Topic: Flat spot btw 2000 and 2500rpm

Hi guys,

I have a 2000 Corolla 20v BT and recently did an engine transplant using an import engine.

So far so good but i have an annoying flat spot between 2000 and 2500rpm.

I've unplugged the connection to the OCV and the flat spot goes away.

Can the problem be the OCV, the signal to the OCV or the VVT gear itself?

Thanks in advance

Ravi

Re: Flat spot btw 2000 and 2500rpm

unplugging that means no vvt
so i assume its the vvt gear or the ocv itself is faulty

http://i89.photobucket.com/albums/k210/mayurh/22671_32659.jpg

Re: Flat spot btw 2000 and 2500rpm

unplugging that means no vvt
so i assume its the vvt gear or the ocv itself is faulty

http://i89.photobucket.com/albums/k210/mayurh/22671_32659.jpg

Re: Flat spot btw 2000 and 2500rpm

I swapped the vvt pulley with a used one, which was running on my previous engine and had no flat spot. The flat spot is still there.
I then swapped the ocv with a used one as well from the same engine and the flat spot is still there!
When driving with ocv disconnected then there is no flat spot.
The thing is that the flat spot is only there when I floor the accelerator. When accelerating gradually, there is also no flat spot so it has to do with vvt.
The flat spot is almost like there is no power between 2000 and 2500rpm and sounds like a miss for that 500rpm.

Thoughts guys?

Thanks a mil

Re: Flat spot btw 2000 and 2500rpm

I swapped the vvt pulley with a used one, which was running on my previous engine and had no flat spot. The flat spot is still there.
I then swapped the ocv with a used one as well from the same engine and the flat spot is still there!
When driving with ocv disconnected then there is no flat spot.
The thing is that the flat spot is only there when I floor the accelerator. When accelerating gradually, there is also no flat spot so it has to do with vvt.
The flat spot is almost like there is no power between 2000 and 2500rpm and sounds like a miss for that 500rpm.

Thoughts guys?

Thanks a mil

Re: Flat spot btw 2000 and 2500rpm

have you changed your o2 sensor?
normally people who have had  flat spots on the 20v and most have sorted it by changing the o2 sensor?
since you tried another vvt gear and ocv..i guess your next bet is o2 sensor
you checked your spark plugs? plug wires?

Last edited by mayurh (2014-03-19 07:39:11)

http://i89.photobucket.com/albums/k210/mayurh/22671_32659.jpg

Re: Flat spot btw 2000 and 2500rpm

check fuel filter

2000 RXiya

Re: Flat spot btw 2000 and 2500rpm

check fuel filter

2000 RXiya

Re: Flat spot btw 2000 and 2500rpm

Hi guys,

O2 sensor is relatively new as it has 30000km on it.
Fuel filter also newish.....plugs brand new but plug wires still original....

Car has no flat spot when ocv disconnected and also no flat spot when car is cold only when hot....

Re: Flat spot btw 2000 and 2500rpm

OIL PRESSURE?

7AGE 6SPD: 2B1 Built & Mapped by Autotrix   "Best 1/4mile time 14.2sec @ Mtuba (MSA EVENT) "
Don't INJURE what you can't KILL!!!                           
Update : 5 May 2013 14.2@161kmph (achieved time with car having a miss fire issue)
http://i632.photobucket.com/albums/uu42/20plenty/7age_2_zps44a6e6ab.jpg
What did the 1 V-tec supporter say to the other V-tec supporter?
NB:Remember!!!
If the 20vs 1st off the line we'll say he JUMPED THE V-TEC!
but if the VTEC's 1st off the line we'll say he OUT LAUNCHED THE 20V!
sweeeeeet!!! we cant lose this way.......(^_^)

Re: Flat spot btw 2000 and 2500rpm

How do i check oil pressure?
I confirmed last night that i do have signal on the ocv by wiring in a light to the connector that couples on the ocv.
Its mind boggling because the flat spot is more like a miss for 500rpm.
Should i take a chance and buy a new vvt pulley and ocv?  even though ive put in other used ones.....eish this is a tough one....

Re: Flat spot btw 2000 and 2500rpm

How do i check oil pressure?
I confirmed last night that i do have signal on the ocv by wiring in a light to the connector that couples on the ocv.
Its mind boggling because the flat spot is more like a miss for 500rpm.
Should i take a chance and buy a new vvt pulley and ocv?  even though ive put in other used ones.....eish this is a tough one....

Re: Flat spot btw 2000 and 2500rpm

Disconnect the 02 sensor and check

Last edited by Twincam-wp (2014-03-21 13:54:18)

Re: Flat spot btw 2000 and 2500rpm

Hi chaps,

Problem still persists with oxygen sensor disconnected.

Any other thoughts?

Re: Flat spot btw 2000 and 2500rpm

Hi chaps,

Problem still persists with oxygen sensor disconnected.

Any other thoughts?

Re: Flat spot btw 2000 and 2500rpm

Not sure if std ECU uses this, but maybe it could be your ignitor. I am running dicktator with TP100 ignitor and I had the same type of problem where just before I hit VVT, my car would kinda miss then suddenly go. After replacing that, it has gone smoothly.

1995, 20v, Dictator, SRI, 50mm exhaust
95wkw 145nm @ JVS Tuning Cape Town on 24-10-13
http://i356.photobucket.com/albums/oo4/morollaTRD/DSC_0576-1.jpg

Re: Flat spot btw 2000 and 2500rpm

Howsit,
Would the ignitor be part of the dizzy or the stand alone module near the coil?

Re: Flat spot btw 2000 and 2500rpm

Ravi Kumar wrote:

Howsit,
Would the ignitor be part of the dizzy or the stand alone module near the coil?

Yes it is the stand alone module near the coil. Try swopping with a friend for testing purposes. Prices I was quoted as follows:
Original Toyota R700
Dicktator R550
TP 100 should be under R200
*Original Toyota is best, I don't know how the others will perform with STD ECU.

Last edited by morolla (2014-04-02 16:23:30)

1995, 20v, Dictator, SRI, 50mm exhaust
95wkw 145nm @ JVS Tuning Cape Town on 24-10-13
http://i356.photobucket.com/albums/oo4/morollaTRD/DSC_0576-1.jpg

Re: Flat spot btw 2000 and 2500rpm

mmmmm... interesting thread.... will try out...

Current- Corolla RSi  20v
      102kW 162nm (Autotrix Dyno)
Ex- Corolla 1.3L
      1 miiiillllllion killerwatts and 2 bazzilion torques ../../extensions/custom_smilies_2/img1/tongue
When you turn your car on, does it return the favour?

Re: Flat spot btw 2000 and 2500rpm

I have a similar "flat spot".
What I've done to cure it, without success:-
-new plug leads, new rotor, new dizzy cap.
-new O2 sensor.
-new spark plugs. NGK lazer platinium
-new fuel filter.
-new ISCV.
-higher timing- 8deg to 15deg.
-New temperature switch- based on the fact that the flat spot is most noticable before engine reaches operating temperature (assumed switch was faulty).

the flat spot is only under full throttle before full operating temperature is reached..

Please note- all the parts used are brand new toyota original parts.

I first noticed this "flat spot" when i switched from OEM to viper full 63mm zorst.

Current- Corolla RSi  20v
      102kW 162nm (Autotrix Dyno)
Ex- Corolla 1.3L
      1 miiiillllllion killerwatts and 2 bazzilion torques ../../extensions/custom_smilies_2/img1/tongue
When you turn your car on, does it return the favour?

Re: Flat spot btw 2000 and 2500rpm

Interesting because I also have a Viper branch with 57mm powerflow zorst.
I don't recall exactly when the flat spot started but could it be the Viper branch??????

Re: Flat spot btw 2000 and 2500rpm

Interesting because I also have a Viper branch with 57mm powerflow zorst.
I don't recall exactly when the flat spot started but could it be the Viper branch??????

Re: Flat spot btw 2000 and 2500rpm

Btw my flat spot\miss is there when the engine is at full operating temp.

Re: Flat spot btw 2000 and 2500rpm

I ran a afpr for a while- it did ease the problem- but the regulator bombed out eventually. So my thoughts are that it may be fueling related and not spark     ???    any ideas????

Current- Corolla RSi  20v
      102kW 162nm (Autotrix Dyno)
Ex- Corolla 1.3L
      1 miiiillllllion killerwatts and 2 bazzilion torques ../../extensions/custom_smilies_2/img1/tongue
When you turn your car on, does it return the favour?

Re: Flat spot btw 2000 and 2500rpm

I ran a afpr for a while- it did ease the problem- but the regulator bombed out eventually. So my thoughts are that it may be fueling related and not spark     ???    any ideas????

Current- Corolla RSi  20v
      102kW 162nm (Autotrix Dyno)
Ex- Corolla 1.3L
      1 miiiillllllion killerwatts and 2 bazzilion torques ../../extensions/custom_smilies_2/img1/tongue
When you turn your car on, does it return the favour?