93 z71 engine miss plz help

deepblue_z71 · 01-24-2007, 12:30 AM

After wading through the forums for a couple of hours looking to see if my question had already been answered I caved in and decided to go ahead and ask. Truck is a 93 Z71 305or350TBI, I hadn't driven the truck in a couple days then I crunk it up the other morning and I noticed it was idiling really rough. When I drove it there was a drastic loss in power. The only thing I can compare it to is, it was like driving with at least two plug wires missing and it's like its only hitting on 5or6 cylinders instead of all 8. The plugs and wires are only 2 months old so I changed the fuel filter, and the problem persisted. So I pulled the spark plug(drivers side closest to radiator) and noticed it was wet fouled, I couldn't tell if it was fuel because I was already drenched in gas after changing the fuel filter! I pulled the dipstick to make sure there was no water in the oil (there wasn't). So I proceeded to change all of the plugs with newly correctly gapped ones, still same problem. Iam going to check for spark at the plugs tomorrow. In the meantime what other things do i need to look at? And what do I need to do if there's spark on all cylinders? And what if there isn't? BTW Nice site!

pop826 · 01-24-2007, 01:47 AM

Have same problem if i find a cure i will let you know. 93 350 utility body

deepblue_z71 · 01-24-2007, 11:42 AM

Update, I scanned it for trouble codes using the jumper wire method and counting the blinks of the SEL and came up with a code 35. On the code list I have this is listed as IAC(Idle Air Control) But Iam thinking that this in itself is not the culprit but maybe a contributing factor?

CD Smalley · 01-24-2007, 07:25 PM

If that's locked in a wide open position it will create a giant vacuum leak.... I'd start there.

deepblue_z71 · 01-24-2007, 09:48 PM

Thanks CD, I'll try that and update here later. Maybe it'll help Pop too. BTW Pop keep me posted and also if anyone else has any ides let me know.

deepblue_z71 · 01-25-2007, 02:18 PM

I put a new IAC and also a new ignition coil on it today, but still problem persists. I decided to try the "darkroom" test and see if there was any arcing in the plugs/wires, and yep sure enough there was arcing on the exhaust manifold, intake, and everywhere else except for the plugs! LOL! Im taking the wires back to AZone today being as they were under warranty and only 2 months old! I'll update this post later with results... Yep it was the faulty plug wires, sometimes it's the simplest things, can't see the forest for the trees and all that... Keep on Truckin'!

texasboy05 · 01-25-2007, 09:42 PM

go to autozone or reillys and get a white can of SEAFOAM fuel system cleaner. let it run for about 10 to 15 minutes n see if it dont help. if that dont do anything id take out all the plugs n let it sit for a day or 2 to let anything that shouldnt be in the engine dry out n try it again

mrbee · 01-31-2007, 05:25 AM

What he said -
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97cavalier · 01-31-2007, 10:35 PM

on that seafoam stuff. Do you put it in on a full tank and let it run for 10 min? How you do it the right way?

mrbee · 02-01-2007, 02:10 AM

I use it through the brake booster vacume line. Crank the truck and have someone hold the accelerator at about 1500-2000RPM. Pop the vacume line off of the brake booster and pour about half of the can into the line.... then kill the truck and wait about 5min. Repeat with other half only this time take it for a drive and dont be afraid to blow it out. LOTS of white smoke is normal that means its working.
That or just pour it into the throttlebody either way works for me.

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