1998 tahoe runs bad when wet outside

[bass1775]

My trucks runs/sputters very badly when it rains for several days. Dry days its fine. I'm thinking moisture in distributor cap or cracked cap and bad rotor. Any suggestions.
I'm new to this forum thing. This is my 1st attempt to post anything. been reading for awhile and decided to get on board. Any tips will be greatly appreciated. Thanks.

[blueflamed03]

yep. Turn all lights off, at night in garage...open hood, and start truck. Have it as dark as you can. Then get a spray mister full of water, and spray engine and cap...not soak it, but if you see blue arks, in cap, or in plugs, theres your culprit.

[bowtiefreak]

I had the same problem, distributer cap was my problem

[bass1775]

Thanks, I'll try both suggestions. Stay tuned!

[bowtiefreak]

how did you make out with this?

[JDWX]

Caps wires common issues with these... I'm still fighting this WITH new cap/rotor/wires.

Been through this 3-4 times and used all AC Delco. They last about 14 months on my 97 yukon. :(

Used ACDelcom cap rotors this time but cheap bosch wires... bad idea probably.

Although THIS, may now be my poppets... Ugh...

[oakster]

Had issues w/my '99 running poorly under load -- using a trailer -- was getting random misfires


I took it to several shops and replaced a ton of parts but never really got it fixed.

[bass1775]

I haven't dealt with this yet. It finally stopped raining and its been running fine. (really good) I'm headed to Myrtle Beach (not in the truck) I'll sort it out when I return. I plan to change cap, rotor and wires. I have the 8.5mm MSD wires on it. They have been on there for at least 5 years. It does seem to go through distributor caps yearly.

[JDWX]

I've had tremendous luck with MSD wires and caps/rotors on my Mustang, which has equal length headers, and under the hood temps that FAR exceed the Yukon (currrent set is 6 yrs and fine), yet the MSD wires lasted about a year so onthe Yukon.

I've had just terrible luck with wires in this truck. MSD, AC Delco. 12-15 months. Just put Bosch on (39 dollar set, haha), they may be already an issue within hours, haha...

I've used the Aldata TSB for routingthe wires appropriately for misfire reduction, and not doing so well.

At 190k on mine, could be distributor issues, coil, etc, even poppet issues. etc etc... Just sorta tired of it all. This is something that shouldn't be an issue really.

[bass1775]

I just did a tune up. replaced cap, rotor, wires, plugs looked good, pcv valve, cleaned IAC, cleaned MAF, cleaned throttle body. Truck runs like new at 132k miles. I'm happy!