[SimonB]

Hi there, as the title says, my 95RRC is running rich and I fear i'm reaching the point where 's going to cost me money to put it right and I wanted to get a few pointers first.

On start-up when cold (I'm in the UAE so it's always at least 20 degrees C) it spits unburnt petrol out of the exhaust. Once it's warm I guess the hot exhaust burns most of the fuel but there's still a strong fuel smell. There's also a slight erratic idle (+/- 100 revs) but it doesn't stall and it's not really an issue

To try and sort it out I got out the multimeter and i've ended up re-wiring quite a lot of the engine loom and the MAF, Fuel and Coolant Temp sensors and Throttle Position sensor are all now giving the correct readings. The car is Middle East spec and has no Cats or O2 sensors and has the yellow 'saudi' tune resistor. It's a non serpentine 4.2 if that makes any difference.

From reading other posts on the forum the next things I was going to look into are:

1. Distributor advance - if this is stuck in the advance position would that cause the problem??
2. Injectors - Is it worth getting these serviced? Would a leak cause a noticeable problem
3. Fuel pressure regulator - Is this likely to fail and what are the symptoms??

I'd really appreciate some feedback if i'm barking up the right or wrong tree with the above and also, anything else that would be worth checking. Thanks in advance for any guidance,
Cheers

Simon

 

[p76rangie]

what voltage are your various wires on your maf unit giving out. the first wire should be a red/black wire, this is a earth. Using the red/black as a earth, what are the the voltages off the other 3 wires with only the ignition on and the motor not running and also with the motor at idle.

 

[SimonB]

Hi Ian,
Just checked and i get the following readings using the Red/Black wire as the earth:

Ignition On - Engine Off: Green/Blue - 311mV
Orange/Brown - 12.50V
Red/Blue - 1.107V

Ignition On - Engine On: Green/Blue - 1.474V
Orange/Brown - 13.52V
Red/Blue - 1.107V

The Engine was hot when I took the measurements and the air temperature's about 30 degrees C

 

[adam1977]

Hi there, as the title says, my 95RRC is running rich and I fear i'm reaching the point where 's going to cost me money to put it right and I wanted to get a few pointers first.

On start-up when cold (I'm in the UAE so it's always at least 20 degrees C) it spits unburnt petrol out of the exhaust. Once it's warm I guess the hot exhaust burns most of the fuel but there's still a strong fuel smell. There's also a slight erratic idle (+/- 100 revs) but it doesn't stall and it's not really an issue

To try and sort it out I got out the multimeter and i've ended up re-wiring quite a lot of the engine loom and the MAF, Fuel and Coolant Temp sensors and Throttle Position sensor are all now giving the correct readings. The car is Middle East spec and has no Cats or O2 sensors and has the yellow 'saudi' tune resistor. It's a non serpentine 4.2 if that makes any difference.

From reading other posts on the forum the next things I was going to look into are:

1. Distributor advance - if this is stuck in the advance position would that cause the problem??
2. Injectors - Is it worth getting these serviced? Would a leak cause a noticeable problem
3. Fuel pressure regulator - Is this likely to fail and what are the symptoms??

I'd really appreciate some feedback if i'm barking up the right or wrong tree with the above and also, anything else that would be worth checking. Thanks in advance for any guidance,
Cheers

Simon

Hi Simon,

Speaking from experience with leaky injectors, I would say they are to blame, a new set cured the problems with my old rangie :thumb:

 

[p76rangie]

Hi Ian,
Just checked and i get the following readings using the Red/Black wire as the earth:

Ignition On - Engine Off: Green/Blue - 311mV
Orange/Brown - 12.50V
Red/Blue - 1.107V

Ignition On - Engine On: Green/Blue - 1.474V
Orange/Brown - 13.52V
Red/Blue - 1.107V

The Engine was hot when I took the measurements and the air temperature's about 30 degrees C

It appears that your MAF is working correctly and giving the right readings.

If it was a leaky injector, you should notice that one sparkplug is blacker than the rest. So it may be worth pulling the plugs and having a look.

If they are all about the same colour, you might want to lean the MAF off a bit. Near the top on the engine side of the MAF you will find a round protruding part in the casting about 10 to 15mm round. The end of it should have a plug/seal. The plug/seal would be level with the end of the casting. If it is still there you can carefully remove it. Underneath you will find a black ring that basically fills the inside of the hole.It will have a grove in opposite sides like for a large screw driver. Turning that ring anti-clockwise will make the car run leaner, clockwise for richer. I would only turn it a 1/4 of a turn at a time and check what it runs like. The voltage on the red/blue wire will change as you adjust it. The lower the voltage the leaner the car will run. However, the voltage is suppose to be between 1 and 1.5 volts, so you are already in that range. I have an accurate wideband air/fuel gauge and I have found that I have to run mine below 1 volt to get the mixtures right. I certainly would not set yours below 0.5 volt. But as I have said, going below 1 volts is outside manufacturers specs and you do it at your own risk.

 

[benji]

Yes, next thing to look at would be the injectors.
MAF sensor is working correctly, apparently land rover spec. is ~1.5 volts, though it's not uncommon to have to drop this down to around 1 volt (with the co. screw on the side) to achieve emissions tests.
To test the fuel regulator you could disconnect the vacum line (plug the plenum) and see if it smells leaner, in your case you wont run the engine dangerously lean.
Have you measured the resistance of the tune resister? If it's gone open circut the ecu goes into catalyst mode and ignores (for the most part) the MAF outputs, and the computer may be trying to 'hunt' the mixture up and down to get a reading from the oxy sensors.
Is your exhaust system in good nick, i.e, not blocked.
www.g33.co.uk has some awesome info on the 14cux. Sorry can't think of anything else.

 

[SimonB]

Thanks a lot for everyone's advice, i've tried adjusting the CO screw down but it doesn't seem to make a lot of difference. I've rechecked all the inputs into the ECU including the tune resistor and they're all OK so I'm pretty sure you guys are correct and it's either injectors or fuel pressure regulator.

I'm loathe to fork out for new set of injectors, can anyone advise if servicing injectors is worthwhile?? I've found a place in the UK that will do them for a reasonable price including changing all seals, baskets and checking the spray pattern.

Benji, you mentioned disconnecting the vacuum hose to the pressure regulator, what does that actually do? I want to make sure I understand properly before I start playing around. I'm assuming that it somehow reduces the fuel pressure??? What are the potential risks in running an engine on too lean a mixture?

Cheers, Simon

 

[p76rangie]

I'm loathe to fork out for new set of injectors, can anyone advise if servicing injectors is worthwhile?? I've found a place in the UK that will do them for a reasonable price including changing all seals, baskets and checking the spray pattern.

These injectors have the same flow rate as the Lucas ones and a better spray pattern. I have swapped to them as they are better and cheaper than getting the originals cleaned.
http://cgi.ebay.com.au/HOLDEN-V8-INJECT ... _500wt_956

 

[benji]

The pressure regulator keeps the fuel pressure at a set psi above the inlet plenum chamber. Thus if the vacum pipe for the regulator is disconnected the fuel pressure should drop. This is how I ruled out the reg. when diagnosing my car. I disconnected the vacum pipe. upped the rev's to 2000, and 'smelt' the exhaust (not that this is a good thing.....) and it was still just as rich. Any mechanic should have a fuel pressure guage. normal fuel pressure at idle I believe is 37 psi.

 

[p76rangie]

The pressure regulator keeps the fuel pressure at a set psi above the inlet plenum chamber. Thus if the vacum pipe for the regulator is disconnected the fuel pressure should drop. This is how I ruled out the reg. when diagnosing my car. I disconnected the vacum pipe. upped the rev's to 2000, and 'smelt' the exhaust (not that this is a good thing.....) and it was still just as rich. Any mechanic should have a fuel pressure guage. normal fuel pressure at idle I believe is 37 psi.

The fuel reg looks to the engine vacuum to tell it what pressure to use. At idle an cruise (high vacuum) it uses a lower fuel pressure. When under power (low vacuum) the fuel pressure is increased. So at idle it should be around 29 psi with the vacuum connected and 36 psi with it disconnected.

 

[nails]

So at idle it should be around 29 psi with the vacuum connected and 36 psi with it disconnected.

How do you measure pressure downstream of the regulator?

 

[SimonB]

Thanks for all the help. I tried disconnecting the fuel pressure regulator vacuum hose and in doing so found it was leaking. I fixed it and though it didn't cure the rich running it did sort out the erratic idle which was good.

Ian, I think I'm going to go with the replacement holden injectors you recommended from Melb Carbs as it's such a good price. Do they just fit in with no modifications - the existing harness plugs will hook straight up to them??
Cheers
Simon