Hi everyone, recently I owned a 1999 UZJ 100 4.7 V8 with dual petrol / LPG fueling, with about 280,000 km . On occasion of my first general service, I’ve noticed the presence and persistence of an abundant smoke from the exhaust accompanied by the typical smell of unburned petrol, which appears when starting cold, especially at idling speed. In fact, while with hot engine the smoke tends to disappear, especially by increasing the number of RPM, unfortunately the smell of unburned petrol persists. In an attempt to solve the problem, I list what it has been done: the diagnosis with the Toyota Techstream scanner and other non-Toyota devices did not read any DTCs in the ECU. Anyway the following parts have been replaced, unfortunately without any benefit: spark plugs, air filter, air flow meter, throttle body cleaning, fuel filter, vapor canister, PCV, fuel pressure regulator, fuel pressure damper, fuel cap, vapor recirculation pipes. It should be noted that during LPG working, neither the smoke from the exhaust nor the smell of unburned fuel occurs, in this case obviously the LPG. At the end of all, I'd want to ask you if there is anyone who can help me about this problem. Thanks a lot all for attention.
exhaust smoke (1 Viewer)
- Thread starter 64fabius
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Hmmmmmm......
56 views and no answer
mechanical problem difficult to diagnose or what ?
Giacomo
56 views and no answer
mechanical problem difficult to diagnose or what ?
Giacomo
atnolan94
I'm Your Huckleberry
It’s difficult because I’d bet only a couple people here have any experience with LPG. That could totally throw off any opinion I have as to what this is.
just based on what you said it seems like condensation as opposed to smoke, and if it goes away with temp it’s likely nothing to worry about. If it is smoke that’s different, but this video appears to be condensation.
just based on what you said it seems like condensation as opposed to smoke, and if it goes away with temp it’s likely nothing to worry about. If it is smoke that’s different, but this video appears to be condensation.
CloudCity
LuxCruisers
Is it suddenly colder where you are? I noticed this last winter with mine as the temps dropped, I thought the rig was smoking and I could smell the exhaust more, but it went away as it got warmer again. I then noticed more posts pop up every year about smoke in the exhaust when winter hits, so that tells me it is condensation for most of us and we notice because it's different. I can't say for sure but these may push more fuel through on a cold start, which could account for the smell, tho I can;t say for sure that's what youre smelling and it would be best to find out for sure if anyone else has better advice.
CloudCity
LuxCruisers
This is from the 80-series section, so different engines, but some of the general advice seems to apply across the board.
LPG isn't common at all here so I can't speculate there, but the cold cats scenario could apply.
LPG isn't common at all here so I can't speculate there, but the cold cats scenario could apply.
Hi CloudCity,
"Is it suddenly colder where you are? "
10°C in Rome
Giacomo
"Is it suddenly colder where you are? "
10°C in Rome
Giacomo
If you are running LPG the first thing you need to do is a compression test and go from there.. They typically lose compression over time due to Valve/Valve seat problems...
It will not smell of unburnt petrol if running on LPG. I am not saying low compression is your issue, just that it is a known issue and you could be chasing your tail if you ignore carrying out this test..
Carry out a compression test and post results.
Also take a picture of the techstream screen showing fuel trims and O2 sensor readings, in graph form preferably for the O2’s..
Also take a picture of the techstream screen showing fuel trims and O2 sensor readings, in graph form preferably for the O2’s..
CloudCity
LuxCruisers
Great advice above, also clean the MAF with proper cleaner, just to remove it as a possibility.
I’m thinking that the two issues are separate.
I believe most of us are familiar with the smoke when it’s cold and cold outside which I wouldn’t categorize as unusual.
not gonna lie, I had to familiarize myself with LPG as it is not as common in the good ole us of a. My understanding is that it burns cleaner and has less odor under any circumstance than gas. My guess is you may have a small overflow at some level (check all the connections with the fuel filter). In that area in the engine a very small leak or even fumes would be detectable inside or outside the vehicle.
hope you resolve soon.
I believe most of us are familiar with the smoke when it’s cold and cold outside which I wouldn’t categorize as unusual.
not gonna lie, I had to familiarize myself with LPG as it is not as common in the good ole us of a. My understanding is that it burns cleaner and has less odor under any circumstance than gas. My guess is you may have a small overflow at some level (check all the connections with the fuel filter). In that area in the engine a very small leak or even fumes would be detectable inside or outside the vehicle.
hope you resolve soon.
- Thread starter
- #16
@Cloucity
I've just replaced the MAF without any improvement.
@fjcruising
I've checked all the connections in the engine compartment but neither leaks nor fumes were detectable.
I've just replaced the MAF without any improvement.
@fjcruising
I've checked all the connections in the engine compartment but neither leaks nor fumes were detectable.
You could just take it and get the exhaust gases checked, most garages in the UK have a 5 gas analyser for carrying out MOT’s, I presume Italy is the same.. If it passes, runs without fault and doesn’t have any stored fault codes then just ignore. If it fails then post the results along with the above.
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@giacomo
i run on lpg and now its cold here (well below 10c) i notice a smell of petrol and smoke does appear although i think its more condensation.However once on lpg less than 3minutes its all ok ,so i think do your compressions and monitor .i burn very little oil so i think its probably normal as ive just had my lpg sustem upgraded. and mot ok ( uk goverment yearly test for those of you accross the pond)
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