Okay, My 305 has been re-built 2 years ago and many parts were repalced as part of the re-build. All sensors are new and correctly set including the IAC and TPS. The only original parts are the MAF and the EGR valve. Besides the warm start up idle issue I mentioned in a previous post, my car just seems to be running weak. The idle is rough, gas mileage is suffering and the rpms seem to remain high after I take my foot off the gas. This is making the car a challenge to drive. I recently tuned it up and set the timing @ 10-12 degrees BTDC. This helped, but it still sucks. What should I try next?

 

What, specifically, did you do as part of the tune-up?

 

Plugs, cap, rotor, accel 8mm super stock wires, cleaned throttle body, set timing to 10 degrees BTCD

 

Start by reading my answer to your idle problem post, follow through on those recomendations and then lower your timing to 6*and all should be fine.....


You should run hard and idle fine. BTW, the 52MM TB is a little large for a stock 305...... It does eliminate the 3rd gear bog in an '85 350 car.

One last thing to consider, using the IAC reset instruction on the tech pages, reset your base idle speed by adjusting your TB opening, readjust your TPS afterward because it will change if you adjust the amount of opening.

 

I have tried the timing @ 6 degrees. This makes my car run even worse than it does now. I also reset minumun idle speed and tps voltage only days ago. I have also tried clearing the ECU's memory to fix this along with my startup idle problem mentioned in other posts. I have had no luck. The larger throttle body didn't seem to make things worse, and it seems to function well with the 10:1 compression ratio pistons, world products heads, and summit tpi cam. Setting the timing @ 6 degrees makes the car bog something horrible and greatly decreases acceleration.

Anyone have any other ideas???????

 

What prom/computer tune are you running? Hopefully not a stock one.....

 

Stock ECU out of '85 IROC with hypertech stage i chip. I had the same issues when my engine and computer were both bone stock.

 

In that case I'd go back to the beginning: Check for vacuum leaks, check compression all around, see if any plugs look different (richer/blackened) than the others, and realize that it will NEVER run worth a tinker's d@mn with that compression, heads, non-stock cam, etc. on a stock chip. And the Hypertech chips are not all that different than the stock ones and in most folks's mind (mine included) are junk and a waste of $$.

Any chance you've done any data logging to see what the engine is really doing?