iac issues? engine acting up

[Keesh]

i just did an engine swap series 1 v6 recently and up till now its been running smooth. im now having issues with it not wanting to run on cold start,

when i first start it, the accelator has to be pressed because the butterfly is getting stuck, now when i start it, it doesnt rev up to 1000 and then die down like it normally does, it just runs **** from the start.

when it starts i cant depress the accelerator or it dies,
sofar ive swapped bits and pieces around, with no luck.

when its running, if i give it a quick rev(open up the butterfly 100%, it will die
no codes logged at all, swapped pressure reg and injector rail, swapped throttle body but had it in bits(dont no if the sensors have to be re alined) after i really get it hot, it starts sucking air normally and have no issues

IF YOU HAVE ANYTHING AT ALL its got me scratching my head, cant take it to work cause its unreg

[accentstencil]

i just did an engine swap series 1 v6 recently and up till now its been running smooth. im now having issues with it not wanting to run on cold start,

when i first start it, the accelator has to be pressed because the butterfly is getting stuck, now when i start it, it doesnt rev up to 1000 and then die down like it normally does, it just runs **** from the start.

when it starts i cant depress the accelerator or it dies,
sofar ive swapped bits and pieces around, with no luck.

when its running, if i give it a quick rev(open up the butterfly 100%, it will die
no codes logged at all, swapped pressure reg and injector rail, swapped throttle body but had it in bits(dont no if the sensors have to be re alined) after i really get it hot, it starts sucking air normally and have no issues

IF YOU HAVE ANYTHING AT ALL its got me scratching my head, cant take it to work cause its unreg

If you had your throttle position sensor off that could be your problem because they need to be correctly aligned.

[Keesh]

i didnt take it off BUT i had the butterfly out for maching, its possible that i rotated the tps.. i duno, but its ****ing me off cause i have an epa on it and cant take it to coburg to get it taken off!

[Cheap6]

There is no provision for adjustment of TPS on VN-VS. The TPS position (voltage) is "learned" by the ECM each time the car is started. If you can only start the car with the throttle opened, the TPS voltage will be different on start to that when you release the throttle which will mean that the ECM doesn't 'know' when to start moving the IAC motor to control the idle speed.

If the TB is sticking intermittently, the IAC position required to maintain idle speed will keep changing = stall when the IAC jumps to the incorrect position and can't correct fast enough.

If the IAC motor itself is sticking, it will also cause a stall.

It may be another fault unrelated to the TB like coolant temp. or air temp. sensor as these may not set a code.

[Keesh]

coolant temp should log a code though correct? i recently had a code ahh 14 mayb either way it needed a new coolant temp sensor..

so if it sets a position when the butterfly is stuck then im asuming it wants to jump back to that position on idle? its only doing it untill hot im still in the process of swapping sensors and such but is there a way to reset the iac? for example adjusting the stopper to an open position then reseting the ecm?

its almost like the engine isnt sucking air? if thats posible could it be gaining air pressure somewhere that its losing vacuum?
im still wondering why its stalls or cuts when i open the butterfly really swiftly

[Cheap6]

coolant temp should log a code though correct? i recently had a code ahh 14 mayb either way it needed a new coolant temp sensor..

so if it sets a position when the butterfly is stuck then im asuming it wants to jump back to that position on idle? its only doing it untill hot im still in the process of swapping sensors and such but is there a way to reset the iac? for example adjusting the stopper to an open position then reseting the ecm?

its almost like the engine isnt sucking air? if thats posible could it be gaining air pressure somewhere that its losing vacuum?
im still wondering why its stalls or cuts when i open the butterfly really swiftly

A code won't always set, even if a sensor is reading incorrectly. It has to be outside the limits programmed into the ECM to set the code. Sometimes the car has to be driven to create sufficient data for the fault to be determined.

I've posted on here previously coolant temp. sensor data if you want to test it but I'd have to search for it the same as you and I'm lazy .

The IAC moves to control the idle speed, so you can't set it to a particular position. The ECM will learn a basic IAC position which it will start each idle 'event' (for want of a better term).

It's similar to the way in which a base injector pulse (= IAC position) is corrected with feedback from the O2 sensor (= idle rpm) and then the base injector pulse 'relearned' to reduce the amount of correction required.

Your last paragraph: The TPS (rate of change in voltage) is also used to enrich the fuel under rapid changes in airflow = to the accelerator pump in a carb.

A faulty MAP sensor (or pinched hose) could do that also.

[Keesh]

pain in the ass to diagnos! ill just have to keep swapping i guess, lucky parts are a dime a dozen at pick a part, ill just grab a variety of sensors! see the thig is ivebeen cleaning my trottle bodys, and i read im not sposda spray inside and i did, dunno if its a huge drama

[Keesh]

i just learned about accelerator pumps in carbys today at tafe so its very relevent! im guna go through my wiring harness aswell just incase theres a loose spot, ive had to rewire the engin harness twice so maybe theres some heatshrink missing or something thanks heaps ill keep you posted

[Cheap6]

pain in the ass to diagnos! ill just have to keep swapping i guess, lucky parts are a dime a dozen at pick a part, ill just grab a variety of sensors! see the thig is ivebeen cleaning my trottle bodys, and i read im not sposda spray inside and i did, dunno if its a huge drama

Spraying inside can wash the lubricant out of the throttle shaft = wear and early failure. I wouldn't stress about it, just not do it again. It's not like it will fail tomorrow. Many other people have done it before you, including professionals. You might, somewhat optimistically perhaps, try some spray grease around the throttle shaft where it passes into the casting..

[Keesh]

i just got antother tb for 15 bux and a pocket full of sensors so ill swap and see how she goes