i posted a similar thread to this but have done a crapload of work since then and the issues have changed slightly since then so i am posting another thread.

the car is a 91 RS 305 TBI (Tough But Inadequate)

when i got this car, it wasn't running. the plugs, wires, distributor had all been changed on the car. the lady said there was a leak in the intake manifold that she had repaired but it still wouldn't run right. there were receipts to prove this, but that doesn't mean the guy did a good job when replacing the gasket.

after that, we changed the idle air sensor and the mass airflow sensor and it ran, but would stall out when in gear at a stop light or when i let off the brake and hit the gas... same with reverse.

so, i changed the EGR, and put an injector on it (because it was in dire need of one on the passenger side) also changed the pcv valve, and traced ALLLLLL of the stupidly annoying vacuum hoses and found a few little things that weren't tight and clamped them down or blocked them off depending upon what they were. (the one i blocked off for sure was the one that controls the valve in the factory air restrictor (i.e. air cleaner) since i put an edelbrock air cleaner on the top, and set the idle.. the idle was set at 20 degrees!!!!!!!!!!!!!!!!!!!!! twenty!!!!!!!!! I set it back to 0 which is supposedly factory spec on this car considering it's computerized, and that is seemingly the only thing the computer does in this car / adjust timing.

anyway, after that, the car runs GREAT - when the engine hits normal operating temp.

there is still some hesitation when you hit the gas, and if you accelerate and hold the gas pedal in a specific spot without moving your foot, it still hesitates and sputters while winding up to whatever RPM you're trying to be at but ONLY IF IT'S IN GEAR and driving..

--- however... when the car first starts, if you immediately back out of the driveway and attempt to drive it, it sputters, hesitates, acts like it wants to die and will not go beyond whatever speed the transmission happens to want to go at about 1800 rpm.. it acts like it's not getting gas... i immediately pull back into my driveway, pop the hood and make sure the connection is still good on the injectors, and when i hit the gas, the injectors spray the hell out of the gas like they should.

then i get back in the car and take it out again and it sputters and hesitates and acts like it wants to die, and the whole car vibrates and shakes and sounds like it has a miss in it or something.

but... once it gets warm, the idle smooths out, the miss pretty much goes away, and the hesitation pretty much goes away, but still doesn't run optimally, or like a newer car would.

i've mentioned the things that have been changed, i may be missing a few things that i haven't mentioned like a new air filter that went with my edelbrock intake, but aside from that, i think that's just about everything.

i HAVE NOT changed the fuel filter on it yet, and it NEEDS to be done, but i will not agree with anyone who tells me that my car is running like **** when it's cold, but runs fine when it's warm because of the fuel filter... it would run like **** consistently... i don't want to keep throwing money at parts until i know specifically what i need.. and like i said it neeeeeeds a new fuel filter, but i'm holding off for a minute.

the general standard answer that everyone gives me is "vacuum leak" that's the basic 101 answer... can anyone provide something a little more in depth that may actually help me pinpoint the issue? i've gone over all of the vacuum lines about 4 dozen times..

the only thing i haven't looked into though is to see if there is a vacuum line that goes TO the transmission (it's an auto) and what condition it is in on either side. i assume there is one, but i can only make assumptions as to how it fairs since it's not all that easy to jack the car up high enough to look under there in my garage.

also, with that said, when i got the car it was running on fumes, hardly any gas in it, but it WAS bad gas.. in the last month and a half, i put a full tank of gas in it with some seafoam, and seafoam in the oil, but i'm still on the same tank of gas, and i have driven the car 100-150 miles at most since i put gas in it.. i'm still on the same tank of gas..

I say that because, someone before mentioned driving the car like normal after changing the EGR for a while i guess in order to break it in, or to clean the **** out of the motor, or for some reason.. i don't remember for sure... so, if there is a period of time / amount of miles that i need to drive the car before that happens, i probably haven't driven it far enough to work that kind of crap out yet.

so.... that's that...

any ideas besides the blatantly obvious???? (most of which has been fixed at this point)

thanks

 

Disable the egr valve & test drive it, the solenoid might be letting some vacuum pass.

 

I had a 'dead' spot on the gas at about 25 mph cold or warm. I replaced the ignition coil and it went away. Before that i had changed the plugs, plug wires, distributor cap & rotor, set timing to 0, pcv valve. With an old ignition coil you might not be getting full spark. Granted, mine didn't act like it was gonna die it would only hesitate but worth a try imo. BWD-E46 is the part #. It was $40.

The fuel that came out of my filter was cloudy (assuming this isn't normal) and i didn't notice any performance difference with the new one.

 

brand spankin new EGR. is that why you are saying this? or because you didn't see that i changed it. asking because i legitimately don't know.

 

as for the coil, that's a thought that i haven't given.. i'll check it out and see if it's new or not. it would only be assumption at this point, but it would be nice to assume they changed it when they changed the rest of the ignition system out, but, they also didn't change all the other crap i had to change out, so i'd lean towards the fact that it's the original one since 1991 lol.

interesting thought though, i'll look into it for sure thx.

 

I'm not questioning the egr valve, I'm questioning the solenoid that controls it. Read what my post says.
BTW tbi cars don't have a mass air flow sensor.

 

wasn't questioning your questioning, i just don't know much about egr's or what makes them tick really, but i get what you meant now.

as for the mass airflow sensor, i think i meant map sensor. the LT1 motors have the same piece on the top of the motor near the intake, and i'm used to working with LS1's which have mass airflow sensors. but also being used to LS1's you just plug the damned thing into a computer and it tells you what's wrong and you fix it. don't like how it runs, plug it into a programmer and tell it what to do and it does it. i'm not used to this gen 1.5 fuel injection / half car half computer almost cyborg but not quite intelligent - stuff yet.. am used to all computer or no computer, still trying to figure out where this car lies in that realm. far as i can tell the only thing the computer actually does is handles the timing and probably messes with the idle, but not sure what else. i think an msd box and a carb would be a good fix for that... lol

 

also, the coil hasn't been changed since 1991 it looks like, but i don't want to go throwing parts at it until i can find a specific problem. granted, it would help to change it but i think it may have something to do with a sensor somewhere else, like, one of a few various sensors that does not activate until the car is warm.