Rough running

Rough running

Author
Discussion

Paulprior

Original Poster:

864 posts

104 months

Thursday 23rd May 2019
quotequote all
i intermittently get a very rough running, it feels like i have lost at least half the cylinders, there is only enough power to maintain speed for 1 or 2 minutes, it then coughs for a while before returning to normal.
I would like to check the signal to the injector signals, my understanding is that both banks have a constant 12v and are switched on the negative via pins 11 and 13 on the ECU, if i used LEDs fixed in the dash area so i could monitor then what are your thoughts on how / where to connect, dirrect to the injectors, the switch signal at the ECU, just the negative at the injectors???
One other observation from someone following is that they claimed they could smell petrol during this misfire, could a permantly on be possible and would it flood one bank or semi flood both ???
Interested in any thoughts or experiances others may have had

paulathome

686 posts

217 months

Thursday 23rd May 2019
quotequote all
Hi I had this issue a few years ago it turned out to be an injector fault where it suddenly shorted to ground which opened all 4 injectors on the left bank.
I put a noid light on that bank and when the fault occured the light came on permanently.
It was so intermittant it took 4 years to find it and only when it failed completely. I realised when number 7 injector was unplugged the fault cleared. Put a new set of injectors in and all good.
Hope you find it.
Cheers paul

Steve_D

13,737 posts

257 months

Thursday 23rd May 2019
quotequote all
Yes they are negative switched by the ECU and in banks.
You could connect to the ECU and just give your LEDs an ignition +12 but this would not prove if the issue was on the positive supply to the injectors.

Random I know but I have seen an instance of the negative wire on the No. 2 injector wearing through and shorting onto the coil mounting bracket.
This would flood 4 cylinders and give your petrol smell witnessed from behind.

Steve

Paulprior

Original Poster:

864 posts

104 months

Thursday 23rd May 2019
quotequote all
Hi Steve
Do you see any problem with just connecting directly to the injectors?, I assume my led situation would be off before starting, high speed flash while running, off if I loose the supply or ground,
To monitor for your negative short scenario I guess connecting from injector negative to ground would light up full time if it happened and pulsing during normal operation?
Paul

Paulprior

Original Poster:

864 posts

104 months

Thursday 23rd May 2019
quotequote all
Paulathome
What is a noid lamp ?🤔
I have had this problem for 2 years now, it could happen once a run, or maybe every 3 months, very frustrating, that’s why I thought some lights in the cabin would give an easy and clear direction at least

paulathome

686 posts

217 months

Thursday 23rd May 2019
quotequote all
No problem connecting to the back of the injectors to see if you have the same trouble as mine.
Just be careful you don't end up bending a con rod if the cylinder fills with fuel maybe take the fuel pump relay out.
On mine when the fault occurred the noid light was on as soon as the ignition was turned on until I pulled each injector plug of the injectors
and when number 7 was removed the light went out.
Paul

paulathome

686 posts

217 months

Thursday 23rd May 2019
quotequote all
A noid lamp is basically a small bulb attached to a connector that mates with the injector connector. Basically does what you trying to achieve with your LED idea.
Paul.

blitzracing

6,387 posts

219 months

Thursday 23rd May 2019
quotequote all
Just look for kits on Ebay- they are not a lot.

Loubaruch

1,164 posts

197 months

Thursday 23rd May 2019
quotequote all
I had a similar problem ages ago and it turned out to be an intermittent connection on the large ECU plug/socket. One bank was not firing.

Plenty of Noid lights on sale, ebay etc.

Paulprior

Original Poster:

864 posts

104 months

Thursday 23rd May 2019
quotequote all
Hi
I looked at the noid lamps, as you say they dont cost much, but also not so easy to use for an intermittent fault that only lasts 1 or 2 minutes, i looked in the engine bay but couldnt see an easy way to connect a lamp, what i could really do with is a male to female adaptor to fit between the injector and its plug and make a connection there, has anyone seen such a thing?, if not then i will have to try at the ECU connector and see what it shows, i have had that all apart last year and checked and cleaned all the pins, but it looked good

Steve_D

13,737 posts

257 months

Friday 24th May 2019
quotequote all
The connectors used are called 'junior timer' connectors (no idea why).
Go here https://www.polevolt.co.uk/acatalog/Junior_Power_T... and buy male and female. With those you can make a link wire so the injector is still connected and link from that back to the car interior for you LED.

Steve

Paulprior

Original Poster:

864 posts

104 months

Friday 24th May 2019
quotequote all

Hi, could someone please confirm the pin arrangement on the ECU connector, reality is nothing like the schematic I have but I’m thinking that pin 1 is at bottom right and red, so pin 13 would be top right with a yellow and blue ??

Paulprior

Original Poster:

864 posts

104 months

Friday 24th May 2019
quotequote all

Paulprior

Original Poster:

864 posts

104 months

Friday 24th May 2019
quotequote all
Sorry but the phone changed the pic around, would pin 1 be the red on the right?

Steve_D

13,737 posts

257 months

Friday 24th May 2019
quotequote all
Sorry left my wiring folder at work. will look it out in the morning.

Steve

Steve_D

13,737 posts

257 months

Friday 24th May 2019
quotequote all
Does this help

connector's pins starts at 1 in the lower left-hand corner. The pin numbering continues to the right, and then boustrophedonically through the two other pin rows.
Pinout of the 40-pin ECU connector
Pin Color Name Description/Notes
1 red/green Air bypass valve 48-58 ohms to pin 26
2 brown/orange MAF and main relay Input (+12VDC)
3 yellow Throttle position sensor 5k ohm to pin 25
4 black Ground O2 sensor heater return
5 gray/black Tune resistor No wire in NAS vehicles
6 yellow (or yellow/pink) Speed transducer To main conn (0-12V six times per revolution)
7 green/blue Coolant temperature sensor To brown connector
8 purple/yellow Heated front screen Input from main connector
9 white/light green Diagnostic serial port Output to 5-pin TTS connector
10 black/yellow or red EFI warning light Output to main conenctor
11 yellow/white Even (right) bank injectors Output
12 blue/red Main relay Output to main relay coil
13 yellow/blue Odd (left) bank injectors Output
14 black Ground -
15 brown Ignition and main relay Input (+12VDC always applied)
16 blue/purple Fuel pump relay Output to fuel pump relay coil
17 gray/yellow Purge control valve Output
18 white/pink Diagnostic serial port Input from 5-pin TTS connector
19 white/gray or white/green Fuel pump and inertia switch Input (+12VDC when ignition on)
20 red Throttle potentiometer Swings 0.29 to 5.00 VDC
21 yellow/black to yellow/green Air conditioner compressor load Input
22 blue/red MAF sensor -
23 unk Left lambda sensor Blue shielded
24 unk Right lambda sensor Blue shielded
25 red/black Sensor ground Ground side of coolant, fuel, MAP, and TP sensors
26 green/white Air bypass valve 48-58 ohms to pin 1
27 black/gray Ground -
28 blue/gray Air bypass valve 48-58 ohms to pin 29
29 orange Air bypass valve 48-58 ohms to pin 28
30 pink Fault display data Output to main connector
31 black/green or black/yellow Diagnostic plug Input
32 gray/white Fuel temperature thermistor Input from gray connector
33 black/gray A/C compressor clutch relay (if fitted) -
34 orange/black Transmission neutral switch Input from main connector
35 blue/green MAF sensor 0.3 to 0.6 VDC with ignition on
36 black/green Condenser fan timer Tall green unit (AMR 3678)
37 (n/a) (no connection) -
38 brown/pink Fault display data Output to main connector
39 white/black or white/blue Engine speed Output to main connector; harness includes 6.8KΩ resistor
40 black Ground -


Paulprior

Original Poster:

864 posts

104 months

Friday 24th May 2019
quotequote all

Hi Steve
Thanks for the great info, but unfortunately it doesn’t seem to tie up with my 95 model, any idea from this pin picture what would be pin 1 ??

Steve_D

13,737 posts

257 months

Saturday 25th May 2019
quotequote all
Paulprior said:

Hi Steve
Thanks for the great info, but unfortunately it doesn’t seem to tie up with my 95 model, any idea from this pin picture what would be pin 1 ??
Pin 28 is by your 'pinky'
Next to it middle row is Pin 27
Next to that Pin1

Pin numbering goes along one side then back up the middle row then down the last row.

So your earlier pic where you thought the red was pin 1 is correct only it is probably red/green and pin 13 is yellow/blue


Steve

Edited by Steve_D on Saturday 25th May 09:48

Penelope Stopit

11,209 posts

108 months

Saturday 25th May 2019
quotequote all
You may be interested in this purpose built injector breakout cable, the 900MM cable can easily be extended to reach inside the car if needed


https://www.scantool-direct.co.uk/4mm-banana-break...

Paulprior

Original Poster:

864 posts

104 months

Saturday 25th May 2019
quotequote all
Thanks Steve, the pin identification is great, not what i expected though, i was thinking that next to 1 would be 14 and the 27 ?, but there is obviously some cable colouring variation on mine, maybe they ran out of the proper stuff that day
Penelope, great, that would certainly do the job, Steve D option would also do it.
Today i have been out for a lot of driving, 200 miles with friends, it first misfired for a very short time after 3 or 4 miles, then again maybe at 50 miles, again at maybe 100 miles, we then stopped for lunch, after this it was running very rough most of the time and eventually full time, it wouldnt even tick over any more, i pulled over and took the ECU out from being tucked behind the kick board and beside the battery to just laying on the floor, started driving for 15 minutes but still the same, stopped at another place for 15 minutes, started up and it revved ok but tickover was rough, asked my wife to give the cables / relays a little kick and started driving again, virtually straight away everything worked perfectly and drove home for another 1.5 hours with no issues at all.
I have tried moving the cables around while at tickover to see if i could hear any change, but nothing, so im now thinking about testing another ECU, my question is that there obviously some very expensive TVR 14 CUX around, or some much cheaper Land rover ones, are they all compatible as long as i swap my chip into it ??
I will show the existing one on the next reply as the photo is on my phone