1989 Vette

Help !
My 1989 Vette has 4000 miles on it , The problem is after it runs for some time and I turn it off it will not start till it cools off to about 150 , Then it runs bad . The next day same thing runs good till I turn it off and ...
I replaced the ignition module but the same thing is happing .

Thanks for any help .  

did you have the module tested 4 or 5 times in a row.????

when you put it back on...    did you put any dielectric tune up grease under the module.??? without it... the module will overheat in 10 to 30 minutes and cause the car to stall/????

did you examine the pick up coil connector..    was the grease in it turning green????   if so.. time to change it.. green corrosion is the copper wires being eaten up by acid...

lets go through testing first...     got a digital volt meter... they start at 5 bucks... set it to 2K ohms.. (2,000 ohms)
it should read somewhere between 500 and 1,500 ohms..   if it does...

before disconnecting..

flip the meter knob over to 20 volts AC...    spin the shaft.. if the reluctor and pick up coil are good..  it will put out just over one volt AC


to get the distributer out and back in...   it's important to see exactly where the timing marks are first... take a look at the timing marks...  straight down behind the water pump... are they clean..???  can you read them...

take some tape and mark the wires... be sure to mark were the number one wire goes to on the cap... masking tape works well...   and which way is front...

draw a diagram of where they went on the cap...

once you can get the distributer cap off.    bump the motor around till the rotor is pointing toward the where the number one wire went on...    now... take a look at the timing marks...  straight down behind the water pump... i usually have to remove the smog pump on earlier models... a 5 minute job..

i put a long breaker bar with a 5/8 deep socket on the crank center bolt..   move the crank till the timing marks line up at 15 before...    pull the rotor.  it should still be pointing toward the number one position on the cap..

 take a look at the pickup coil and reluctor teeth   are they lined up perfectly >< if not... move the crank counter clockwise a few degrees with the breaker bar..   bring it clockwise until they line up exactly..><    look at the harmonic balancer... look at the timing mark... see where it lines up...   make a mental note of it...

with the rotor off... put a piece of tape on the top flange of the distributer shaft..  i usually put some scratch marks... with a pen .. mark a forward arrow...    

now... you know where the distributer lines up exactly... with the engine off... you can take it out... and put it in.. and lock it down.. getting it so close  after a bit of practice...  you will get it exact...

you do have to make sure when you put it back in that the shaft is pointing in the right direction... the oil pump shaft has to be positioned so the distributer drops all the way down...  then turn the housing so the reluctor teeth line up... lock the housing .. put it back together and it should start..



now.. the trick for changing the pick up coil...    after you remove the distributer drive gear...    and file any burs off the pin hole in the shaft...

turn the housing upside down... fill it with brake cleaner or carb cleaner...    start turning the shaft and working it out...  more and more... don't let it get stuck part way out.. when it gets tight...  push it back in and add more spray...  this softens the varnish that builds up on the distributer shaft between the bushings..  lets you get the shaft out without a hammer...      

be sure to lube the shaft with some assembly lube when you put it back together..  



parts that you should probably replace
autozone part numbers

Duralast capacitor and harness Part Number: U518
this is the condenser and 3 wire plug that goes into the cap behind the bat and tach terminals..   be sure that the hold down screw gets installed tight.. it is the high voltage return circuit for the coil...

Duralast / Pick-Up Coil Part Number: DR110
this should be the pick up coil part number for your 89 .,... double check it at the counter...

Felpro / Distributor Mounting Gasket Part Number: 70194
this is the distributer mounting gasket..   a buck or so with tax... stops any leaks


Permatex/ dielectric Tune-Up grease  Part Number: 81150
this is the proper grease for under the module...  it has solids in it..  it is thermally conductive...  DO not use it for lubrication of moving parts...  you won't like what happens...  Do not use it on screws...  you won't like what happens...
the solids swell...  and lock the moving item in place.. sometimes forever.. for the proper use... its perfect... it has to be used under the module... or the module will overheat and burn out..    white color transistor thermal grease is also available..


i hope this helps...    do ask questions.. i do drop in.. almost daily...  sometimes hourly..  

I have a good spark , Could it be a gas problem ? I changed the filter on the frame are their anymore on the car ?  

i have a really off the wall idea....  give the ignition lock cylinder a shot of wd40...  work the key in and out a bunch of times slowly...    

give it another shot and with the key in.. turn it back and forth through all the positions...

i just wonder if the VATS system is kicking in.. do to dry and slightly tarnished contacts... in the ignition lock cylinder..

look over and see if the security system light is flashing when the engine dies....     if it is on.. while the proper key is in the lock.. the lock cylinder may be bad or the VATS contacts inside are loosing contact..


find a scan tool... plug it in ... read the data... there is a list in most manuals.. that gives normal scan tool volt readings... so you know whats normal and whats not..  

I scaned for codes , all I get is 12 with key on and 1 with car running . I did a fuel pressure test(38/39) and that's good . Would I get any spark if the ign module was heating up ? Would anything other then the module stop the car from starting after it runs/heats up ? If I keep driving a long time ( 40/50 miles ) it will start running dad and not go into passing gear for lack off power then it will turn off .
It keeps running in my driveway till I turn the key off then it will not start till it cools off 2hrs at first now 4-6hrs + 0r - .
It acts like a bad module so should I get a code if it was ? . The car only has 4000 miles on it and it's a 1989 .

Thanks For any help .  

bad modules... will not set codes...

bad pick up coils will not set codes...

when i have modules tested .. i have them test it 5 or 6 times in a row on their machine...   if it is going to fail... it will probably do so when it gets hot..

what kind of grease did you put under the module????/  everytime you remove it .. you have to use fresh..  or it will overheat and burn out..

examine the pick up coil connector if the grease has turned green you have corrosion problems..... the pick up coil will need to be changed...  

They did test the module 5 times and it heated up to the point I couldn't hold it and still tested good . I used the grease that came with it .
I looked at the pick up coil connector no green .
Is thier anything that I could test when it will not start, unplug something ...
The car starts good cold soon as the rpm's start to drop ( 6/7 rpms ) it starts to run rough when it reaches operating temp I turn it off let it sit 5-10 min and no start ,
Fule pressure up and good spark .
If I drive 30 + or - miles it will run more and more rough till it stops then no start for hrs but turns over great , still have fule perssure and good spark .
Car has 4000 miles on it if that helps .

Thanks for any help .  

if you have spark....   how much???? will it throw a 3/4 inch spark...

i am thinking ...  heat soak....      module...   coil.....  ecm...       if you did not have spark... i would think pick up coil...

don't forget the module has a separate section to signal the ecm ...

when you said.. you used the grease that came with it...   does that mean that you reused the existing grease.????   packets are 99 cents...  little tubes of dielectric grease are 3 bucks..   if the module has operated without proper amount of grease.. it will fail...  it may work... but since it was broken internally... the connections are still broken.. it just happens to still work before it gets really hot..

your problem is going to require the replacement of parts... not just testing..

start with the coil.... they are cheep...depending on where you buy them... when they fail... they will sometimes do strange things...   with reduced coil output.. the engine can misfire and get really hard to start.. if not impossible.. and it will pass a spark test..  but not a coil output test...    a 3/4" bright blue snappy spark...  when bad... there will only be an orange wimpee spark..  

then the module and pick up coil...  

if you can if you have a strong magnifying lense.. open the case on the ecm and examine the individual solder joints for thermal cycling..    circular cracks in the solder connections.. mark them with a sharpie marker... if you don't know how to resolder them...  there are people who do.. like ham radio guys and vcr repair guys..