OK guys,
This is a tad bit annoying for me because im getting 3 Different answers from 2 different techs of mine and i figured what best to start at then the people that drive the car the most.

OK I have been having major problems with my car since the winter break and im trying to figure out why in the world does this happen all and once sometime i just want to .

- The car is sputtoring (sp) from 4K on.
- The car is running extremely (rich/lean)

- The car has a very hard time starting where i have to put my foot on the peddle to get the car to start while cranking the igition. (this only happens when motor is hot)

- The car will start right up if i dont drive the car for a day or two but will keep me worlds of problems if i drive it go get gas and try and turn the car back on

- Car will drive fine cold, once heated up forget it

- Car may die for no apperet (sp) reason. Although doesnt happen ofter

Now, being an LT1 guy im saying the Opti which is my guess. However, this is where my dilema starts. The car get tuned last year and once the battery died the car computer PCM **** out on me and started doing this same stupid stuff (got the computer tuned after and tighted the lifter car ran great after)

and i know all the tuner guys say it cant happen but it did.

well after acouple months probally may the cars battery went out again probally from the extreme winter we had. So, i had to replace it again and this is when the problems started.


So my problem is this............
where do i start
one person is telling me opti
while another person is telling me computer
while the last person is telling me igition module

and all of them are very good possibilties but shouldnt i start with the computer because they run both of them ?

And..... if its the computer how in world does everyone hold a tune and i cant ?
2 different computer same f'in problem


please help anyone with any suggestions i would greatly appericate it.

BTW it not the coil, starter, or anything fuel related i already checked those. While the battery and Alty are brand new too.

 

have you checked spark plug, wires? if youve already replaced PCM and have the same problem, then im thinking its not related to the computer.

opti is a pain in the *** to do but if youve been having problems for that long i would at least take it out and look at it, why not change it if you've never changed it, be a good start.

BTW: what year is your LT1?

 

im thinking ignition other than opti. Plugs wires,etc....fuel pump. Maybe even the cat... fuel filter... i would look at the fuel filter first.

 

O2 Sensors

 

Start with wires, plugs, O2s.

 

plugs are brand new NGK plugs, Wires are 10.4 MM taylor wires, Fuel Pump was installed last year. There are NO cats on the car. However i do have 02s can that cause that many problems and how do i find out if the o2s are bad ?

The car is a 94 Formula motor was bore out to a 396 LT1

 

One way is to scan the car and check the O2 voltage. They are supposed to read within a certain spec. I'm not sure of the numbers, but a search should do it for ya.

 

Unplug the O2's and see how it runs when it warms up. It'll throw codes but that will cause it to stick in open loop and then that will tell you if the O2's are the problem. Then you can test them and go from there. At least that's what I would do.....

 

I think their v is like 400-900mv fluctuating.

 

MAF sensor can also give you lot of trouble...Particuluarly if you run a K & N sytle 'oiled' filter. I've had trouble with mine in the past. Runs fine when cold because the computer is in open loop. Once warm and the computer switches to closed loop it goes crappo. Unlplug the MAF sensor and see if it cleans up - this will thow a code, just like unplugging O2 sensor but the 'puter will switch to open loop and could very well clean up.

I would think it is something in this rhelm (MAF, O2's..) as any other items like wires and distributor shouldn't be affected by warming up....It sounds like some kind of control sensor that is effecting closed loop control. I have seen Coils change with heat (and starters, N/A here)...but you said coil was good...so I would look at computer sensor inputs.

 

everything you guys are saying i have already have done except the 02 sensors never really thought about that.

The coil was just replaced cuz it had oil all over it.
The MAF sensor is now a Genadettli, just replaced tho and problem still happening.

I do not have emissions on the car and the computer has been tuned for that. The 02 sensors are going to be checked but is there anything else i should check and like i said i have a oil leak on the car by the cranck seal so the opti is gonna be fixed today but if that doesnt fix the problem with my 02 sensors disconnected then im totally lost at that point.

 

Just try forcing open loop and see what happens. ANd fix that leak pronto, I lost an opti to that. At speed the air flow will blow that oil up onto the opti, believe it or not.

Insofar as the MAF sensor, KTM might be onto something. Try lightly rapping it with a screwdriver while it's idling badly (warm) and if it changes the way it's runnning (hicups, stalls, etc) it's that.

 

+1 for O2's...seems to be a closed loop problem. This is a 396, has this car had a tune done for it?

 

the tune was done from PCM4Less who did a great job. i never really thought of the 02 sensors but im going to try it when i get home. thanks for the help guys. any other suggestion would be aweasome.

 

What about fuel pressure?

 

from my experience when i had about the same problem you mention it was my opti. I've had 2 other friends that went the opti route that did not fix their problem and found later it was a plugged cat which they just removed from the exhaust all together.

 

i have no cats but i was thinking on my break why would it only happen in higher RPMs if it was the 02 sensors wouldnt it happen all the time, obviously when the car is warm.

 

I can see the o2's causing a problem at higher than idle if they are old or have had some led past through them, also check the o2's wire and plugs for anything not normal, you may have got some moister in the plug or wire, yea it is a long shot but.. o2's play alot in the tuning when in close loop, changing mine gave me better throttle response and a red hair of MPG and power, even though they appeared fine.

 

well i know my 02s are from the orginal block with 88,xxx miles on it the 02s never were changed. This could be my issue compared to a year old opti.

 

Change Them.