Hey guys, I picked up a clean 1 owner 93 VX this past Saturday with only 94k miles! Only problem is, it has the part throttle hesitation issue. I instantly thought it was the 02 sensor and replaced it the same day I bought the car but to no avail! The previous owner changed out the plugs, wires, fuel filter, cap and rotor trying to fix the problem as well.

It only does this when the car is warmed up. Like other posts I've read on here, when it's cold it doesn't have the issue. There's also NO check engine light on.

I tried unplugging the 02 to see if the hesitation would stop and nothing changed except for the check engine light coming on. It's a california model if that matters.

Thanks in advance, I'm stumped!

 

Some aftermarket plugs, wires, cap, and rotor are not very good. Do you have properly gapped NGK plugs installed? Have you inspected/tested the other ignition components? Is the ignition timing set to spec?

 

He said he replaced the ignition components with OEM honda and NGK plugs. I'm not sure about the timing. I bought it from the original owner who also happens to be a mechanic. He hadn't been driving the car much this past year 2010 and that it had been sitting for a couple months. When he finally got it started prior to posting it for sale he noticed the hesitation issue.

 

Unfortunately, you generally can't trust everything that sellers say. I'd recommend that you start by inspecting the plugs, wires, cap, and rotor.

There's a diagram link in the FAQs sticky for setting the ignition timing.

How old is the gas in the tank?

 

When I came to pick it up, it had a full tank (seller said he just topped it off). Since then I filled up again on Saturday. When I did the calculation I only got 37mpg with 200 freeway miles and 100 or so driving around town for deliveries Saturday evening if that helps...

 

What is the make and model # of the O2 sensor you bought? The VX is very picky... there are many sensors that claim to be a direct replacement, but in fact are not.

 

it was a bosch. I returned it to Autozone since it didn't improve the situation at all.

 

Most VXs are picky, but the '93 - '95 CA models used a 4 wire O2 sensor like most other 5th gen civics.

Bosch is junk. Denso or NTK is what you want.

 

Ahh... yep, I missed that. If you've confirmed that it's a California model, the sensor isn't as picky.

 

I've heard that before, also part of the reason I returned it. I tried unplugging the O2 all together to see if that made any difference and it ran exactly the same other than the CE light coming on. That's why I doubt it's an O2 related problem. From what I've read when the ECU picks up the code for the O2 the hesitation stops... but what do I know :p

 

I completely agree.

 

Dropped it off at the mechanics shop yesterday. We'll see what he says... I give up

 

Got a call from the mechanic

"Err I didn't notice any hesitation issue, could be driver error er ur clutch springs er worn out err they took er jobs!"

Dumb ****s! I'm picking up the car tomorrow and going to start with cleaning out the EGR valve. smh...

 

Last night I completed my Federal lean burn conversion. The car is now running a 5 wire L1H1 02 and P07-A00 ecu.

Only problem is, now the part throttle hesitation i was experiencing previously has gotten much worse. Car runs perfect (open loop) until it reaches operating temp then it bogs and forces you to give it much more gas than before. I can tell having to drive this way is going to kill my MPG for sure. It's almost as though the car won't operate in lean burn mode at all. Won't cruise at a steady speed, actually slows down unless i push the gas down more than halfway! grrr!!

<<When i pulled the old 02 it was white if this helps any.>>

My thoughts are that since the wideband setup is much more sensitive, it's amplifying the problem.

My next guess would be:
clogged EGR, (****ty mechanic said this was working fine last week)
faulty TPS,
faulty MAP

help!!?...

 

I just unplugged the MAP and test drove it. Idle was rough but the hesitation went away completely! Does this mean the MAP needs to be replaced or does it mean the real problem is just being masked because the car is now running in limp mode?

 

Are any CEL codes currently thrown. Was a MAP sensor code thrown when you unplugged it? Have you considered the points I made in post #4?

 

Yes MAP code was thrown when I unplugged it. I inspected plugs, wires, all new. Car is running lean for sure thought judging by white residue on plugs and old 02. The mechanic who had my car last week said timing was fine. Going to autozone to replace MAP on my lunch and will report back...

 

This^ is also my concern. Did you voltage test the MAP sensor connector wires?


The wires can be resistance tested. Cap and rotor? When was the fuel filter last replaced? Have you measured the fuel pressure and tested the FPR?

 

It's not the MAP sensor. Replaced it at lunch to no avail.

new cap/rotor, new fuel filter

Haven't measured the fuel pressure or checked FPR. Are those pretty simple to replace?

EDIT:
If it's able to run rich in limp mode wouldn't that cancel out the FPR as being the culprit?

 

It will get expensive replacing parts randomly.

That's quite possible.

I'd now try cleaning the EGR valve and its port in the IM.

 

1st timer here, registered for another reason but this caught my attention...
I have a vx too. I agree that replacing parts randomly is uncalled for. Or, if you're going to do that, do the least expensive first, which may also benefit you in some other way. How about oil weight? Maybe you have a vtec problem. Try a can of motor flush and a fresh oil change 5w30. Do a compression test if you have the ability. Loosen the distributor bolts and twist it side to side until your idle sounds good and you are in the middle somewhere. And do check the NGK plugs are correct... parts stores do not know this car well and may mislead you. Plugs for the D15Z1 should be a ZFR4F11 NGK - now known as an NGK 4043 v-power. And get a factory service manual! Also check your computer - it should be a P07-A01. Good luck

 

On my way home from work I decided to unplug the 02. Low and behold the car ran perfect all the way home aside from having the check engine light on. I'm boggled by this because when I tried this before with the P07-L01 and 4 wire 02 (Cali non lean burn) the hesitation was still there. I purchased the NGK/NTK L1H1 brand new so it's really hard for me to believe it could be fouled out already...

Earlier today I seafoamed the intake manifold through the brake booster. I slowly poured half a can while the car was idling then shut it off, let it heat soak 30min then started back up, let it idle for about 5 min then drove it down the street at WOT. (I think i smoked out the whole neighborhood!) <<didn't fix anything.

I just finished cleaning the EGR valve and intake/exhaust ports with carb cleaner. I even used a vacuum pump to open the valve so I could get in there real good. This didn't seem to improve anything either.

Farlander:
FED VX ecu models
P07-A00 (92-93 VX)
P07-A01 (94-95 VX)
it really doesn't matter which one you use.

 

Having the same problem on my coupe. GL findin an answer

 

You may want to voltage and Ohm check the O2 sensor wires.

 

Would a hairline crack in the exhaust manifold right where the 02 connects possibly cause the car to run too lean in "lean burn" mode in effect causing the hesitation? I did notice a crack there but there doesn't appear to be any exhaust leaking from it... shot in the dark maybe?