I have an 88 Iroc 5 speed with the stock 305, headers, and a flowmaster exhaust. I removed the smog pump when I put the new headers (Hedman shorty headers) and new exhaust (flowmaster 2.5 in, dual 2in output) on and also put in 26lb (accel brand from summit racing) injectors because the old injectors we're going bad. During this I also installed new spark plugs that were hotter than the OEM, bosch platinum spark plugs, and installed a new O2 sensor. I probably should have installed new oem injectors but I am planning on making cam changes in a few months and wanted to make sure I had injectors that could handle a change in hp. I have tunercat software and a willems eeprom programmer. I am using the AT29C256 eeprom chips and write onto the last 4000 (hex) - the back half of the card, so the computer has no problem reading the bin. The problem I'm having is that I cannot get the car to idle below 2500 rpm. I've driven the car around the block and to the gas station in its current state and I noticed that as the engine temp increases the "idle" rpm also goes up. I've never had the engine warm up to its optimal temp - 190 thermostat. These are the adjustments I made through Tunercat:

ECM Switch Table;
1. turned off EGR diagnostic

ECM Constant Table;
1. "Injector Flow Rate (single fire)" - from 20.8#/hr to 26.0 #/hr

2. "Injector Flow Rate (double fire)" - from 20.8#/hr to 26.0 #/hr

3. "Egr On (TPS) - from 5.9% TPS to 99.6% TPS

4. "Min. Mat to ENable EGR" - moved to 150.5 Deg C

5. "Hot engine 02 Timer" - moved to 30seconds
"Warm Engine O2 Timer" - moved to 60 seconds
"Cold Engine O2 Timer" - moved to 130 seconds

6. "AIR Control Enable Coolant Temp. Thresh" - moved from 14.75 deg C to 150.7 deg C

7. "Display Injector Flow Rate" - moved to 4.25 gal/hr
(I calculated this from Summits web page that gave the injector rates in CC/Sec and just converted to gal/hr)

8. adjusted the fuel shutoff for RPM and mph and fuel resume in those settings.


ALSO,I played around with the pulse width moving it from 5.554 msec to 6.943 msec and a few spots in between to see if that had a significant effect and it did not.

I've read through all of the DIY Prom and the Sticky threads at the top of the message boards a couple of times each. Maybe I've missed something but I'm lost at this point and looking for advice on what I need to adjust. I am using $32B code (88 TPI 305). I just want the car to be able to drive again. Any help or hints on what to adjust would be greatly appreciated.

thanks alot,
Jeff

 

thats alot of injector for a 305 with minimal mods, but changing it in the chip is what you need to do and looks like you got it right, however, I am only use to speed density.

the main thing is just to change the injector constants (flow rate) and work from there. i just got the new accels from summit as well but the 24#s (for lt1 cars) for my 350 tpi.

basically I have my injectors set to 24 constant stock is 22 for 350 tpi's, and it seems to be working fine.

I still need to tune my timing and fuel charts soon, but now I am making an emissions chip to help pass that first.

and thats how I have my air and set set to to make sure they are disabled.

do you have the charcoal canister evap purge system still? might want to disable that as well.

 

I'm not sure what the charcoal can evap system is or how to disable it.

 

2500 rpm idle is either a large vacuum leak, or, throttle is stuck open, or, TPS volts are too high and causing throttle follower to open the IAC, or, IAC is stuck open.

The speed increase as the engine warms up could just be the oil getting thinner when warm (which is the main reason more IAC is needed for cold engine to keep a same RPM as a warm engine needs).