chezaleanne

So long story short, I have changed a lot of crap on this car in the last year, I finally have it fixed to the point to where I can safely drive it with out over heating. Well everything seems to be fine, running great unless im driving at a constant speed of 40 mph. It starts to ..... hesitate and jerk kinda violently, and the rpm gauge is erratic. It doesn't shut off or anything it just keeps doing this off an on. Its totally fine when im driving at high speeds tho.

CEL light came on and it says:

P050 Idle Air Control Sensor
P0501 VSS
P0420 Cat System Eff Below Threshold (Bank1)


My point is, I dont understand why it is running these codes because the codes and the car symptoms do not seem to match or is it just me ?
Any ideas, Im low on cash and do not want to run out and start changing parts that mat not need to be changed at all. (I have wasted money doing that)

carlos8

nothing related?

1- VSS = CEL, no vtec, wrong speed signal to the ecu (specially automatic) and at certain speeds it can feel hesitate.

2- O2 sensor = CEL, jerking, hesitate.

for mention a few.

It's your RPM gauge or speedo who is erratic?

chezaleanne

Rpm gauge gets erratic and I recently changed both 02 sensors

it is an automatic

chezaleanne

Also I did not know vss could cause hesitation, thanks for that, I posted because I am a new and novice mechanic when it comes to my car and I do not know all the tricks of the trade yet.

Former User

Reset the ECU to see whether all those codes return.

When did you last give the engine a tune up and what did you do?

You must create informative rather than vague thread titles. Title edited.

Brewbot87

If your vtec ain't working it usually goes into a safe mode and won't rev past 4-5000 rpm. If its the same rpm every time, I would kinda think that., especially seein as its an auto trans. Check oil level 1st than start testing vtech snsrs

chezaleanne

2000 Honda Civic Ex
4-cyl SOHC no vtec
completely stock
167k miles

Car history, I bought it used with 150k miles, ran great for 6 months, started over heating. I changed temperature gauge, and water temperature sensors, no leaks in the hoses, changed water pump, flushed the fluids because all it had was rusty water in it from previous owner. Blew a head anyway. Had it taken to a machine shop, got it back fixed. Ran fine, then I had a 3rd cylinder back fire, so I changed all the plugs and wires, had a bad 02 sensor code, changed the senors. Then I had engine ping and a knock sensor code, changed that. I change the oil in it and I only use high mileage royal purple, and filter.

So all the fluids are good. It pretty much runs fine unless im in what would be 2nd gear, then it does the jerking and hesitation thing with rpms going between 1000-2000 erratically.

chezaleanne

So I guess Im going to get an idle sensor and hopefully that will fix it, also I just recently ran seafoam through the tank, I was told it wouldnt be a bad idea since I had blown a head before and that there is probably a lot of carbon build up on everything. I havent noticed any kinda difference in performance since I did that tho. Could a bad idle sensor or vss cause a loss in power? I feel like it takes longer to get up in speed than use too.