconnected

The small hose on the passenger side rear fuel injector cover is the regulator hose

Do you have a service manual? Download it from the WIKI if not.

 

[BrianB]

Well, so much for testing fuel pressure tonight, the test fitting broke off in the filter while I torqued it to 20ftlb like the oem bolt. I guess it wasn't supposed to have that much pressure on it. So I have to see if they have another fitting tomorrow.

- - - Updated - - -

I do have a manual, it's on disk. I honestly haven't printed off the section yet. I will do it tonight.

 

[BrianB]

LarryB,

I tested the fuel pressure as per the service manual section 11-88. I also did a test of my own just for my knowledge of leaving the resistor jumped in checking and then plugging it back up and testing.
The following is resistor jumped in 52psi with regulator disconnected. 44 with regulator hose connected
now for pressured with resistor hooked up 50psi with regulator disconnected. 40-41 with regulator hose connected.

So I believe my pump if fine, I wonder what a new resistor would do as far as psi.
So if my pump is ok, O2 sensors seem to be ok, pressure regulator works, I'm guessing I need fuel injectors? Or them cleaned?

I'm leaving the pressure tester on it for about a hour I'm curious if it will leak down any. Also incase I need to do another test.

Any opinions on just getting new injectors from say autozone? I've stuck with all Honda parts so far but their injectors are steep. Or the RC injectors? Possibly bump up the size from the 250 to the 270 since I have intake, header, exhaust?

- - - Updated - - -



Or there's always the option of cleaning the ones I have which I am considering, the only issue I have is how long is the electrical side of a injector reliable? I know they can clean and test them but the electrical stuff is still 22 years old.


Sorry this is long winded I'm just trying to think of everything.
Thanks,
BrianB

 

[Larry Bastanza]

Fuel injectors hold up pretty well. I have had them cleaned on a 1996 at 80K miles, installed CTSC 6 years ago, perfect running engine.

Clean them, they will test spray pattern and flow and give you a detailed report. If by chance one does need replacement they will tell you.

Regards,
LarryB

 

[BrianB]

Ok, sounds good.
I still don't know why they decided to go now. Maybe all the spirited driving on the NJ turnpike the other weekend

thank you for all your help.
I will post a update once I get the car back together. Looks like I'm pulling injectors tonight.

 

[BrianB]

Today I re installed the fuel injectors and the car runs great!! Real smooth, and no CEL.
I replaced the O2 sensors as well as the fuel pump resistor and main relay. I know I didn't need those but I ordered a buch of parts before actually finding the problem... So I figured just go ahead and install all the new parts.
Also I replaced my drier/reciever in the A/C system since I found a leak at the connection, evacuated the system and recharged it with fresh 134a since it had already been converted previously. So now I have a smooth running and ice cold NSX! It would of took me way more time to figure out what was going on with my car if it wasn't for this forum, thanks to all that commented with suggestions and advise.

Next month new stop tech rotors, Hawk HPS pads, and debating on stainless lines. The rotors and pads are on the way! I guess there's always something.

BrianB

- - - Updated - - -

As far as fueling goes I was tripping lean codes on my 96 with a 2000 motor. Larry B tested system fuel pressure first which was normal,so he sent my injectors to RC..well 2 were clogged,and the others partially blocked....after they were returned car runs better.

This was pretty much the same as my injectors.

 

[BrianB]

LarryB,
Thank you for all your help