Car starts, dies under load

[Stag]

I think the obd link error is probably significant. Can you double check for bent pins in the ecu and harness plugs? To my Mind that's the most likely reason for the link error.

No bent pins unfortunately

[jonbill]

Could anythong

[shnazzle]

Did you plug that knock sensor back in?
So it starts again and all that. Back to square 1?

[jonbill]

Could anythong

Not sure where I was going there 😂

[Ardent]

No, me neither.
Could've been anything.

[shnazzle]

No, me neither.
Could've been anything.

Diagnostic interlude for jonbill

https://youtu.be/Oai1V7kaFBk

[Stag]

Knock sensor fixed and reinstalled, turns out the crank sensor cable had been chewed apart by the auxiliary belt, will sort first thing tomorrow

[Stag]

Sorted the crank sensor, checked all grounds with multi meter. Have we run out of ideas ? ):

[shnazzle]

Sorted the crank sensor, checked all grounds with multi meter. Have we run out of ideas ? ):

Well and truly other than ecu got shorted somehow during swap or a wiring issue. 

It needs a proper look. I think we've covered all we can without seeing it

[Carolyn]

If you promise to be thoroughly careful, I'll lend you my spare MRS ecu.

It's very precious to me, as I have a JDM car.

It has no immobiliser and will work on any Roadster.

I know, for sure that it is in working order.

Please check that all the pin holes in your plugs are clean and clear, before you plug it in.

Let's see if it runs the car?

Ok?

[Stag]

If you promise to be thoroughly careful, I'll lend you my spare MRS ecu.

It's very precious to me, as I have a JDM car.

It has no immobiliser and will work on any Roadster.

I know, for sure that it is in working order.

Please check that all the pin holes in your plugs are clean and clear, before you plug it in.

Let's see if it runs the car?

Ok?

This has made my day, I'll pm you my address. If you want you don't have to worry about paying the post and packaging for the valve buckets if you send it out to me. Thank you so much Carolyn

[Stag]

@Carolyn let me know once you've seen my message and sent it out. If you could send it next day I'll happily pay the postage. Thank you again

[shnazzle]

Unplug negative battery terminal, tuck it away and press the brakes a good few times to flush out any risidual current before you plug in Carolyn's precious ecu

I wouldn't put it past her to hunt you down and engineer next year's Perry Byrnes trophy out of your goolygongs if you mess it up. 

It'll be something simple. And I'm not 100% convinced it is the ecu. But running out of options. Bonus of the mr-s ecu is that it is simpler. No immobiliser or 3rd o2 sensor. 

Vacuum; can you check that you put all the vacuum pipes where they should be? 

Also, like mentioned earlier, it's concerning that your ecu won't connect to obd2 anymore. 

Just for clarification, does the car rev when you unplug the maf or remove the maf?

[shnazzle]

Maf is bugging me most. A wiring issue in particular. But we've swapped harnesses and mafs...
Argh!! 
By the by is the check engine light on?

[Stag]

Unplug negative battery terminal, tuck it away and press the brakes a good few times to flush out any risidual current before you plug in Carolyn's precious ecu

I wouldn't put it past her to hunt you down and engineer next year's Perry Byrnes trophy out of your goolygongs if you mess it up.

It'll be something simple. And I'm not 100% convinced it is the ecu. But running out of options. Bonus of the mr-s ecu is that it is simpler. No immobiliser or 3rd o2 sensor.

Vacuum; can you check that you put all the vacuum pipes where they should be?

Also, like mentioned earlier, it's concerning that your ecu won't connect to obd2 anymore.

Just for clarification, does the car rev when you unplug the maf or remove the maf?

I'm very thankful, I'm am going to take a lot of care.

In regards to the vacuum, I have done. Ive checked them all.

It does rev with no lag but only up to 3k then it bounces, like it's hitting the limiter. If you scroll up the thread I posted a video

[Stag]

Maf is bugging me most. A wiring issue in particular. But we've swapped harnesses and mafs...
Argh!!
By the by is the check engine light on?

The light comes on when I unplug the maf of course buts that's all. No other lights annoyingly

[shnazzle]

Unplug negative battery terminal, tuck it away and press the brakes a good few times to flush out any risidual current before you plug in Carolyn's precious ecu

I wouldn't put it past her to hunt you down and engineer next year's Perry Byrnes trophy out of your goolygongs if you mess it up.

It'll be something simple. And I'm not 100% convinced it is the ecu. But running out of options. Bonus of the mr-s ecu is that it is simpler. No immobiliser or 3rd o2 sensor.

Vacuum; can you check that you put all the vacuum pipes where they should be?

Also, like mentioned earlier, it's concerning that your ecu won't connect to obd2 anymore.

Just for clarification, does the car rev when you unplug the maf or remove the maf?

I'm very thankful, I'm not going to take a lot of care.

In regards to the vacuum, I have done. Ive checked them all.

It does rev with no lag but only up to 3k then it bounces, like it's hitting the limiter. If you scroll up the thread I posted a video

Haha. I think you mean you ARE going to take a lot of care. 


I just saw the vid. Must have missed it earlier.
With the maf disconnected, that is limp mode. Absolutely. 

There's a disturbance in the Force.

Do me a favour and unscrew the maf, pull it out, leave it plugged in and run the engine. 
Bit of a circus trick but keep it running by using the throttle cable and move the maf around, blow on it, and see if there is any change?

[Stag]

Unplug negative battery terminal, tuck it away and press the brakes a good few times to flush out any risidual current before you plug in Carolyn's precious ecu

I wouldn't put it past her to hunt you down and engineer next year's Perry Byrnes trophy out of your goolygongs if you mess it up.

It'll be something simple. And I'm not 100% convinced it is the ecu. But running out of options. Bonus of the mr-s ecu is that it is simpler. No immobiliser or 3rd o2 sensor.

Vacuum; can you check that you put all the vacuum pipes where they should be?

Also, like mentioned earlier, it's concerning that your ecu won't connect to obd2 anymore.

Just for clarification, does the car rev when you unplug the maf or remove the maf?

I'm very thankful, I'm not going to take a lot of care.

In regards to the vacuum, I have done. Ive checked them all.

It does rev with no lag but only up to 3k then it bounces, like it's hitting the limiter. If you scroll up the thread I posted a video

Haha. I think you mean you ARE going to take a lot of care.


I just saw the vid. Must have missed it earlier.
With the maf disconnected, that is limp mode. Absolutely.

There's a disturbance in the Force.

Do me a favour and unscrew the maf, pull it out, leave it plugged in and run the engine.
Bit of a circus trick but keep it running by using the throttle cable and move the maf around, blow on it, and see if there is any change?

How did I make that mistake ?? I'm going to take care of It.

I'll try this tomorrow, what sort of change am I looking for, cheers Louis

[shnazzle]

Just determining for once and for all whether the maf system is doing something. Try holding it at like 1500rpm or something and then jiggling and blowing on the maf sensor internals, faking changing airflow. The cat should suddenly start to rev differently as it should be changing the fueling based on the air you're blowing on it. If it does, the maf is working. If it does nothing, it would seem the maf is shorting things out somehow. As you've replaced the harness, that leaves the ecu, right? 

If it does rev as it should, some other electrical issue is causing limp mode. But the way it is distinctly bouncing off 3k rpm, it's definitely an electronic trigger to stop revving the car to protect from damage.

[Stag]

Big help yet ag

Just determining for once and for all whether the maf system is doing something. Try holding it at like 1500rpm or something and then jiggling and blowing on the maf sensor internals, faking changing airflow. The cat should suddenly start to rev differently as it should be changing the fueling based on the air you're blowing on it. If it does, the maf is working. If it does nothing, it would seem the maf is shorting things out somehow. As you've replaced the harness, that leaves the ecu, right?

If it does rev as it should, some other electrical issue is causing limp mode. But the way it is distinctly bouncing off 3k rpm, it's definitely an electronic trigger to stop revving the car to protect from damage.

Big help yet again, I'll try this at 5 ish when I get back from work. cheers

[Stag]

Tried doing this quickly before work @shnazzle there was no way I could get it to run for more than 4 seconds with out stalling

[Carolyn]

 Also possible...

AFTER you've tried the ECU.  Leak at the in lat manifold to head.  Did it get a new gasket?

[shnazzle]

Tried doing this quickly before work @shnazzle there was no way I could get it to run for more than 4 seconds with out stalling

Which is very telling in its own right isn't it?

The signal from the maf must be utterly utterly fubared.

Unplug it and it uses the ecu's simulation based on the fueling table and throttle,which is bad but good enough to get someone to the nearest garage.

Back to maf. Unplug Neg battery terminal (always do this when playing with sensors). Maf out. Test resistance with multimeter between pins 1 and 2 of maf when looking at the pins. What's the reading?
Now plug the connector into the maf (maf still out), reconnect the battery. Power on. Do not start the car.
Multimeter on voltage, negative terminal stuffed in pin 3 from the left, positive in pin 4. Stick them into the back of the connector where the wires go.

Watch voltage. Blow into maf, does voltage change?
If not, maf is dead. Unlikely as it sounds. I'm putting my money on this.

If voltage does change,wait for the ecu, see what it does. And I lose another night's sleep

[Stag]

Tried doing this quickly before work @shnazzle there was no way I could get it to run for more than 4 seconds with out stalling

Which is very telling in its own right isn't it?

The signal from the maf must be utterly utterly fubared.

Unplug it and it uses the ecu's simulation based on the fueling table and throttle,which is bad but good enough to get someone to the nearest garage.

Back to maf. Unplug Neg battery terminal (always do this when playing with sensors). Maf out. Test resistance with multimeter between pins 1 and 2 of maf when looking at the pins. What's the reading?
Now plug the connector into the maf (maf still out), reconnect the battery. Power on. Do not start the car.
Multimeter on voltage, negative terminal stuffed in pin 3 from the left, positive in pin 4. Stick them into the back of the connector where the wires go.

Watch voltage. Blow into maf, does voltage change?
If not, maf is dead. Unlikely as it sounds. I'm putting my money on this.

If voltage does change,wait for the ecu, see what it does. And I lose another night's sleep

Perfect, I'll try this later on tonight. Know I've said it time and time again but thanks again for all the replies youve all been great, learnt so so much from this experience

[shnazzle]

You're very welcome. We just want to see it fixed now