pantera1683

Okay, for the past month or so I have been having an intermittent problem with the Z stumbling while cruising. I first noticed it while driving at constant highway speed on a trip from Dallas to Houston. It would stumble or "hiccup" for a few seconds at a time as if it wasn't getting enough fuel. It did this for about 1/2 an hour and went away. I pulled the plenum and changed the alternator, coils and wires. I checked all the vacuum hoses and added zip ties to the connections. The hiccups would pop up very rarely after that.

On Vets day I got caught in a downpour and the stumbling came back, but this time it had a hard time accelerating from a stop. It struggled to accelerate until I stabbed the gas pedal, then it would accelerate normally. I pulled over and it shut off. It did start back up immediately after and seemed to work fine after. Yesterday, it was driving fine until I got a block from home, the stumble came back coming trying to accelerate from a stop and the idle went to 1200 rpm and kept rising to 2000 rpm.

Here is some background on the car. It is a 94 with 36k miles on it. It sat for several years before I purchased it earlier this year. I bought it with 33,5k miles and the PO only put 2k miles on it in the preceding 2 years. The fuel filter and plugs were all changed earlier this year.

Any ideas?

Polo-1

Check O2 sensors ( plug in's) for water in them. Or time for new ones.
Check TPS voltage. Check the sweep, in the area that you are having the problem ( 1/8-1/2 trhottle sweep). Watch the VOM for a jump or drop.

pantera1683

Okay, it's been a couple days since I cleaned the IAC valve and so far so good. It's idling normally and no more stumbling. I'm driving to Ft Worth from Houston tomorrow and will keep you guys updated.

Goldcylon

I have to clean mine all the time on my car and it gets pretty sooty. Becareful on the replacements on Ebay. I was having wild sticking throttle issue due to the IAC valve seperating and being stuck in the air horn.

pantera1683

Good to know, I picked up a new one from Ecklers at the same time I purchased a LED tail light kit. 20% off sale-I couldn't resist. I also got a sweet deal on a TPS sensor from Rock Auto, it was on closeout $22. I will just keep them as spares if my symptoms don't come back.

On a side note, how hard is it to clean the throttle body?

Goldcylon

For a quick clean you can just pull off the front of the air horn while its still on the car. Thats what I do as you wont believe how much soot and crap gets on the primary and seconary intake flappers. Beyond that is the removal of the TB Cables and the torx haed bolts that go to the front of the plenum that mates the back end of the TB and the Plenum together. Make sure you have the gasket kit on hand if you start the process. GC

Sounds like you bought the same LED light that I have been running for years. Be advised you will need and eletronic flasher module in order for these to work correctly the standard mechanical flasher will not work. GC

pantera1683

Thanks, an electronic flasher comes with the kit and I bought an extra one as recommended for the hazard flasher.

I figure it would be a good idea to remove the TB to clean the soot since my car was sitting for so long before I bought it and seeing how sooty the IAC was.

pantera1683

I just returned from my Ft Worth trip and things went well for the most part. It was smooth sailing both ways until I got back to Houston. I was trying to make it all the way home without having to refuel but the level got down to reserve so I refueled. As soon as I got back on the highway it stumbed. It did a couple more times and then everything was fine for the last 20 minutes to my house. Do you guys think it might be fuel related?

On a side note I stopped by the Amsoil store in Arlington and picked up a few cases of AMO 10w 40:-D

C1ANDZR1

Just curious to learn, how do you check the TPS voltage and the sweep?