Ok, I have a 91 RS 305 5 speed. It's always ran like a champ, excellent throttle response. The past couple weeks when I can it (while it's still cold) It bogs out and stutters, acts like it's working hard but struggling if that makes sense. It's not cold here, like 85 degrees, and usually the car was it's fastest on the first 10 minutes of driving, not any more. Even when it's warm, fully warm, it is faster at 3/4 throttle than at WOT. The car is also overall much slower. I have a street by my house that by a certain point I would always be going 95 MPH, always for the past 2 years, now it'll only get to 85 or so.

Engine has 130,000 on her but it has always been extremly well maintained.

Any idea what's up?

Thanks, Matt

 

sounds like it's running lean there, try some injector cleaner in case they might be a little clogged.

 

Mine has been doggin too, I just replaced the fuel filter today thinking it was running lean and the computer was taken spark or something and overall it was just losing perfermance.

I have cross-fire injection so if i sprayed some carb cleaner on/around those injectors would this clean it, how else could i go about cleaning the injectors, thanks.

 

it would clean the spray nozzles but getting some fuel injector cleaner that goes in your fuel tank is better to clean the inside of the injectors where they really get clogged.

 

As soon as you find out what it is,LET ME KNOW! My cars doing the exact same thing and its pissing me the hell off.

 

Thanks for the responses, I'll give it a try tomorrow and let you know if the injector cleaner worked.

 

Check the IAT and CTS sensor

Kat

 

For 4 years I drove with the stock ignition coil and some ok gm 8 mm wires and delcos... performance dropped over those 4 years so gradually that I never really noticed until my cold starts started getting longer...

I did the full tuneup and holy mother of mercy I got one hell of a wake up out of the car... popping in a MSD blaster coil messed around with my low end midrange torque too for the better...

with all good things there must be a balance and with the increase in performance came a hit on the brakes... I did 6 months of my regular daily driving wear in a span of 6 days... needless to say I hit warning metal quick...

Here's some things you can do to wake up a tired setup...

-Use some engine cleaner to clear up blocked passages and remove varnish.

I got a can of this stuff called revive for carbs and its supposed to clear up passages by reacting with normal carbon buildup. It took 45 mins to clear the junk out of my system but throttle response went up noticibly so I'm guessing I was a bit clogged up in the system as a whole. I had to manually clean my egr passages though and after seeing what was in there, I'm guessing what was in the exhaust piping was just as bad.

-Give it a tune-up with a new coil too.

I did it, and all I can say is if I was pulling the stock numbers at the rear wheel a month before the tune-up, what the hell am I doing now cause it jumped severely higher in performance...

-Change ALL fluids. Oil, coolant, transmission, differential, power steering.

I do this just out of peace of mind and actually it runs a good amount better too.

-Lube up ALL bearings.

How ya gonna get speed if your wheels can't spin? Seriously, when lubed up all wheels have an easier time spinning so its easier to accelerate.

 

I dumped some sea foam in the tank, drove it about 100 miles now and it still seems to be doing the same thing, i'll give it a little longer and see if the sea foam does the trick.

 

try checking out ur cat. if ur converter is getting clogged it can cause that same problem under load and seem fine at lower power.

 

Ok, I replaced the fuel filter, ran sea foam through her and then injector cleaner. It seems to be running much better!!

Thanks for the help!