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89 engine misses

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Ducter

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Hey guys, I just got an 89 k5 and it has a miss to it. At idle it seems fine but when driving it it misses, going to wot seems the miss goes away but you can tell the motor isn't at full power.

I used the paper clip deal and replaced the egr valve based off the code. So far no codes showing but I had to disconnect the battery to weld in a patch panel so not sure if that wiped the code or replacing the egr.

I can't really drive the truck as the front is on blocks and scares the hell out of me but have been test driving it around the neighborhood. I have ordered new leaf springs that should be here next week. I would love to have it all straightened out so when I replace the springs I can enjoy her.
 
Lots of possibilities, but low fuel pressure, bad plug wires, distributor cap or rotor and ignition module are the most likely.

Assuming your plugs are good, of course......
 
I'm betting bad plug wires, I was having issues a lot previously when the engine was running with the spark plug boots. Had to replace them very frequently until I had a friend give me a set of kevlar covers to protect the wires from hot manifolds. So far it worked,,, up until the newest issue.
 
To be honest I haven't checked them. Guy I got it from said he put new plugs in and the wires were good. Visually looking at them with out taking them off and out they looked OK but I am learning things he has said and done don't necessarily line up with what I have seen. I will check the plugs and wires tomorrow after work.
 
If you haven't checked them, and he says he replaced them, I'd also be checking that they are all in the correct firing order as well.
 
There a couple of cylinders you can mix up and it will sound pretty close to normal running, but will be noticeable while driving.

I've made that mistake a few times in the past
 
Well, if you are reading this now..............You probably should go to bed.......

But, nighttime is a great time to crank it up in the dark. Open the hood with all the lights off, and look for sparks.
Most bad wires that cause skips these days will be arcing. You can also use a clean Windex bottle sprayer with water to lightly spritz the wires while its running.

If the skip gets worse, or you see sparks, its time for new wires.
 
Good idea about the dark, getting ready to leave and it's still dark so I will try that before I go.
 
Didn't see anything in the dark but checked the wires and a few plugs before it got dark again and didn't see anything wrong. Pulled the egr again to check that it was blowing and sucking air which it was. Mechanic I know said it could be clogged with built up carbon.

Back to the drawing board.

Oh, and I had ordered a set of springs from jegs only to get an email saying they are back ordered and expected shipping date of 12-14. Yeah, no.
 
Missing while accelerating or driving is ignition. I'm betting bad wires or bad plug gap based on the recent work done. FWIW, you'll need to do more than check the wires visually- they can look fine and still be worn out.
 
Second the ignition again as well, had the same type of issue with my mothers truck when she was staying with me for awhile. Was a V-6 truck, so it acted worse when she was on the throttle than the V-8 engines. I went so far as to swap out the cap & rotor, spark plugs, then stupidly, before I acquired my fuel gauge kit, I changed out the fuel pump...

Then one day, as she was leaving for work, I heard her start the truck, in the carport, my room was right next to it. I heard the engine running, sounded fine, but when she went to hit the gas to back out of the driveway, I heard the engine sputter and could definitely hear the distinct tick of an arcing spark plug wire.

Replaced all of them later that day and never had another issue with it again.

Her truck is a '94 with a vortec V-6, and it had the original wires with 200k miles on them.

But as previously mentioned, I was coming across some cheap crap wires from Vatozone that keep burning through at the elbows, for some reason, they get really soft, then the spark just cuts through.
 
Ducter said:
Hey guys, I just got an 89 k5 and it has a miss to it.
Click to expand...
Congrats on the new truck.

Generally speaking, when I buy a new truck I presume the previous owner has not done any maintenance on it and has lied to me about a problem he could not fix. Therefore, I take my first weekend and give it a tune up and maintenance go-over, and try to solve the problem.

If you do not already have one, buy the GM "Light truck fuel and emissions" shop manual from eBay. It will tell you how to diagnose everything on that engine. This is this one you need:

http://www.ebay.com/itm/1989-Chevrolet-GMC-Truck-Engine-Emissions-Diagnostic-Procedure-Electrical-Book-/140815132060?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1989|Make%3AChevrolet&hash=item20c93c659c&vxp=mtr

Here's more listings, maybe there is one less expensive, I just linked the first one I saw...

http://www.ebay.com/sch/i.html?_odk...kw=1989+chevrolet+fuel+and+emissions&_sacat=0

That should help you solve the problem.

Also, if you get a smog check, the shop may be able to tell you what is going on.

And personally, I never trust the previous owner. I assume no maintenance has been done, so I replace everything - spark plugs, wires, cap, rotor, filters (air, fuel), brake pads, oil, coolant, etc. I also replace the injectors and rebuild the "carb" housing including the fuel pressure regulator, and check the fuel pump pressure.
 
Still having the issue. I have changed the egr valve, plugs and wires, distributor cap and rotor as well as the fuel filter. Not really getting anywhere with it and cant afford to throw money at it just hoping it gets fixed. I also checked the ports for the egr, they are blowing and sucking as should be. My timing light took a walk some time ago but thinking thats going to be the next thing I should check?

thanks
 
Can Can said:
Still got your catalytic converter installed in your exhaust? Could be that it's plugged.
Click to expand...

Yes, it has cats but they were less then a year old installed by the po to pass inspection. It's more of a jerking, miss then just no power.
 
Geez, that still sounds like plugs or wires to me...... :dunno:

Is there a chance you've got a fuel supply issue????????? Have you checked your fuel pressures?
 
Try using some carb cleaner and spray around the tbi baseplate and all of the vaccuum line fittings and look for a change in the engine idle. If it raises slightly after you spray or you can see the liquid being sucked in from any connection you have found your problem. Your problem sounds like ignition more than anything. Have you Tested the coil? Could possibly be getting weak. Possible the ignition module is close to Going out too. Usually those die out all at once though. What plugs are you running? I only use NGk or accel plugs these days. A lot of others I've had trouble with. Champion are now junk and I've had two different cars run like crap off them in a short time after putting them in. Ad delco was sold i think so i don't know how good their stuff is anymore.
 
Just tested the egr solonoid getting 0.32 ohms from pin to pin, it's clicking when connecting power to it. Getting 12 volts to it as well. Guessing I will look for leaks around the intake, ports etc as suggested.

No, I haven't tested the coil yet. Not sure how to test it, will do some searching.
 
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