I have replaced to brand new spark plugs.
After some research, it seems that the problem might be the direct ignition cassette.
Could there be other possibilities?
Thanks


Question: How do I deal with a slow and undedicated colleague in the team?
Answer: As others have mentioned, behaving professionally is the single most important thing for your long-term career.  And honestly, as long as you behave professionally, you'll be in pretty good shape, no matter how those around you behave.  

In this situation, there are a couple of considerations you need to take into account.

First, you need to understand that you are responsible for your program working to the desired specifications, by the given deadline.  If your program interoperates with someone else's program, you are also responsible for making sure that that other program also works by the same deadline.  To put this differently:  If the other person misses their deadline, then you have also missed your deadline, even if your own part of the project was on time.  In management terms, this is called owning the inputs.

You have correctly noted that when your colleague declares in a meeting that his program's bugs are fixed, that you can't immediately declare him as incorrect to the manager (your manager would see that as "throwing your co-worker under the bus";  a very bad career move).  Others, on the other hand, have pointed out that it is unprofessional not to declare the true state of the project to the manager.  Both sides are completely correct.

So if it's bad to contradict your colleague in front of the manager, and it's also bad to not contradict him, then what do you do?

The answer is actually pretty simple:  You need to talk to your colleague well before the meeting with the manager, and let them know that at the upcoming meeting you're going to need to tell the manager about the troubles you've been having with their program, and that it's impacting your ability to deliver your side of the project on time, and whether there's anything you can do to help them address the troubles you've been having.  You need to have this conversation at least two full days before the meeting where you will tell the manager, and preferably a full week in advance.

In most cases, just telling your colleague that you're going to have to list their program as a risk at a particular meeting will get them motivated to address the problems you're having, and you never have to talk to the manager at all.  In others, where the problems are more schedule-driven, the colleague will often agree with you, and the two of you can go to the manager together.

I've never had a colleague who didn't either fix things up for me quickly or else agree with my concerns, when expressed this way.  But if it did happen, by giving your colleague advance warning you'd still be in a better position when talking to the manager.  Since you talked to your colleague and tried to work out a solution on your own, and warned them well in advance that you would need to raise the issue at this meeting, your colleague won't be surprised when they do, and the manager won't think that you're simply trying to shift the blame.

Do please remember that when you express your concerns, either to the colleague or to the manager, that your concerns are about your colleague's program which is returning bad data (or whatever else it's doing);  these are measurable things which can be verified and fixed.  Your concerns are not about your colleague being slow or undedicated;  these are not measurable things, which may or may not be true, and which are unlikely to be fixed by bringing them up in a meeting in front of the boss.