Engine seems to die for a millisecond

In the past few months I've been seeing a strange problem with my car happening, and it may be getting worse. When the engine is running (especially at idle or at something other than WOT) my car will occasionally "die" and then begin running again in barely a fraction of a second. The RPM will drop down by a couple grand and then jump back up to normal as if the engine caught itself and fixed it. It can be quite a jolt, driving down the road and have the power suddenly drop like that. This problem is very random in nature, and I only notice it a couple of times in a 30-minute drive. Aldo, it seems to happen more often when the engine is not warmed up.

My car has seen some work in recent months, most notably testing out all of the sensors in the car to figure out why my car is running lean in the 5-6K RPM range. I have all of the SOS stage I stuff installed on the car, and I installed a Walbro 255 fuel pump. All of this happened about six months ago, and the car has run fine for several months up until recently (ie., I don't suspect that any of this is the culprit).

Anyone ever experience this or have an idea what might be the cause? I am at a loss to figure out what is wrong. What worries me the most is that this intermittent problem will manifest itself one day on a tight corner and the quick jolt that it gives sends me spinning into a wall or off a cliff.

Thanks for the help! :smile:

Chuck

Based on everything talked about here, I would suspect the main relay. Take it apart and check for cracked solder joint.

HTH,
LarryB

I agree, sounds like main relay.

I had a similar problem on my 99. My problem was always at 3800-4000. It was very sporadic at first but then grew to all the time at this rev range(even a stall once). The stall finally threw a code. INJECTORS it said. Put in new injectors(thank you Honda extended war.). Nope, same thing and another code, COILS it said(warranty). I gave Acura the car and said to drive for a week and see what they think. It stumbled for them, threw a code and they traced it to the THROTTLE BODY(yup warranty). Whew, thanks for sticking with me Continental in Naperville IL. Don't know if this helps...........I initially thought TPS(throt. position sensor). Hope you work it out........Later!

brakel8r said:

I had a similar problem on my 99. My problem was always at 3800-4000. It was very sporadic at first but then grew to all the time at this rev range(even a stall once). The stall finally threw a code. INJECTORS it said. Put in new injectors(thank you Honda extended war.). Nope, same thing and another code, COILS it said(warranty). I gave Acura the car and said to drive for a week and see what they think. It stumbled for them, threw a code and they traced it to the THROTTLE BODY(yup warranty). Whew, thanks for sticking with me Continental in Naperville IL. Don't know if this helps...........I initially thought TPS(throt. position sensor). Hope you work it out........Later!

Click to expand...

So the new throttle body finally fixed your problem for good?

Picked up a new main fuel relay today from Montano Acura. Even if it's not the eventual problem, I suspect that this is a part I'd be replacing one day anyway.

I'm pretty sure that my problem is not the throttle body. I've been over that part of my car with a fine-toothed comb in the past year, and it's also a relatively new part (it's the Science of Speed big-bore variety).

I'll give an update after I replace the relay in the upcoming days. :smile:

Chuck

The mystery continues......

I swapped out the main relay with a brand new one, and the problem did not completely go away but seemed to subside a lot (if that makes any sense). I drove it to NSXPO, and had no problems while I was there.

Back in Albuquerque, the weather has been good and the temperature has been warm. We had a cold front come through this past week but the weather was nice enough to drive, and I left for dinner on Friday night with the NSX. I pulled out of the driveway and the car "violently" hesitated multiple times all the way up the street. After about a quarter to half-mile of driving, it went away and did not come back the rest of the night.

I'm not 100%, but the problem seems to be with a cold motor and/or colder weather. I suppose it could be something else, but it definitely only happens right after I pull out of the driveway or a parking lot and 90% of the hestiation occurs in the first couple minutes of driving. In addition, it's always after I start the car for the first time that day, when it has been sitting for at least 12 hours.

I am totally clueless at this point as to what could be causing this. Any help would be greatly appreciated!

Chuck

If the problem repeats when cold then you can try different things and see if the problem goes away. The first thing to figure out is the problem fuel delivery or ignition. I would lean towards fuel delivery most likely a bad connection in the fuel pump circuit or a bad pump. With a cold car you can measure the voltage to the fuel pump and the fuel pressure and see what happens.

tooth monkey wild guess here... water in gas???!!!
tx with dry gas/injector cleaner??
reliable fuel vendor??

Chuck,

I have the same basic problem. I wish I knew where to purchase a fule pressure gauge that would connect to the fuel filter so I could check the fuel pressure. I don't feel that it is an electrical problem with the fuel delivery system, it seems more of a problem with the cold start feature, or for lack of better words the choke system. An electrical problem would probably be more consisten, and most electrical problems that are associated with temperature are problems when hot not cold.

One thing that does help is that I let the car "warm up" for about two or three minutes when the engine idles down a bit. That is actually best for any car from what I have read since start and go is pretty hard on an engine. The car still has a bit of hesitation, and almost is associated with how much throttle I am giving when cold. But when I wait fir it to idle down a bit after a cold start it hesitates much less and not so violent. HTH

Jason

Give me a call and I can give you a run down on what I have done, and talk about the timing belt change. I will be moving to Florida in less than two weeks.

And now, for something completely different...

I experienced similar behavior that was traced to a single bad anti-lock brake sensor.

Dying; sudden momentary loss of RPM; and then (as the problem worsened) occasional long seconds of (seemingly) running on less than all cylinders -were the symptoms.

'Dealer Alternative' here in Fort Worth has a few NSX gurus that wrapped up that problem pronto.

Oh if only my (A/C) "black death" were as simply solved!

Sandy said:

And now, for something completely different...

I experienced similar behavior that was traced to a single bad anti-lock brake sensor.

Dying; sudden momentary loss of RPM; and then (as the problem worsened) occasional long seconds of (seemingly) running on less than all cylinders -were the symptoms.

'Dealer Alternative' here in Fort Worth has a few NSX gurus that wrapped up that problem pronto.

Click to expand...

Tell us more please. How did they come to the conclusion of an ABS sensor problem, and which one was it?

"ABS code determined that the right rear sensor was bad" -so reads my receipt.

I can guess that focus on the ABS came from recognizing the engine running behavior when ABS detects a static wheel.

The right rear was culprit. $50 for diagnosis and $170 for a "Vehicle Speed Sensor". I believe the head man is Steve and the particular technician is George. I'll PM their # if you like. Believe me, Steve and George are very personable and will impress with their intimate knowledge. Their (very professional) shop is on White Settlement Road.

I had similar intermittent problems and typically at higher speeds and thought I had gotten a bad tank of gas and after reading some threads thought it could have been the main relay. BUT I took the car in to Mark Basch here in Phoenix--so lucky to have such a good tech here..and it turned out to simply be a bad spark plug which had less than 5k miles on it but had been in place since July 2003. I have had no problems since...Mark also had done a compression check but the #1 plug was the culprit...

check your battery terminal connections...my car was dropping RPMs badly one day especially while at Idle and the next day i tried to start it...nothing. So i pulled off the battery wires and cleaned the white gunk off and the car started right up and has not acted up since...It doesnt cost anything to try this so you might as well.

Update on this thread:

The problem never really went away competely, but it did seem to be a cold-weather-only thingy. Over the summer, it only happened once or twice. Now that it's cold out, it's back to happening on about every other drive.

I do have another clue to add to the mystery, which might help me to find the solution to the problem. When the car "dies" (hesitates) now, there is an audible click that comes from behind the seats. I think it might be behind the driver's seat, but I'm not 100% on that. I'm not sure if the click is CAUSING the hesitation or if the click is being caused BY the hesitation, but the two are happening at the same time.

Just in case you didn't read my first post on this thread:
Stock '91, except-

Walbro 255 fuel pump, OEM resistor removed
AEM fuel pressure regulator
SOS Stage 1 goodies, including ECU and throttle body
New TW (water temp) sensor
New main relay, installed after the problem began
Taitec headers
New O2 sensors, installed after the problem began
Injectors cleaned and blueprinted at RC Engineering
Odyssey 575 battery
TCS is competely disconnected

Anyone have any ideas?

Well I think that I would pull the spark plugs and look at them. Spark plugs will tell a lot about how an engine is operating. Keep track of which cylinder each spark plug was servicing. Look down into the spark plug chamber for oil. If there is oil take brake parts cleaner and spray into the chamber, let it soak and then suck it out with a small plastic tube connected to your shop vac. Do this before removing the plugs. Replace the valve cover spark plug chamber gaskets. Remove the plugs. Compare the color, combustion chamber part, of each plug to the others. They should be a nice light brown color. Check for a broken insulator. Remember if you drop it, replace it. Check the resistance of the coils, since you have them laying on your work bench anyway (Pg 23-95 in the 91 service manual). Check the gap on the plugs. Clean the threads on the plugs and be sure to use spark plug anti-seize on the threads. Torque them with a torque wrench. Make sure that the wire connector to the coil snaps securely in place. You could even check each spark plug by connecting it to one of the coils, connect the coil to the engine harness, ground the threads of the spark plug with a spring clamp on a separate wire to a good ground, pull the fuel pump fuse and have someone crank the engine while you watch the electrode on the spark plug. You may have to ground the coil also. Rotate all the spark plugs thru your tester. See if they all spark the same.

This may not fix your problem, but it will at least eliminate a few things, and won't cost much other than some time.

Brad

Everybody jumps and screams "MAIN RELAY" as soon as stuff like this happens but they do it prematurely most of the time. I looked up the symptoms my car was having and got responses screaming MAIN RELAY or IGNITION SWITCH depending on who was saying it... so I said what the hell and bought a new main relay and swapped it in...

Car still was messing up.

So I did some poking around and found out that the connector for my fuel pump resistor had gone bad from sitting in the hot engine bay or in the sun or something and cracked on the inside, leaving the terminals a bit of wiggle room to where they would sometimes loose connection for a second causing the car to stumble (or not to start)... Yours isn't operational but I'm just giving my example here.

Point is, look at the service manual as i found it has testing procedures in there that will keep you from throwing parts and money at the problem based on people's popular suggestions...