off idle miss

[fryedaddy]

my 428 runs pretty strong but im getting a low speed miss from idle to about 2000 and after that it smooths out and runs well.any thoughts.been working on the 850 last week?

[fryedaddy]

i read a similar thread,im good.i took my cap off my msd dist amd i saw the problem right away.i cleaned all the components and put some dielectric silicone on all the working parts and its good.it was not advancing till rpms got high then it advanced all at once at 2500 rpm. i watched my tach it would jump all at once and now it revs smoother

[winr1]

Yay 


Ricky.

[Stangman]

Nice find.

[fryedaddy]

Yay 


Ricky.

[fryedaddy]

Nice find.

?

[fryedaddy]

 i may have misunderstood,im having a bad day,sorry

[Stangman]

No really nice find.

[winr1]

"Yay" meant was glad ya found the problem :-)



Ricky.

[fryedaddy]

miss got worse.when you pull out and go down the road,it sounds like a low rpm studder box.it sounds awful.but the weird thing is it is hauling butt from 3000 up.i was getting some no ethanol 93 a week or so back and the tank was empty at the store and i could only get a gallon or two to pump but the tanker was there and he filled it up and i finished fueling.could i have got some crap-water in my fuel cell and why does it smooth out and run good at high rpms.plus i drove it all winter and i have not changed my spark plugs out.i took the rockerarms off and checked my pushrods,they are fine.any ideas at this point.im getting frustrated.

[C8OZ]

Lots of possibilities, of course, but I wouldn't dig too deep before taking a very close look at dist. cap/wire boots/plug insulators for carbon tracks.

[fryedaddy]

Lots of possibilities, of course, but I wouldn't dig too deep before taking a very close look at dist. cap/wire boots/plug insulators for carbon tracks.

wires are new,well about a year old, msd dist i cleaned it and the cap out and i run the lite springs,they seemed to be ok

[fryedaddy]

you can barely notice it in park but when you put it in gear and take off thats when it sounds and runs bad

[fryedaddy]

i have a spare dist cap and rotor i just now put on.i couldnt tell just by cranking it,so i guess i will go for a short ride and see what it does

[machoneman]

you can barely notice it in park but when you put it in gear and take off thats when it sounds and runs bad

If it misses at idle in park (yeah, I read the part about taking off) one could rig up a fuel line from a one gallon can perched under the fuel pump, bypassing your gas tank altogehter.

But that'll only work of course when the vehicle is stationary!

[fryedaddy]

i just got back.no change it still sounds like a studder box set on 1500-2500 rpms.if i run it hard you would never know somethings wrong with it,but if you barely mash the pedal it sounds like it wouldn't fall out of a tree if you kicked it in the ass

[fryedaddy]

maybe i have a damaged front accelerator pump diaphragm.i have been messing with it a week or 2 ago

[Heo]

I have filled up once when the tanker was at the pump
drowe a few miles from the station before it died. water in the fuel
so i would test with a separate gas can

[fryedaddy]

I have filled up once when the tanker was at the pump
drowe a few miles from the station before it died. water in the fuel
so i would test with a separate gas can

maybe the water wont burn good at low rpms and when i go faster its getting so much gas that it dont bother it as much

[Heo]

And the water does not vaporise as easy as the gas
so att low rpm maby big waterdroplets shortening
the plugs.....or something

[fryedaddy]

im going to drain my fuel cell,put some fresh 110 in it and put in a set of plugs tomorrow. i believe i will get some new carb base gaskets,i have reused the ones on it now several times  if that don't help then its back to the drawing board

[fryedaddy]

i went ahead and took out the spark plugs.i checked them a week or two ago and they were nice and toasty.now most are sooty but the tips of the electrodes are white.i cant put the new ones in till tomorrow.

[fryedaddy]

new plugs didn't help any.it still misses at low rpm and will smooth out when you squeeze the pedal down a little further i cant tell if its a misfire or vac leak or fuel issues or other.

[fryedaddy]

i think i may have found the problem.i cant fire it up till grandkids wake up but i just noticed both the hot and ground coil wires were loose on the coil.could this be the problem?

[fryedaddy]

well,i guess it was spark related.tightened the +- on the coil and its running some better. a week spark would explain why my plugs went from toasty to sooty all at once.i would be more worried if it was 1 or 2 cylinders instead of all of them.i think i need to get a new cap and rotor to get back to 100%.i put a used one on while trouble shooting and my other one is a year or 2 old too.could it be a exhaust leak causing that strange sound.i have hookers into 3 inch x pipe and 3 inch mufflers.the guy at the muffler shop told me to tighten the pipes up after some miles

[fryedaddy]

looks like at this point i will have to be a parts changer. replace everything till i find it.

[fryedaddy]

i know this is getting to be a boring topic.if this will help any in diagnosing my problem.i went for a ride and it misses or studders or stalls or whatever its doing when you are barely pushing on the pedal.it dont matter if you are crusung at 25 or 55,when you barely mash the pedal is when its doing whatever its doing.when you mash down a little harder on the pedal it smoothes out.even when i let off the gas it does this right before i let completely off on the throttle  any ideals anyone

[C8OZ]

Can you get it to do this with a light power-brake sitting still?

[fryedaddy]

Can you get it to do this with a light power-brake sitting still?

thanks for the reply but i just solved it.i had to go to a chevy website to get someone to reply and figure it out. sorry,low blow just kidding.ok here it is.it was my modulator line clogged.blew it out with a air hose and a bunch of goo came out and now i cant make it miss.i tried.  its fixed.now lets end this stupid topic.no more replys from me.whew i feel better now.

[cjshaker]

The modulator line for the transmission? I'm at a loss as to why that would cause a low speed miss, or any miss period, for that matter.

[fryedaddy]

The modulator line for the transmission? I'm at a loss as to why that would cause a low speed miss, or any miss period, for that matter.

yes trans modulator is run off vac from the carb.i looked up symptoms of bad modulator and one of them was poor idle,it could be all the above.i put new plugs,new gas cleaned the inside of the dist,set timiing,and adjusted the acc pumps on the carb, but whatever, its fixed

[C8OZ]

thanks for the reply but i just solved it.i had to go to a chevy website to get someone to reply and figure it out. sorry,low blow just kidding...

Glad you got it fixed! 

In other news, I think it's time for me to log off of the internet for today.

[jmlay]

Is the modulator bad allowing atf into the line? If so I would say you have a short term workaround rather than a fix.

[fryedaddy]

Is the modulator bad allowing atf into the line? If so I would say you have a short term workaround rather than a fix.

whatever it was it took years to clog,no big deal swaping a modulator,just screw it in.its obvious im not a mrchanic.i have a high school education and worked in a glass factory for 33 years but i know just enough to get myself in trouble working on the engines.i have owned and driven as many fe cars as most,but my skills dont go much further than a top end swap.i have never really built a engine from scratch.i relied on my uncle till he passed a few years back.he had 21 certification's at one point and he could do just about anything,and he raced fords to boot. but all i wanted to know is why i have a miss at 2000 that clears up when the rpms raise

[machoneman]

Is the modulator bad allowing atf into the line? If so I would say you have a short term workaround rather than a fix.

Glad you found it but....only ATF getting sucked into the intake manifold, given no vaccuum leak from the attachment hoses, could cause your oil-fouling miss. Agree you should now be regularly checking the modulator and lines for more leaking ATF as that may betray another tranny related issue. 

[fryedaddy]

Is the modulator bad allowing atf into the line? If so I would say you have a short term workaround rather than a fix.

Glad you found it but....only ATF getting sucked into the intake manifold, given no vaccuum leak from the attachment hoses, could cause your oil-fouling miss. Agree you should now be regularly checking the modulator and lines for more leaking ATF as that may betray another tranny related issue.

i understand the mod line plugged off or not could not cause my 2000 rpm miss.what is weird is it would do it throttling up or down you could be doing 4000 rpms for miles and then let off the gas slowly and when you drop to 2000 it starts.i have been changing so much stuff im not sure what the fix is.