Posted in the drag racing section because you guys are the only ones that know anything! I'll try and keep it as short and sweet as possible. Setup is your basic sfwd/pws 700hp car:

Car fried an oil pump and some bearings so rebiult the bottom end with all the same stuff that came out of it and put it back together without changing anything. Everytime it crosses over into vtec it breaks up violently sounding like a machine gun for about 500rpms before pulling clean. Its more pronounced the lower vtec is set. The car will not make a decent pass like this because even just coming off the throttle take it out of vtec since its actived at 75% throttle and up as well as rpm based.

I have:
Changed/checked/inspected vtec solenoid and pressure at solenoid
Pulled apart and inspected rails and rockers
Changed cams
Changed distributors
Unhooked msd
Changed coils
Changed plug wires
Changed ecu's

I'm totally lost now and I have no idea what is wrong or what to fix. There are ways to semi bandaid the problem like not having vtec based on tps and just rpm based so it wont fall out between shifts but I would like to figure out whats wrong with it. I have some logs if anybody wants to see them just post up or pm me your email. Thanks guys!
Ben

 

We compression and leak down tested motor as well, all was perfect.

 

Just your basic 700whp honda huh? LOL. What computer are you using? Check to see if you have a "vtec fuel added" value.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SpeedDreamz.com &raquo;</TD></TR><TR><TD CLASS="quote">Just your basic 700whp honda huh? LOL. What computer are you using? Check to see if you have a "vtec fuel added" value.</TD></TR></TABLE>
S300. Vtec fuel added as in there is a low cam and a hi cam fuel table?

 

its not in the calibration. we put it on the dyno at 3am or something to see what was going on with it....... i have never heard a car make a noise like this before. and before the oil pump broke, i dont think the car ever missfired....it always ran clean and smooth.

we even tried manually turning on the vtec solenoid by touching a wire to the battery in the middle of a pass. if you set the vtec real high, it will pull through it but have a violent jump in power, and obviously be down on power pre-vtec. however, like ben said....thats just a bandaid and wont get it down the track properly.


a missfire, or a break up....is the understatement of the year. it really sounds like Rambo or something. at the track ben put back in the old gsr cams and the old gsr cam tune...and its doing the exact same thing. its def. not in the calibration.

it doesnt act as if its wiring related. it really seems mechanical.

and for what its worth the car idles perfect, part throttles as good as it can with 1600's and no injector driver, and even full throttle is perfect before and after the "spot"

 

I think i've run out of things to change/inspect.

 

cam gear timing maybe off? I dunno....

 

Vtec rocker pins sticking or something maybe? I'd pull the rockers out and inspect everything...

 

Pulled them all out last night and inspected each one individually and could not find anything wrong. Checked all the spring tension in the rockers, checked all the pins in the VTEC rocker. Put in a new set of shafts- thinking there was maybe a hole clogged.
Does anyone think the actual head could have a crack in it, so that when VTEC engages it won't hold oil pressure fast enough til it builds up and then activates?
I'm such at a loss on this, it's killing me.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tricura &raquo;</TD></TR><TR><TD CLASS="quote">I'm such at a loss on this, it's killing me.</TD></TR></TABLE>
Me too

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tricura &raquo;</TD></TR><TR><TD CLASS="quote">Pulled them all out last night and inspected each one individually and could not find anything wrong. Checked all the spring tension in the rockers, checked all the pins in the VTEC rocker. Put in a new set of shafts- thinking there was maybe a hole clogged.
Does anyone think the actual head could have a crack in it, so that when VTEC engages it won't hold oil pressure fast enough til it builds up and then activates?
I'm such at a loss on this, it's killing me.</TD></TR></TABLE>

Its got to be mechanical. Everything worked on the old engine, new short-block and now a problem, so possible something was left out or damaged in the shorty swap.
There is a pressure port at the front of the head (im sure you know) that only reads oil pressure once vtec is engaged. If you tap into that with a press gauge, and bring it into vtec, it should have pressure. If it does, that would answer your question about cracked head and not holding pressure.

If everything mechanical checks out 100% follow the helms flow chart. Its tedious, but its got to be something. Also try a few diff solenoids. I remember trying to diag an issue a few years back, swapped solenoid with a spare at the shop, ruled that out... about 4 days later gave it another shot from a running car and it worked! 2 bad solenoids, what are the chances, but that's what it was. (although i don't think that's your issue)

Good luck guys! Hope to see you this weekend.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2 0 3 &raquo;</TD></TR><TR><TD CLASS="quote">
There is a pressure port at the front of the head (im sure you know) that only reads oil pressure once vtec is engagaed. If you tap into that with a press gauge, and bring it into vtec, it should have pressure. .</TD></TR></TABLE>
Tested that, when jumping the vtec solenoid at around 5k it read about 50psi of pressure.

 

It may lie in the oil pump breaking and trashing the bearings. You may have some bearing material in the oil passages, near the vtec sld or the rocker assemblies. Why did the oil pump break? That is another problem you need to address.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SpeedDreamz.com &raquo;</TD></TR><TR><TD CLASS="quote">It may lie in the oil pump breaking and trashing the bearings. You may have some bearing material in the oil passages, near the vtec sld or the rocker assemblies. Why did the oil pump break? That is another problem you need to address.</TD></TR></TABLE>
We disassembled the rockers and rails (cleaned everything), and took the allens off the head and blew them out. The block was line bored with a new crank, new oil pump, so everything should be good there.

 

That is what we are not 100% sure, machinist said possible wrong oil in car or need heavier oil. It all started when at the track the car would not go into VTEC, when got it back to the pits only had 30psi of oil pressure max. By that time don't know if that damage was done or we were doing the damage. This problem may have been there from before but have no way of telling. The bottom end was completely redone with all new bearings, line bore checked, new oil pump, new pistons and rings, rods checked and block completely cleaned. Head was not checked but cleaned.

 

Joe, is this anything like what happened with my car?

Electronic disturbance in the harness?

It only happened for a few hundred RPM (right around VTEC crossover), and if the RPM's were brought up fast it would pull through it.


Modified by tepid1 at 3:23 PM 4/30/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tepid1 &raquo;</TD></TR><TR><TD CLASS="quote">Joe, is this anything like what happened with my car?

Electronic disturbance in the harness?

It only happened for a few hundred RPM (right around VTEC crossover), and if the RPM's were brought up fast it would pull through it.


Modified by tepid1 at 3:23 PM 4/30/2008</TD></TR></TABLE>
Hhmmmm? That sounds like something I may have to look into. We did disconnect the MSD box and it was still there, but maybe something similar to that.

 

For what it's worth no matter what dizzy I used it would not go away.... The MSD dizzy pulled through better than the OEM, but it was still there and at the same exact few hundred RPM every time.

The car had a custom harness though. When I pulled the wires apart (seperated the loom) the problem went away.

 

i really think its mechanical. its totally different than an interference missfire like on your car.


that and nothing else has changed. new distributor, removing msd etc had no effect...positive or negative

 

Just for the heck of it, since everything else has been ruled out:

-Injectors
-Fuel Pump

 

have you made sure the screen on the vtec solenoid is not clogged w/ shavings...

 

unplug everything, and plug it back in!

i bet you it works ask Joe

good luck Ben, better get on it 3 days to go!

 

might have a clogged fuel filter like we had this past weekend. With high load, it went lean and started breaking up.

Like Joe said, It sounds mechanical

Nothing funny in the datalog?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheWickedOne &raquo;</TD></TR><TR><TD CLASS="quote">Just for the heck of it, since everything else has been ruled out:

-Injectors
-Fuel Pump </TD></TR></TABLE>
They haven't, we are running dual Bosch and checked both of them, have not pulled injectors to check them yet.
If you stay in it, it does pull clean and will make power to 10k.

 

Out on a limb here but... have you check to see if the vtec o-ring in the middle of the head has a tear in it?