weird 1jz/ma61 problem

[naten]

hey guys,

Just after a bit of help with this weird problem im having.

When crusing on the highway above say 120, if i sit on the one speed continusly for a period of time the car looses power/shudders. If i keep the pedal pressed the same it continues until i take my foot off the gas, slow down slightly and accelerate again.

The car has no worries on boost at any speed and to me its a really weird problem. The best way i can describe the shudder is imagine when you take off with a button/semi button clutch and you dont give it enough gas and it shudders. Its basically like that.

The car is a ma61 with 1jz stock ecu, front mount, walbro pump, boost cont 3" zorst.

I was thinking maybe TPS, oxy sensor or ecu?

Any suggestions would be welcomed

cheers
nath

[ViPeR_NiPPleX]

Check to see if the ecu has recorded any errors. Open the flap on the diagnostic connector, short terminals TE1 to E1, then grab a test light and connect it to terminals VF and E1.

For more info and what the codes mean: http://www.off-road.com/toyota/tech/codes/

If you are too lazy for that, try just unplugging the oxygen sensor. But i'm skeptical as to it being o2 related.

[wilbo666]

Check to see if the ecu has recorded any errors. Open the flap on the diagnostic connector, short terminals TE1 to E1, then grab a test light and connect it to terminals VF and E1.

VF and E1 isn't correct. VF is used for OBD (Serial)...

Light between +B and W

Cheers
Wilbo

[naten]

dang went to check it, shorted te1 and e1 went to attach light and there is no W pin in the diagnostic connector.

Ill have to pull the ECU out tomorrow to check the codes

[ViPeR_NiPPleX]

VF and E1 isn't correct. VF is used for OBD (Serial)...

Light between +B and W

Cheers
Wilbo

VF according to this document is "Voltage Function" and when the IDL switch contact is connected to ground, it works as the output similar to the CEL. I've yet to confirm it works however.
http://www.autoshop101.com/forms/h27.pdf

[ViPeR_NiPPleX]

dang went to check it, shorted te1 and e1 went to attach light and there is no W pin in the diagnostic connector.

Ill have to pull the ECU out tomorrow to check the codes

The W pin is an output directly on the ECU. If you have access to that, use it instead.

[wilbo666]

VF according to this document is "Voltage Function" and when the IDL switch contact is connected to ground, it works as the output similar to the CEL. I've yet to confirm it works however.
http://www.autoshop101.com/forms/h27.pdf

Yep, it is also used for OBD

47 OBDII#2 - Serial Data.pdf

And as said, you will be able to find the W pin at the ECU...

Cheers
Wilbo

[ViPeR_NiPPleX]

So this debate hangs purely on whether his ECU is OBD1 or OBD2?

[wilbo666]

So this debate hangs purely on whether his ECU is OBD1 or OBD2?

What debate? I've only been talking about OBDI ecu's btw... OBDII should use a pin labled SIL to my knowledge for the OBDII serial output.

The VF pin does the 'Voltage Feed back' Function you mention and also the OBDI serial output (OBDI ECUs).

I'm pretty sure he has a non-vvti JZ, but even if he doesn't if you want to pull the diagnostic codes (not OBDI or OBDII serial data) you connect a bulb / multimeter between +B and W. It's the same on OBDI and OBDII



Edit: I just re-read that PDF, and while you are right in saying that you can use it to tell you if you have any error codes stored... however it won't tell you what the codes are... so much better to simply use the W pin

Cheers
Wilbo

[ViPeR_NiPPleX]

Shit, so VF when IDL pin is closed doesn't simulate the same output as the W pin? Well that blows haha. Was hoping for an easy solution for those who haven't wired up their CEL.

[wilbo666]

Shit, so VF when IDL pin is closed doesn't simulate the same output as the W pin?

Nope, epic fail



Cheers
Wilbo

[naten]

ok its been a while but i finally got a chance to get to the ecu and wire up a check light.

Before the issue occured i got code 78 which is to do with the fuel pump circuit, from memory mos wired up my fuel pump different and not off the ecu so that probably explains that one.

Went for a drive, problem occured as usual so i pulled over when it was safe (maybe 5 min) and pulled the codes, it spat out code 14, 47 and 78.

I dont think the 78 has much to do with it but 14 and 47 are odd.

Code 14 is IGNITION SIGNAL--NO "IGF" SIGNAL TO ECU

Which to me seems really werid as to why it would occur only when sitting on 120+ for a period of time

Code 47 is Open or short in sub–throttle position sensor circuit for 0.5 sec
or more.

I dont have a sub-throttle postition sensor so im not sure why i dont get that code all the time.

So im going to assume that its most likely to be the ignitor. Overheating maybe?

cheers
nath

[naten]

hmmm looked up the trsm for a 2jzgte and code 14 says:

No IGF signal to ECM for 4 - 7 consecutive
IGT signals with engine speed less than
3,000 rpm

Upon more reading seems the IGF is the 'confirmation' signal to the ecu to say its still working/firing.

Should also add car has idling issue (low idle) but im almost positive its the ISCV.

Ecu has had caps replaced too.

[wilbo666]

I had a similar problem to this once, it was the ECU. I replaced the caps, still did it... got a new ECU, fixed the problem.

My issue was VERY intermittent as well to make it more annoying.

See if you can find someone to let you try your ECU in their car.



Cheers
Wilbo