Hi, I've recently done a major service on my 3.0L TF
Spark Plugs, Rocker Gaskets etc.

I installed ACDelco Platinum plugs all round.. these have a 1.1mm gap which i did not check as I've read that you can damage them by even checking the gap with a feeler gauge.

New plugs went in, car ran beautiful for about a month then I decided to have the LPG serviced by a mechanic.
LPG system was fine but he discovered my o2 sensor was stuffed.

I replaced the sensor with a universal sensor and noticed a massive increase in MPG.
The day the sensor was replaced I noticed a problem with the gas.

when taking off from a full stop as I accelerate the engine will hesitate for a second and make a sound that I think is a missing sound? it's a small (barely audible) putt that lasts for about .2 seconds as I accelerate.
This only happens when accelerating between 1 - 2k rpm, it doesn't happen when over taking etc.
Also the car runs fine on petrol..

I rang my mechanic and he said to replace the spark plug leads and adjust the gap of the spark plugs.

firstly I can't change the gap on platinum plugs can I ?
And why did this only start as soon as the faulty o2 sensor was repaced?

Any idea's would be helpful before I go out and buy ignition leads and new spark plugs with a smaller gap or destroy the ones I have trying to change the gap.

Cheers.

the gas computer may need readjusting.

Hi, I've recently done a major service on my 3.0L TF
Spark Plugs, Rocker Gaskets etc.

I installed ACDelco Platinum plugs all round.. these have a 1.1mm gap which i did not check as I've read that you can damage them by even checking the gap with a feeler gauge.

New plugs went in, car ran beautiful for about a month then I decided to have the LPG serviced by a mechanic.
LPG system was fine but he discovered my o2 sensor was stuffed.

I replaced the sensor with a universal sensor and noticed a massive increase in MPG.
The day the sensor was replaced I noticed a problem with the gas.

when taking off from a full stop as I accelerate the engine will hesitate for a second and make a sound that I think is a missing sound? it's a small (barely audible) putt that lasts for about .2 seconds as I accelerate.
This only happens when accelerating between 1 - 2k rpm, it doesn't happen when over taking etc.
Also the car runs fine on petrol..

I rang my mechanic and he said to replace the spark plug leads and adjust the gap of the spark plugs.

firstly I can't change the gap on platinum plugs can I ?
And why did this only start as soon as the faulty o2 sensor was repaced?

Any idea's would be helpful before I go out and buy ignition leads and new spark plugs with a smaller gap or destroy the ones I have trying to change the gap.

Cheers.
hi when was the last time you had the gas serviced as it sound like it might need to be done as if the o2 sensor was on it's way out when the gas got put in then it would need to be looked at since it runs fine on petrol

The universal O2 sensors are not ideal and I have had issues in the past with cars as well

Get yourself a proper sensor NOK is a good brand but one that is factory fitted

Also, do not expect the AC Delco platinums to last more than 40 thou k's as they are well known for not lasting

As for regap, this can be done easily. Try at 0.9

I would be looking to the 02 sensor first as the issue started then

How does it tun on petrol?,if fine i would rule out plugs or O2 sensor ,as they would do it on both usually if knackered,and you can close the gap of iridium type plugs if your carefull,just not open them in my experience,leads could be an isue as lpg places higher loads on these and the igntion sytem as it is harder to ignite,He may have broken one when pulling them out?,has the computer thrown a fault code?

but as stated in another thread,i have had another car do the same when it had a faulty o2 sensor,coughed and spluttered and then took off,took ages to find!,so could be worth another look,but as i said earlier,surely it would do the same on both fuels?,my case was petrol only vehicle

Steve

Thanks guys.
I set the gap on the front bank to .9mm and it's not missing anymore.

Obviously the o2 sensor has leaned out the LPG mixture enough that the plugs weren't producing enough spark?..
I'll see how it goes then do the back ones... fun !

Now I can buy a strut brace rather than leads and plugs!

Closing the gap may have made life easier for the plug wires. They could be on the way out. Look for grey powder in the dist cap and at the spark plug end of the wires. Powder at either end can indicate wires about to die.

The oxygen sensor only affects cruise fuel so if the problem was under load or when acceleration it wasn't the sensor causing the trouble.

Cheers, Alan

According to many spark plug manufacturers LPG is harder to burn, they pretty much all recommend decreasing the gap for when the car is running on LPG by .2 mm

I'll see how it goes before replacing the leads as

1. They're bloody expensive!
2. A pain in the but to replace.