Hesitation In Rain

[Chris95GST]

My car gets a bad hesitation problem when it starts to build boost in the rain. It does it to a lesser degree when its dry in third gear at the higher RPMS, but it definitely does it a lot more when its humid or raining. Does anyone know what might cause this. When I change to knew I changed my plugs and wires and it seemed to help the problem a little but I still get hesitation pretty bad when it rains and at the top of third.

 

[vernvision]

Hmm that is very interesting. You said that changing the plugs and wires helped. I would start thinking about the coil packs and or transistor. The damp conditions might be allowing the possible leak in one of these units to start bridging and if there is a lot of dirt there then it could be aiding in the conduction. Check all your eletrical connections and look for any damaged wires. The fact that this gets worse with dampness or rain makes me beleive that the problem is electrical. Check to make sure you are not leaking in the back area where the fuel pump is as well as check those wires out as well. Hope you find out what's wrong and keep us posted.

 

[FonZ454]

Are you running a stock maf or GM MAF-T and where is your air filter located? MAF's don't like moisture at all, make sure none is getting to it.

Plugs gapped correctly?

 

[vernvision]

Yeah I didn't want to say the MAS because it is an expensive replacement but yes that is true they cannot get wet. It will cause the paper inside to get screwed up and it will start giving you all kid of problem with the sensors. The MAS or MAF will not always throw a code either. If you got a buddy with the same gen car or MAS you could try swapping it to see how things work before you spend like $500 for a replacement.

 

[Chris95GST]

I'm running the stock MAS sensor. I don't think water got into it. I'm going to change the plugs again and see if I can find any loose wires. What would a sign of a dieing coil pack be?

 

[vernvision]

I have not had a coil pack die in on of these on me yet (knock on wood). I replaced mine at 125,000 miles when I changed the motor the first time. On other vehicles that I have worked on or owned usually they start leaking a oily fluid or when they get hot they will start causing the engine to miss. They can also just die completely. If you can get to a wrecking yard you could see if they have one off an engine that is no good or they won't sell. The main ignition problem I have had besides plugs and wires is with the transistor which is right next to it. They are suspetable to heat soak and if you have a crack in it that might be the problem.

Right now you know though you are just shooting blindly. If you can scan for codes 1st you might have an obvious failure that will let you know right away.

I know this sounds weird but also make sure that your heater core isn't leaking slowly and dripping stuff where the ecu is. It is amazing how the coolant can travel around the wires in there. I had that happen one time and it starts very slowly. On cold days like when it is raining or snowing and using my defroster, my car would especially start running like crap. I couldn't find the obvious so I started buying parts I thought would fix it. Also you can check the circuit board on your ecu for leaking Capacitors.

Needless to say I am better stocked than the dealership parts dept. If you are going to start doing alot of the work on this yourself you need basic diagnostic tools like a logger where you can check and clear codes. I only suggest the wrecking yard because if you can pick up most of these parts for a lot cheaper than buying new. If you find the part that is bad then if you don't trust the one you got at the wrecking yard then you can buy it new. You will then have some parts to swap when you have problems or off them on ebay.

Either way when you do find what is wrong please post it. This is one of those issues that drives us all nuts because of it being intermitent and hard to diagnose.

 

[90laserRSfwd]

I agree with this guy ^^^