4age 20v Too Low Rpm Limit, 6500rpm???

[David[RL]]

hey

 

we just swapped in a silvertop 20v in a ke70:

 

we use blacktop 20v M/T ECU and wiring loom

we do use a map sensor

we don't use the oxygen sensor or speed sensor

the engine idles well and pulls hard up to approx 6500rpm, but it should rev to 8200rpm!!

 

I want some input on why it doesn't??

 

wiring should be OK, we use 99RON fuel

it runs alittle cold water temperature because we fitted a very big radiator, does the ecu set the rev limiter lower when it's not 90-95C?

the tacho is correct

we don't use the ISCV valve, we set the idle at the throttles else everything should be pretty much stock

 

[LittleRedSpirit]

hey

 

we just swapped in a silvertop 20v in a ke70:

 

we use blacktop 20v M/T ECU and wiring loom

we do use a map sensor

we don't use the oxygen sensor or speed sensor

the engine idles well and pulls hard up to approx 6500rpm, but it should rev to 8200rpm!!

 

I want some input on why it doesn't??

 

wiring should be OK, we use 99RON fuel

it runs alittle cold water temperature because we fitted a very big radiator, does the ecu set the rev limiter lower when it's not 90-95C?

the tacho is correct

we don't use the ISCV valve, we set the idle at the throttles else everything should be pretty much stock

 

Connect all the sensors or the ecu will freeak out. What about the knock sensor? The ISCV is good I don't know why you wouldnt use it.

 

You will need to find the error codes and see what its grumbling about.

[MYSTIK[RL]]

as little red spirit said connect all the sensors.

 

the ecu would currently be in what is called "limp mode" ie reducing the rev limiter because the speed sensor isnt connected

 

plus not having the O2 sensor hooked up it will be using a shit load more fuel as well.

[Hiro Protagonist]

Most likely culprit is the speed sensor, but you should add the O2 as well (only really matters if you're going to be doing a lot of cruising, it is ignored during wide-open throttle).

Edited July 25, 2009 by Hiro Protagonist

[David[RL]]

Connect all the sensors or the ecu will freeak out. What about the knock sensor? The ISCV is good I don't know why you wouldnt use it.

 

You will need to find the error codes and see what its grumbling about.

 

 

we use the knock sensor

we didn't have have space for the ISCV in the stock location so instead of putting it somewhere else I just removed it.

I've already connected the sensor to see if it made a difference but it didn't

 

do YOU have the speed sensor connected?

if so, can you rev above 6500rpm when standing still in neutral? if you can the speed sensor shouldn't do any difference

 

KE70 never came with speed sensor so I would need to buy a brand new just to test it

according to various wiring diagrams the speed sensor is not necessary as in the engine light will glow, but it will not go in limp mode

 

same goes with the oxygen sensor, engine light will glow but no limp mode

oxygen sensor is only used in the low rpm/load area as far as I know, can't really see why it should go in limp mode because of that..

it do run somewhat rich, but most of the problem was the map sensor connected up in wrong area

 

but I will have to connect up the warning light and look for some error codes..

 

 

thanks

[greenmac80]

well if all that stuff is checked then there are two things i can think of.

 

on a site www.club4ag.com a lot of guys have had this problem. but there were a few different reasons for it.

 

1. check to make sure your STA wire is actually hooked up to ignition correctly. if it isn't then the engine will still think its cranking?

 

2. on cold start the ecu uses a different fuel map? cold start enrichment? perhaps as you said in your first post the coolant is the problem. if your water temperatures aren't getting to normal

operating temps then the motor will most likely rev limit early to protect itself. quite a common trait on efi engines.

[LittleRedSpirit]

we use the knock sensor

we didn't have have space for the ISCV in the stock location so instead of putting it somewhere else I just removed it.

I've already connected the sensor to see if it made a difference but it didn't

 

do YOU have the speed sensor connected?

if so, can you rev above 6500rpm when standing still in neutral? if you can the speed sensor shouldn't do any difference

 

KE70 never came with speed sensor so I would need to buy a brand new just to test it

according to various wiring diagrams the speed sensor is not necessary as in the engine light will glow, but it will not go in limp mode

 

same goes with the oxygen sensor, engine light will glow but no limp mode

oxygen sensor is only used in the low rpm/load area as far as I know, can't really see why it should go in limp mode because of that..

it do run somewhat rich, but most of the problem was the map sensor connected up in wrong area

 

but I will have to connect up the warning light and look for some error codes..

 

 

thanks

 

I don't use the speed snesor, Ive never had one and Ive also always been able to rev over 6500. All the way to 8300 in fact. The key difference is I didnt use the Toyota ECU, instead a programmable adaptronic. I have read about this issue many times. Its always sensor or error code related. The ecu is protecting your engine.

 

I'm of the belief that if you got it, flaunt it. Even if a sensor is going to only make things 2% better, its worth connecting. An oxygen sensor is a wonderful thing to install. Thats free fuel economy right there. 20vs will idle at about 1600 rpm without the ISCV, so Id use it if I could. If the ecu wants speed sensor input, give it to it. She knows what she likes.

 

Perhaps you could put up some pics of the setup around the throttles?

 

Good Luck.

[David[RL]]

I don't use the speed snesor, Ive never had one and Ive also always been able to rev over 6500. All the way to 8300 in fact. The key difference is I didnt use the Toyota ECU, instead a programmable adaptronic. I have read about this issue many times. Its always sensor or error code related. The ecu is protecting your engine.

 

I'm of the belief that if you got it, flaunt it. Even if a sensor is going to only make things 2% better, its worth connecting. An oxygen sensor is a wonderful thing to install. Thats free fuel economy right there. 20vs will idle at about 1600 rpm without the ISCV, so Id use it if I could. If the ecu wants speed sensor input, give it to it. She knows what she likes.

 

Perhaps you could put up some pics of the setup around the throttles?

 

Good Luck.

 

hello

 

I blocked off the pipe to the ISCVV, and set the idle manually on the throttle, idle is at 1000rpm when hot and approx 900 when cold

the reason we didn't put on the speed and oxygen sensor is because we don't have the parts, it looks like we have to buy it just to test, but before that I will read the error codes..

I don't have that picture but I can probably do it, what are you looking for?

 

I think it's strange with the speed sensor because it should rev til 8300 even when standing still.. and then it won't get any signal from the speed sensor?

[LittleRedSpirit]

hello

 

I blocked off the pipe to the ISCVV, and set the idle manually on the throttle, idle is at 1000rpm when hot and approx 900 when cold

the reason we didn't put on the speed and oxygen sensor is because we don't have the parts, it looks like we have to buy it just to test, but before that I will read the error codes..

I don't have that picture but I can probably do it, what are you looking for?

 

I think it's strange with the speed sensor because it should rev til 8300 even when standing still.. and then it won't get any signal from the speed sensor?

 

 

Your correct in your logic IMO, but who knows how Toyota coded it. Error codes for the win. Might be just a bung ground ruining a signal or something.

[MYSTIK[RL]]

Your correct in your logic IMO, but who knows how Toyota coded it. Error codes for the win. Might be just a bung ground ruining a signal or something.

 

as far as i know toyota coded the ecu's on the st/bt to go into limp mode when there is no input from the speed sensor.

 

for example of this as there have been quite a few ae9x with the 20v conversion that have the problem of not having the right redline limit and its been due to not having the speed sensor connected.

 

but if you want to avoid the problem just go with an aftermarket ecu :)

[beerhead]

Without a speed sensor the factory 20V ecu's loose about 10 deg of timing advance at top end. Without it plugged in the motor also has a reduced rev limit so that in top gear you can't exceed the Japanese speed limiter. Either build a 555 timer circuit connected to an NPN transitor to make a ground pulse or you can do an indicator flasher wired into a relay to make a pulse to trick the ecu as a test :wink: