Ive been having some problems lately and i wanted to see if anyone had any ideas on the culprit. I was hoping that the FP regulator that i just replaced would do fix it... although it was bad, the only thing this has fixed is the prolonged cranking during startup

Symptoms:
1. Car shakes under a load (worse higher gear at lower RPM(>2000))
2. in 6th on the highway it seems as there is a border to how much i can hit the gas to accelerate without a it shaking, then as soon as you hit that point it will shake like ****
3. a miss could be possible but it would be very small, kind of hard to tell from the LT1s usual roughness
4. WOT is fine, pulls like **** if i try to roll through the gears
5. Some surging taking place... seems almost like i can feel it "catching" every now and then
6. Some pops in the exhaust every now and then... but certainly not in any certain pattern, and not that often (although more than usual)
7. Problem happened overnight... did not happen over a period of time

although my car is OBDII is has been converted to OBDI, and no SES light. I looked over the car tonight checked the vacuum lines, MAF, also plugs and wires, but nothing seemed wrong

most things have been changed withing 20K miles... fuel filter, plugs a couple of times, cap and rotor, wires, coil, clutch, and etc

so what do you guys think... Fuel pump? Opti? something else?

i planned on buying a fuel pressure gauge and checking that out, but i really don't know how to datalog to figure that out... after all it is the PITA OBDII connector, OBDI computer setup

help me out guys, give me your ideas

 

Troubleshooting an opti can be a real PITA if the car isn't throwing codes. I think that checking the easy stuff (like you are doing) is a good start.

Just something else to check because I saw this in 2007 - check the MAF connector on the intake elbow. I had an intermittent weird problem (admittedly the car was throwing a code) where the car would run funny. As it turned out, I didn't fully seat the MAF connector and the car was bouncing between MAF control and default control based on how much the motor was twisting in the engine bay under load. Just a dumb idea based on something that I found once...

My gut tells me opti. How old is this opti?

 

the cap and rotor has 20k or less on it... i have no idea on the rest of it.

also, i already looked over the MAF. It looked pretty clean to me

 

Hmmm, the lack of codes is what is bothering me...

 

anyone else have opinions?

 

I am seeing some of your issues described in this thread about bad optis...

http://www.frrax.com/rrforum/index.p...opic=10536&hl=

 

Could be a vacuum leak. Did you gap your spark plugs correctly?

 

Just for the heck of it,might spray some carb cleaner on the maf wires ever so gently,and see if there is a difference.It's quick and cheap.Hope this helps.

 

ill look into the maf but it did look pretty clean last time when i looked...

However, it did start to throw a SES light last night so who knows... but i really dont have a way to get the code retrieved

the more i think,the more i think it could be the Opti... any more ideas or thoughts anyone?

 

Update: Okay, i guess it isnt throwing a SES... i just forgot to reconnect the sensor on the elbow, but ive reinstalled it and it hasnt thrown the SES in a few days

However, i did notice a small pinhole leak on the radiator that was just a few inches under the cap that i had fixed. from the way it appears it didnt happen much since there was not much coolant gone from the system... maybe a quart or two... given the location and amount of coolant lost could it still affect the opti?

any ideas anyone? i would like to know a little more positively before i just start throwing parts at it

 

Okay, changed the opti today with a new GM one... as long as i was in there it got a EWP also

The problem is still there... im at a loss and very confused. Im probably going to check the coil tomorrow and im probably going to throw the old computer on it an so i can go over the computer and look for codes that the OBDI may not have found

Anyone else have any more ideas on what this could be?

 

Run the car at night and check the engine bay. Look for a light show, any arcing. You can try spraying a light mist of water on the coil wire and see if it's arcing.

 

me and a friend of mine (a mechanic from work who also has a 95 TA) looked it over a few times and we didnt see any arching... honestly both of us are pretty stumped

Other ideas?

 

Did you ever get your fuel pressure checked? Sounds like you eliminated spark, maybe your fuel pump is going. You said you're getting some surge right? And fuel filter and FPR already changed out? You could try cleaning out the injectors or something. If you're willing, GM will check out your car at the dealership for like $90 I think. They will tell you exactly what is wrong with it. Not a bad price for stumpers like this IMO.

 

Okay, looked over the car today... Checked a few of the plugs... they looked like new (though they pretty much are). Checked the grounds on the coil... they also looked good. Also, i cleaned the MAF, it had a little dirt but not much.

BUT, i also put the untuned OBDII computer back on and needless to say she threw a couple codes from the looks of it. Im sure one was the code for the cat , but when it started flashing at me i figured that the "no cat" code wouldnt make it do that. So all i have to do now is bring it to work tonight and have my friend hook up his new $1600 scanner (8-900 for him) to it and find out what is wrong

God i hope that scanner finds something useful

Ideas? Comments?