Strange Acceleration

[David P]

Linking B+ & FP in the diagnostic port will answer that one.

[Guest Roger NE]

Linking B+ & FP in the diagnostic port will answer that one

 

Yes I had thought of doing that David . . . but really I wanted to do a test while driving to see what is going on . . . which I have just done

 

As suspected, the Pump suddenly gets full power from the ECU when you reach 3750 rpm if you are at WOT . . . so I'm obviously suffering fuel starvation below this when at WOT. (as mentioned previously, there is no problem at half throttle)

 

So I have found the CAUSE !

 

Now I need to find the solution - I know I could just crudely feed the fuel pump from 14V all the time, but I really don't want to do this - the Mk4 has a sophisticated PWM control system, which I have now actually seen varying the pump speed depending on the driving conditions . . . so having fitted it I'd like to retain it.

 

There are two possible reasons for this problem - maybe my Mk3 Fuel Pump isn't as powerful as the Mk4 ones, so isn't providing enough fuel when it's running on reduced power.

 

Another possibility is that I don't have a thick enough cable from my EFI Relay to the Pump ECU - unlike the Mk4 there is no external cable for this on the Mk3 . . so for neatness I just paralleled a couple of spare wires in the engine loom . . . but they were fairly thin and maybe I'm getting too much of a voltage drop.

 

Has anyone measured the full power voltage that is fed to the Fuel pump by the FP ECU? I notice I am only peaking about 11 volts . . not the full 14 volts I would expect.

Edited July 26, 2014 by Roger NE (see edit history)

[jagman]

Fit mkiv pump and direct wire to pump via relay , use ecu o/p wire to switch relay .

2 thin parallel wires is not the way ,as if 1 wire broke or had high resistance the other wire is overloaded and you would not know.

Keeping the sophisticated PWM system is just another thing to go wrong , if needs be fit a return line cooler from a derv car .

11volts has got to be low , I run 17.5 v across my pump , works a treat and has for thousands of miles , I would also expect alternator output volts - probably the control unit is U/S

[Guest Roger NE]

I appreciate the reply Jagman . .

 

But why would I want to get rid of the sophisticated PWM Pump Controller and fit a relay? That's a backward step in my opinion (and what the crude original system in my Mk3 did, with another relay to switch in a resistor to reduce the pump voltage at low revs).

 

Running the pump flat out all the time is a) unnecessary, b) creates excessive fuel pressure and c) is bound to cause premature failure of the fuel pump. (having now hooked up a test meter and driven around I can see that at present it only runs flat out about 10% of the time)

 

I also don't think I need to replace my mK3 pump with a Mk4 one - certainly that will be the last resort if all else fails, but it is delivering plenty of fuel at the top end, even though it's currently only getting 11V on peaks.

 

The problem that I have is lower down the rev range, when the ECU is giving less power to the pump (it doesn't actually reduce the voltage, it alters the width of the pulses to reduce pump speed without reducing its torque)

 

Having now sussued what is causing this effect at 3750 rpm, I am hopeful that my problem is down to a voltage drop on the thin wires (within the engine loom I have used for neatness) - if I run a dedicated thicker wire from my EFI Relay to the Fuel Pump ECU that the voltage will increase . . . and solve this problem.

Edited July 28, 2014 by Roger NE (see edit history)

[jagman]

Well you've been buggering about trying to diagnose a problem that was hidden all BECAUSE of the complexity/sophistication .

The control module is the likely culprit , way above any wire issues for that size volts drop .

The control module was made/ designed for a mk 4 pump , it's speed and torque characteristics , (one goes up and the other down BTW), you are running a different pump ( how close is the torque/speed?)

Running flat out won't alter fuel pressure but provide greater return flow , reliability wise the effect is tiny ( hence I'm running1.5 x supply volts without issue comment) .

The voltage is altered for reasons of noise, return fuel heating and electrical efficiency .

The simple answer is fit a quality wire , mkiv pump , high current relay and good earth and end the fuel starve problem .

Keep the ecu signal to control the relay for engine fire / crash purposes and the delay at shutoff to maintain prime pressure of fuel

[Guest Roger NE]

Well you've been buggering about trying to diagnose a problem that was hidden all BECAUSE of the complexity/sophistication

 

True . . . but I have only spent about 10 minutes checking things on the car - the rest has been discussing possibilities on here, which is always interesting

 

That's nothing considering I spent probably over 100 hours going over the circuit diagrams working out all the electronics before doing this engine transplant! (which all worked first time, by the way - whole transplant done in 2 days)

 

The voltage is altered for reasons of noise, return fuel heating and electrical efficiency

 

Yes, as well as pump longevity (mine has done over 200,000 miles so far, and I expect to get another 100,000 out of it)

 

Those are all the reasons I want to keep the sophisticated stock 2JZ system!

 

As I say, based on what is happening so far, I doubt I will need to fit a Mk4 pump (apart from the expense, it's a lot of work to drop the petrol tank)

 

Once I have time to remove the glove box I can investigate whether the low voltage is due to voltage drop on the thin cables from the EFI Relay I have used - it's quite a long run, so may well be the problem. If it IS, then I'm pretty sure fitting a much thicker one will fix this slight issue. (it's not even a major problem - just that I like everything to be right!)

 

Unlike some people on here, although I love my Supra, it's my Transport, not a hobby. So I don't spend money on it unless it's essential. I've owned it 15 years, and it's been the most reliable car I've ever known.

 

The weak link was always the 7M engine, so fitting a 2JZ was just to make it more reliable - but the whole project cost little over £150 net (having got a lot of money back from selling my 7M engine parts and ancillaries)

Edited July 28, 2014 by Roger NE (see edit history)

[jagman]

You are in a half way situation , none of the advantages of an in tank pump , yet the control system for the wrong pump ,

Nearly 3 volts drop on such a low voltage system is waaaay too much on wires alone and even if it were full volts available does the mk3 pump satisfy the mkiv engine ?

The FP ecu ,s are now old and who knows what condition they are or how much they have drifted , a plain relay / control /rewire would seem the easy answer ,but i can see a intank pump fit being a pain .

i guess the engine would love to see the correct fuel flow though

[Guest Roger NE]

does the mk3 pump satisfy the mkiv engine ?

 

Yes! The engine is getting enough fuel at high revs . . . even though I'm losing 3V . . . so my Mk3 pump is obviously fine ! (I doubt if there's any real difference between the Mk3 and Mk4 pumps - they look almost identical)

 

The only problem at present is at medium revs when at WOT . . . when the ECU is running the pump at reduced speed, I'm not getting enough fuel, PROBABLY because of the voltage drop I am getting.

 

Nearly 3 volts drop on such a low voltage system is waaaay too much on wires alone

 

You clearly don't understand basic electrics - If the fuel pump is taking 10 amps, then I'd only need a third of an ohm resistance on the wires I am using to lose 3 volts . . . it's quite likely that's exactly what is happening. If I run a decent cable, instead of using the thin wires in the engine loom, then I will get that 3 volts back . . . and I expect I will no longer have this problem at medium revs.

 

The FP ecu ,s are now old

 

There is actually nothing to wear out in the Fuel Pump ECU ! It's all solid state electronics . . . and no reason why it won't go on for another 20 years - unlike relays, which have a limited life. And actually all the clever work on what fuel is requires is done by the Engine ECU - all the FP ECU does is convert the signals to high power switching of the pump feed.

 

(And by the way, even though I have a big box of spare modules in my loft, I've actually never had ANY electronic module fail in my Supra - they're actually all designed and built to very high standards, with big safety margins on the components).

Edited July 28, 2014 by Roger NE (see edit history)

[jagman]

I have been an electrical engineer for coming up 40 years now , so I have a fair idea of basic electrics , in fact advanced electrics as well.

The drop you have would require 22/24 gauge wire to have been used or very poor terminations .

Using two parallel supply cables can cause its own issues ,what I can't tell is the quality of your wiring installation , crimping/ soldering , only you know that .

Pump wise , external comparisons don't mean much , what is the maximum flow of the mk3 pump @ what voltage ? And what is the NA mkiv pump ?

Then what is the static pressure of fuel of the mkiv NA and mk3 ?

Solid state electronics don't "wear" so much , as there are no moving parts , but dust build up,condensation , dry solder joints or cracked boards are not unknown . Many jap cars used electrolytic capacitors and these have a limited life , around 10 years old they leak and corrode the tracks / damage surrounding components ( you can smell this when it happens ) .

As to quality electronic components , I spend most night shifts replacing failed units , and we use the very finest , massively expensive electronics , and very seldom by comparison replacing relays ... Simplicity works

[Guest Roger NE]

I have been an electrical engineer for coming up 40 years now

 

In which case forgive me if I was patronising you, but I don't understand why you can't see that you could easily get the kind of voltage drop I seem to be getting.

 

I would say the wire inside the loom I used is equivalent to about 26 swg . . . it's about 6 feet long, so having thought about it, the voltage drop I am getting is quite likely, despite all the joins being soldered.

 

Once I get time to remove the glovebox to get at the wiring, I will do some measurements, and if as expected will run a new thick cable to the EFI relay at the front of the car, which I'm pretty sure will remove this weird effect I am getting.

 

Regarding electronic modules - sure, some equipment uses awful components and cheap circuit boards, including a lot of domestic stuff like TVs (I've recently had to replace the PSU electrolytics to fix my 4 year old LG TV). But I have professional equipment here which is 40 years old and still working perfectly.

 

And as I stated before, Toyota also used extremely good quality boards and components on the Supra - and I have never had ANY electronic failure in my 23 year old car (the only time I'm aware of Toyota having problems is with a batch of duff electrolytic capacitors they used in their 1JZ ECUs)

 

So I have no desire to replace the Pump ECU with a crude relay system on the grounds of reliability!

 

And regarding whether there is much difference between the actual Fuel Pumps - the point is that it's really not that critical ! As long as you have SUFFICIENT fuel pressure that is all that matters. (which I currently have at high revs, and feel I will at lower revs when I sort this cable)

Edited August 2, 2014 by Roger NE (see edit history)

[Shane]

(I've recently had to replace the PSU electrolytics to fix my 4 year old LG TV).

 

 

 

and I have never had ANY electronic failure in my 23 year old car (the only time I'm aware of Toyota having problems is with a batch of duff electrolytic capacitors they used in their 1JZ ECUs)

 

 

 

I do hope you used low ESR capacitors in that or you will be doing it again soon

 

In my experience both in domestic, commercial and prototype engineering, you don't need a duff batch as such, electrolytic caps can fail for various reasons and I believe it's the cause of the horrible no fuel pump feed fault on the 2jzge ecu that most people never actually fix at component level, they just end up finding another ecu, I did. But, speaking again from experience, the symptoms you have rule that particular fault out.

[jagman]

Clearly banned ..

[Nic]

Clearly banned ..

 

Ever get the feeling you're :banghead:he's definitely an oddball

 

I gave up bothering to reply to any of his threads after this one http://www.mkivsupra.net/vbb/showthread.php?295354-N-A-Exhaust-Headers every thread of his seems to play out the same way.

[Graham1984]

Ever get the feeling you're :banghead:he's definitely an oddball

 

I gave up bothering to reply to any of his threads after this one http://www.mkivsupra.net/vbb/showthread.php?295354-N-A-Exhaust-Headers every thread of his seems to play out the same way.

 

Oh that was a classic.... he is right though Nic, you know F all

[straightsix]

Clearly banned ..

 

A 2JZ does not a MkIV make....

 

We'll have no trouble here!

 

Edited August 4, 2014 by straightsix (see edit history)

[Ian C]

I'm so glad the rudest and most aggressive asker-for-help has gone, I can stop ignoring these threads now. I had stuff I could have contributed but didn't feel like being yelled at and accused of clearly knowing nothing

[Guest Roger NE]

Ian I don't believe I have ever been rude to anyone on here!

 

And I've certainly never accused you or anyone else of knowing nothing . . . I don't know where you get that idea.

 

I'm sorry if you feel that my use of capital letters to STRESS particular words in a sentence is offensive, but that's all I use them for, not to shout at anyone! It's just typing capitals is easier than using the underline feature.

[Gaz6002]

Ian I don't believe I have ever been rude to anyone on here!

 

And I've certainly never accused you or anyone else of knowing nothing . . . I don't know where you get that idea.

 

I'm sorry if you feel that my use of capital letters to STRESS particular words in a sentence is offensive, but that's all I use them for, not to shout at anyone! It's just typing capitals is easier than using the underline feature.

 

Well you'll have to see sooner or later that the way you come across makes people actively not want to help you, right? Take the hint?

[Guest Roger NE]

Well no offence has ever been intended to anyone, but I don't really understand how people have imagined that!

 

If ever I have questioned what people tell me, it's not because I don't believe them . . . it's probably either that I'm not sure what they mean, or I've felt that they haven't properly understood what I'm asking.

 

Plus I like to understand things - I'm not one for just accepting something without an explanation of why something happens.

 

So all I can think is that people have taken things the wrong way!

[Twisted]

Plus I like to understand things - I'm not one for just accepting something without an explanation of why something happens.

 

Happens a lot on here

[Gaz6002]

So all I can think is that people have taken things the wrong way!

 

But... everyone? Yeah, you're right. It's us. You're absolutely absolved of any wrong-doing.

 

Perhaps it's this acute defensive mechanism that's your issue.

[Nic]

So all I can think is that people have taken things the wrong way!

 

It seems there are a lot ! of people in the CLUB that are taking things the wrong way, do you really know that for sure? There must be another explanation !

 

Disclaimer - any gratuitous use of explanation marks, capitals and complete disregard of what another member has posted are not my fault.

[Gaz6002]

He won't be replying to that.

[Lbm]

He's gone on a long holiday. Apparently