XClericK

Hello,
My 99 Honda Accord (v6 vtec) has intermittent trouble with acceleration after 30-45 mins of driving. When at a constant speed of around 40-50 mph, the engine's rpm drops without letting off of the pedal. After a couple of seconds, it jumps back to it's original rpm and the throttle can be controlled again. This problem will reoccur until shutdown and it happens only after driving for over a half an hour. Sometimes after a long drive and being parked for an hour, the symptoms happen immediately after startup. The CEL light also illuminated after the first time it happened and the codes are P0170 and P0171. I took it to Goodyear for a complete fuel system cleaning. After picking it up, there were no problems whatsoever! The CEL even cleared itself out. However, after a couple of days, the symptoms started to happen again and the CEL along with the same codes reappeared.
I hope someone has come across the same problem and can point me in the right direction. I'm leaning towards replacing the Fuel Pressure Regulator but am not 100% confident because the problem only occurs when the engine has been running with a load for over a half an hour.

SpeedRacerEX-R

Fuel filter, pressure regulator, fuel pump. I would start in that order

XClericK

Thank you for your help! I'll get back to you after each replacement.

antrmo

you didnt mention whether you lost actual engine power or if just the gauge was dropping? unless i miss read?

XClericK

Well, to put it in another way, imagine driving on a long stretch of road where you keep your foot on the accelerator pedal to maintain your speed just at the speed limit. The speed is at a constant 45 mph and then your rpms drop as if you are letting off of the pedal but your foot is in the same position it has been when you were cruising at 45mph. You try to press down further on the pedal but no response. After a couple of seconds and pumps at the pedal, the rpms return with your pedal pressing. This will happen intermittently throughout the rest of the drive after 30-45 minutes of driving. Never does it after startup from sitting overnight and when it happens, it ranges from 1 to 3 seconds of no response.

antrmo

lol.ok sorry but you still havent said whether you lose engine power...ok but you did say when you push the accelerator ,no response ,so I will assume you are losing engine power, sounds like the evap maybe kickin in and causing a lean mixture. read up on emissions and thats what evaps do i believe.well not suppose to cause that, but under certain times and protocols the evap opens the charcoal cannister to burn up vapors and such. also the ecu will run a self test to make sure the evap system is holding pressure, a self diagnostic. I maybe forgetting some parts but might be your issue.

F1_Racer

TPS (Throttle Position Sensor)....... ? Is check engine light on?

ferio-ichi3

I say distributor.

XClericK

I was thinking the same thing. Either that or the MAP sensor. The CEL came on right after the first time it did that. The codes are P0170 and P0171.
Funny thing, I got the 3 stage fuel system cleanse package at Goodyear and the problem and the codes went away until about 50-60 miles of driving then the problem returned along with the codes.

XClericK

The fuel filter is in the fuel tank in this model, I replaced the fuel pump and the pressure regulator. Still no luck. Thanks for the suggestion!

XClericK

Thought it was that too. Put a brand new one on yesterday and still the same :-(

XClericK

I will check the evap. Thank you for your help! And yes, I did mean to express that the engine does lose power.

holmesnmanny

If the tachometer is messing up intermittently it's likely the ignitor is failing after it heats up.

XClericK

Thank you for your input but it was already replaced when I changed the distributor. :-(

XClericK

So far the following items were replaced:
MAP Sensor
TP Sensor
Fuel Pump
Fuel Pressure Regulator
Air Filter

The problem is happening more frequently and quicker now. It also is happening at higher speeds of up to 60mph and within 15 to 20 minutes of driving.

XClericK

Sweet! I just called my friend and he told me that he got the distributor from a junk yard and swapped the original ignition control module. I was under the impression that he replaced the distributor with a new one. I'm going to replace the ICM and report back in a few!!

XClericK

Guess what!? I replaced the distributor along with the igniter and it fixed the problem. I thought my friend picked up a new one but he told me it was just a used one with the old igniter. Problem solved!

XClericK

Thanks dude, if it wasn't for your suggestion, I probably would not have double checked the distributor and would have been going on circles!! It was the igniter! Wish I could buy you all a round of beer for your help!! Thanks everyone!!!!