928sg Posted June 4 Report Share Posted June 4 I'm back at it again and I've forgotten all the stuff I learned in 2021 setting up the Thunder. It's a 32 valve V8 with ITB's and I had it running although badly back in 2021. I'm trying to set the idle, and I feel like there is a setting that is causing the idle to be high. Back in 2021 I could get the idle set at 700 RPM easily just by adjusting the main throttle cable to the linkage quadrant. This time around it's idling around 1500 even after its warmed up. I even fully seated the idle screws on each ITB, and disconnected the linkages and still the high idle persists. The only way I was able to drop the idle was to go into the calibrating settings for the trigger and lock the ignition timing, however as soon as I get close the calibration setting for the timing the idle goes back up. Any suggestions? I've attached the config file. Any suggestions would be greatly appreciated. 5-31 2024 modified tach output.pclr Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 4 Report Share Posted June 4 Your TPS was reading 4% when you saved that map, assuming it used to read 0% when closed, could this suggest it is now more open? Or has the sensor since been moved or something? The difference when you open the set base timing screen is the timing is locked to whatever reference you have set (currently 0 in your map) rather than using the normal advance from the ignition table. So you could achieve the same by putting less advance in the main ignition table, but before suggesting that it would be good to understand what has changed. Have you had the engine apart or something? What's happened between 2021 and now? If its ITB's you really want to change both the fuel and ignition tables to use TPS for the load axis anyway so I can create a better starting map once I know more of the story. Does it have a vacuum manifold or anything similar for a brake booster or idle valve connection? Any chance of a vacuum leak here? Have you checked for leaks by spraying water around the manifold and injectors etc when its running? Are the ITB's all individually linked or are they in pairs like IDF style? Quote Link to comment Share on other sites More sharing options...
928sg Posted June 4 Author Report Share Posted June 4 ITB's are pairs like IDF & I do have a manifold for map sensor and the brake booster. I can check for leaks, and that is on the list for today. What happens if I spray with water? Engine has been rebuilt since 2021. I will look closer at the itb linkages. as I had the same problem with the linkages completely disconnected. Quote Link to comment Share on other sites More sharing options...
928sg Posted June 5 Author Report Share Posted June 5 went back to basics, and disconnected all of the linkages. Set all the idle bypass screws to closed and capped on the main vacuum line to the HVAC system. Got it all set up and synced and idling smooth. Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 5 Report Share Posted June 5 Attached is your map modified to better suit ITB's. I changed fuel and Ign table axes and mapping, charge temp table, lambda target, disabled IAT trim, setup idle ign control, & set up accel enrichment. The fuel will likely be way off now so adjust the master fuel to get it closeish first before adjusting any fuel table numbers. Check you are happy with the ignition advance I have put in there, I dont know these engines well or any details such as your compression ratio or cam timing so this is just a generic/typical 4 valve big bore advance curve. 5-31 2024 ITB fuel and Ign setup.pclr Quote Link to comment Share on other sites More sharing options...
928sg Posted June 6 Author Report Share Posted June 6 Adam, Thanks~! I will give that a try. It is definitely a big bore engine. Bore is 4.095" and stroke is 3.75 coming in just shy of 6.5 liters, with Ti connecting rods, and gun drilled billet cams. Compression is 11.4:1 ITB's are 50mm and I'm running ID 725 injectors, and I have a set of 1050's if I need them. I'm also setup for e85 but not there yet. Quote Link to comment Share on other sites More sharing options...
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