Hi Guys,

I'm hoping someone else has had this problem and can let me know what the fix is?

I have just re-fitted my SC after running in a new shortblock. For the first +/- 100 Km's I had no problems, the SC was runnig fine it even felt it had a little more low down power than when it was on the original engine.

I then changed the original plugs for a set of NGK R5672A-8's (copper and one step colder), I also re routed some of the vacuum hoses to make the install a little neater.

Since I have done this the engine hesitates @ 6000RPM with WOT, after one or two seconds the engine picks up and revs hard to the redline, sometimes cleanly and sometimes with a few more hesitations. I have noticed that I seem to get less hesitation if I go through the VTEC point at less the WOT.

I've removed the plugs and checked them they looked fine so I refitted them (it doesn't feel like a plug issue), I've also double checked the vacuum hoses and the wiring around the ECU, all looks good.

Has anyone got any ideas on what my problem may be?

 

Well it's not the plugs, I just swapped them back for the originals and I still get exactly the same hesitation @ 6000rpm.

Also no CEL is thrown

Any helpers?

 

Hi Kevin,

Suspiciously its at the VTEC engagement point, where the MAP takes over fuelling completely from the lambda. Also where your oil level becomes critical for the lifters to do their job.

I would say check your MAP connections
Check your oil level
Check your oil supply fitting (leaks / blockages etc)

MB

 

MAP connections checked OK!

Oil just re-filled with fresh oil OK!

No oil leaks to be seen, could be a blockage, but it seems to consistent regardless of temperature exactly 6000RPM etc.

I think I might take off the SC belt and see if it runs through VTEC OK without boost.

Kevin

 

another thought .....

Check the sc pulleys and make sure they are tight and secure. One of my pulley bolts was stripped and caused the pulley not to tighten sufficiently. It eventually scored the mounting plate and caused hesitation under acceleration.

 

I'll check the pulleys, but I've only just re-installed it so I'm pretty sure they are OK.

 

I haven't tried VTECing off boost but let me know how it behaves, any noises etc!

MB

 

This post has great merit. Don't dismiss it so quickly.
You have quite a few things to look at here. Vortech provides a "MAP" box that is wired into the ECU and splices with the other Vortech box. "Checking" these connections may not be enough. You must ENSURE that the connections are solid. By this, I mean that they should be REALLY well crimped or double crimped or even better, soldered.
In addition and also, coincidentally, you may have a MAP sensor wiring harness that needs to be firmly secured. This is why Honda put out that TSB for a better way to hold it on (fancy zip tie). Unclip it and wiggle it back on and put a zip tie to hold it firm.

Guys with Comptechs have, for years been chasing their tails around in circles with similar symptoms only to discover that those connections very quickly faulted. Granted that this was more of a problem with Comptech but the same principles apply.

 

Thanks for your feedback "xviper" my initial concern was that my problem was connected to the MAP sensor. I have double checked all the connections, both at the sensor and on the wiring at the ECU.

All seems to be OK!

It is possible that the Vortech MAP voltage clamp may be causing a problem that is why I intend to remove the SC belt to check the VATIC engagement without boost.

If I still have a problem, I think I can then start to look at the MAP sensor itself, or possibly as Mark stated an oil issue that's preventing a good VTEC switch over.

If the problem is not apparent without boost it will probably point to a voltage clamp or wiring issue.

If anyone has any other thoughts on how to get to the bottom of this issue please let me know?

THanks
Kevin

 

I removed the SC drive belt and took the car for a drive.

No problems at all, the car pulled smoothly up through the VTEC zone with no hesitation at all.

I think this proves that the oil pressure and switch to the high CAMs is OK, which leave me thinking the problem is most likely related to the Vortech electronic control boxes.

The wiring can't be incorrect as the car was running OK in the beginning, I can only assume I either have a poor electrical connection or one of the boxes has developed a fault.

Next thing to try is to remove all the clip type electrical connectors and solder them in place.

I hope this solves the problem otherwise I'm looking at replacing the black boxes.

Have I missed anything or do you all agree?

By the way NA sucks after you get used to the SC!