Oromis

I've got an '03 2.5XS Auto with 90k miles. I have a slight hesitation between the time I hit gas to the time the car starts to move forward. I just had a bunch of work done to the car and thought the problem would have gone away after the head gasket, intake seals, plugs, wires, water pump, belts and water pump were replaced. Valves were adjusted. I have a new air filter I am going to put in tomorrow and other 90k service stuff is going to get done over the next month.

I have been meaning to watch the tachometer when I hit the gas to see if the RPMs actually drop for a second when I hit the gas but I never remember to look. It doesn't always happen either. It is one of those things that other people in the car may not feel but the driver definitely does. What could be causing the delayed response in acceleration? Clogged injector? Vacuum leak? Transmission witchcraft(unlikely)?

I should also mention that I have the dreaded muffler squeal at higher RPMs. Could it be that the squealing muffler debris is causing some sort of clogging of exhaust gasses until enough pressure is built up to push out the tail pipe.

The overall delay is only 1 to 2 seconds but that is a big difference when pulling out into traffic or when trying to hit the gas at the apex of a corner.

sfjohnson

I have this too; just posted in another part of the forum. Did you figure it out? I'm thinking of going after plugs, then throttle position sensor. Under 4k for me, letting off the throttle I end up with teeth in the airbag! And my clutch won't last if I don't figure this out quick.

MikeDrives1

knock sensor

__________________
- 2001FSTi: Currently rebuilding....
- 1996 Civic LX. The daily gas sipper.

sfjohnson

Brilliant, I'll give it a shot. Figured I'd get a CEL, but see on Scooby enthusiasts that's not always the case.

tallazzPilipino

how many miles on the front o2 sensor?

(Sent from my Android via Tapatalk)

__________________
romidontplaythat! ouiiiii...
- two USDM SF6s

sfjohnson

150k probably for mine (bought at 79k, so minimum of 80k)

sfjohnson

Update: replacing the knock sensor and plugs helped some - still feeling the 'switch' that hits after a few seconds at 3k+ rpm, but certainly not as bad as before. Any other suggestions? Or things to look for / log? Unfortunately, mine is an '01 so I can't log with OpenECU so far as I know.

GEORGEROV

Is the fluid in the transmission clean and up to the correct level ? . Do the engine revs go up as soon as you hit the accelerator ? .

sfjohnson

Its not clutch/transmission slip. 5mt and yes to proper oil level. The rpm's stay put, maybe even dip 50-100 or so if going uphill, then like a switch engine tone changes and takes off. So the idea of ignition timing from a faulty knock sensor seemed reasonable. May be a separate issue, but idle is often lumpy, with pops in exhaust note.

sfjohnson

The plot thickens; stumbling returned with a vengeance this week, worse than ever after several weeks of being very mild, including P0136 CEL. New upstream O2/AF purchased and going in this weekend. Found a couple corresponding threads showing rear O2 CELs with failing front O2/AF sensors. Doesn't make sense to me, but we'll see!

jsahara24

Good luck, let us know how it goes this weekend.

Sent from my DROID3 using AutoGuide.Com Free App

Plastickmat

Also interested in this ! Lines up to most of my symptoms and most likely any parts your replacing will need replacement in mine since its got 311 000kms.. ! keep us updated!

sfjohnson

Update: ended up doing timing belt and clutch bearings at the same time as replacing the front O2/AF, but the idle is much smoother. Before I thought motor mounts were going bad; now it's barely noticeable that the engine is running. The rear O2 is still throwing the P0136 CEL, but have a (bigger) exhaust leak from the work, and will be putting Borla/Stromung on next weekend! Odd there's no CEL for the front; and would be great if someone knows the sensor readings to monitor (with UltraGauge or the like).