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[Stal1878]

Hi there chaps, first post here so be gentle

Right. Last week I bought a 1996 Jeep Cherokee 4L. Its got an LPG conversion.
Everything was going fine until I ran it out of petrol and the "Check Engine" light illuminated. Now, this might sound like a silly thing to do, but it has an underslung LPG tank, so the petrol tank is small. The petrol gauge doesn't really work, so I thought if I run it out I'll know how much the tanks holds and will be able to roughly work out how far I can go on a tank of petrol.

Anyway, I did the thing with the key/ignition and get error codes 12, 27 and 55. I disconnected the battery to reset the codes and it worked fine for about 5 miles, then I changed onto LPG coasting downhill and the engine spluttered while it swapped to gas and the Check Engine like came on again....

I've checked the plugs on the injectors and had a quick look for loose wires ect, but I've never had a petrol vehicle before so its all a bit alien to me. Can anyone help me find out why the light is coming on and possibly how to fix it?

Also, how do I tell if I have OBD I or OBD II? I understand '96 was a changeover year for a few things? There is a plug under the drivers side dash, which I believe might help to find out. I'll take a picture of it for you lot.

Not having had/driven a Jeep before I can't comment on any lack of power, but it seems to go ok and doesn't seem to be missing. Idle is fine on petrol, a little rough on LPG, but only slightly so.

Thats for reading and sorry my first post had to be one about problems 

Cheers, Ben

[Stal1878]

Pictures of the plug under the dash:

[attachment=1]

[attachment=2]

[Mike Pavelin]

Code 27 is an injector driver fault. If you have a multipoint LPG system, and bearing in mind it's running rough on LPG, it could have a faulty emulator. Ans. yes, it's OBDII

[Panic mechanic!]

   replace the emulator !

[Stal1878]

I don't know what kind of LPG system it has, don't think its multipoint though. It has a big cylinder bolted on top of the throttle body, which I assume is single point and is a sort of LPG carb?

Cheers for replies

Oh, my lack of petrol knowledge continues to shine, whats an emulator? 

[Panic mechanic!]

its single point and the emulator is a black box ususally mounted on the bulkhead. if you find one of the injectors  and then trace the connector back to this black box thats the emulator ( they are about £30 to replace)

[Stal1878]

its single point and the emulator is a black box ususally mounted on the bulkhead. if you find one of the injectors  and then trace the connector back to this black box thats the emulator ( they are about £30 to replace)

Do you have any idea why switching to gas would cause the injectors/emulator to play up? I assume the injectors are idle when running on LPG.
I was thinking of getting this code scanner http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=300518356231&ssPageName=STRK:MEWAX:IT as apparently you can get more specific codes from the OBD than the flashing dash, is this going to make tracing the code 27 any easier?

Cheers

[Panic mechanic!]

the emulator turns off the injectors so they are idle when running on gas but it also fools the engine management into believing they are firing normally,once they start playing up the first sign is that the engine check light comes on as the engine management gets  doesn't recieve the right signal

you could get one of those but you won't get a lot more useful information unless you understand what is being shown to you by it.

http://cgi.ebay.co.uk/petrol-injector-emulator-lpg-conversion-6-cylinders-/230550436125?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item35ade0791d#ht_2063wt_1040

thats what an emulator looks like off the vehicle.

[Stal1878]

I've got a "Duel Curve" system on mine, with emulator(Dodge Injector Simulator PN 4114). Made in El Paso, Texas so doesn't look good for getting a replacement over here 

Pretty sure this is the one I have, although didn't get the code of the ECU(its the only one that uses emulator 4114).

http://www.dualcurve.com/59362.htm

[Panic mechanic!]

you need to find the smaller of the two boxes that it shows in the instructions (injection simulator) and check all the connectors ad connections between the two.

[Stal1878]

you need to find the smaller of the two boxes that it shows in the instructions (injection simulator) and check all the connectors ad connections between the two.

Its bolted on the firewall. I'll have a look at the wiring when it stops raining 
They seem to be going all other the place so might take a while to trace them all 
Is there anyway I can check/test to make sure its the emulator before I buy another one(and most likely destroy the system trying to fit it)?
"sigh" I hate electrics....

Cheers for your help bud 

[Panic mechanic!]

Ill be honest with you and say I am not sure with your system as altho basically the same in operation as all systems it is not a common setup over here.
 I would check that you are getting 12v supplies where you should be on the  injector simulator and that all the grounds are good thats where most electrical probs lie.
Where are you by the way?

[Stal1878]

Ill be honest with you and say I am not sure with your system as altho basically the same in operation as all systems it is not a common setup over here.
 I would check that you are getting 12v supplies where you should be on the  injector simulator and that all the grounds are good thats where most electrical probs lie.
Where are you by the way?

Near Bridgwater, Somerset.

Its odd how the Jeep has a US made conversion on? I thought there where plenty of systems made over here?

[Panic mechanic!]

I would not say its odd I would just think that its likely to have been originally owned by a US serving military person and brought in over here . it is a very rare system to see over here and the systems we generally use a lot simpler to repair and replace if you know what you are doing as the rend to be modular as it were.
They all work the same tho and to be honest yours is a lot harder to work on as its soldered into the original vehicle loom which makes it less prone to problems unless its been not been soldered.

[Stal1878]

I'd say it was a decent conversion. Having not at a Jeep before, I cannot tell where the original wiring ends and the LPG stuff starts, its all in the same loom, no connectors ect ect