Silver top in AE86, now has vvt gremlins. NEED HELP

[that one guy]

**Im new to this so if i say or ask somthing dumb, wierd, covered elsewhere, unintelligible, (ect.) please tell me, i dont want to be a 'noobie' for very long**
I have a 84 sr5 that has recived more love than any other sr5 deserves, it now has: GTS Trans, fuel lines, rear end, tokiko shocks and lowering springs on the way, and a CLEAN (and freshly installed) 20v silvertop. therein lies the problem. I am not new to cars so the things me and my fabricator/allknowingmechaninc friend did made sence and helped performance but not the main problem.
THE PROBLEM: car accelerates beautifully in all gears untill around 5k when power begins to drop off log style untill non existant at 6500 (peak power of the silvertop is at 7200)
ASSUMED CULPRITS: ignition and fuel systems. we installed a fuel surge tank (common and good for carb to efi conversion cars and race vehicles) and changed the plugs to denso 7's, returned the timing to 14 degrees btdc (15 is stock[12 is good for 91 octane, im now running 15% ethonol])
REALITY OF IT ALL: those things gave me awsome power.... untill a little after 5k.........

ive now traced the problem to the vvt. i found the ecu pinouts and did a continuity test on all connections to find that the loom is ok. i then ran the car with the vvt actuator plug (witch has continuity) and it ran the same. meaning vvt is not engaging. is there anyone out there with a silvertop (in any car) that could be of some help. any information on the vvt (even info about how it acts where everyting is cool) would be appriciated.
(sorry for the essay)

[REN69]

Someone had this problem here before.. I believe Ichi (TRDragoon) had it with his Blacktop 20V, it has something to do with the ECU. Are you running a manual or Auto ECU?? I think his problem was running an auto ECU with the manual transmission.

[that one guy]

i have that the manual trans ecu so it matches, i checked that before i started to do the swap way back when.

[project trueno]

which ignitor module are you using? Hopefully not the original AE86 one

[punter]

This shows the effect of the VVT pulley, does look alot like what your describing.

The green line is VVT switched off for the entire run.
The red line is VVT switched on the the entire run.
The blue line is VVT switched from on to off at 6400 rpm.
Engine was a stock blacktop with headers and CAI running a linkplus ECU on 96 octane pump fuel.



I would suggest that your vvt pulley is frozen "on", they are known to fail although its not all that common. putting the pulley in an engine builders acid tank for 3-4 days sometimes frees them up.

Although, unpon re-reading your post its seems (from your description) that your power drops off alot faster than this graph.

[micro214_kp61]

i'm not totally getting the problem.. so past 5K the motor still revs but doesn't make any more power or it spatters past 5K?

i'm not sure if the '84 SR5 has a built in speed sensor like the GT-S but if it doesn't try running it with a speed sensor first.

[punter]

Originally Posted by micro214_kp61

i'm not sure if the '84 SR5 has a built in speed sensor like the GT-S but if it doesn't try running it with a speed sensor first.

Probably won't solve it, if thats not connected all that will result is a lower rev limit, but can't hurt.

You said you set it a 14 deg BTDC, I run my silvertop on 8deg (our best fuel is 98 vs japans 100) and last time I checked standard was 10 deg.
Could have something to do with it, although in saying that I think you'd notice if it was knocking.

[that one guy]

to explain what its like when it looses power, it feels almost like the engine is 'dragging' like it is misfiring or running lean so that it keeps moving but has no push.
the timing is actually 13 and is how it came from japan (witch i thought was correct) and does not knock because i run approx 97-101 octane on 10-25% ethonol the rest CA premium (91) (% realy depends on my mood)
i also ran diagnostic and flashed ecu
i ran some tests and had my head in the passenger foot well agian checking pins and eventually drove around with the vvt on 'full on' vvt 'full off' and vvt ecu controlled
still had the problem! although i got the ecu to start doing the vvt agian it only gained a little power. i now think that i am still not getting good fuel supply to all the injectors. im going to replace the fpr after some more tests tomarrow it really is getting down to only a few things it could be. also, i forced the engine through the 'dead spot' and made it rev to 7200 where it freed up ant took off like crazy. hmmmmm funny thing is it does this, but not every time.
the more i drive and the more i experiment the more i think it is fuel and the last thing to test/replace is the high pressure components (injectors, rail, fpr, ect)

[REN69]

now to me it sounds similar to a dizzy cap problem... check your dizzy cap to see if its not lose or cracked, could be you're losing spark due to this.

[punter]

What fuel pump are you running?
You sure the FPR vacum lines are good?

[cuzman]

I have a 20 v silver top in my wagon, the vct kicks in bout 4500 rpm

Make sure you have a good fuel supply eg pump and return line
Make sure the intake track is clean and clear of retrictions
Fuel filter is good
SOunds to me more like an ignition prob..are the leads good test with a multi meter
Are you using the 20v ignition modual or better
Is the exhaust clear of obstuctions eg some cats will clog up over time making the car a pig at high rpm (very rare but can happen)
Ethonol suxs it works for a bit but will destroy your motor and stuff up your rubber seals in the fuel system!!!!!!!including fouling the plugs...try a high octain race fuel to mix with your high octan pump gas..if you persist with ethonol no more than 10% max....

Is the air fil;ter clean??? check the vct wiring with a multi meter with the car running, at bout 4500 rpm the signal sould change telling the vct to adjust the timing on the intace sprocet,
if this hapens and every thing else is correct with no improvment change the vct sproct.

Hope this helps,, thet me know how you go....all the best cuzman