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Hello, i am new to this forum, however i have tried googling, reading forums and even going to a local mechanic and can not find an answer to my problem. This post is going to be fairly long but i want to give you as much information as i can. First of all i live in Europe, so some prices may be different. I have a 7th gen 1.4l Honda Civic with LPG fuel system (gasoline is expensive where i live). Since i have LPG the check engine light is always on so i don't worry about it too much. The CEL has something to do with LPG, becasue the computer gets confused after getting wrong info from emission sensors. However it is a standart practice in my country to drive around with the check engine light if you have LPG. It even passes technical inspection because there isn't much you can do about it (if you erase the code it comes back after a while). If i drive on gasoline the CEL goes out. The LPG does not give me any issues, however i started having some troubles this summer. I was driving with my friend and all of a sudden my car went into limp mode and the CEL started falshing. I drove to the local repair shop and they replaced my spark plugs, which fixed the prooblem. About 6 months later (just before Christmas) my car started acting up a little bit: rpms dropping and jumping back up when idling, "stuttering" while driving, getting "dead spots" in the rev range (while accelerating the engine would loose some power at around 5k rpm). Since my local repair shop charged me 50 euros for spark plug replacemennt i just assumed that they put in garbage plugs. On the receipt it said that the plugs cost only 20 euro. And that's for 4 spark plugs! So obviously i thought that the trashy spark plugs went bad and replaced them with some better ones, which would work well with LPG. But after changing my spark plugs i went on a drive and my car just stalled in 4th gear while doing 50km/h. This was very unusual. I stopped on the side of the road and tried starting my car up again, but it would run for a couple of seconds then the rpm would drop to 0 and the car would stall. With some help i towed the car to my local mechanic and they suspected that it was a faulty camshaft sensor. They also got a faulty camshaft sensor code. After replacing the faulty cam sensor i drove for about 700 kilometers and my car stalled again! I went to the same repair shop, they had a look at my car, scanned the codes (there were none) and told me that it runs perfectly fine. And it does on a cold engine, but the more you drive it the worse the stalling gets. If you drive at a constant speed it will sometimes stutter, the rpm will drop but then go back up again. I asked some people on facebook honda group what could be causing the problem. One guy said to cleam my IAC valve and i believe intake manifold (butterfly valve). I did clean the butterfly valve but it didn't change a thing. I could not unscrew the IAC valve from the intake manifold so i did not clean that part. Some people said that my valves need adjusting. There is some rattle, however i doubt that it could cause stalling. reading on forums i saw that my fuel pump or fuel filter could be faulty, However this is not the case because it runs fine on LPG and gasoline until the engine gets warm and runs for a while. Some people on old forums suggested that this could be a bad main relay, but i have not checked that yet. Also i saw that it could be a bad ignition switch, but after some testing i ruled that possibility out. Currently i think that my problems could be caused by a faulty coolant temperature sensor or an EGR valve. I have not tested these yet, because i do not have an obd 2 reader to check the coolant temperature sensor voltage and temp readings. From the symptoms i think my EGR valve might be getting stuck, so i will try unplugging it and driving around. I really hope that it isn't tho because a new one is like 150euros. Do you have any guess what could be wrong? Am i looking in the wrong places? Also i forgot to menton that lately my LPG starts cutting out more often. I don't know if this is related, maybe the lpg needs some adjusting, but the same thing happens when im running on gas, so LPG is not the problem. Any answers will be appreciated. Sorry if i made some grammar and spelling mistakes, english is not my first language and i am trying to d my best to explain the situation.

 
Rep Power: 222

What brand are the plugs and the crank sensor? Should be NGK for the plugs and OEM Honda for the crank sensor.
EGR could be part of the problem, the passages in the intake manifold get clogged up

 
Rep Power: 0

The plugs are Denso iridium TT. As for the crank sensor it is OEM i believe. But no idea, i did not get a receipt for that repair