86 iroc 305 tpi when i restart engine it idles at 1500 rpm for 30 to 60 seconds some time longer then idles at 800 for 5 seconds the raises to 1100rpm for 15 seconds then finally idles at 800

work done engine rebuilt to stock specks.complete drive line rebuilt. Intake sys. cleaned and has no vacuum leaks all new sensors except the MAF it tested ok. new IAC valve,TPS,Computer and E-prom,new fuel pressure regulator,fuel pump and injectors,EGR and temp sender. all GM parts all electrical items checked for proper ohm range and tested during operation all wiring checked and addition of a complete ground harness added
have run computer diagnostic with a snap on unit and have found nothing . this car has been through a ground up restoration . and last winter i took the engine and trans out again and went through it again their is nothing mechanically wrong with the engine. Went through the electrical system pice by pice found nothing . Went through all vacuum components found nothing wrong. I have the factory service book and have gone through it over and over again. I have had this trouble for 5 years.

 

Welcome to thirdgen.org!!

Check the CTS for proper operation when warm, your manual should show it's resistance for different temps...you should also be able to see the readings on the ScanTool you have.

It's normal for the RPMs to rise for 10+ seconds on restart, but not the way you describe.

 

Depending on the outside temp this sounds about normal.. the 1500 rpm might be 15-30 secods longer than "normal" but nothing I personally would be alarmed about.

 

Thanks guys
The sensor is 190 ohms at 180F and 3.25k at 68F
Have 3 delco sensors and all are in the same ohm range. Though
not exactly to the book specifications this is the correct sensor for this application

Thanks again ccc

 

Have you monitored the IAC counts during the startup/idle issues? See if it is changing to the RPM's, also monitor CTS reading, take note of it all...can you take snap shots with your scanner? I notice you use a SnapOn scanner, I have the MT2500, but never tried the "movie" on it.

 

Hi
Sorry it took so long but hear are the results

Engine Cold
RPM Counts Engine Temp.
950 132 59 F
925 129 61
900 120 118
875 103 124
875 93 138
800 84 160
750 75 192

Engine Hot
RPM Counts Engine Temp
1500 118 190 F
975 49 192
1075 51 192
1050 50 193
825 27 196
725 23 203
Sorry it looks a bit messy the text did not Line up when I posted it.