I just finished doing some head work on my gsr. I installed dual valve springs,titanium retainers,flat faced valves,and stage 2 cams. I also had the head milled .01. I replaced all the valve seals, gaskets,etc. The engine runs perfect and hard until VTEC engages. When VTEC engages the car gives me a fuel cut. I tried changing the vtec crossover point and same problem. with the throttle at 100% vtec at 5000, car revs to 5000 very well then engages vtec and constantly bounces in and out of vtec but does not rev past 5000. If throttle is at about 20% car revs up to 5000 revs down to about 3800 and back up to 5000 but never passes vtec. no cel code is poping up. Car idles very smooth, and runs very nice before vtec. Any suggestions????

 

Which ECU are you running? What is your VTEC engagement point? It could be your VTEC pressure switch. This guy had a similar problem:

https://honda-tech.com/zerothread?id=1223543

 

When you got back your head from the machine shop, did you check to make sure the dowel pin under the middle cam cap was there? Also did you check to see if the oil control orifices were in their correct spots or if they were there at all?

 

did you tune it? because that could also have to do with the new valves, springs, and cams you put in, VTEC runs off of timing so when you change the cams that changes valve lift + duration and etc.

 

I checked and double checked everything. I tried from GSR to chipped p28 same problem. Thank you very much for all your inputs. I really appreciate it. Last night I went ahead and changed the cams back to stock and bamm, that was the whole problem. I don't think the compression is high enough to spin those VTEC lobes. I think the ecu was seeing to much load that's why the fuel was cutting out. It pulls really nice even with the stock cams. In a couple of days I'm going to throw in a CTR intake and exhaust cam, I like my vtec LOUD. lol. Thanks again everyone.

 

Simply changing the cams should not have fixed that problem unless the cams were damaged, in which case the car wouldn't have run. Could you have had the timing belt off by a tooth? Did you disconnect and reconnect any sensors? To me, it sounded like you problem stemmed from the ECU defaulting to limp mode.

When you mentioned the fuel cutout in the original post, was it similar to hitting the rev limiter, but at a lower RPM?

 

The rev limiter is different. It felt like msd rev limit set to 5000 but a little rougher. The cam timing was perfect, I checked it like 3 or 4 times. It idled perfect and ran great until vtec tried to engage. The cams are brand new they look terrific. It's too bad I can't use them on this motor. Time to build a high compression b20 for my little bubble civic. You guys have been a great help. Thank you.