Ecu fun

[Vixpy1]

Having some fun with the Ecu in my 4.0 precat.

It runs very lean , rover gauge shows no reading at all on the Maf sensor , and the coolant temp is stuck at 35 degrees .

Change the Ecu for the one in my Range Rover and he maf sensor seems to read fine , coolant temp does not read . Buzz the wires and no continuity on coolant wires to Ecu . Will sort that but shortly

Send griff Ecu to be tested at reputable place and it tests all fine .

Now massively confused . Maf sensor is a new genuine one and the voltage it gives out is perfect .

[Sardonicus]

Wiring Loom ? but also check your sensor grounds/earths rear of the N/S cylinder head

[Vixpy1]

Sardonicus said:

Wiring Loom ? but also check your sensor grounds/earths rear of the N/S cylinder head

If its the loom then why does the range rover ecu read the maf fine, thats what is confusing me

the coolant temp problem is defo a wiring one

[blitzracing]

Each sensor has its own ground wire, back to a common point on the ECU. No sensor uses the engine or chassis ground. From memory I think the temp sensor wire should show 5 volts open circuit, but this will drop when you plug the sensor in.

[Sardonicus]

blitzracing said:

Each sensor has its own ground wire, back to a common point on the ECU. No sensor uses the engine or chassis ground. From memory I think the temp sensor wire should show 5 volts open circuit, but this will drop when you plug the sensor in.

Should of made myself clear but the ECU grounds at the head Mark with multiples then the ECU supplies sensor grounds remotely from these

[Vixpy1]

like i said, coolant temp problem does'nt worry me, i'll simply run new wires back to the ecu.

Its the maf problem i'm confused about

[spitfire4v8]

How are you determining the afm output? can you show an engine running rovergauge screenshot? You should see the fuel map tracing when you rev the engine too. If the afm is disconnected it reverts to throttle angle and will run surprisingly well!

[Vixpy1]

spitfire4v8 said:

How are you determining the afm output? can you show an engine running rovergauge screenshot? You should see the fuel map tracing when you rev the engine too. If the afm is disconnected it reverts to throttle angle and will run surprisingly well!

On rover guage, On the griff ecu it reads 0 on the bar graph reading and moves along the rpm axis onlty on the map, plug the range rover ecu and it reads on the bar graph and moves around the map as its supposed too. when i dyno it with this ecu its significantly richer.

weirdly, despite not reading any actual reading, when you unplug the maf the car does run richer.

i can;t do a screenshot at mo as range rover ecus in car at home and griff ecus is at APT

[blitzracing]

Id take a couple of steps backwards, and get the test meter out on the AFM connections-:

Red/Black Ground
Blue/Green Air flow signal- should be .2-.7 volts (no air flow).
Tick over on the 3.9 is about 1.7 volts
Brown/Orange +12v
Blue/Red CO trim value. This is factory set 1.8 volts for catalyst engines, although I believe this setting is ignored with Lambda correction. Non cat cars are in the range of 1-1.5 volts.

[Vixpy1]

blitzracing said:

Id take a couple of steps backwards, and get the test meter out on the AFM connections-:

Red/Black Ground
Blue/Green Air flow signal- should be .2-.7 volts (no air flow).
Tick over on the 3.9 is about 1.7 volts
Brown/Orange +12v
Blue/Red CO trim value. This is factory set 1.8 volts for catalyst engines, although I believe this setting is ignored with Lambda correction. Non cat cars are in the range of 1-1.5 volts.

We did that first, tick over was a perfect 1.67 volts, have ground and 12v

[blitzracing]

This information is contradictory- you have a Range Rover ECU that works OK, and the MAF readings are good, yet the TVR one has zero MAF reading, yet tests OK ? Not something daft like a corroded pin on the ECU that's open circuit on your connector, but is OK on a test bed connector?

[Vixpy1]

blitzracing said:

This information is contradictory- you have a Range Rover ECU that works OK, and the MAF readings are good, yet the TVR one has zero MAF reading, yet tests OK ? Not something daft like a corroded pin on the ECU that's open circuit on your connector, but is OK on a test bed connector?

Thats my confusion, i have asked company that has the ecu to look further into it

[Steve_D]

Sardonicus said:

blitzracing said:

Each sensor has its own ground wire, back to a common point on the ECU. No sensor uses the engine or chassis ground. From memory I think the temp sensor wire should show 5 volts open circuit, but this will drop when you plug the sensor in.

Should of made myself clear but the ECU grounds at the head Mark with multiples then the ECU supplies sensor grounds remotely from these

On my 97 Chim the ECU grounds go to a stud beside the timing cover above the oil filter. The Lambdas earth at the back of the cylinder head.

Steve

[Sardonicus]

Steve_D said:

Sardonicus said:

blitzracing said:

Each sensor has its own ground wire, back to a common point on the ECU. No sensor uses the engine or chassis ground. From memory I think the temp sensor wire should show 5 volts open circuit, but this will drop when you plug the sensor in.

Should of made myself clear but the ECU grounds at the head Mark with multiples then the ECU supplies sensor grounds remotely from these

On my 97 Chim the ECU grounds go to a stud beside the timing cover above the oil filter. The Lambdas earth at the back of the cylinder head.

Steve

Fair enough but all ECU grounds to the engine block seen that one secured with a 5/16 bolt IIRC

[blitzracing]

The point about the independent earth wires, is you don't want to use just the engine block as ground as you can end up with a small voltage difference between the block, and the ecu ground, so it skews the sensor reading. I suspect the lambda probes may well have more than one ground, as you are drawing a large current for the heaters, that would cause a voltage shift on the low voltage output if it was grounded by the screened cable that feeds back to the ECU, so better to additionally sink the heater current locally.

Edited by blitzracing on Thursday 29th March 11:04

[Vixpy1]

Still struggleing with this, had the ecu rebuilt, they said there was nothing wrong with it, i said do it anyway.

Its come back and its exactly the same, massivly lean on full throttle.

However i have linear reading on the maf, but not direct. I'm not sure how you can have one without the other.

However thinking about it it may have been like this before, i saw linear and direct on the range rover ecu but i'm not sure if i checked the linear on the tvr ecu, sure i did ..

I've done a log which i will upload shortly.

[Vixpy1]

Pulse width stays roughly the same on load, which does'nt seem right at all

https://www.dropbox.com/s/i86t5x2fzqjqovy/CharlieT...

Edited by Vixpy1 on Monday 16th April 11:24

[blitzracing]

The poor old ECU may well drop some sensor readings if you monitor everything at once. Turn off all the logging you dont need and leave just the vital stuff. In this case RPM, Throttle pot and AFM. All in direct mode. You should be able to see clear correlation with the AFM, TP and RPM all rising clearly together . I must admit I cant make much sense out of those readings as they are.

Just another thought- Ive seen some funnies with RoverGauge on very early ECU tune revisions, but this was on the MGR.

Edited by blitzracing on Monday 16th April 15:52

[TRIUMPHBULLET]

One thing you could try,see if the eprom on the Range Rover ecu is removable.
If so you can swap and see if the faults follow the ecu or the eprom.

EDIT
On second thoughts that might not be viable as the precat ecu is an early version I believe.
Eprom mapping is different to later versions.
Steve Sprint is handy with this type of thing if he still frequents the forum,he may be able to help.

Edited by TRIUMPHBULLET on Monday 16th April 18:27

[Vixpy1]

TRIUMPHBULLET said:

One thing you could try,see if the eprom on the Range Rover ecu is removable.
If so you can swap and see if the faults follow the ecu or the eprom.

EDIT
On second thoughts that might not be viable as the precat ecu is an early version I believe.
Eprom mapping is different to later versions.
Steve Sprint is handy with this type of thing if he still frequents the forum,he may be able to help.

Edited by TRIUMPHBULLET on Monday 16th April 18:27

The eprom are the only thing left now thats not been changed.