2000+rpm hesitation... fuel pump?

[Kaz-kzukNA1]

does anyone know what the resistance should be of a good resistor?? can't find any mention anywhere

[Edit: found your question after posting my original reply below....]
0.55 ohm at room temperature for your NSX.
0.32 ohm at room temperature for 97+ models.



Hi, Jonathan.
Can you re-create the same issue at idle rpm or raising the rpm while in P position?

It depends on the failure mode but if the fuel pump resistor block intermittently fails, you will have problem starting the engine or even keeping the idle rpm.

Therefore, it could be not related to the resistor block.

For your reference, the most common failure modes are;

• the internal crack of the resistor (you can't see it from outside). You may be able to re-create the same issue by spraying the ice cold spray.

• the intermittent damage to the crimped section of the wire just at the edge of the resistor terminals.

Example here;
http://www.nsxcb.co.uk/entry.php?205...mp-Resistor-01

http://www.nsxcb.co.uk/entry.php?205...mp-Resistor-02


If you can easily re-create the same issue, may be you can borrow the good resistor block from another owner?

I have two new resistor blocks at my place.
If it is in stock in Japan, I can release one of them for you but Honda Japan is closed for the new year holiday until 4th and then they will need some time going through all the email so won't get reply for several days.


I have one used resistor block with damaged wires.
If I can find suitable terminals, I can create temporary resistor block for you.
You are more than welcome to try it first before buying the new one, although it's not mega expensive so might as well replace it with new one if you are still using the original one.


If you can drive up to Bucks and if you are using the OEM fuel filter fitting, then you can use my fuel pressure gauge as well although with your issue, may not fancy driving the long distance….


Probably you will need measuring the fuel pressure while the issue is still there any way.
You can't rule out the fuel pump yet....


If you can re-create the same issue at idle rpm (closed loop once warmed up) but not getting the CEL, the fuel pressure is not low enough for the closed loop fuel control to max out on the trimmer.
There is no PF compensation in the closed loop calculation on our NSX.
Pressure regulator can fail but you will see on the pressure gauge.
Hope you can measure the fuel pressure while the issue is still there.....


Kaz

[britlude]

i've just found your threads on this issue, and the appropriate pic to answer my first question....




ironically i have to drive to birmingham next weekend, but don't tell Sarah, it's her birthday surprise, so i'm just covering all the options... if the problem does reappear i'll be shorting the resistor for the time being whilst i wait for email replies/deliveries.. i have a pressure gauge/etc on it's way, but of course that won't be here until after next weekend....

[NSXGB]

Jonathan, if you need one in a hurry, or find they are on back order, I've got a new one you can have until the new one arrives.

[britlude]

re. rubber seal over the door, fitted to the door 'moulding'...... studied my Baines rubber extrusion catalogue at length, working out the ideal 'replacement' (not that any are a direct replacement) and found one suitable... not on their 'normally stocked' list.... you guessed it, not on the shelf, and min order of 300 metres!!! bum... so another search, found a supplier in southampton.....

....a a quick call, 'oh we don't keep any extrusions', oh i say, do you get them from Baines... 'yes' came the reply......

looking increasingly like the SOS rubber, unless i can find where they get it from.....

[sorepaws]

How much do we need to get to replace all the seals on the members cars ? And then Jonathan how much will you charge us all to fit them ? - Your new business opportunity in 2018 - Happy New Year BTW

[britlude]

too late.. i've ordered 2 sets of the rubber trim lengths from SOS.. (one set £78, 2 sets £101 plus border ransoms!) so i may have a set to sell on later.....

i've just ordered some oem bits from an untapped UK source, pricing looks good, we'll just see what the service is like!

[britlude]

right where were we??? ah yes, waiting for a pressure gauge set to turn up... and while i was away for my girlfriends birthday surprise (Blue Man Group in Birmingham) it arrived.

the plan was to take the NSX and arrive all relaxed and fresh, but that plan went out the window....

we set off, not going mad, cruising at about 2600-2700 prm, after about 30 miles the car started to feel fluffy, getting progressively worse, driving progressively slower until we got to an exit on the M25 (A127!) just before we got there it had a big stutter and the warning triangle came on on the dash!!! panic! fortunately it went out as i lifted the throttle.... luckily it was a roundabout junction, so i could stop somewhere safe and do a quick fuel resistor bypass...

resistor bypassed, and car restarted, all seemed well, so gingerly carried on....

another 10 miles on, it did the same, coughed, stuttered, red light on dash.... pulled onto hard shoulder, this time at the exit of the first tunnel anti-clock from Dartford crossing.... LUCKILY (tho not realising it at the time) this was the last bit of hard shoulder as the M25 then turned into 'smart' motorway..... anyway, stopped, light went out, engine responding ok to throttle inputs, so decided to abort mission as there was another 125 miles to go, so gently took it to the waltham abbey turnoff and headed back, finding slow vehicles to slot in behind and kept it just over 2000rpm...

it got back with no further issues..... bearing in mind we were now back in rochester at 10am, and the surprise was in Birmingham at 4!!!! car was fine, i was panicking! hopped into the cube and trundles up there without incident (apart from the debris of a big porsche and a small estate when the porsche had decided to overtake something, not looked in his mirrors and sideswipes said estate with his back drivers quarter.... we presume it was the porsche at fault as he was driving like a moron when he overtook us minutes earlier)

Blue Man Group was excellent, and the surprise a success! if you ever get the chance to catch them do-so! just don't turn up late, they give late-comers some very special attention!

right back to the plot.... pressure gauge connected (bearing in mind the car's cold, pump's cold, it's all cold)
this is what i have..... (psi)
pressure readings2 by jon sutherland, on Flickrpressure readings by jon sutherland, on Flickr

blipping the throttle with the fuel resistor in line gave a 40 up to 45 to 40 pressure boost as expected, and without the resistor 42-50-42 again as expected


the light on the dash was the top right......
WP_20180107_15_14_03_Pro by jon sutherland, on Flickr

i'm hoping the light comes on when the computer runs out of adjustment for the pulse width on the injectors, ie. the engine is still lean on the O2 sensors even tho the injectors are at 100%...... and when i was stationary or off the throttle, the fuel pump could catch up, pressure restored and all is well....... there was no mention of that dash light coming on, only related to the hazard switch! mine being JDM doesn't flash the dash light with the hazard switch anyway!

next is to drive it around til it starts to exhibit the symptoms and pressure rest again! it also means i can use some of the FULL tank of petrol (in anticipation of a drive from home to birmingham and back!)

[Kaz-kzukNA1]

Hi, Jonathan.

Looks like someone replaced your gauge plate.
With JDM, where the triangle marker sits on your gauge, it should show the marker for the CAT high temperature warning.
It's ' sort of ' equivalent to the rapid blinking CEL on full OBD2 car when too much unburnt fuel entered the CAT.

Are you still using the JDM spec CAT?
There is a silver stick like temperature probe on each CAT.
The mating connectors are mounted next to the RR w/speed sensor behind the boot carpet at the forward right corner of the boot.

Please note that if you have ACG charging system failure, both the battery marker and this CAT high temperature warning will be triggered at the same time.


Please do not keep running the engine at the same load for long period when this warning is triggered.
Otherwise, it will melt down the honeycomb structure inside the CAT body.

If you saw it while driving, please slow down (like 50% of the speed you were carrying) until the warning light disappears.
If it happened at idle rpm, please park the car where no flammable materials are under the car and stop the engine for more than 10min to cool down the CAT.


As you suspected, you really need to measure the fuel pressure while the issue is present otherwise it could lead to wrong diagnosis.

If the fuel pressure is fluctuating but not enough to trigger the CEL, then due to the delay in O2 feedback control loop and only two O2 sensors for 6 cyl engine that several cyl will be getting very rich mixture.


Or, you may not have fuel pressure issue but instead, having intermittent multiple cyl IG issue due to ignitor failure, IG coil, etc resulting in misfire that is not consistent enough to trigger the CEL and allowing so much unburnt fuel entering the CAT.
Even with the full OBD2 spec ECU with 3pin IG coil and misfire detection module (yours is pre-OBD2), I know from the fact that it couldnÂ’t detect intermittent misfire caused by the IG coil triggering rapid blinking CEL but no continuous CEL and thus, no error code despite the big misfire that anyone can feel.


If O2 sensor is sending intermittent wrong voltage data, again, it could result in similar issue without triggering the CEL but normally, it's hard to make the CAT so hot without triggering the CEL if the issue was caused by the O2 sensor.


Still, there is a chance of multiple issues of mixture and IG....


Again, hope you can measure the fuel pressure while the issue is happening on the engine.


Kaz

[britlude]

very interesting Kaz.... when i got my car, way back when, that particular legend section was missing on my car... whoever did the 'MPH' conversion managed to lose that particular transparency (along with the trip reset button, later found under the carpet!) and i made a replacement from the legends in the handbook i had... obviously the UK handbook wasn't correct for the JDM car!

I am still running the JDM cats, and indeed have the 2 temp probes still there, all present and correct with the cables running into the boot area (next to the CD player location) and it would seem they are still functional! which, in this case, could be a huge clue in finding the cause of this particular issue!

when the light came on, don't worry, i slowed down immediately, stopping where safe!!!

i haven't noticed black smoke from the rear, and i haven't got sooty marks on the exhaust tips or the rear of the car, so i doubt it has been running rich, so i'm leaning toward an ignition issue (ok, the weather and thought of being under the car this time of year may be affecting my leanings! lol).....also the issue happened with fuel resistor in-line, and shorted out, both at the same sort of revs....

looking on NSXprime ignitor issue threads, it seems to be highlighted when under load, and it seems i am more likely to reproduce the issue when the car is warm and i am going up an incline, loading the car more... both occasions on saturday were on a motorway incline.

i shall try to fit the pressure gauge in a viewable position and see if i can reproduce the fault state and monitor the pressure.... i might also run some wires from the coil feeds to a line of LED to give a visual indication of the coils being driven... whether i'll actually be able to see any breakdown in the fast strobes i don't know, but it is a theory!

having seen the prices of ignitors, i was toying with the idea of the bosch COP upgrade developed 'open source' by Operator on NSXprime ( http://www.nsxprime.com/forum/showth...osch-cop-coils ), and now supplied by A.S. Motorsport.... basically using modern COP coils with the trigger circuitry built in to convert the ECU signal levels to drive the coils.... removing the ignitor and gaining 25 years in automotive development....

I shall see what i can find.....

[britlude]

quick update..... 2 second hand ignitors on their way..... one from Germany, one from USA... if it is the ignitor it could leave me stranded, so a couple of, maybe ok, cheap spares as insurance to buy a bit of time! if it is the case, then i can buy a new one or upgrade accordingly


(lings only want £520 for one!!!!)