I have a 95 GSR and it hesitates at low rpm. I just finished putting in a Skunk2 manifold, new fuel rail and new Type R injectors, B&M fuel regulator and gauge, new plugs, changed my timing belt and water pump, put in an undersize crank pulley and adjusted my valves. I have my timing gears at stock settings till I can Dyno tune.

I get the some kind of hesitation as I accelerate and get close to 3000 rpm. After that I get pretty smooth acceleration--even better than before.

Why the hesitation?? I have no clue. I don't find any vacuum leaks or anything. Don't burn a drop of oil and have never suspected a compression problem. Is it a fuel problem? Oxygen sensor perhaps??

Any help in what to look for would be appreciated.

thanks
tf

 

what is your FPR set at? Try moving down to 40. Also, a high flow fuel pump always starts to act strange when your low on gas

 

i have the pressure gauge set to 50 with the vacuum off and plugged (low recommended) i increased it to 55 today to see if it would help thinking I was too lean. still no improvement.

I am using the stock fuel pump.

any other ideas would help alot.

tf

 

What ECU are you running? If you're still running a dual runner GSR manifold ECU, maybe the fuel maps on the ECU are bogging you down . You may need to run an ITR or modded ECU if you're not already with the skunk single runner manifold.

I'm trying to make an educated guess here... so I may be wrong.


[Modified by Gee3, 4:13 PM 7/19/2001]

 

i've never heard mention of this. I thought that the maps reset when you reset your ecu. I am running the stock GSR ecu. Anyone else hear of this being an issue???

 

My reasoning is that the Skunk Manifold is very similar to the ITR mani., both are also single runners. Thus, running an ITR ECU would be better since the fuel maps are geared for the single runner mainfold and not the GSR dual runners. Am I making sense? Resetting the ECU won't physically change the stock fuel curves programmed from the factory. Re-chipping the ECU or swapping ECU's would be beneficial to your set-up to optimize the fuel and power delivery.

Anyone else have any opinions or help on this?

 

i'm about to do many of these same mods in just a few days so i've been reading up. one thing i remember distinctly is that adj fpr's can enrich your mixture but not lean you out. if i had to take a wild, not-completely-educated guess i might suggest you're running rich not lean, possibly due to the injectors (don't know the flow difference: GSR vs. ITR) or fuel rail (don't know about this part). another wild guess: something got screwed up with the throttle body (throttle position sensor?)? are you stock or? did you put a new one on at the same time and forget to mention it? don't know if any of this helps but keep us informed! i can't imagine ECU (difference) is affecting you right up to but not over 3000. uh, wait. what cams do you have?

 

That person is right. you want to run a ecu from a 92-95 Civic VTEC that is chipped. Preferably get one from skunk and lean it out with a vafc. the gsr computer adds too much fuel when switching cams or when the butterflys are supposed to activate.

 

i'm running all stock sensors on the new manifold.
the cams are stock too. I have adjustable cam gear but set to zero till i sort the rest of this out.

Will things change if I put in a turbo. i'm planning that next. will the civic vtec ecu be needed if I go with a turbo?

Know a good source for a replacement ecu to go with the single runner skunk2?

thanks for all the suggestions. I hope we are on the right track here??

tf

 

also, weren't all the civic vtecs SOHC rather than dual cam?? that will make a difference too won't it??

in all my research no one ever mentioned that adding a type R manifold or a skunk2 modified manifold to a GSR meant you had to change out your ECU!!

tf

 

what's most important is not to use a single runner program with a gsr manifold (which doesn't apply to you, of course). i still think the particular problem you're having is not ECU related. if you ever do end up looking for a new ECU you owe it to yourself to check out hondata (dotcom). stage III has (easily adjustable) launch control rpm, vtec x-over, full throttle shifting, shift light, rev limit, etc. i hope to get one in about a month...

 

Hi,

I think it sounds like your rich down there, perhaps the GSR fuel maps are rich since you "would" have the longer low rpm specific runners with the GSR manifold.

If you can't switch ecus, maybe a VAFC or Field to try leaning?

I got a Yoshio tuned ecu for my car, specific for Toda b specs, larger 270 cc injectors, and the skunk manifold.

Good luck,

FB

 

well. looks like the rich folks were right. I lowered my fuel pressure to the lowest point on factory specs (49psi with vacuum on). It seems to have solved the problem of the hesitation. Now I really could use some valid proof of whether I need another ecu/reprogram.

i talked with Skunk2 (Group A Motorsports). They say only OBD-2 cars need to be converted to OBD-1 because of fuel mixture problems not remapping.

thanks. hope my problem helps others.

 

so should i skip the b&m fpr 'n gauge? save some money...use it towards a v-afc?

let us know your butt-dyno impressions of your new goodies when you get a chance

 

no, i would get them. they are very necessary to adjust pressure when you do other mods. I am very happy with my changes. it is a great prelude to adding the turbo.

tf