Hesitation only at constant throttle warm

[wagon.spec]

I have a honda shop manual. I went through the trouble shooting steps and replaced the O2 sensor and the coolant temp sensor (that talks to the ecu, not the cluster or fan switch), I also rewired the o2 sensor and ECT sensor and I still have a stutter (or miss) at constant rpm, such as cruising in fifth gear. Full throttle it runs amazing, but I know that there is no reason for this stutter. Plugs are good, plug wires are good, new dizzy, as I said the O2 is new (oem), and the coolant temp sensor is new. I can't figure this one out for the life of me. It throws no codes at all. Motor is an f22a6 with proper ecu, proper injectors, and proper fuel pressure regulator. I have a walbro 255 but the only time I have heard this causing problems with a rich condition (with a stock fpr) would be sudden vaccum change, clearly not the case with my problem only being present at a constant cruise speed. I thought it was the TPS so I replaced it with the Honda OEM one off my old motor (which worked fine) adjusted it and still have the stutter. Everyone says that the ECT on f/h can be a pain in the ass. I had a guy, he used to have a shop drag civic with an f22, state that he had lost 17whp until he had his ect problem sorted (he may have had a cel, but I am unsure.) any help would be greatly appreciated. Thank you in advance.

EDIT: I forgot to mention that it seems to only happen once the car has neared operating temperature. It doesn't stutter until around 160 degrees fahrenheit

[h22sparkle]

I have a honda shop manual. I went through the trouble shooting steps and replaced the O2 sensor and the coolant temp sensor (that talks to the ecu, not the cluster or fan switch), I also rewired the o2 sensor and ECT sensor and I still have a stutter (or miss) at constant rpm, such as cruising in fifth gear. Full throttle it runs amazing, but I know that there is no reason for this stutter. Plugs are good, plug wires are good, new dizzy, as I said the O2 is new (oem), and the coolant temp sensor is new. I can't figure this one out for the life of me. It throws no codes at all. Motor is an f22a6 with proper ecu, proper injectors, and proper fuel pressure regulator. I have a walbro 255 but the only time I have heard this causing problems with a rich condition (with a stock fpr) would be sudden vaccum change, clearly not the case with my problem only being present at a constant cruise speed. I thought it was the TPS so I replaced it with the Honda OEM one off my old motor (which worked fine) adjusted it and still have the stutter. Everyone says that the ECT on f/h can be a pain in the ass. I had a guy, he used to have a shop drag civic with an f22, state that he had lost 17whp until he had his ect problem sorted (he may have had a cel, but I am unsure.) any help would be greatly appreciated. Thank you in advance.

EDIT: I forgot to mention that it seems to only happen once the car has neared operating temperature. It doesn't stutter until around 160 degrees fahrenheit

The stutter sounds like a spark issue. Check the coil,distributor and sparkplug gap.

[wagon.spec]

plugs from ngk are pre gapped(and i verified) my moroso plug wires are fine, my distributor is new (and its an internal coil car) its coolant temp sensor related I would bet money. Just can't figure out past that
EDIT: Also, unplugged the egr and the car ran awful at steady state throttle. CEL came on (as expected with the EGR unplugged) however I got 3 codes. 6, 12, and 14. EGR, ECT Sensor, and IACV/BadECM
ECU doesn't fix problem (have a buddy with no CELS with an f22a6)
Most likely wiring to the ECT? I will admit I had to do a lot of soldering and changing plugs on the harness. (My car is a 1991 Wagon EX-R, it came factory with an automatic transmission and a f22a6, which really confused me. Also has manual seat belts, but yet still no ABS, rear disc. It seems my 91 Canadian EX-R wagon was a bit of a frankenstein from the factory. But I swapped a f22b1 in with a manual, and some male/female plugs had to be played with or replaced. Then I put another f22a6 head on it and a PT6.)
I am rambling something awful. I just can't quite figure this one out. I have absolutely no CEL with the EGR plugged in. If I unplug the EGR I get 3 codes? Any light shed on this would be wonderful. I have had so many problems with this damn wagon....

[JDMDriver]

I experienced lag in high to hard acceleration on my CRX (different car I know but still same basics and still a honda).

After some trouble shooting I checked out my air filter and it was dirty (and I forgot to include it in my thought process). Changing my filter greatly improved the strong lag I was experiencing at the high to hard acceleration.

[JDMDriver]

In addition, I did experience really strong lag prior to me changing my filter.

For a long time I felt this lag but attributed it to me doubting myself and telling myself that was how it was from when I purchased the car so its just normal, just being an old car or just me hoping too much when pitted against a newer car with a Provisional driver that is disrespecting me.

Well my car stalled then eventually died and it turned out i needed a new ignitor.

I noticed changing the ignitor improved my noticeable lag but it didn't eliminate it. However in my diagnosis having changed my ignitor assisted in ruling out that component until my eventual discovery of my clogged filter.

My new ignitor and new filter combined to eliminate my lag to almost unnoticeable levels. I know my response can still be improved but I put it down to my spark plugs (not replaced coming up to 4 years), fuel filter (not replaced since I started owning the vehicle 8 years ago) and timing (not done coming up to 4 years).

I will not be surprised if your problem is a combination of components or service requirements that has been overlooked and not provided.

[wagon.spec]

I don't mean to come off as arrogant but I am very keen to do things properly. It runs absolutely great WOT. It only has this stutter at constant throttle. And only once it is warm. I am getting Hondata next week regardless. So I am really hoping it is ecu related

[cp[mike]]

the "constant throttle when warm" conditions lead me to suggest that you check, and possibly clean, the EGR valve and ports. http://www.youtube.com/watch?feature...&v=sJEfr2E6i4s

[h22sparkle]

Check the gap anyway I went with NGK that was pregapped and it was off by 0.02 and its caused my Evo to misfire perhaps something leaned on the box causing it to be out of proper gap range.

[deevergote]

Did you use a Bosch o2 sensor by any chance?

[wagon.spec]

denso o2, I know for a fact that the EGR ports are clean as I cleaned everything 5000 miles ago or so when I put this head on. I believe it is electrical. I am getting Hondata this week so I may choose to just run open loop. However I wouldn't mind fixing the problem

[reklipz]

An exhaust leak, perhaps?

[wagon.spec]

Well, I am currently running hondata and I do believe my IACV was the problem if anyone cares. I am running with it unplugged without any problems. However, I do understand hondata does not run the EGR so it was most definitely one of the two. However, I had no problems with that EGR valve on another engine. That being said, I suppose ECU may have been no good.

[Accord problems]

do you have a auto transmission or a manual transmission ? if auto it can be the lock up solenoid .