Another high idle has entered the battle
09-23-23, 02:29 PM
#1
Rotary Enthusiast
Thread Starter
Another high idle has entered the battle
Hi, recently picked up a stock original series 4 rx7 turbo. It has a high idle around 2000rpm. Sometimes it値l drop to 1500rpm and sometimes it値l hunt evenly up n down a few hundred rpm from there. just posting this to document what I did to hopefully fix it.
Throttle cable doesn稚 appear to be binding but have removed, cleaned and lubed. I took upper intake off so as to check the fast idle was set correctly and the function of the thermowax. Found the intercooler to throttle body intake hat was not tightened all the way down, could this contribute to the high irregular idle?
The bac coolant passage was blocked so thermowax was not extending rolling off the cam. Cleared the blockage, checked the bac clicks when 12v applied. tested the tw with boiling water, it will now extend so set the idle temp cam to just above the first mark and will check how long it takes to come away after reassembly and adjust if necessary. Also freed up the roller that was stuck. If I manually pull away the thermowax rod the throttle linkage stops hard against the throttle stop and closes the primary butterfly the last little bit. Cleaned the throttle body somewhat. Cleaned all of the throttle linkages with carby/tb cleaner and lubed. I have disengaged the dash pot for now to rule that out. Checked and set tps using ohm method, one dead spot around 2ohm point after that clean sweep to 4.7ohms. 😞 so that will need replacing eventually. Going to reassemble today.
wish me luck!
Throttle cable doesn稚 appear to be binding but have removed, cleaned and lubed. I took upper intake off so as to check the fast idle was set correctly and the function of the thermowax. Found the intercooler to throttle body intake hat was not tightened all the way down, could this contribute to the high irregular idle?
The bac coolant passage was blocked so thermowax was not extending rolling off the cam. Cleared the blockage, checked the bac clicks when 12v applied. tested the tw with boiling water, it will now extend so set the idle temp cam to just above the first mark and will check how long it takes to come away after reassembly and adjust if necessary. Also freed up the roller that was stuck. If I manually pull away the thermowax rod the throttle linkage stops hard against the throttle stop and closes the primary butterfly the last little bit. Cleaned the throttle body somewhat. Cleaned all of the throttle linkages with carby/tb cleaner and lubed. I have disengaged the dash pot for now to rule that out. Checked and set tps using ohm method, one dead spot around 2ohm point after that clean sweep to 4.7ohms. 😞 so that will need replacing eventually. Going to reassemble today.
wish me luck!
09-23-23, 10:47 PM
#2
Rotary Enthusiast
Thread Starter
Got it all back together, need to adjust high idle screw down a bit but come back to that later. Thermowax disengages from cam now. Tps set I noticed a dead spot. Idles surging around 1200 rpm. Unplugged tps smooth idle around 1000rpm. Plugged tps back in turned car off and on smooth idle around 1000rpm, give it throttle goes back to surging. Turned it off n on again, adjusted idle stop screw and idle mixture screw (jdm fc rx7 doesn稚 have idle adjustment on bac) and have a 750rpm smooth idle. Once fully warm it idles and drives 95% well stops pulsing and idles properly. So I need to get a new tps and then can fine tune the warm up system and set the dash pot. Fun times
Last edited by ben.farnath; 09-24-23 at 12:15 PM.
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j9fd3s (09-24-23)
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