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Help Please 94 Silverado 383 Stroker Killin me

  
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Help Please 94 Silverado 383 Stroker Killin me

 
mgroff13 mgroff13
I love my Chevy Chevette! | Posts: 17 | Joined: 03/12
Posted: 10/08/12
03:35 PM

So I posted here over the winter/spring about my old girl. Lots of help at the time.Thanks. My issue then was an no start...erradic idle/throttle accel Problem ended up being I was trying to use a 305 throttle body/injectors put the orig back on it and it ran great except I keep blowing injector seals (the rubber o rings) inside the pods can not figure y. Well the part stores around here only sell them in a kit $30. 3 times. Im done with rebuilding it. So my boss had a 92? W/T w/ a running 350 300000 miles but runs ok so i take the pod off b4 he crushed it put it in and its crazy unresponsive in gear.!? In park it will respond decentish. but driving it is out of the question have to floor it to keep running. low rpms and low oil pressure at idle. Ive looked at alot on the net and hear 94 95 Silverado with 383 done to them have major problems I LOVE this truck what can I do The whole motor is new or machined new heads bored n stroked block hyper k pistons edelbrock profomer plus cam edel eps intake new sensors only thing not new is throttle body injectors and distrb itself. Someone plz help it COLD in Ohio and my other car is a 73 Olds Omega I would like to put in the garage for the winter but last winters proj is killing me. Ive heared 454 injectors and hear cop car injectors and suggestions any one out there rebuild thier 94 silverado 350 to a 383 w/o converting 4l60 out for 700R? Anyone ever have this injector prob blowing or not enough flow to run right? ANY HELP IS GREATLY APPRECIATED THANKS FOR LOOKING  

mgroff13 mgroff13
I love my Chevy Chevette! | Posts: 17 | Joined: 03/12
Posted: 10/08/12
03:39 PM

PS EPS intake has no egr and I got ride of the "purge selindos in front of tb and put line from canister strait to that port on tb THANKS  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/08/12
08:55 PM

lets look back at the prior post

http://forums.superchevy.com/70/9073960/tech-talk/94-silverado-all-new-sensors-on-fresh-383-wont-sta/  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/08/12
09:17 PM

first off...

do you still have access to the SCAN tool that will display LIVE data stream...

second.. grab your old 305 throttle body.... open the throttle lever slightly.. attempt to wiggle it... does it have play in the shaft .. where it fits through the bore???  

now look at the 350 throttle body... does it have play when you open the throttle slightly. at 300,000 miles.. that one might have 1/16 of an inch of wear when the throttle is part way opened.. i have seen this many times... its fixable..

please post what you find...

################################

now... i would like to know if you have done anything with the fuel pump in the tank.. like swapping it to a different pump... so instead of 25 PSI max..  you now have a pump that will create 90 pounds pressure..

when installing the injector orings.. i always lube them..  sometimes with just a blast of wd40..  sometimes with clean white lithium grease..    

if the fuel hose o-rings get cut and loose in the fuel system... they can cause excessive high pressure...

but lets move to the current issues..

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

with that scanner ... can you take your time and post some numbers...


                     
coolant temp------------
throttle sensor-----------
injector pulse -----------
desired idle--------------
actual idle  --------------
map sensor--------------
throttle angle-------------
block learn --------------
spark advance -----------
block learn cell-----------
integrator---------------
idle air mtr steps---------  

mgroff13 mgroff13
I love my Chevy Chevette! | Posts: 17 | Joined: 03/12
Posted: 10/09/12
01:48 PM

Yes I do still have my "BRICK" SNAP ON SCANNER...Its at my dads house ill go get it sometime this week so I can post the info ur looking for. BUT I did NOT use the whole throttle body just the injector pod. Just went out to garage and dugout all my throttle bodies 2 big bores and a small bore all have a little play side to side even the one on the truck.  More play in them when throttle is open then when closed. I have not change fuel pump in 5 yrs and when I did I put a stock pump back in I have heard that 94 & 95's have a higher pump rating but I dont always believe what I read on the internet.  Which O RINGs are u talking about where the lines meet the TB? Also threw the couple engine swaps the fuel lineS got damaged and the TB sits a little higher on the eps intake with the TB adapter so I cut the lines and put rubber fuel line hose into bridge the gap maybe 6 inches on each line. Is this screwing me? I was thinking it was a reluctor prob in the dizz. There is a guy on Craigslist with a new 454 throttle body w injectors for $150 but if I can fix this one I would go that route none of the carb shops around here wanna mess with the TB's shaft I keep getting the same excuse that they break during overhauling so they dont mess with the shaft. I usually use White Lith but the 3rd time I used a small amount of bearing grease seemed to last a little longer but still ended up leaking out the top of injector. Seems to me that I holds until I wanna show off and smoke brother-n-laws 347 stroker in his ford. Thats when I blow the seals and nobody has heard of this. No body can tell me what would cause excessive press until u. We all thought with a return line there should be no way it would be excessive press. Logic not experience...lol. So like I said original TB orignal dizz and reluctor original cpu and prom everything else is new if I had more $$$ I would buy a "coil over" dizzy 700R and new Holly and call it a day but pockets are pretty bare with 3 kids and trying to keep up on Omega the proj Nova and the old ladies Venture van. Thanks Wayne ur an internet GEARHEAD SAINT. Would a pressure regulator be smart investment? just hate throwing $$$ and parts at this thing.  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/09/12
06:54 PM

click on the link to see a parts list...

right click on the image and open it in a new window.. and you get a BIG picture of the throttle body..


930512TX03 007
Chevrolet Trucks 1994, K1500 pickup 4wd, Fuel system-exhaust-emission system, 1994-1995   CK THROTTLE BODY INJECTION/DUAL INJECTOR (MODEL 220)   (TX03-007)  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/09/12
07:18 PM

ok... lets look at what happened to the injector seals..

in the seal kit.. there are 2 large ORings that go near the top of the injector.. and 2 large metal Oring sized washers to hold them down...

if you are blowing the Orings out the bottom...  you are assembling them wrong or the fuel pressure return has been blocked and max pressure is being applied..

i usually install the ORings on the end of the injector.. lubed and only part way on the small end.. so the injector can roll the orings into position..  the orings as far as i know... do not go in the housing first...

i really worry about fuel line cuts.. how did you cut it.. with a proper tubing cutter i am hoping...

and you are using fuel injection hose...   you should be able to convert to compression fittings and steel tubing ..  a secret... many parts stores have giant rolls of steel fuel line tubing just sitting on the shelves in the back of the store..  

mgroff13 mgroff13
I love my Chevy Chevette! | Posts: 17 | Joined: 03/12
Posted: 10/09/12
08:01 PM

Yes I used a tube cutter and its rubber hose with 2 hose clamps and the seal Im having trouble witch is the one labeled #6 on the exploded diagram. So Ill check return line. using a air nozzel would be suffient? When It blows it fills the top of injector pod housing where the injector plug in floods over the top draining down the TB mostly into the TB's butterfly. So what is the fix for the shaft being loose. I found an holley 502-6 for $150 barely used on CL but its for 87-89 truck only diff I see is TPS mounting is there a way to convert it to my applaction. Holley has a 502-9 that is for my truck $500. Ebay 250. If Im fighting a TB issue I would assume replace it then rebuild this one. So would a "wallered out" TB shaft make it irratic and low rpm n oil press at idle?  

mgroff13 mgroff13
I love my Chevy Chevette! | Posts: 17 | Joined: 03/12
Posted: 10/09/12
08:02 PM

Also if I go with 454 TB is there gonna be issues its new  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/09/12
08:14 PM

i am trying to break this up into sections..

lets talk about the WOBBLE in the Throttle shaft....

this gets complicated..  as there are several different things happening at the same time..

first... lets look at The TPS voltage...   usually 0.53 to 0.93 volts with the Throttle closed.. there are SPECIFIC voltages in the repair manuals..

the TPS Voltage lets the ECM know if you have your foot off the gas.. at minimum voltage... or somewhere above minimum voltage all the way to about 4.5 volts which is wide open throttle..

at minimum voltage...  the computer knows you have your foot off the throttle so it turns on the idle program..  leans out the fuel ratio.. if the engine is operating above idle speed when you close the throttle.. the idle air control motor will be backed out about 80 counts..  the computer will slow the motor by decreasing the idle air counts till it reaches a stable idle speed it desires according to the programming..



as you move the throttle is comes out of idle program.. backs out the idle air control motor.. richens up the fuel mixture...  as the engine RPMs come up..  the idle air control motor moves in and bottoms out at 0 counts then backs out to 80 counts and waits for you to close the throttle.

now... if you have a worn throttle shaft bore..  the throttle blades catch on the sides of the throttle bore.. allow the throttle shaft to come to a slightly different angle each time the throttle is closed..  this creates havoc in the programming as the ECM never knows when you actually have your foot off the gas so it can drop into idle programming...

but also.. if the tps voltage is higher than any minimum voltage the ECM has encountered this key cycle...  it will keep the air fuel ration richer.. keep the idle air control motor backed out farther..  just making for a horrible running condition..

even more..  if the TPS is higher than what the PROGRAM is designed for base idle minimum voltage.. as you attempt to start the engine..  because the TPS voltage is high.. it will put the fuel system into the CLEAR FLOOD MODE... where it will narrow the fuel injection pulse width.. as it things you have flooded the engine and are trying to clear the excess fuel out by holding your foot on the throttle..

know that i have confused you... and worn my finger tips off..

lets look at what you will see on the SCAN tool... don't ever turn loose of that brick..  the newest scan tools... even snap on versions... don't read live data on OBD1 GM cars. .

so... get into the LIVE Data...
key on .. engine off...

look for TPS voltage....   operate the throttle pedal a few times...

note the minimum voltage... the exact decimal ...

work the pedal some more slowly... as you open it.. the numbers should slowly increase from below 1.0 volts to about 4.5 volts on the display of the scan tool..

each time bring the throttle back at a different speed... does the minimum voltage always come back to the exact same thing..???

now.. start the engine..    look at the TPS voltage again.. does it have the exact same minimum..

also look at the ECT... engine coolant temp sensor .. is the reading on the scan tool close to what you have in real life..   not -20F   when the engine warms up. you should have a 190F to 215F readout on the scan tool..

now thats its running.. At IDLE.. foot off the gas pedal... if possible.  lets look at the IAC numbers.. along with the TPS numbers.. and the fuel injector pulse width..

TPS should be again less than 1.0 volt...
IAC should be 20 to 50 counts..
INjector pulse width should be 1.2 to 1.4 MS... milliseconds...

you have 2 ways to set the proper amount of throttle opening at idle..
with the engine warmed up and no codes...
if you have less than 20 idle air counts.. back out on the idle stop screw.. T15 under the seal..
if you have more than 50 idle air counts.. turn the idle speed screw in to open the throttle..

you can also set minimum idle opening.. base idle...  by backing out on the idle stop screw till the throttle blades stick. then in just far enough they don't...  you will want to use a small screw driver and force a doubled up shop rag into the vertical passage behind one of the mounting bolts on the throttle body main housing. this is packing the passage to stop air flow.. to allow you to set base idle... about 500 RPMs... then pull the rags. out..   bring the rpms up.. hold them for 20 seconds at about 2500.. then ever so slowly... bring them back down.. this lets the ECM relearn where the idle air control motor really needs to be..

lets step into what needs to be done if the throttle shaft bore is worn...  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/09/12
08:47 PM

if there is play when the throttle shaft is opened slightly... and the TPS minimum voltage comes back to a different spot each time..

you have enough wear to rebush the throttle body...

warning.. this requires some skills... requires some special sized drills... requires some thin wall valve guide liners...

and requires some slightly out of the normal range of tools.. its NOT impossible...

you will need to collect some parts up front..

do you have either a cylinder head shop in town.. or an engine rebuilder.. you will need 2 or 3... 0.375 or 0.376 thin wall valve guide liners..  they usually charge 2 or 3 bucks each over the counter...

you will need some 3/8 wooden dowel... and some small hose clamps.. to clamp one guide liner to the dowel with.. usually with a few raps of masking tape..   they are TOO LONG to use.. so you will have to cut them...    you can either grind them through.. then flatten the end on the grinder while its still mounted on the dowel..   you can also cut through them with a high speed cut off disc.. in a dremel or your 4" angle grinder.   i usually use sections about 5/8" long..

now...  please don't mention the shaft size to the rebuilder or they will give you smaller liners that will ruin your day..

the shaft size is 0.372...

3/8 is 0.375...

the thin wall guide liner has.. if its for 0.375" . has 0.015" thick walls..

375+ 0.030 is 0.405..   since letter Y drills are 0.404" and are sometimes easily found..

if you drill the throttle shaft bore.. press in a section on each side..   lube it with some usually moly assembly lube work the shaft back into the bore..  it needs to be free and easy to turn once you  get it all the way in...

the issues are... sometimes... the drilling from both sides is not perfect.. so it will bind..
i happen to have an old valve grinding kit.. and have a 3/8 knurling tool.. but i also have a 0.375 valve guide reamer..  about 80 bucks last time i checked..  i drive the reamer through and the shaft fits perfect...

but wait...

the SCREWS holding the throttle blades to the shaft...   those a TINY special metric version.. 2.5MM x 0.45 or .65.. i have forgotten right now..  with a special large head...

where the threads of the screws extend past the throttle shaft.. they are distorted..  you have to use a dremel or a die grinder to grind the exposed threads off..  if you attempt to remove the screws... without grinding the exposed threads off..  you will jam the distorted threads into the threads the shaft.. breaking the screw off ... this ruins you day.. as its almost impossible to get the broken piece out without a very expensive machine designed for removing broken drills and taps..  burns them away one molecule at a time..

i had some decent replacements.. bought a dozen as a sample.. they worked perfectly.. i went back for more.. some sewing machine guy bought all their tiny metric stock out..  if i need 10,000 .. i can get more..   lately.. i have been reusing them by supporting the screw heads with a tool through the throttle body .. and center punching the end of the screw.. this does work..  its just not as good as new screws..  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/09/12
08:58 PM

there is an article that covers some of what i talked about..


http://www.chevyhiperformance.com/techarticles/148_0401_factory_tbi_system_install/viewall.html


if i can find a source of screws...  i might try to pick up a pile of cores and rebush them...

one of the wholesale auto parts stores near me lost their supplier of these rebushed units. . where they were turned around in a few hours..    most of the professional mechanics i know. just strip the injector housing off and send a  bare + TPS throttle body housing ..  as its check engine lights and idle control issues they are attempting to fix...  not injector issues..  

mgroff13 mgroff13
I love my Chevy Chevette! | Posts: 17 | Joined: 03/12
Posted: 10/10/12
01:51 PM

Ok Im with you as far as the all the tps iac etc idle and diagnoses still got to go get the brick to do this but all the hassel of running for parts and buying special tools and drill bits n such. I would assume buy the new 454 TB off of Craigslist if it will work. I fancy myself a good mechanic but that seems more like a machinist job. So I have heard it will work other places but nobody seems to be as knowledgeable as you. I do understand that w/o the readings we cannot pinpoint the exact problem.  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/10/12
08:00 PM

google GM tbi bushings

there are several places that sell bushing kits..

there are several articles spread out in the magazines about rebushing carbs.. its the same process...

did you end up with an extra 305 throttle body???

http://www.lindertech.com/gm_tbi_svc.htm

check your private messages when you log in..  

waynep71222 waynep71222
My first time was in a Chevy | Posts: 218 | Joined: 04/12
Posted: 10/10/12
08:08 PM

more to read on this thread on a sister magazine site

http://forums.chevyhiperformance.com/70/8666447/general-chevy-technical-discussion/installing-a-93-tbi-350-and-4l80e-into-70-3-4-ton/  

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