Flat Spot

[aimre]

Hey guys,

i seem to have a small problem that i cant get rid of.
The problem is, i have a flat spot through the rev rangem at about 2000 rpm when light throttle is applied, if i apply slightly more throttle, i can get through the flat spot, then drop back to orriginal throttle position and it will continue up the revs on its merry way.

To try and fix this, i have:

Changed spark plugs
Fuel filter
and inspected the dizzy cap (without removing it) for damage.

What could this be and how do i fix it?? :confused::confused::confused:

Thanks

PS. Ive searched

[BlitZ]

leads?

Hey guys,

i seem to have a small problem that i cant get rid of.
The problem is, i have a flat spot through the rev rangem at about 2000 rpm when light throttle is applied, if i apply slightly more throttle, i can get through the flat spot, then drop back to orriginal throttle position and it will continue up the revs on its merry way.

To try and fix this, i have:

Changed spark plugs
Fuel filter
and inspected the dizzy cap (without removing it) for damage.

What could this be and how do i fix it?? :confused::confused::confused:

Thanks

PS. Ive searched

[EuroDude]

Yeah it sounds like the ignition sparks are not providing enough power (possibly due to bad spark lead resistance or bad spark plugs), I have doubts its the Dizzy, but it wont hurt to get a new Dizzy Cap (not expensive) or clean the white powdery crap from your old Dizzy Cap terminals.

But if its not affecting the upper Rev range, then the Valve Tappet clearances may be out and causing rev issues.
Adjust them ftw. Here's a guide: http://www.ozhonda.com/forum/showthread.php?t=15443

[aimre]

so it is spark?

What lead do ppl recomend?

[destrukshn]

try your spark plugs.
or cleaning your throttle body.

[aaronng]

When you replaced your spark plugs, did you make sure to get plugs with a 1.1 mm gap? Also, take off the dizzy cap to check for corossion.

[aimre]

When you replaced your spark plugs, did you make sure to get plugs with a 1.1 mm gap? Also, take off the dizzy cap to check for corossion.

I got the exact sprak plugs that it says to get on the rocker cover.

Willl try throttle cleaner and the dizzy cap checking. Can i remove the cap without removing dizzy?

thanks

[aaronng]

Willl try throttle cleaner and the dizzy cap checking. Can i remove the cap without removing dizzy?

thanks
Yup, just remove the leads (remember the location for each plug) and unbolt the cap. There should be quite a bit of corrosion as usual. Clean it out and put on some dielectric grease.

[ECU-MAN]

check the rotor cap for craks, also check the neck of the leads for marks that look like cracks,

you can wrap them with shit loads of electrical tape and fix them

[Professional]

More things, check the ignition timing. It may be the issue.

[aimre]

how do i check timing, i need a timing light right, somehow i got one, but dunno how to use it

[aimre]

Ok Guys, pulled the cap off the dizzy, here what i found:

http://img.photobucket.com/albums/v47/aimre/CIMG1005copy.jpg
http://img.photobucket.com/albums/v47/aimre/CIMG1000.jpg
http://img.photobucket.com/albums/v47/aimre/CIMG0999.jpg
http://img.photobucket.com/albums/v47/aimre/CIMG0998.jpg

[ECU-MAN]

change the rotor button

cap is a bit old, but should still work fine

can you take a pic of your ignition lead, the part that goes down the head. close up like above.

[kyle]

ecu man you need to change you rank title to 7.

[aimre]

change the rotor button

cap is a bit old, but should still work fine

can you take a pic of your ignition lead, the part that goes down the head. close up like above.

Will take better pics tomorrow, but luckily i got these today. Two dizzy side and one sparkplug side

http://img.photobucket.com/albums/v47/aimre/leads3.jpg
http://img.photobucket.com/albums/v47/aimre/leads2.jpg
http://img.photobucket.com/albums/v47/aimre/leads.jpg

[ECU-MAN]

ecu man you need to change you rank title to 7.

..lol..

[ECU-MAN]

can you please take a picture of the lead ( top pic ) on the other angle, I need to see the shaft of the lead.

cheers

[green_machine]

check resistance of leads,timing,and fuel sample(wat fuel u use??)

[aimre]

98 fuel, tried weq's spare leads, and same thing

[TODA AU]

Hey guys,

i seem to have a small problem that i cant get rid of.
The problem is, i have a flat spot through the rev rangem at about 2000 rpm when light throttle is applied, if i apply slightly more throttle, i can get through the flat spot, then drop back to orriginal throttle position and it will continue up the revs on its merry way.

To try and fix this, i have:

Changed spark plugs
Fuel filter
and inspected the dizzy cap (without removing it) for damage.

What could this be and how do i fix it?? :confused::confused::confused:

Thanks

PS. Ive searched
What sound accompanies the fat spot?

If the flat spot corresponds with a missfire or crackle & pop out the tail pipe, it's ignition.
In this case follow ECU-MAN's instructions.
If the engine simply goes dead~flat, it's fuel.

1) Check TPS setting, if incorrect, you could be on the overrun fuel cut.
2) Check fuel pump - earth & inlet filter for obstruction
3) Check engine earth

[tinkerbell]

i also have a "flat spot" - though it is not an issue, it is very mild and simply feels like the engine "picks up" more once past the 3000 mark...

it happens between take off to 3000ish, it just feels like timing is not *quite* enough...

it is only during very light throttle though...

is this similar to your "flat spot" amire?

is your ECU etc stock?

[aimre]

What sound accompanies the fat spot?

If the flat spot corresponds with a missfire or crackle & pop out the tail pipe, it's ignition.
In this case follow ECU-MAN's instructions.
If the engine simply goes dead~flat, it's fuel.

1) Check TPS setting, if incorrect, you could be on the overrun fuel cut.
2) Check fuel pump - earth & inlet filter for obstruction
3) Check engine earth


There isnt any exhaust noise indicating ignition.


How do i do 1)?

Do our cars only have one intank fuel pump?



i also have a "flat spot" - though it is not an issue, it is very mild and simply feels like the engine "picks up" more once past the 3000 mark...

it happens between take off to 3000ish, it just feels like timing is not *quite* enough...

it is only during very light throttle though...

is this similar to your "flat spot" amire?

is your ECU etc stock?

Mine only happens at light throttle. I take of normal, then when i get to about 2500 it looses power, so much so, that u sometimes lurch forward in your seat, this power loss happens for about 1000 rpm and u get through it by putting slightly more gas.

It usually only happens in gears 1 and 2 (or at least i notice)

[ekhybrid]

yes i have this problem too
only happens when its cold and there is light throttle applied

[tinkerbell]

take of normal, then when i get to about 2500 it looses power, so much so, that u sometimes lurch forward in your seat, t


yes, sorry, very different 'flat spot' to mine...

in that case, it could quite well be fuel related, maybe even fuel injectors... how many KM on the car/engine?

to check for 1) TPS sensor you need a multimeter and a sewing pin - can be easily described if you want to try it... but a bad TPS sensor setting will usually demonstrate other drivability symptoms...

[TODA AU]

An incorrectly set one will bring on over run fuel cut prematurely.
This could be from something as simple as being knocked by a heavy object.

[tinkerbell]

yes, that is true...

for those wondering - "over run fuel cut" is where the ECU senses that the throttle is closed above around 1100rpm and therefore the PGM-FI system shuts off the fuel injectors to reduce fuel consumption...

i.e. TODA AU is saying that the TPS sensor might, at light throttle, think the TPS is closed, and therefore shutting off the fuel injectors to save fuel.

to test the TPS, get a multimeter, set it to 0-5v or similar, and place a fine metal pin (i use a sewing pin) into the centre wire on the TPS (whilst still plugged into the TPS) and attach the +ve (red) cable of the multimeter to the pin (alligator clips help here) and the -ve (black) cable to the chassis.

turn the key to ON position and see if there is any voltage with the throttle closed (if there is no voltage, you are not hooked up right!)

it should be less than 0.5V (preferably like 0.45ish)

then hold open the throttle...

it should be more than 4.5V

if either of these are not right, then the TPS has been bumped and needs to be reset...

[tinkerbell]

yes i have this problem too
only happens when its cold and there is light throttle applied

also AFAIK - the "over-run fuel cut" only functions when the engine is warm...

pls correct me if i am worng...

[todas**t]

my mates car got a flat spot to after it got tuned. but its funny on a stock ecu for it to happen

[fatboyz39]

As above check TPS AND MAF operations.

I don;t see why a stock motor would have a flatspot unless on of the sensor are goneski.

[aimre]

As above check TPS AND MAF operations.

I don;t see why a stock motor would have a flatspot unless on of the sensor are goneski.

how does one check MAF?

[tinkerbell]

you buy a Nissan or Mitsubish to check the MAF...

[tinkerbell]

have you checked the TPS as described amire? what was the results?

[XB-16-AX]

get ur fuel injectors inpected/cleaned .. and while your at it inspect/test/ replace your fuel pump.

if you have tried all the above that everyone is telling, RE-SET your ECU.

obviously check for CEL codes first prior to resetting. (very last option)

i did this to mine at one stage and solved it. and never came back.

[aaronng]

get ur fuel injectors inpected/cleaned .. and while your at it inspect/test/ replace your fuel pump.

if you have tried all the above that everyone is telling, RE-SET your ECU.

obviously check for CEL codes first prior to resetting. (very last option)

i did this to mine at one stage and solved it. and never came back.

I would have checked for codes and reset the ECU first. LOL

[aimre]

I would have checked for codes and reset the ECU first. LOL

Well the check engine light hasnt ever come one, so im guessing it dont have any codes to throw out.

Ill check TPS maybe tomorow if i got time.

thanks for the help:wave:

[XB-16-AX]

CEL light should go on when key is turned then after a sec or so it should switch off..

if ur CEL light never turns on, then possible bulb is dead or connectivity from ECU to cluster has been cut, damaged.

Its important and critical to have the CEL light working, as this will help greatly with troubleshooting engine faults. - well at least a good start to check!

[aimre]

CEL light should go on when key is turned then after a sec or so it should switch off..

if ur CEL light never turns on, then possible bulb is dead or connectivity from ECU to cluster has been cut, damaged.

Its important and critical to have the CEL light working, as this will help greatly with troubleshooting engine faults. - well at least a good start to check!

It works, it just hasnt come on while driving

[aimre]

Ok, tried to do this, but failed, i couldnt get a voltage outa the wires, i tried the pin through the wire.

Which colour is the one i should be loking at? (incase i missed one, theres 3)

also is there an easier way of checking the voltages?

Thanks

[tinkerbell]

also is there an easier way of checking the voltages?

Thanks

bring it to my place at Epping this arvo...

PM for details...

[aimre]

bring it to my place at Epping this arvo...

PM for details...


Epping is SO far lol. Ill give this one more try. Its the middle wire, from the plug that BEHIND the TB not the one on top.

http://img157.imageshack.us/img157/2025/craig3hj1.jpg

The thing on the TOP of that pic right?

[tinkerbell]

yep - that is it...

if is an EG it might be light green, if it is DC it migh tbe red/black...

[tinkerbell]

the plug must be connected to the sensor and ignition ON to perform the test...

[aimre]

0.52v idle

4.57 full throttle

[tinkerbell]

well done!!!!!!!!!

ok, the specs for the "closed throttle" is possibly a little too high,

it should be under 0.5 when closed to tell the ECU it is closed...

a) check if your throttle cable has some play in it, if it is too tight, it might not close properly...

check this and retest - if it is still over 0.50v then see below:

b) try to adjust it by lightly tapping it with the butt of a screw driver handle, observe the voltage as you do this, an dont hit it hard, just tap it... if you can get it below 0.50v this way, then that is good!

c) if you cant get the voltage to change by softly tapping it, you need remove the throttle body and determine if the TPS is held on by screws or not - if not - you have to cut a fine grove in the top of the fasteners with a fine hacksaw blade to loosen them... if held on by screws - lossen and see below:

once loose, you can adjust the TPS to read <0.50v (i aim for 0.45-0.47v) without re-installing the throttle body, then re-tighten the fasteners and then re-install the throttle body...

check the voltage once re-installed, and test drive...

i hope this solves your flat spot...

if not - it is one thing that can be ruled out!

[aimre]

I got some more info.

i noticed after driving and arriving at a set of lights, the cars idle slowly drops down to like <500 rpm idles rough, sounding like maybe running on 3cyl. after about 5-10 sec of this, the car raises it idle quickly to about 1200 then drops back down to 750 and stays there for the rest of the time.

ALso today when when reving around 2500 in neutral, it sounded like the car missed a beat every few seconds seconds. Sounded like the gurgling u get sometime when backing off, but like, its one gurgle every few seconds.

[tinkerbell]

i'd say you have a ignition system problem,

this needs to be diagnosed IN PERSON... not over the internet...

[aimre]

i'd say you have a ignition system problem,

this needs to be diagnosed IN PERSON... not over the internet...

granted, but who could do this, i dont want to pay a mechanic for hours+ work who cant find the problem

[tinkerbell]

see page #1

your "location" isn't too enlightening BTW... Simpsons quotes don't really help anyone...

[aimre]

Sorry, im in sydney

[aimre]

Anyone know? Cos some mechanics dont have a clue and will keep guessing, and all it will do is cost more money than it should

[aimre]

i read EG a notorious for having faulty coil/dizzy?

Could this be a problem?

How much is it to replace?

[tinkerbell]

i have a brand new coil here at epping...

it is easy to replace, but i doubt it is your problem...

you can test it though:

1. remove the dizzy cap, rotor and plastic cover,

the "coil" is the thing with the tall post and two wires screwed onto it, a blue one and black yellow one.

2. remove the screws holdign the wires on and test the resistance between the terminals - it should be 0.6-0.8 ohms...

3. now test between the black/yellow wire and the metal bit of the post - this should be much higher - like 13'000 to 20'000 ohms..

if not - then itt is out of spec and should be replaced...


i can also get brand new (non OEM) dizzys for $390...

( i had to fit one to my car last week LOL!! but wreckers wanted $450 for a used one, so i bought from the USA!)

[aimre]

[quote=tinkerbell;1104348]i have a brand new coil here at epping...

it is easy to replace, but i doubt it is your problem...

[quote]

Argh!!, what else is there left with these cars....

Im gonna try using someone elses dizzy and see how that goes.

Ill test the coil first but..

[aaronng]

Not sure if it has been asked, but have you replaced your fuel filter?

[aimre]

Yeah, one of the first thing i did.

Mate of mine recomended checking the fuel pressure. Anyone got something i can test that with?

[XB-16-AX]

dude,

have u tried re-setting ur ECU if not already done so?

and is it throwing u any codes aswell? ..

Try cleaning ur O2 sensor on the exhaust.- To clean this just get a very light sand paper and rub it gently around the tip of the 02 sensor.

look around the engine bay and see if you have any vacume hoses that may be loose or is punctured. - replace if needed.

Also do u have or sense/hear any exhaust leaks?

as for what everyone else has said and you probably done/checked already,

try my remedy above and see how u go.

[aimre]

dude,

have u tried re-setting ur ECU if not already done so?

and is it throwing u any codes aswell? ..

Try cleaning ur O2 sensor on the exhaust.- To clean this just get a very light sand paper and rub it gently around the tip of the 02 sensor.

look around the engine bay and see if you have any vacume hoses that may be loose or is punctured. - replace if needed.

Also do u have or sense/hear any exhaust leaks?

as for what everyone else has said and you probably done/checked already,

try my remedy above and see how u go.

Ecu hasnt been reset, will try that tomorow night.

No codes thrown out. Ill try the o2 sensor in a week or 2 when i pull the car apart.

All vacuum lines are in.