Low idle on cold start after TB upgrade

**Tegzieboi_BAR** · 02-06-2010 03:44 PM

Hi there guys,

Due to a sticky Throttle Body on my B18CR and numerous failed attempts to fix it, i decided to upgrade it to a Blox 66mm TB. I port matched the B18CR IM and fitted it with a new Blox TPS.

Since it has been installed my engine revs have dropped to a very low 400-500 RPM on cold start, almost feeling like the motor is about to stall as soon as i turn it on. Soon as the engine warms up only slightly (1 or 2 minutes) the revs gradually head back up to 1000 and stay there so theres no issues once the engine is warm.

With the standard TB my motor revved up and around 1200-1500 when cold and dropped to 1000 once warmed up. What could have caused this dramatic change in revs? The IACV remains as was, and i never had issues with it. All idle adjustment screws have been fixed to the best position but the issue remains. Can anyone give me an insight as to why this could have occured and how it can be fixed. Its really not a major problem but it has got me baffled

Thanks in advance,
Pav

**Tegzieboi_BAR** · 03-06-2010 09:43 AM

Anyone? Perhaps the TB gasket could be leaking? Im using a modified OEM gasket, will make up one to suit n c if anything happens, hav my doubts tho.

**AXS** · 04-06-2010 03:43 PM

if it was leaking it would actually rev higher not lower, so i doubt its a leak of any sought.

**Tegzieboi_BAR** · 04-06-2010 03:52 PM

I think it has to somehow be related to the IACV... we did a test n pulled out the IACV plug which did absolutely jack all, which suggests that the air might not be reaching it. I think the ITR gasket may have blocked a hole somewhere along the line, will pull it apart tomorrow n hopefuly solve this puzzle.

**delsol9000rpms** · 05-06-2010 01:04 AM

there is coolant lines going to the bottom of the throttle body to a sensor, its sort of works like a thermostat which is for cold start not sure what its called but. you most probably dont have it on the new throttle body...

**AXS** · 05-06-2010 03:14 AM

most after market tb's dont have coolant lines, my skunk2 tb doesnt, im running a stock b18c7 ecu and cold starts are fine, idles at 1500 rpm then drops to 900-1000rpm when warm.