Electronics help with TPS circuit.

[Mos]

Ah ok, makes more sense .. I repinned that large plug into the original MX83 plugs.
Mos.

[cambelt]

what sp1 sensor did u use bmw turbo , a toyota one , the aristo one or a common reed switch one
Dave

[BMWTurbo]

I have retainted everything factory aristo. so SP1 and SP2 are both aristo factory items.

I didn't change housings or sensors.

[BMWTurbo]

On a side note someone suggested the engines might be detonating and retarding the timing...

I think it's way to oabrupt to be a timing issue, but want to look into it. What fuel pumps are people using? Have they had thier injectors cleaned of flowed?

I know my factory BMW fuel pump won't flow massive amounts, but I don't see anything to suggest it's limiting atm.

[PlacentaJuan]

i have a walbro 255, bro.

a lot of people make suggestions about what it could be, but the fact of the matter is that this problem is fixed by limiting tps voltage!!!

if the engine was detonating then limiting tps should have no effect since it would not interfere with the knock sensor or anything ...?

also when i got my car dynoed at 239kw, it was running at about 17psi, which was going *slightly* lean, and the operator said that 15psi would have been about spot on for air/fuel.

when i restrict the exhaust so that the car runs standard boost (~11psi) this rev limiter things kicks in MUCH later and sometimes hardly at all.

[BMWTurbo]

oh.. that's interesting... The TPS voltage might have a tie in to the amount of knock is acceptable... I know with the old Declo '808 systems the TPS had a lot of calibration style tables that used to tie it in all over the place, but the main mapping was done with MAP.

By restricting the exhaust and running std boost you can run almost max TPS and only have minimal issue.. This sort of supports the knocking possibility. I'm tempted to D/C the knock sensors and see if it still does this.

Perhaps the Supra ECU has a higher knock index before it steps in. Or it could possibly be due to mapping creating less knock.

I have spoken to someone who isn't getting this problem and he had his injectors cleaned and flowed...

Just exploring all avenues

[2JZR31]

I wired up my Aristo conversion myself and have never had an early rev limiter prob at any stage even when my wiring was only half done and done wrong at that. I have had shitloads of other probs which I slowly had to figure out my own because the people that knew wouldn't tell me without handing over money. So I will give all the info I can to help DIY'ers do as much work on their own car as possible. I will try to address some of the theories that have been brought up in this thread.

I only wired in what I had to by fixing one problem at a time. I did not wire in all the wires that normally go from the body loom plug to the E10 small ECU plug. Some people see these wires that loop around and join them all up without checking what they do. So that is one place you might start looking if thats how your car was originally wired up. However it might be the right thing to do. I can only speculate that some of these wires send and receive signals from outputs or inputs that are no longer in use and may be causing probs.

I have always had SP2 hooked up as my trans is unmodified. I drove it with only SP2 hooked up for ages and gearshifts worked fine and there was no odd rev limit but the 180 speed limiter was still active. I had error codes for SP1 since it was not hooked up. I also had an odd prob of the hitting limp mode when the engine was held at high RPM for a while. Like revving through 3rd gear at the drags. I replaced cam sensors any everything to try and fix it since I was getting the CAM and CAS code too. However, I fitted a speed cut defender which required that I hook up SP1 via the SCD. Once SP1 was connected the odd limp mode prob went away and so did the CAS and CAM codes. So it seemed that this sensor not being connected caused a limp condition in my car but no early rev limit. BTW you do NOT need a signal modification circuit to hook SP1 to the ECU it will work if you hook it straight up. No division is required. So in my experience SP1 should be hooked up. It may be the cause of the OD light flashing (SP1 error code) and cause limp mode.

BTW I used the SP1 to run my speedo from the beginning but it wasn't hooked to the ECU. But it read over half the real speed. The Jaycar unit only increase speed up to 100%. I was told that I needed to buy a $330 unit, and the Jaycar ones were really shit and would not work with the "analogue signal". However I just ran 2 Jaycar ones in series to get the right speed multiplication. It works fine. The SP1 signal is a square wave anyway!

I have the kick down switch hooked up to my accelerator pedal, but before I connected it I still never had the odd rev limit.

My car runs 115mph at the drags with stock turbos so its probably one of the faster Aristo equipped cars and I never hit the rev limiter on a downshift made by the ECU due to the car accelerating too fast for the changes to keep up. However looking at my AVRC readout from my last go at the drags, I was hitting 6995 RPM on the 1ts to second shift so it must have been damn close! I expect it to happen once my GT35 is sorted though . So it is an issue but only if your car goes damn hard. Its a no brainer anyway. Just look at the speedo when the cut hits. If you are doing 80km/h in first when it happens you know its the real rev limiter

I know my tacho lags behind the real RPM and so does my mates in his actual Aristo so its hard to rely on. Thats why the AVCR is good with its digital accuracy and recall function. You can also use a multimeter with a frequency function to monitor RPM accurately. Hook it to the tacho output or speed sensor.

BTW my Aristo 2JZ does not have the bung for the booster in the plenum. This may be a clue to the age of my setup. Maybe this prob only happens with the newer ones?

When I first wired up the car I didn't get the wire for the IACV so I had a really high idle, so I messed around with the throttle stops and TPS. Maybe I do have the prob and have inadvertently avoided it by messing with this? Unlikely but a possibility.

I run an 044 fuel pump and have had my injectors cleaned and flowed. I ported my wastegate and run a true free flow exhaust without the restrictive 2.25 section that houses oxy sensor. I have never had the odd limiter kick in even at 21psi!

Norbie said that when he had cooling issues the engine lost huge power and he reckoned it was because knock was setting in and it retarded the timing. He never said anything about a low rev limit. Ed Sir2JZa70, had a rooted fuel pump and the car ran super shit quarter mile times due to lean outs and I don't think it had a low rev limit.

Does it sound just like the real rev limit where it will bounce on the same RPM until you back off? Does it shut down or just loose power?

[BMWTurbo]

Great info denis When I see you next I'll taqke you for a drive to show you exactly what it does.

BTW mine has the bunged hole on the top of the plenum for the booster. There could be something with this I don't know.

With Looping the wires I think there were 4-5 in total that leterally went from the engine loom around to the ECU Plug A. I connected these in order to save tracing later. I hadn't thought about this and might do a quick trace to see exactly what they do.

I believe Wolfie has the same problem with his 2jz conversion. Are Norbies and Ed the non-bunged inlet versions the same as yours?

[2JZR31]

Norbie's has no bung , but I don't think looking at Norbie's car is of much value for this prob since its a manual. Ed's car is a manual too so it might not be a good indication either. His white one has the bung I think but I'm not sure if its running. I only mentioned the bung because supposedly only the old ones don't have it, and when they revised the engine they may have altered the ECU too.

Don't know about Wolfie's. Are you sure that Wolfie has the prob? Sounds like he hasn't even hooked the selector switch up, but I drove without mine hooked up and it still never had the prob. Maybe we need to test my ECU one of the cars that have the symptom.

[BMWTurbo]

Norbie's has no bung , but I don't think looking at Norbie's car is of much value for this prob since its a manual. Ed's car is a manual too so it might not be a good indication either. His white one has the bung I think but I'm not sure if its running. I only mentioned the bung because supposedly only the old ones don't have it, and when they revised the engine they may have altered the ECU too.

Don't know about Wolfie's. Are you sure that Wolfie has the prob? Sounds like he hasn't even hooked the selector switch up, but I drove without mine hooked up and it still never had the prob. Maybe we need to test my ECU one of the cars that have the symptom.

Yeah norbie's and Ed's manual aren't very indicative... I can free rev the engine without hitting the rev limit so I wouldn't count them as proof as such.

I was wondering if it was in fact ECU based. (well it has been proven it is with PlacentaJuan fitting the supra ECU to fix the problem), but whether or not the ECU age causes it also. The strange thing is I've spoken to an aristo driver 'dust' on here who said his std aristo has done the same thing.

Maybe we need to arrange a swap

[PlacentaJuan]

thanks 2jzr31, yes it sounds likve a rev limiter where it just bounces off a certain revs (have no tacho so cant be sure exactly what it would be displaying)

as opposed to a fuel/boost cut or speed cut where engine power drops right off for about a seconds or more before coming back to life.

[MR 1JZ]

Yeah norbie's and Ed's manual aren't very indicative... I can free rev the engine without hitting the rev limit so I wouldn't count them as proof as such.

I was wondering if it was in fact ECU based. (well it has been proven it is with PlacentaJuan fitting the supra ECU to fix the problem), but whether or not the ECU age causes it also. The strange thing is I've spoken to an aristo driver 'dust' on here who said his std aristo has done the same thing.

Maybe we need to arrange a swap

placenta's ecu works fine in my car

[BMWTurbo]

It's definitely a rev limit. I've watched the tacho and it jumps all over the place above 5000rpm when it's doing it.

I took the car to rev limit ie just on 7000rpm this mornig to confirm and it's the pulsing on and off with power...

[cambelt]

So BMW your running thee aristo dash cluster in your bimmer or using the signal from the sp1 on the auto , because the dash modifys this signal a bit , or really gives it a negative output to the ecu..
And dennis the factory toyota sensor is 4 pulse and the nissan one is 8 or 10 pulse thats why your speedo was up the creek . How did you tie the negative of the speed sensor to the sp1 input of the ecu or did you take it from the positive ( pulse side of the sensor).
Main reason for the questions is that most toyotas for sp1 use a 4 pulse negative square wave pulse, ie switches to ground , you can achieve this by wiring the sp1 speed sensor a bit different to how its done factory . Im just not sure if the ecu would agree with a positive pulse if thats the way a couple of guys have wired it .
Dave

[Mos]

So BMW your running thee aristo dash cluster in your bimmer or using the signal from the sp1 on the auto , because the dash modifys this signal a bit , or really gives it a negative output to the ecu..
And dennis the factory toyota sensor is 4 pulse and the nissan one is 8 or 10 pulse thats why your speedo was up the creek . How did you tie the negative of the speed sensor to the sp1 input of the ecu or did you take it from the positive ( pulse side of the sensor).
Main reason for the questions is that most toyotas for sp1 use a 4 pulse negative square wave pulse, ie switches to ground , you can achieve this by wiring the sp1 speed sensor a bit different to how its done factory . Im just not sure if the ecu would agree with a positive pulse if thats the way a couple of guys have wired it .
Dave

The dash doesn't do anything special to the signal in this case. Yeah, the ECU has a pull up resistor on the SP1 input and the dash has an open collector output for SP1 that just buffers the speedo sensor output, but connecting the speed sensor directly to the SP1 input should have no effect on the shape of the pulse.

The MX83 speed sensor has a single IC inside it with an internal 10k pullup resistor on the ouput, so while it is switching to ground, the output is actually a genuine squarewave without any external circuitry. While I can't say for sure, I wouldn't have any reason to believe the aristo speed sensor was much different operationally.

If you feed a signal that uses a pulldown resistor and a transistor pulling to power you will get a squarewave at a peak-to-peak amplitude dependent on the ratio of the pulldown resistor in the sensor and the pullup resistor in the ECU - this may or may not be registered as a valid signal.

If you feed a signal that requires the pulldown resistor but doesn't have it, the pullup transistor will just help the pullup resistor, resulting in no waveform at all, as there's nothing pulling to ground - this would most defn not work.

Mos.