Lack of power - NA

[GreaseMonkey]

Just a thought, as some others have suggested, I'd probably check/ clean the main Throttle Butterfly Assembly (Throttle cable operated/connected to). As this can get clogged with dirty greasey oily film behind it which I think may affect the reaction of the throttle butterfly in relation to the TPS (Throttle Position Sensor) sensitivity/ readings.

 

I've had a throttle fault recorded indicating/ caused a TPS malfunction, which was cured after removing the throttle body cleaning the throttle body intake & butterfly with some carb cleaner and a medium (green)/ fine (grey) scotchbrite to remove the tar like residue.

[adnanshah247]

was just talking to my mechanic and as i was telling him about the problem he half way said check the cat or o2 sensor. so there you go darryl!

[Ryan.G]

I would consider looking at cam timing and spark timing. Make sure the marks on the cam and crank pulleys line up and also get a timing light to check the ignition advance at idle.

 

 

Bring it up SRR one day mate and i will check it with timing light and stick on dyno.

[TRD-Rob]

 

Bring it up SRR one day mate and i will check it with timing light and stick on dyno.

 

always there to help,top man

[Homer]

 

Bring it up SRR one day mate and i will check it with timing light and stick on dyno.

 

Thanks mate! Will check over as much as possible before then, otherwise see you on Thursday

[TRD-Rob]

Thanks mate! Will check over as much as possible before then, otherwise see you on Thursday

 

bloody mods

[Chris Wilson]

I had an N/A in the other month that was allegedly well down on power and the owner had spent over 500 quid messing with new plugs, new leads, new disi cap, had the valve clearances checked, cam timing checked, blah blah. He was thinking in terms of a lower mileage engine.

 

 

I freed the two partly seized rear calipers, replaced a cracked rear disc (from the heat generated with the friction) and fitted new pads. Good as new....

[Homer]

Back from the dyno, the results were 'interesting'

 

If you guessed timing, you were right

If you guessed intake butterfly, you were also right!

 

On the first run it came out at 206bhp at the flywheel, so about right for an NA.

 

However, there was a dip in torque around the mid range which didn't look right..

Ryan then checked the timing and found themarker to be about 60 degrees out.. obviously impossible so only can assume the marker on the crank pulley is wrong!

 

He then adjusted the timing on the dizzy which resulted in about a 10lb/ft jump across the rev range

 

Next he found a disconnected hose under the butterfly valve on the intake, reconnected that and then had a further 20lb/ft jump in power in the mid range. I guess the buterfly was open all the time as the top end was no different, but the mid and low range gained a fair bit of torque after reconnecting the line.

 

So, end result was 212bhp & 205lb/ft. That's a 6bhp at the top end, but most importantly a big 25-30lb/ft jump through most of the mid range.

 

Huge thanks to Ryan for taking a look at it today, top bloke as always!!

 

PS: It's noticably better on the road now, but still bloody slow, having a single supra has ruined performance cars for me!

 

Black line is the first run, green line is after the fixes:

 

[Scott]

Least it's a healthy snail now

[DodgyRog]

That looks spot on mate, almost exactly the same as mine before decat

 

The torque curve and power curve are almost exactly the same

 

[Chris Wilson]

Seems Toyota's variable intake volume is well worthwhile. Big difference in mid range torque, N/A figures are more technically interesting than supercharged ones, in many ways.

[Kirk]

Good news mate

 

Thinking of checking mine as it seems to be a touch lacking plus I'd like it to be as good as possible before I fit this mines ecu

 

How did he check the timing? Timing light?

 

I know the dizzy is adjustable but how do you go about doing it?

Edited October 7, 2010 by Kirk (see edit history)

[Homer]

Seems Toyota's variable intake volume is well worthwhile. Big difference in mid range torque, N/A figures are more technically interesting than supercharged ones, in many ways.

 

All I can say is from the SRR dyno and the arse dyno, it has a bit more punch in the mid range than it had this morning I've still to look at the service manual to see what the effect of the disconnected vac line is, but am expecting it to be that the valve is open. It certainly makes a difference after reconnecting the line!

 

How did he check the timing? Timing light?

 

I know the dizzy is adjustable but how do you go about doing it?

 

The timing light was showing a 60 degree or so deviation so base timing had to be assumed as good and the markings were just wrong (I checked the cam and crank pulley lines when the engine was out and they were correct).

 

Ryan used the dyno to adjust the dizzy position, it didn't seem to be an exact science but he kept going at it until the best power was acheived. What was interesting was that any adjustment to the dizzy position was uniform across the entore rev range. Once maximum power was reached, it was left at that

[Kirk]

I think a session with ryan would be a good idea to see what I can get out of mine if anything.

[Ryan.G]

 

Ryan used the dyno to adjust the dizzy position, it didn't seem to be an exact science but he kept going at it until the best power was acheived. What was interesting was that any adjustment to the dizzy position was uniform across the entore rev range. Once maximum power was reached, it was left at that

 

I was looking for MTBT or as some call it MBT "Minimum Timing for Best Torque"

 

Google is your friend to understand this more as im crap at explaining things but this chart shows why i was looking for...

 

http://www.daytona-sensors.com/engine_tuning/Timing_Torque.gif

[Neil-NA]

Hmm interesting about the torque thing, last year mine was making 203bhp and 184lbft torque.

 

My graph is all over the place, will try upload the pic in a min, is there a section for NA dyno graphs?

[Neil-NA]

My poor dyno, im guessing the torque curve looks quite a bit different to the ones above, run was done in 5th if it makes any odds.

 

[Tricky-Ricky]

Glad you got it sorted Darryl, and after reading this, all i can say is having bought an N/A car i am glad it wasn't a Supra LOL!

but i know exactly what you mean with the singled Supra comment.