Engine hesitation in 2nd, 3rd gears etc below 3000rpm

S2G-Unit · 8 March 2017

MY 1994 has been sitting since December, just drove it this week. I noticed if I would accelerate from a stop in 2nd gear, the car would stutter & would not give me smooth acceleration all the way up to about 3000rpm.

I noticed the same on the highway in different gears.

TB/WP done in 2012 with fuel filter
O2 sensors & sparks plugs done again last year
Fuel pump resistor changed about 3 years ago
Fuel injector cleaning service done last year (they were not removed & sent out though)
Main relay changed about 4 years ago
I emptied the fuel tank & filled up with 93 octane yesterday

Do I maybe need to reset my ECU by pulling a fuse?
Could my old coil packs need cleaning or changing?
Air filter in need of cleaning again?

Any suggestions?

***update 04/10/2017***

So it has happened again on very rare occasion. Today it was 23C out & it happened again. I realised the TCS light on the dash was blinking green, so it seems that might have been the issue. I never noticed before I'm guessing because I could never see the TCS blink when it was bogging, because of torso length, seat positioning with my AP2 steering wheel.

After a search, it seems like it might be the wheel speed sensors?

asylum · 8 March 2017

Do you have this problem everytime or only when you just slightly accelerate ?

If all the time : I would first try to bypass the fuel pump resistor because it slows your pump under 5000 rpm. If the problem disapear, your fuel pump is weak.

If only when you slightly accelerate : try to disconnect the O2 sensors. It will throw a CEL. But it will run in a safe mode ignoring the O2 sensors. If the problem disapear, I would first check if there is an exhaust leak near the O2 sensors and only after that incriminate an O2 sensor.

After that you can check : spark plugs, coil packs and injectors. But these should give problem whatever the rpm.

S2G-Unit · 9 March 2017

asylum said:
Do you have this problem everytime or only when you just slightly accelerate ?

If all the time : I would first try to bypass the fuel pump resistor because it slows your pump under 5000 rpm. If the problem disapear, your fuel pump is weak.

If only when you slightly accelerate : try to disconnect the O2 sensors. It will throw a CEL. But it will run in a safe mode ignoring the O2 sensors. If the problem disapear, I would first check if there is an exhaust leak near the O2 sensors and only after that incriminate an O2 sensor.

After that you can check : spark plugs, coil packs and injectors. But these should give problem whatever the rpm.

I honestly don't drive my car hard & might accelerate a bit hard to merge on to the highway. As I just took out the car, I've been driving very gingerly & haven't applied very much throttle at all while driving. Tonight, I did notice after the gym, on the way back home that the engine was back to normal since I guess it was warmed up. It only seems to happen when cold. Tomorrow I'll try unplugging the fuel pump resistor & see.

asylum · 9 March 2017

The fuel pump weakness will be more noticeable when you accelerate hard under 5k as you ask for more fuel. An O2 sensor problem (either caused by a bad sensor or an exhaust leak) will be noticeable when you accelerate (very) slowly at low rpm. I had the second issue because of a leak just after an O2 sensor.

Dr. JL · 9 March 2017

I had a similar situation with recently "cleaned" fuel injectors. Spent many $ and much time to eventually change out the fuel injectors with new. Problem solved. You can read many similar threads if you search for "hesitation".

Old Guy · 10 March 2017

Take the car out on the highway and in 2nd or 3rd gear (as conditions permit) do a steady throttle application. Does the problem truly disappear above 5000 RPM? If so, I suggest that you follow up on asylum's suggestion. The definitive test for the fuel supply system is to do a fuel pressure check; however, if you don't have the gauge and adapters and don't want to spend the $ to have someone do the test, then by-passing the fuel pump resistor is a simple, no cost test. However, it is not definitive. If you by-pass the resistor and the problem does not go away, that does not guarantee that the pump is OK.

I am less inclined to think injectors. If the problem was with dirty / poorly flowing injectors, the problem would not go away at higher engine loads. It should become worse. The same with the ignition system. With the exception of running really lean, the fuel mixture becomes harder to ignite as the mixture density increases (higher engine loads). Ignition misfires usually show up as engine load increases and don't go away.

If the throttle roll on test shows that the problem does not go away at higher engine loads, then all the possibilities are back in play.

You said that the injectors were cleaned; but, they were not removed from the car. I am really curious about how you would clean an injector and then check its flow to confirm its operation without removing it from the car.

S2G-Unit · 12 March 2017

Old Guy said:
Take the car out on the highway and in 2nd or 3rd gear (as conditions permit) do a steady throttle application. Does the problem truly disappear above 5000 RPM? If so, I suggest that you follow up on asylum's suggestion. The definitive test for the fuel supply system is to do a fuel pressure check; however, if you don't have the gauge and adapters and don't want to spend the $ to have someone do the test, then by-passing the fuel pump resistor is a simple, no cost test. However, it is not definitive. If you by-pass the resistor and the problem does not go away, that does not guarantee that the pump is OK.

I am less inclined to think injectors. If the problem was with dirty / poorly flowing injectors, the problem would not go away at higher engine loads. It should become worse. The same with the ignition system. With the exception of running really lean, the fuel mixture becomes harder to ignite as the mixture density increases (higher engine loads). Ignition misfires usually show up as engine load increases and don't go away.

If the throttle roll on test shows that the problem does not go away at higher engine loads, then all the possibilities are back in play.

You said that the injectors were cleaned; but, they were not removed from the car. I am really curious about how you would clean an injector and then check its flow to confirm its operation without removing it from the car.

It wasn't thee true injector cleaning/flow testing. Just had my garage use the injector cleaning machine throughout the engine.

It's -30 celcius!!! for the next few days. I'll get back to you guys soon.

goldNSX · 12 March 2017

asylum said:
I would first try to bypass the fuel pump resistor because it slows your pump under 5000 rpm. If the problem disapear, your fuel pump is weak.

I can second that. It costs nearly nothing to check it, just your time.
The fuel pump gets more current at around 4000-4200 rpm but as the starvation needs time you might recognize it a little bit later.

I'd check that ASAP as your car is running lean with a weak fuel pump. If it has never been replaced I'll bet you'll be the next one to replace it.

darock · 17 March 2017

+1 on the fuel pump resistor bypass check.

Had the same issue. It got way worse when I installed the new headers which obviously makes the engine produce more power than with the boat anchor headers. Therefor it has more fuel demand, especially at lower rpm where the headers really make a difference.

Bernhard

S2G-Unit · 11 April 2017

***update 04/10/2017***

So it has happened again on very rare occasion. Today it was 23C out & it happened again. I realised the TCS light on the dash was blinking green, so it seems that might have been the issue. I never noticed before I'm guessing because I could never see the TCS blink when it was bogging, because of torso length, seat positioning with my AP2 steering wheel.

After a search, it seems like it might be the wheel speed sensors?

asylum · 11 April 2017

Possible. What are your tire size front and rear ? This could also cause TCS action when not required.

S2G-Unit · 11 April 2017

asylum said:
Possible. What are your tire size front and rear ? This could also cause TCS action when not required.

I've had the car for 10 years with 215/35/18 & 265/30/19 without any issues until now.

asylum · 11 April 2017

Tire size seems ok.

Old Guy · 11 April 2017

Rough roads can trigger TCS operation during acceleration. If you are approaching the limits on tire size differential, this may trigger early TCS action on roads that may only be moderately rough.

Unlikely to be a wheel speed sensor. Wheel speed sensors tend to be 'all present' or dead. Not somewhere in between. If there was a bad electrical connection, it is possible that a wheel speed sensor signal could come and go. However, the TCS gets wheel speed via the ABS, so if a wheel speed sensor had failed or was failing intermittently, you should be generating the appropriate trouble codes for both systems. Scan to see if you have any stored codes in the two systems.

At the risk of missing something obvious, I think it should be fairly easy to diagnose whether the source of the hesitation is the TCS. Just turn the TCS off at start up. If the problem does not return, then it might be safe to link it to TCS operation.

Did you ever do the fuel pump resistor by-pass test or get the fuel pressure checked?

S2G-Unit · 11 April 2017

Old Guy said:
Rough roads can trigger TCS operation during acceleration. If you are approaching the limits on tire size differential, this may trigger early TCS action on roads that may only be moderately rough.

Unlikely to be a wheel speed sensor. Wheel speed sensors tend to be 'all present' or dead. Not somewhere in between. If there was a bad electrical connection, it is possible that a wheel speed sensor signal could come and go. However, the TCS gets wheel speed via the ABS, so if a wheel speed sensor had failed or was failing intermittently, you should be generating the appropriate trouble codes for both systems. Scan to see if you have any stored codes in the two systems.

At the risk of missing something obvious, I think it should be fairly easy to diagnose whether the source of the hesitation is the TCS. Just turn the TCS off at start up. If the problem does not return, then it might be safe to link it to TCS operation.

Did you ever do the fuel pump resistor by-pass test or get the fuel pressure checked?

Hesitation happened on a regular simple non bumpy road. I will try the fuel-pump resistor by pass test.

Larry Bastanza · 12 April 2017

If you have a bad wheel speed sensor you should get a check light. I would try disabling the TCS and see if the issue goes away.

HTH,
LarryB

Lude_2_NSX · 17 April 2017

I had a similar issue, so I installed a fuel pressure gauge on the fuel filter and found I was very low on PSI (like 30 PSI). Once I bypassed the resistor, it jumped up to 40 PSI or so. I replaced the fuel pump and removed the bypass, and the PSI was sitting right at about 47 PSI, no more hesitation.

S2G-Unit · 11 May 2017

So I've bypassed the fuel pump resistor & there is no difference. The issue is to do with TCS, I've realized when the car is hesitating, the TCS light blinks.

After starting my car the TCS light on the dash is always off as it should be. However, the TCS button on the dash/cluster only sometimes has a green light on it. When the green light is on, I can push that button & disable TCS & have the dash light up the TCS button. Whereas other times, the TCS button has no light & I can keep pushing that button & TCS never disables.

??????

Old Guy · 11 May 2017

I have a 2000. Perhaps Honda changed something on the later drive by wire models because the TCS on/off button on my car has no green light, just TCS that lights up orange when the headlights are illuminated. The only TCS indicator is the TCS light in the dash cluster.

What does the owners manual state the purpose of the green light is?

Have you tried checking for error codes in the TCS unit?

S2G-Unit · 11 May 2017

Old Guy said:
I have a 2000. Perhaps Honda changed something on the later drive by wire models because the TCS on/off button on my car has no green light, just TCS that lights up orange when the headlights are illuminated. The only TCS indicator is the TCS light in the dash cluster.

What does the owners manual state the purpose of the green light is?

Have you tried checking for error codes in the TCS unit?

Will double check the manual.

robbiedawg · 11 May 2017

Old Guy said:
I have a 2000. Perhaps Honda changed something on the later drive by wire models because the TCS on/off button on my car has no green light, just TCS that lights up orange when the headlights are illuminated. The only TCS indicator is the TCS light in the dash cluster.

What does the owners manual state the purpose of the green light is?

Have you tried checking for error codes in the TCS unit?

From the Prime Changes by Year, light setup on the TCS button changed in '95

Traction Control Light no longer shines green when activated, still shines yellow when inactive

Engine hesitation in 2nd, 3rd gears etc below 3000rpm

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