The dreaded 4AGZE power dip at 5500rpm... How to overcome.

[Crampy]

Hi all.
I was just trying to find out if it's just the AE101 MAP sensored 4AGZE that has the power dip of death at 5500rpm, or if the AE92 MAP one does it also?
My MR2 was sweet, but that was due to it being AFM.

Also, has anyone found a way to stop this dip (or lessen the effects)?
Other than changing the ECU too. I have read on somewhere that you can change the knock sensor for another toyota one and that helps. Any truth in this?

Chur.

[Crampy]

Well, after sifting through stuff on Twincam.org, I found someone saying the AE92 MAP computer doesn't cut power back like the AE101 does.
Is this true???

[KinLoud]

wow - haven't had a post about this for ages!
From memory problem might have been related to failed/failing knock sensor?
Any other opinions

I had an AE101 GTZ but never had this problem unless I ran 91 octane (usually 98 octane)

Ken
Auck
021 408 863

[evil_si]

i had this happen on dyno and believe its to do with engine temp sensors and a form of ecu protection circuit,

first run power dropped off at 5500,
2nd run 20 mins later with car still running in between it pulled right thru 5500 to rev limit with no power drop,

id told the tuner not to turn car off between runs as i knew from experience that even if it was warm and shut off that it needed a "set" time of engine running before it would pull thru 5500rpm

[Quirky]

I have a 4agze MAP, and I dont notice any power drop?

From what I see, the torque starts to dip, but I make full power at 7500 rpm and only mods are pully and front mount intercooler...

[~SlideWays~]

I had this problem with my old ae86 with MAP 4agze for years. In the endI backed the timing off via the CAS and it was like a new car to drive, it flew passed 5500rpm.... wish I'd done it years earlier lol.

It still MUST have something to do with operating temperature because it was really bad when mine ran cold during some thermostat testing.

Even after the CAS adjustment I could still juust feel it back off a bit when not completely up to normal operating temp (water temp).

Hope that helps.

[Crampy]

The thing is, I know it's a common problem, but not on all cars as already mentioned here.

My mates GT-Z has a shocking drop in power at 5500rpm (even at full operating temp), so was hoping to see what to do about it. He's got a Subaru W2A intercooler setup for it, so that should help, especially with the pulley kit on it.

Now, I know the SC12 will be running out of puff up high, but out of all of the 4AGZE powered cars I've been in, the newer ones have always lacked. My MR2 would pull right throught to red line and just haul ar$e, even with the stock interheater. So if not all cars do it, it can't just be the way the computer runs, it has to be the knock sensor or other getting on a bit.

It also doesn't help that his car is a apain in the ar$e to check the timing on, as it doesn't have the extra timing marker that normally comes with big pulley kits.

After a bit of sifting through club4ag and twincam.org forums, I have seen some people recommend changing to an AE92 MAP ECU, as apparently they don't do it. Then someone on another forum says they all do it.
Then apparently you can use a knock sensor from a 7MGTE, which is not as sensitive. Also, just heard of some people putting a 500 ohm resistor on the knock sensor line to "hmmmm, dampen" the signal coming from it.

[~SlideWays~]

It only happens on the MAP ones.

I've had both AFM and MAP.

Also experienced 2 MAP ones with the problem. One with front mount and one completely standard, it doesn't make a difference.

Just make sure yours isn't running cold and try the timing. Whats to lose?

[KinLoud]

I'm sure it was related to a sensitive/faulty knock sensor

[~SlideWays~]

I'm sure it was related to a sensitive/faulty knock sensor

Partly explains why backing off the timing works. But not the relation to temperature - this could be an ecu setting to stop putting engine under load before it is at operating temp?

There could be a millions explanations, possibly relating to who built the pyramids, but either way mine was fixed via ign timing.

[matt dunn]

I'm sure it was related to a sensitive/faulty knock sensor

Partly explains why backing off the timing works. But not the relation to temperature - this could be an ecu setting to stop putting engine under load before it is at operating temp?

There could be a millions explanations, possibly relating to who built the pyramids, but either way mine was fixed via ign timing.

I had a feeling it was inlet air temp, not engine temp,

and inlet air temp is related to knock,
as more heat in the intake, is more likely to cause knock.

[themaleman]

my ae92 MAP didnt seem to have a power drop at 5500. went as far as 200km/h in 4th. its had both ae101 and ae92 knock sensors and havnt notied any difference what so ever

[kompressor]

I fixed this by using an ae92 map ecu in my ae101 I opened up the ECU and chopped the internal wires. I re-soldered new wires inside the ecu as the pin-out is different.

[FLAWLES]

I'm sure it was related to a sensitive/faulty knock sensor

i had the same issue with my old girl, spoke to ken ( many many years ago,now )
bit the bullet and went and got a ze knock sensor
replaced it

fixed it
sold the car

the power drop i had was nasty, it screamed all the way till 5500rpm then it felt like you hit a wall, and then you were n/a again

didnt think about adjusting teh cas tho

[themaleman]

http://www.youtube.com/watch?v=LOIJQ-RAKRo

pretty shit video quality. but shows my ae92 maped levin pulling through.

car was pretty much standard when i took this years ago

edit: had abv mod

[method]

Drop your boost a touch.

Its probably the knock sensor. I had this problem too.

[Crampy]

I fixed this by using an ae92 map ecu in my ae101 I opened up the ECU and chopped the internal wires. I re-soldered new wires inside the ecu as the pin-out is different.

I have also heard of some AE92s having the dip as well. So, it'd be a big pain in the Ar$e to rewire the ECU for it to just do the same thing.

I might have a look at pulling the CAS back a bit and seeing how that goes.

[Crampy]

Is it the knock sensor itself or the knock sensor circuit being too sensitive?

I've seen all sorts of weird and wonderful ways of fixing the problem.

[themaleman]

I have also heard of some AE92s having the dip as well. So, it'd be a big pain in the Ar$e to rewire the ECU for it to just do the same thing.

remember not all ae92s r the same. as said above it sounds like the maped ae92s dont have the dip in power

[Crampy]

I have also heard of some AE92s having the dip as well. So, it'd be a big pain in the Ar$e to rewire the ECU for it to just do the same thing.

remember not all ae92s r the same. as said above it sounds like the maped ae92s dont have the dip in power

Yeah but I have also seen on another forum where a guy with a MAP AE92 had the power dip.