^^^^ Yeah that looks pretty good to me
CEL is on in my 91'
- Thread starter Turbophein
- Start date
Fuel Injectors?
Any updates? I'm still trouble-shooting with no change in the hesitation. Fuel pressure checks good at idle. All vacuum systems check good. New front and back ground wires and a fuel pump relay on the way from AcuraPartsNow.
Updated: Fuel pressure checks good "at idle".
Updated: Fuel pressure checks good "at idle".
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Here's my update...
After an engine-out refresh and considerable time and money invested, my '91 is full up after a fuel pump relay replacement. I had the typical hesitation below 4K RPM, trouble-shot nearly the entire SM chapter 11 and finally stumbled upon pages 99 through 101. I never had a CEL, so all I had was the help of Primers, my SM, time (to think) and cash. During the past 5 months of refresh/trouble-shooting, I've read threads of MAP, fuel pump, fuel pump resistor, skipped timing, coil packs, spark plugs, main relay (i.e. timing, ignition and fuel) failures. I finally ordered and swapped out the $32 FPR and she runs smooth and (for the first time) I hear the FPR close as commanded by the ECU under high load conditions. For other NSX'ers who are burdened with this symptom w/o a CEL, I encourage you to look at the master wiring diagram found at the end of chapter 23. It's an eye chart, but ultimately allowed me to logically follow the flow of power/relay/control.
After an engine-out refresh and considerable time and money invested, my '91 is full up after a fuel pump relay replacement. I had the typical hesitation below 4K RPM, trouble-shot nearly the entire SM chapter 11 and finally stumbled upon pages 99 through 101. I never had a CEL, so all I had was the help of Primers, my SM, time (to think) and cash. During the past 5 months of refresh/trouble-shooting, I've read threads of MAP, fuel pump, fuel pump resistor, skipped timing, coil packs, spark plugs, main relay (i.e. timing, ignition and fuel) failures. I finally ordered and swapped out the $32 FPR and she runs smooth and (for the first time) I hear the FPR close as commanded by the ECU under high load conditions. For other NSX'ers who are burdened with this symptom w/o a CEL, I encourage you to look at the master wiring diagram found at the end of chapter 23. It's an eye chart, but ultimately allowed me to logically follow the flow of power/relay/control.
The hesitation below 4K RPM is back...
Maybe a failing fuel pump, manifesting under the lower voltage provided through the fuel-pump resistor? It may be useful to bypass the resistor and see if that changes anything.
Just checking, did you try simply replacing your fuel pump resistor? That fixed my hesitation.
After installing a fuel pressure readout in the cabin, I could see that the pressure maxed out at 2.9kpa below 4k rpm. Now it, easily goes to 3.3kpa below 4k with the new resistor. After researching as well, and buying a spare fuel pump, relay, and regulator.. it ended up being the easiest and one of the cheapest fixes.
Mike B
ok so I have was driving around with the tps unplugged last season, so I decided to swap out the TPS just to see what would happen. It runs and hesitates all over again, and even worse now if I unplug the sensor, it still runs horribly. Has anyone figured out a solution? I also get no CEL light anymore so I am not sure where to check next. the car is not even drivable after it warmed up today.
My car used to do the exact same shit. It turned out to be my rear coil packs for me. All of which tested out fine on an ohm check on the primary side. However, you cannot easily check the secondary side.
so I have still been dealing with this issue, I recently found out that if I shutoff the car and restart it, the car runs great again for a few minutes and then repeats the cycle.
very strange, the only thing I can think of that would cause this issue is the ecu, maybe using a preprogrammed tune for initial startup that lasts for a few minutes or what I originally thought was the car just warming up and then hesitating. idk but I hate driving the car like this. anyone else have any luck
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I bought a simple Fuel Pressure gauge that bolted right into the fuel filter, I to thought it was my fuel pump, but I have great pressure.
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very strange, the only thing I can think of that would cause this issue is the ecu, maybe using a preprogrammed tune for initial startup that lasts for a few minutes or what I originally thought was the car just warming up and then hesitating. idk but I hate driving the car like this. anyone else have any luck
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I bought a simple Fuel Pressure gauge that bolted right into the fuel filter, I to thought it was my fuel pump, but I have great pressure.
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i did jump the plug on my resister, for full power at all times. no luck.
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that fuel pressure is fine. your fuel pump is not the issue.
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ok so here is a quick breakdown of what went on throughout the last couple years
I had corrosion in my coil packs and some water in the spark plug wells originally causing a misfire. I replaced the rear coil packs twice, along with a bunch of other things I tried that were mentioned in this thread. I've come to the realization that the coils and plugs need to be changed at the same time. if the coil has corrosion then so does the tip of the spark plug. when I changed the coil it certainly helped until the corrosion took over the coil also. which is why I thought I had this problem solved a couple different times.
so this is my newest plan of attack for this issue. i ordered 6 new OEM NGK plugs, 3 aftermarket coils(they are cheap and work fine for this test, if you want a oem unit you can buy it afterwards if this fixes your issue), and my new trick is going to be using dielectric grease on the plug tip and coil and around the spark plug well seal on the coil pack itself. this should allow no moisture to effect the spark ever again! if my problem comes back it should have nothing to do with the rear coils or plugs after this.
Those pressures seem high. Did you check the service manual? I remember the desired pressures being 40 and 50 psi or thereabouts with vacuum and atmospheric, respectively.
Edit: I just checked. With vacuum at idle, you want 36-44 psi and without vacuum connected to the regulator you want 46-53 psi. I guess yours isn't too far off but it does seem a bit high. Perhaps the return line is kinked or otherwise obstructed? Perhaps the regulator is bad? I have a spare regulator from an NA2; if that is the same as an NA1 regulator, you could try it.
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I finally fixed my sick engine....
To save some cash during my recent engine refresh, I bought refurbished fuel injectors and shipped them off to the west coast to be checked. After a year of trouble-shooting the hesitation and multitudes of cash spent, I've replaced the refurbished fuel injectors with Acura OEM injectors. Now it runs vastly better at all RPMs. I think the time with poor spray patterns has fouled a few of the plugs since there is still an infrequent and random exhaust pop.
To all who struggle with this type if engine hesitation, check your fuel pressure, replace the fuel injectors and spark plugs.
To save some cash during my recent engine refresh, I bought refurbished fuel injectors and shipped them off to the west coast to be checked. After a year of trouble-shooting the hesitation and multitudes of cash spent, I've replaced the refurbished fuel injectors with Acura OEM injectors. Now it runs vastly better at all RPMs. I think the time with poor spray patterns has fouled a few of the plugs since there is still an infrequent and random exhaust pop.
To all who struggle with this type if engine hesitation, check your fuel pressure, replace the fuel injectors and spark plugs.
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that's great to hear!
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So new coil packs and new plugs with dielectric grease did not cure the issue. I haven't had a chance to install the refurb injectors I bought, hopefully they work and won't have issues like above, but these are OEM refurbed units. I will post my results when I get them.
My NSX was in pretty poor repair when I purchased it 4 years ago. I've been methodically repairing/replacing all types of parts. When I first noticed the engine hesitation, I decided to accomplish and engine-out refresh, but didn't correlate the hesitation with the refurbished injectors I'd just installed since they received a good bill-of-health. The hesitation continued after the refreshed motor was reinstalled (still with the refurbished fuel injectors). So, I went probable cause to probable cause, starting from least to most expensive. I was about the pull the trigger on a new ECU when I was discouraged by SOS since NSX ECUs rarely, if ever fail. I eventually doubled back to decide the injectors were culprit when I looked closer at the PGM-FI trouble shooting pages. FIs are listed as causal for a majority of engine-related problems. Yesterday I cleaned the plugs, did the ECU reset and now notice vast improvements each time I drive her. I figure the ECU is undergoing the process of relearning the correct fuel trims/ignition timings.
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I had my injectors professionally cleaned after I bought mine, definitely a good maintenance item.
Glad to hear you got it figured out!
Glad to hear you got it figured out!
Last night I replaced the my spark plugs with new NGK PFR6G-11 plugs. Their use with under-performing fuel injectors definitely damaged them. I suspect they where over-temp'ed with the equivalence of a lean A/F ratio. Lesson learned...to run efficiently, internal combustion engines need to be properly cooled, lubricated, have an efficient fuel delivery spray pattern and a timely spark.
I've been running the Prospeed RDX Injector setup for years and just had the rough idle/hesitation issue and found one bad injector - replacing it tomorrow.
DAMMIT! I replaced the injector and still no go...so its now unavailable rear coil pack...
Autozone has them:
http://www.autozone.com/ignition-tu...tring=search&isIgnoreVehicle=false&model=pack
Gary
Curious if you had this resolved?
Yes - it was the Ignitor module, not the injector or the coil, both of which I replaced.
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