Getting through the emissions test

michaelc291

New member
The time has come again for the annual test on my 1994 XJ. Last year it just squeaked through by 0.1%. This year I feel that it might not make it at all.

Can anyone suggest ways that will cut the emissions. I have tried all sorts with little success, so ANY SUGGESTIONS will be welcome.

Just one thing. The car runs on LPG (autogas, GPL, propane) whichever you like to call it. It starts on petrol (gas, which is very confusing for some) then changes to LPG automatically, so most of the time it's running on LPG and the engine insides will be very clean as there is no carbon.
It runs on top quality synthetic oil which I change infrequently, since it never gets dirty.

Thanks in advance.
 

I don't have any tips for you. I've seen the "guaranteed to pass" additives, however I would have to be pretty desperate to use that.

Did you do the LPG conversion yourself, or is it a kit that you bought? Sounds pretty cool.
Could you run on just Gas / petrol if you wanted to go on a long trip?
 
in california, back when i was on the bmw forums, guys would run 90% rubbing alcohol mixed into their gas tank with premium fuel to get their cars to pass when they had trouble.
 

I don't have any tips for you. I've seen the "guaranteed to pass" additives, however I would have to be pretty desperate to use that.

Did you do the LPG conversion yourself, or is it a kit that you bought? Sounds pretty cool.
Could you run on just Gas / petrol if you wanted to go on a long trip?

Many thanks for the reply. Yes, I did the conversion myself. It has two 60lit tanks in the back and is a system made by Tartarini, it's a Tech 97. Tartarini are one of the biggest manufacturers of LPG equipment around and many other manufacturers are Italy based.

The system is not multi point injection as most are these days, but relies on a mixer on top of the throttle body.
The engine always starts on petrol the switches over to LPG at 1800RPM. In winter I always warm up the engine before changing over otherwise it may freeze up. The vapouriser is connected into the heater pipework as the liquid gas freezes as it changes to vapour.

I bought all the parts from a UK company called Autogas2000 who I had used many times before, they offer good backup if needed. I have had virtually no bother with the conversion and all the original parts are still working.

If I were to do another I would use a multi point system because it is that bit more efficient. It just needs a little nipple putting into the inlet manifold as close to the head as possible. The gas is then metered in just like the existing Jeep system.

I get about the same MPG as on petrol but the advantage of LPG is that it's half the price!!! I get 600km (380mi) per fill so it makes the old Jeep quite economical to run. Don't forget our fuels are a lot dearer in Europe (I now live in Spain) than the US.

I would still welcome all ideas to get the emissions down. Would it help to change the plugs? I have changed the air filter.
Cheers and thanks...........Mike
 
Rubbing alcohol threw me a bit because of the different terminology on this side of the pond. We call it surgical spirit or Isopropyl Alcohol. Google says it's used for cleaning but I have never come across it being used as a cleaner in the UK.
I have now got to try to find a supply of it here in Spain which may not be easy. A lot of things are hard to get in Spain. I really don't need to be going to a pharmacy and buying it in little bottles.:lol:

There is a lot of truth in the saying that the UK and America are two nations divided by a common language.
 

I forgot to ask. How much rubbing alcohol do you add to a gallon of petrol? (gas)
 
let me try and find the posts. i think they put a gallon in the e30 bmw tanks, which are around 12 gallon tanks, but let me google and find the posts to verify
 

ok, it looks like its one gallon of alcohol or ethanol and 3 gallons of regular fuel, not premium.

some guys said their vehicle failed, but when they did the 90% isopropyl alcohol and went back later, and passed so well, the inspection place thought they brought a different truck.

i just googled "isopropyl alcohol to pass emissions" and every type of car forum has people who have done it to pass.
 
Many thanks for the info. I have found out where I can get it here in Spain. It seems supermarkets are the places to look. Its called alcohol isopropilico. So I'm off out this morning to get a gallon.
The test is not due for 3 weeks so I'll add it to the tank a few days before the test. I have a little emissions tester so I'll do my own before and after checks.
I don't keep much petrol (gas) in the tank as it's only used for starting, maybe a quarter tank, so a gallon should be plenty.
 

Big things are usually the basics.
The correct sparkplugs. Clean air filter. Free flowing good exhaust .
Clean gas.

If you are burning oil. Where? Leak by in cylinders? You coukd try cleaning them with additives or using atf for a day or two before changing oil.
Add a catch can between crank case vent and intake. Catching the oil rather than burning it.


Never look down on anyone unless you are helping them up - Jesse Jackson
 

If you're in CA, you can get it to pass "even if you don't pass." If you don't pass, immediately start tracking how much money you're paying in repair work to get it to pass. There's a maximum amount that you need to pay where you no longer need to pay any more and the CA DMV will "exempt" you. So, if you're in CA, check out the DMV's Website and you can get the details.
 

Lives in Spain


Never look down on anyone unless you are helping them up - Jesse Jackson
 
Lives in Spain


Never look down on anyone unless you are helping them up - Jesse Jackson



Thanks everyone for all the suggestions. The alcohol is going into the tank today and I'll go for a run to see if there is any difference.
I have done a test with my gas tester and will do another when the alcohol has had a chance to get round the system. It won't be as accurate as the test station one, but will do as a guide.
The test is booked for later in the week. I'll be sure to update you. Mike
 
Here is my latest update. IT FAILED THE TEST.

Lots of thoughts as to why. Did I not put enough Alcohol in the tank, has something else gone wrong?
The result was quite a bit worse than last year.

Here are the figures. Pass figure is 0.3% CO. Last year's result 0.29% CO. This year's result 0.73% CO so this is a huge increase and I have no idea why. It makes me think that something else is causing the problem.

As usual I am open to all suggestions why it's gone so high and how can I reduce it to pass the test. What could I change? There is nothing wrong with the engine as such, no knocks, rattles, excessive blow by, the oil pressure is good, no leaks.
I have 60 days to get it fixed and taken for a re-test.
Thanks All.
 

Get an ODB2 tester that you could check injector timing and O2 sensors.
Running rich from a stuck injector or bad O2 sensor.
How many CATs are on your system? Are they OEM or not? You might check if they are still present. I mean the media inside. Bad CAT will not convert the NOx to N2 water and CO2.





Then is your EGR valve and system working correctly.


Never look down on anyone unless you are helping them up - Jesse Jackson
 
You are following my thought process. As far as I know the Lambda (O2) sensor has never been changed. There is only one, in the exhaust downpipe. I was already considering changing it as that seems to be the most likely culprit. I hope I can get one locally, but Spain is not very good in the spares kind of thing. It's all rather third world. I'll try and do a test on it to see what voltages I am getting. I have been reading up on the net what all the wires are doing.
There is one cat installed which is probably original. It rattles like hell and has done since we bought it years ago. The testers, both in UK and Spain, don't seem to be bothered about that.

I do have what looks an O2 sensor in the front end of the cat, but it's NOT an oxygen sensor, it's a temperature sensor. Nobody has yet been able to tell me why it's there or what it does. The stainless cable runs up to a little box behind the instrument cluster and some wires then go on to heavens knows where. It obviously is set to switch something at a preset temperature, but again, I know not what.
This Jeep was originally exported to Japan from the US and then later imported into the UK. I bought it at a quayside auction in Southampton as it came off the ship. We bought a second, slightly newer one 18 months later. His and hers. I converted both to LPG. Both the UK and Japan drive on the left so both cars are RHD.

The car does not have an OBD connection but I have the older flashing light system where you count the flashes of the 'Check Engine' light to get the code, that's on the agenda for tomorrow. Hopefully it may give a code.
New plugs have been gapped and are ready to go in. 35 thou or 0.9mm.
Watch this space. Mike










Get an ODB2 tester that you could check injector timing and O2 sensors.
Running rich from a stuck injector or bad O2 sensor.
How many CATs are on your system? Are they OEM or not? You might check if they are still present. I mean the media inside. Bad CAT will not convert the NOx to N2 water and CO2.





Then is your EGR valve and system working correctly.


Never look down on anyone unless you are helping them up - Jesse Jackson
 

Verify sensors before changing. Jeeps are notoriously sensitive to non OEM sensors. Random changing without verification can introduce another issue and its difficult to solve 2 issues esp when you think you ?fixed? one with a new part.
If the CAT rattles the media
May have broken down and is no longer doing its job. You might want to verify the media is intact. If not consider replacing.

There are usually twor o2 sensors one pre cat reading how rich and how rich or what O2 is not used. The second measure the effectiveness of the CAT

Fast switching up front and slow switching outback. If they are both fast you dont have a cat.



Never look down on anyone unless you are helping them up - Jesse Jackson
 
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