I have a 99 4 cyl 5 spd manual I recently bought. It seems that when it is damp outside or has been high humidity for some time, and cool, the engine likes to run rough and many times dies. This happens mostly when the engine is cold, but I have had it quit on me after it has warmed up on the way to work. Yesterday, It was damp and I went to the store which was a very short drive, 3 minutes tops. When I got back in, the truck wouldn't start. It would turn over as always, but would not fire off. I sat there for some time and it finally started. I assume that there is some sensor that gets whacked out when it is damp and causes this. It also seems to be flooding out as I have smelt gas during the event.

Any suggestions on what to replace?
Thanks

 

Check out Distributor cap... Look for condensation underneath the cap.

 

If there is no condensation there you need to start looking at ALL of your connections. I had an issue like this (wouldn't start in the rain, would randomly die in the rain, or damp weather) went through replacing a lot of parts, ended up being the connections to the battery! Not having the best connection to start and adding moisture to it can cause you problems.

 

Thank you both for your replies. I'll check both of those things. The battery isn't the right one for it as it doesn't sit in the battery shelf correctly. It's actually held in with rubber bungie straps. I haven't looked the connection over real good, but will.

 

btw, a 99 4 banger I am guessing is EFI, if so, you are not flooding it. Just happen to be smelling gas

 

Just to let you all know, it wouldn't start when I first tried when I left work. I didn't think I was going to get it started. However, I did finally get it going, and when I did, it did seem to be flooded. I stopped on the way home and bought a cap and rotor, got home and put it on. I didn't see any obvious moisture, but the cap was pretty nasty. I also checked the battery cables and almost pulled the negative cables out of the terminal. There was rust on the clamping strap on the wire side. I went and bought a new new and put it on.

I noticed that the dome light was pulsing a little. So, I'm guessing I might have other connection problems or a soon to be bad alternator.

I'll see what happens next.

Thanks again.

 

It sounds like could be distributor, cam or crank sensor. Hows your temp guage reading when the truck is running fine. Normal,low or moves around?

 

on chrysler caps that have a vent on the top, ALLWAYS plug the vent. j-b weld works good, took me years to learn that.

 

Well, I had the same problem this morning. The cap and rotor, as bad as they were, wasn't the problem. And the new battery cable end on the negative cable didn't resolve the problem either. Although, both needed replacing.

Running down the freeway, the temp gauge holds steady. As a guess, it looks like around 190. It's below the 210 mark. Gauge doesn't display any strange behavior.

Would any of those sensors show to be bad during a diagnostic? Would it show bad it hot or cold? There is a gas station near by work that has a good reputation. They work on a lot of vettes.

 

A good garage that has a good obd2 computer (like snap on brand not some 200.00 code reader)will be able to show the whole computer map and can tell if both of those sensors are working correctly.