[TxGreaseMonkey]

Yeah, I was thinking you had an older Acura.

[TxGreaseMonkey]

Hesitation is not normal in any car. I would work tirelessly to eliminate it, especially in an Acura.

[paulkramer]

Hesitation is not normal in any car. I would work tirelessly to eliminate it, especially in an Acura.

Tirelessly, and at great cost :(

[paulkramer]

I've already replaced one vacuum line, I just ordered the forward main vacuum line.

New PCV and PCV hose are on their way, I also just ordered TB, IAC and IM gaskets.

Maybe the cure is in one of those...

[TxGreaseMonkey]

Possibly, but you bought an Acura for performance, right?

[paulkramer]

LOL - sort of - why do you ask?

I'm TRYING to find the solution, jeez!

I bought it primarily because it's a Honda - reliability and longevity and economical operation. LOL @ the last one - I got bitten by the modding bug and I've spent too much money on this car.

One of the main reasons I bought the RSX instead of a Civic was styling. I just didn't like the looks of the Civic coupe. It's grown on me since then, but I still prefer the RSX' appearance.

If I'd wanted performance (of course I'd like to have my cake and eat it too, but that's not possible) I'd have at least bought the Type-S.

As far as I can tell though, the only Acura that performs is the NSX.

HONDA = Hold On, Not Done Accelerating

[DrRotor]

Wow. This is a tough one.

Assuming all other things equal and there are no other causal factors (like an intake manifold/vaccuum leak, etc) you likely have induced this performance degradation in changing the catalytic converter (CC). Interestingly, by changing out the CC, you have negatively impacted at least two variables that could affect smooth operation of this engine:

#1-The exhaust system gas flow (meaning air/fuel/exhaust) is carefully orchestrated and engineered during system design. In some places within the path, gas flow is meant to slow down, in others, it is meant to speed up. Exhaust pipe diameters, radius and number of bends, even the exhaust pipe "tip" are all engineered so as to optimize gas flow at different points for different reasons. Reducing resistance to gas flow generally has a positive effect on most engines (namely older engines), but can cause problems in other (newer, emissions-equipped) engines.

#2-When the catalytic converter was changed out, not only was gas flow changed, but the temperatures as sensed by the O2 sensors changed. The O2 sensor signals the computer as to actual temperature measured. The computer (not knowing anything about a CC change) continues to do its job by attempting to change the fuel mixture (thru enrichening or leaning) based upon optimum temp/actual temp deviation so as to effect optimal baseline temps and thus acceptable emissions. The result of your scenario has manifested itself in the ways you describe.

FIX: I know this is probably a real pain, but I would reinstall the original CC and re-check performance. You just may fix your car---and for no money---wouldn't that be great! Good luck with it, whatever you decide!

NOTE: Be sure to check local laws in "modifying emissions systems." Finally, if you determine the new CC did in fact introduce the problem, check with the performance CC company via wesite, etc for their recommended solutions---sometimes they have "fixes" to overcome these type performance degradations.

[paulkramer]

DrRotor - thanks, you may be spot on.

Hence the desire for Hondata reflash - it's supposed to be mapped for freer flowing intakes + exhausts.

I've never heard of anyone complain about performance issues after installing intakes, race headers, etc. - without reflash.

But most of the people that add those items to their cars have the programmable ECUs and they make their own adjustments.

And, of course, I sold the OEM CC for scrap months ago.

[paulkramer]

I just re-read your post and had a thought -

I doubt the A/F sensor is impacted much by installing a shorty header (the only new exhaust part before the sensor), and the secondary O2 sensor surely is affected by the aftermarket cat, but it plays no role (on my car) in air/fuel metering. It only tells the user if the cat is "malfunctioning". That can be resolved with a "defouler", which I just haven't gotten around to doing.

However, the change in backpressure is likely an issue with the now less restrictive exhaust. But most of the "experts" for this car have told me the stock ECU can compensate for such a minor change as a less restrictive bolt-on exhaust.

[paulkramer]

I received and installed an OEM PCV and tubing today. Seems to run even smoother, but not 100%.

These cars are renowned for their jerkiness getting off the clutch in first gear, so it's a little difficult to know if I still have a problem, LOL.

I think I still have a vacuum leak - I was listening to the car in the garage tonight after pulling in and hearing a sound. I notice when I turn the steering wheel that there is a brief "pfffff" sound that appears before the RPMs bump up from turning the wheel. Is that normal?

[paulkramer]

Update - I replaced the forward vacuum hose that runs from the IM to the metal portion of the vacuum "hose" (I replaced the aft rubber portion that runs to the MC a while ago) and I replaced the IM O-rings and re-glued the tiny vacuum line to the IM runner while I await the arrival of the replacement solenoid.

My brake pedal is firmer and sits higher up. I am afraid to say that the engine feels smoother too, with less of the hesitation I described at the beginning of this thread. Afraid because there is always the psychological effect of replacing something and thinking the problem is gone... I'll reserve final judgement until I've driven the car for a few days.

Next up, apart from the cracked IM solenoid is the TB O-ring. I was able to replace the primary IM O-rings without completely removing the IM, maybe I'll be lucky that way with the TB O-ring.

I was surprised to see clean, fresh-looking oil on the old IM O-rings. I guess (and hope) that is normal PCV blow-by.