91 lumina hunting idle and dieing

91 lumina with a 3.1, suto with air and 110k miles. new computer, new coolant sensor, new crank sensor. Starts and hunts for an idle. serging up and down around 1500 rpm sometimes up to 2000 and sometime dieing. at first there was "no communication" with the snap on scanner thats the reason for the new computer, ecm. the radiator fans would come on way too early or sometimes not at all. thats the reason for the coolant sensor. and the output of the crank sensor is supposed to be .1 volts or greater. thats the reason for the new crank sensor. but after the crank sensor it still doesnt put our much more than .05 volts. after the new ecm it has fast communtcation to the snap on scanner, but the fans will not kick on and the engine still serges bad and misses. it will die sometime and restart easy. we had a 96 cutlass supreme there with a 3.1 that had many of the same parts. we swapped the map sensor, nothing, swapped the iac, nothing, cleaned the iac and the thottle body throat. still does the same. we unhooked the coolant sensor in order for the fans to kick on so we can try to figure it out, but the engine light is on. it goes off when it is plugged in and still doesnt run any different. still serging or hunting for a continous rpm from aroung 500 up to 2000 and all in between. we have about 40psi fuel pressure. the car has been sitting for about 9 months. the gas doesnt smell too old. we just put head gaskets on the car because they were blown, i got the car off my grandfather. Id say that the fans didnt kick on and he got it too hot and poped the back head gasket. it is driving me crazy, i need to get this car running. we checked the iac like it says in the book. 40 to 80 ohms across a and b and c and d. they are the same. we checked the ohms on the crank sensor and its good. maybe the wires from the crank sensor to the coil pack? help help help. please. thanks

Vacuum leaks, egr stuck partly open?

i checked for vaccum leaks, none, how do you check the egr? it had a dead miss in it last night. we checked the tps, the coils, and the icm. all good. going to the cat converter and the plugs next. it had one felpro head gasket on it when we did the heads. you think someone could have got the pushrods mixed up before. the ex. or intake are longer than the other, i cant remember whick right now. and i dunno if this got worse after my grandfather bought it or it has always done this.

You would have bent a valve if the rods were switched, then low vacuum and a misfire, do a compression test if you suspect that, remove the egr clean it and reinstall, leave disconnected for test purposes.

come to find out that our three long plug wires are the 1 3 5(they are labled). they go to the back of the motor. BUT!!! the intake says 2 4 6 on the back. where the heck is the #1 cylinder. i dont think the motor has been changed by the looks of things. If #1 is up front then it is wired wrong and that would explain the bad exhaust smell, the very quick heat up of the engine, and it running like poop! help max.

Check this link.http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800679c5

Did you happen to disconnect the battery lately for anything? I have a 94 that had a haunting idle problem easy fix no cost! I replaced the alternator so i disconnected the battery to do the job, well when you disconnect the battery on a Lumina it resets the idle.

I found this helpful as well..
http://pic90.picturetrail.com/VOL2210/713502/5641765/327187837.jpg

max, the intake says 2 4 6 on the back, thats right because the intake runners cross. so the 1 3 5 cylinders are on the back. i suck. and Mo, i have unhooked the battery a number of times messing with this car. thank you tho.

now it has a miss instead of a hunting idle, we check all of the injectors and all the coils and modual. would the coils check good if they were breaking down? the car has been sitting for about 9 months so we drained all the gas and put new gas in it to the top. we had a fuel pressure gauge on it off the fuel rail. when we hit the release button moslty air and a little fuel came out for about 5 minutes after most of the fuel came out that was pressurized. AIR? where would that come from?

Cracked fuel hoses, for one, what was the pressure?

37 to 40 psi.

Press. is ok.

found a pin hole in the pressure fuel hose, as a temp fix we duck taped it. still has a miss. run good for a second then miss, and on and on. checked resistance on all the pulg wires and changed the coil packs one at a time with some used ones, even though all of them checked good. some times it will idle fast and sometimes slow :banghead: .

How hot should the cat converter read on the snanner after running about a minute and a half???? not 700 degrees right? especially when a lazer temp reader read 110 degrees off the cat. i think the O2 sensor is bad. anyone know?? no O2 sensor code though.

On a cat you want at least 100 degrees hotter coming
out of the cat than going in. If not the cat isn't doing
it's job of reducing emissions.

so if the cat doesnt do its job then what happens? could it be clogged? cause im not trying to save the world with this car. ill cut it off if it gives any problems.

If the substrate inside the cat has melted due to over
heating from it being either fuel soaked or due to a
misfire, it will eventually clog and no exhaust will pass,
or if it does, very little. That's why using a vacuum
gauge hooked to a manifold vacuum source is so
helpful in diag engine condition. You can also take
it to a half decent exhaust shop and have them
do a back pressure test for very little money.
They can help determine if the cat is clogged.

You can also pull the o2 sensor out and see if the engine
seems to run better. Pulling the o2 out temp lets
the exhaust out of a non clogged hole. You'll set
a code for the o2, but at least you'll be able to
find out hopefully, if the engine can now breath.

would a clogged cat make it miss? it sounds like an ignition miss. its not a constant miss like a mechanical miss. the fans dont kick on and it idles about 2000 rpm. the icm checked good and so did the coils. new crank sensor, ecm, iac motor, checked the tps, new coolant sensor, new head gaskets because i got it with one blown, new O2 sensor. if i cant get this thing fixed in one more week it will be crushed. it started out as a free car. now i have some dough in it!! PLEASE SOMEONE FIX THIS POS

I admit I've never seen a clogged cat cause a miss, but
it will surely not let the engine breath which is just a
large air pump. If you have a miss, really the only
way to get to the bottom of the prob or at least a
lot further than a lot of things is to put the engine
on an ign scope. A scope can monitor primary
ign waves, and secondary waves. It cna help
determine if an inj is messing up, if there is high
resistance in either the pri or secondary ign, can
compare companion cylinders for for ign strength
or lack of and can really help get to the nittiy
gritty of what is going on..

Problem is, finding a GOOD shop with a tech that
can read scope patterns as in Raster, Parade and
Superimposed. But if you CAN locate a shop that
do a decent scope setup and readout, it can save
a lot of headaches. The other deal is our system
is a DIS system IE a waste spark system so one
can really only see the ign in Super imposed.

Here is an article that might help you. I realize it's
not specific to your problem at hand, but it might
shed some light upon your dilemma.

http://findarticles.com/p/articles/mi_qa3828/is_199907/ai_n8876015

I still have to get mine started as well. I bought a
factory service manual from eBay for 99 cents
and I'm just waiting for it to arrive to start my
fixin'..

Anyway I hope this helps a bit.

Whoops. I made a mistake about the Super imposed
pattern being the only pattern. One can see other
patterns if one used an adapter for the scope to
DIS system. I have one for a small scope I have
here at the house.

http://www.aeswave.com/new/www/images/products/76/UEI-adl7100.gif. I have to use
this adapter for the secondary pattern.

Anyway enough showing my a**. If I can find anything
out, I'll be sure to post so maybe we can all get to
the bottom of these 3.1's running so weird.

Whoops. I made a mistake about the Super imposed
pattern being the only pattern. One can see other
patterns if one used an adapter for the scope to
DIS system. I have one for a small scope I have
here at the house.

http://www.aeswave.com/new/www/images/products/76/UEI-adl7100.gif.

http://www.aeswave.com/Products/Product.asp?i=12&ci=3

I have to use
this adapter for the secondary pattern.

Anyway enough showing my a**. If I can find anything
out, I'll be sure to post so maybe we can all get to
the bottom of these 3.1's running so weird.

i was told that it could be the injectors that are making the car miss. three of them check 12.6 ohms and three check 12.7. they are supposed to check 11.8-12.6. so what do you think?

i was told by guy A that the ohms is ok. guy B scoped one injector out and said that it was bad. scoped it on a graph thing. he said that it shouldnt spike like that. i found a bad vacuum leak and stopped it. it still misses. ??????????????????????

If one inj is spiking high, then it has too much resistance
in the circuit or is possibly clogged or partially. You can
do a drop RPM test. Pretty easy. Get it to idle and
then pull each plug wire from the plug for just a couple
of seconds, make it quick. When you pull a wire,
listen for the RPM to drop. If it does that's a good
cylinder and is firing. When you come across one
where you pull the plug wire and you get NO drop
in RPM then you've found your bad cylinder.

I'm not sure on this, but I believe you can so the
same to the inj plugs, but you must be pretty quick.
Get it warned up and idling. Then pull each inj
connector from the inj and see if you get an rpm
drop. If you do, then that's a good cylinder and
is firing. When you come across one where the
RPM doesn't drop, you've found your bad cylinder.

I just received my service manual from a seller
over at eBay. It is massive. At least 3" thick and
appears to have everything about a Lumina in it.

http://i8.ebayimg.com/03/i/000/fc/6d/f7a7_2.JPG

I'll go through it to the troubleshooting misses, etc,
and see what is avail which I'll post you want.

I'd also check the IAC Valve. It might just be so bad it's dipping down to where things don't function properly.