Thread: running like garbage

Maybe it was set up for gas? Just a thought. Probably going to be a case of elimination. Replace all the normal stuff so that you know they are good (leads, plugs etc) and work from there. My RRC on duel fuel runs better on petrol than gas (not cheaper though).soon I will get it re-tuned just for gas I think as I have proven it can go where I want it to on a single tank.

Put some gas into it, you need one of these:

LPG Filler GUN Hose Automotive Comes With Acme 1 3 4" Adpter | eBay

Your mass air flow meter (MAF) may be damaged by a backfire, take the air cleaner assembly off and poke the flap and see if it jams up.

Are pulling out the injector or just unplugging it. From memory the cold start injector has a habit of leaking and making the engine too rich. Just leave it unplugged. The motor should still start ok with out it.

Originally Posted by amtravic1

Are pulling out the injector or just unplugging it. From memory the cold start injector has a habit of leaking and making the engine too rich. Just leave it unplugged. The motor should still start ok with out it.

yeah, im taking it out. but if i cover the hole with my finger it almost stalls.. i have checked the flap in the intake and that seems to be in order.

First thing's first, grab a copy of the RAVE manual, it's invaluable

Ignition
* First thing I'd be doing has already been suggested, new plugs, new leads.
* Is the distributor installed correctly?
* Have you set the static timing? I think it's 6deg adv with no.1 at TDC. LPG requires more advance, so this may have been altered.
* Is the original amplifier still installed to the side of the dizzy? or has the BOSCH conversion been done? (I highly recommend the BOSCH conversion with the external amplifier)
* Use your DMM to check the ignition coil, if you don't know how to test, either search the forums, check with the RAVE or just try a substitute coil
* You can use a timing light to check that spark is going to each plug, just put it on each ignition lead one by one and you should have a constant steady flash from each lead. If not, it could be missing or other problems. New plugs and leads should cure this, but if it persists, you could have a bad earth connection, dodgy distributor, or it could be as simple as ignition timing or pickup coil-stator air gap.

Injection
* Disconnect the cold start injector at the plenum and clamp off the fuel hose to remove the CS injector from the equation.
* If you can get the engine running, disconnect each injector from the harness one by one, you should hear a difference in how the engine is running, if you don't hear a difference at all, I'd say you have leaking/faulty injectors
* There's two sensors (well one sensor, one switch) in the front-passenger side of the intake manifold. The rear-most is the CTS (Coolant Temp Sensor) for the ECU, the front-most is the cold start injector switch. Disconnect it.

* You'll need to check the performance of the CTS with a good digital multimeter. This is the sensor that tells the ECU if the engine is cold, therefor richens the mixture. If the sensor is faulty, it's going to make the whole thing run like a dog. They're cheap to replace, so you might want to put a new one in, just to eliminate it from the equation, and for piece of mind.

* Disconnect the multi-plug from the air flow meter. It'll run without this connected, but you'll have no power to move the rig. This will tell you if the AFM is causing the problem. Check the black plastic lid, if there's silicone around it, someone's opened it and tampered with the settings. If you can get it running okay, while it's running, reconnect the AFM multi-plug, does the engine run any better or worse?
** There's also a few tests you can run on the AFM with a DMM, they can help tell if your AFM is buggered.

* You can also substitute the CTS with a resistor, can't remember which value to use, but you basically install it across the terminals in the harness connector and it tricks the ECU into thinking the engine is already at operating temp. Leaning the mixture.

* Check for a good connection between the ECU and the coil, the ECU needs to know the engine RPM, it establishes this by a pulse taken from the negative side of the ignition coil.

* Inspect the whole injection harness. I bought my 87 classic after the engine caught fire, thanks to a VERY dodgy LPG conversion, they'd spliced into the ecu harness and left all sorts of shonky soldering and other messes exposed, in the end I had to replace the harness, it was thrown in the too-hard basket.

Intake
* What condition is the air filter in? you can temporarily run without it to diagnose the engine, but you really should just make sure there's a clean one in there, getting debris in your engine can make turn a small job into a big one.

* Check the idle setting on the throttle body, it could be closed right off, mine was for some reason.

Fuel
* If you remove the vacuum hose from the fuel pressure regulator and there's fuel in there, you need a new FPR. This would cause rich running

I'm sure I'll come up with more suggestions, I'll add to this when I think of them.

checked plugs and leads thismorning, they both seem fine. the plugs are a little sooty but its running rich so i assume this is why.

the dizzy looks to be in order, cap is on the average side and the button is fine.

checked spark and its fine.

havent touched the static timing, it seems to run ok on gas so i suppose that its been advanvanced to suit.

have tried running with and without air filter and no difference.

had a look at the air flow sensor thismorning and it has the silicon job around the top. thought this looked dodgy so i unplugged it and tried to start it, it spluttered and tried to start but didnt get running.

thats all ive done thus far, i am downloading the rave manual and see what i can figure out.... it does run on gas but on petrol has always been guttless and thirsty. so maybe the whole thing is set up to run gas? never worked on a gas car before, is there much difference?

I'll see if I can find out what value resistor I used when troubleshooting my CTS.

If disconnecting the AFM made no difference to running on petrol then either the AFM is buggered, or it's been thrown wayyyy out of whack. The AFM measures the air flow, air temp etc and this is taken into account by the ECU to determine the injector opening time. You can lean or enrichen the mixture by adjusting the gear and spring inside the AFM.

Before you play with those goodie bits tho, check the FPR (between the firewall and the inlet manifold at the back of the engine.

Theoretically, the ECU (which controls petrol and injection) should have no effect on the running on LPG. BUT, I'm guessing that you've got an LPG "Mixer" between the throttle body and the AFM, all this does is inject gas into the air in the plenum so it gets sucked in, pre-mixed through the valves. The thing is, this sort of gas system will take signals from the ECU to adjust the LPG mixture. LPG needs to be richer than petrol, so the whole system gets modified to run both (basically the ECU is tricked into running rich).

Unless you have LPG injection, you'll never get LPG to run perfectly, while also having Petrol run perfectly. It's one or the other with a mixer, you can't have both. You can however get middle-of-the-road for both. Basically, if LPG needs to be rich, the injection system needs to be enriched. So you've got a truck that runs great on LPG, but drinks petrol like it's going out of style. Leaning the mixture off, or taking it back to factory settings, or getting it to run properly on petrol, may make it undriveable on LPG. You should be able to start it on petrol (which will run like a dog) but flicking to LPG should make it perfect.

Now I'm very biased against LPG mixers and prefer LPG injection, so you won't like my opinion. But I'd be ripping the entire LPG system out, fixing the wiring harness if you can, and reverting everything to factory settings so you can get it to start, run, drive and rock crawl on petrol.

But if you want to retain the LPG system and have it re-certified so you can get it rego'd, you're going to have to deal with atrocious petrol mileage.

I ripped the LPG system out of my 87 classic (3.5 EFI), reverted to petrol, rebuilt the engine and haven't looked back.

Having said all that, I'd still be checking the FPR, the CTS and eliminating the CSI.

whats your average L/100 just running straight petrol. and it runs fine on gas just not on petrol...