JUST TURBO'D MY CAR, NEED HELP FIXING PROBLEMS SO I CAN GET IT TUNED!!!

[boostedEG]

ok so i got my car running a few months back (not turbo'd yet), and ever since it has had this problem where after about 20-30 minutes of highway driving (4000 rpms @ 70mph) it would suddenly have a 6500-ish rev limiter. and about 20-30 minutes later it would have the normal 8200 rev limiter (untouched P72)

i didn't know what the problem was, but it didn't really bother me too much because i didn't need to rev it that high unless i was racing or something, and so i didn't worry about it.

well now i have turbo'd my car. it is tuned with VAFC and DSM 450's and runs like complete crap. i know thats a ghetto setup but i am getting neptuned as soon as my problems are fixed.

when vtec hits (5000 RPM's) the car sputters and falls on its face. i regapped the plugs to .025 and at first this fixed the problem, but then started doing it every now and then (mainly when the engine was cold), and seems to be doing it pretty much all the time now. i had to unplug my vtec solenoid.
this first started happening when i installed the DSM 450's and resistor box (which was 2 days before it got turbo'd)

and about a week ago it started having a 6500 rev limiter ALL the time.

its also slow even under 8-13 PSI unless i set the VAFC at -48 to -50 which i believe makes it very very very lean. if i set it at -30 its almost as slow as when it was never boosted.

i thought the vtec problem and the lack of power were related to a weak spark. i had new plugs, and MSD plug wires, i didn;t think there was any problem with those, so i swapped on my friends distributor, still had the problem. then i swapped in his stock P28 ecu. it no longer had the 6500 rev limiter, but it still cut out real bad when vtec hit, and still seemed to lack power.

so i figured the ecu was somehow fucked up causing the low rev limiter (which would make that the second ECU my car has fried) but then my friend put my P72 in his car and it revved to 8200 no problem. so the ecu is not fucked up (?) we then put my P72 back in my car and again it has a 6500 rev limiter.

i dont have my knock sensor hooked up yet if that makes any sort of difference.


does any one have any clue what this could be? to those people who own a shop (tobi, etc) if you think you know what the problem(s) might be and want to PM me an estimate that would be great. i just need some sort of an estimate upfront because the only money i have at the moment is the money i saved up for neptune, meaning i dont have much to spare.

[ComputerJLT]

ygpm

[M@]

Right off the bat my guess would be an O2 sensor.. but I didn't read all of that.. so I can't say for sure.

Time for me to pass out.

[xiong]

knock sensor

[B20badboy]

Ask Servion or Toby they would most likley know, Mine was haveing the lack of power problem but I think it was my turbo it went out last week. Now it will not build any boost.

[Mario]

Ask Servion or Toby they would most likley know, Mine was haveing the lack of power problem but I think it was my turbo it went out last week. Now it will not build any boost.

Charge pipe didn't blow off?

[HONDA GHANDI]

If you dont have the knock sensor hooked up you obviously have a CEL. Have you checked to see if there are any other codes stored in the ECU other than knock? That would be a good place to start.

[B20badboy]

Charge pipe didn't blow off?
No the turbo does not spool unless at 5k or higher. I also have oil all over the place now and about 1/2 of shaftplay.

[servion]

If you dont have the knock sensor hooked up you obviously have a CEL. Have you checked to see if there are any other codes stored in the ECU other than knock? That would be a good place to start.

:werd: Check all the codes you are throwing and try to eliminate or at least account for all of them.

With a stock ECU, VTEC won't kick in without the proper oil pressure. So, if the vtec pressure switch isn't reading the full oil pressure required to engage vtec, it won't engage. When your 6500 rev-limit is happening, does vtec kick in? A stock ecu also reduces the rev-limit when vtec is not engaged. Perhaps thats part of your issue.

Are your plugs good? What's the gap set at?

[M@]

FWIW, I don't run a knock sensor on my motor and I have no problem with bogging (OBD2 ecu/head)

[boostedEG]

i am throwing a code for knock sensor and code 22 for vtec oil pressure switch circuit malfunction or something like that. (one of the wires pulled out of the plug) however vtec does still work because the VAFC forces vtec to work.

is it possible that the VAFC is forcing vtec, but the ecu 'thinks' vtec is NOT engaging (due to the oil pressure switch not hooked up) and is reducing the rev limiter?


either way i am going to hook up the knock sensor tonight if i can find a wiring diagram, and i will solder on a new plug for the oil pressure switch.

i havent checked the plugs in about 2 weeks (have not driven for 1 week though), but last time i checked they were good, and gap was at .025" i will double check that as well.

[ComputerJLT]

there are two different rev limiters one when the computer is not in vtec and one when it is.

If your VTP sensor is not working make it work; but since it works some times that leads me to believe you're running low oil pressure. THATS NOT GOOD. If your turbo is shot you could loose enough oil pressure to really break the motor. Make double sure your wiring to your VTP sensor is intact and working and if it is stop driving the car because you'll fuck something up big time if you haven't already.

[riceburner700]

shouldnt turbo plugs be gappaped at .044? i though

[ComputerJLT]

shouldnt turbo plugs be gappaped at .044? i though

fuck no; usually .025-.035 .044 is stock; any amount of extra cylinder pressure will blow that spark out.

This guy is probably having problems with his VTP. If the sensor is working right that means his dead turbo is letting all the oil fly right by the bearings letting the motor lose oil pressure. THAT IS VERY BAD. The VTP sensor tells the computer "ok there is enough oil pressure to engage the vtak y0" and if you dont have that oil pressure it wont engage to help save the motor. the VAFC takes over and kicks it in anyway dropping oil pressure that much more.

I lost a motor once to a turbo going south; if the bearings are shot they'll provide no resistance and oil pressrue will drop just like the journal bearings in a motor; loose tollerance = low pressre = death.

If serious damage hasn't already been done by doing that then you need to take care of the oil pressure problem; then TUNE IT; driving around on a stock motor and shitty tune means nothing but busted ringlands.

[boostedEG]

lol, dont worry i have good oil pressure the motor only has 1-2 thousand miles on it.

my turbo does not have any excessive shaft play. and the oil seals are not blown.

the whole problem was the wire that came out of the vtec oil pressure switch. i got that hooked up aswell as the knock sensor and i no longer have any cels, it revs to 8200 no problem, and it does not sputter when vtec kicks in anymore. and it feels like it has decent power.

now just to get it tuned!! (before she blows up)

[boostedEG]

thanks to everyone for helping me figure this out.

[M@]

Glad you fixed it.. good meeting you.

[ComputerJLT]

lol, dont worry i have good oil pressure the motor only has 1-2 thousand miles on it.

my turbo does not have any excessive shaft play. and the oil seals are not blown.

the whole problem was the wire that came out of the vtec oil pressure switch. i got that hooked up aswell as the knock sensor and i no longer have any cels, it revs to 8200 no problem, and it does not sputter when vtec kicks in anymore. and it feels like it has decent power.

now just to get it tuned!! (before she blows up)

yea; I dont take oil pressure issues lightly :-p every engine i've lost has been due to some stupid mistake in the oil system; shot turbo's; improper bearing crush; worn out oil pumps; etc. Though the d-series is at a disadvantage because their oil pumps don't have much reserve capacity. VTEC B oil pumps do.

[HONDA GHANDI]

:werd: Check all the codes you are throwing and try to eliminate or at least account for all of them.

With a stock ECU, VTEC won't kick in without the proper oil pressure. So, if the vtec pressure switch isn't reading the full oil pressure required to engage vtec, it won't engage. When your 6500 rev-limit is happening, does vtec kick in? A stock ecu also reduces the rev-limit when vtec is not engaged. Perhaps thats part of your issue.

Are your plugs good? What's the gap set at?

The ECU uses the VTEC pressure switch to check VTEC as a feedback function. It doesnt read actual pressure and decide if VTEC can be used or not. Just an FYI and to clear this up for anyone trying to diagnose a VTEC code.

[ComputerJLT]

The ECU uses the VTEC pressure switch to check VTEC as a feedback function. It doesnt read actual pressure and decide if VTEC can be used or not. Just an FYI and to clear this up for anyone trying to diagnose a VTEC code.

code 21 means the solenoid isn't doing what its supposed to; the vtp does check for pressure because if you unlpug the sensor vtak won't kick in

[M@]

code 21 means the solenoid isn't doing what its supposed to; the vtp does check for pressure because if you unlpug the sensor vtak won't kick in
:worshippy You're obviously smarter than a guy who owns his own shop and who's worked on Honda's his whole life... (and that's been a LONG while). :D

[ComputerJLT]

:worshippy You're obviously smarter than a guy who owns his own shop and who's worked on Honda's his whole life... (and that's been a LONG while). :D


dont believe me go unplug the vtp sensor

/edit: it does in crome

[riceburner700]

it was just a question, didnt have to jump down my throat, god damn what crawled up your a$$

[ComputerJLT]

not crawling up anyones throat; sorry it seemed that way. I'm not sure about b-series but my d16z6 would go apeshit if i didnt have enough oil pressure for the vtp to kick on (~35psi is where the switch is at). It would throw a code and sometimes sputter when it tried to go into safe mode.

[HONDA GHANDI]

It wont kick in with the sensor unplugged because it creates an open circuit and sets a code. Im just trying to clear up that oil pressure is not read directly through the switch. It is not a sensor, just a switch that opens at about 10 psi. So even if you have low oil pressure the VTEC switch can allow operation.

[boostedEG]

It wont kick in with the sensor unplugged because it creates an open circuit and sets a code. Im just trying to clear up that oil pressure is not read directly through the switch. It is not a sensor, just a switch that opens at about 10 psi. So even if you have low oil pressure the VTEC switch can allow operation.


yup, i was in a friends car once that was just really low on oil, and only made like 20 PSI, and VTEC would try to kick in, but there wasn't enough oil pressure to push that shaft across to lock in the vtec rocker arms. made some weird noises when it tried though.