Hesitation/bog problem advice

93_Clubman · Postby **93_Clubman** » Wed Dec 02, 2015 12:20 pm

Believe ampz thinking in that post was that if it was getting more air than what's just metered through the intake track then the car would continue to run & not almost immediately stall when the IAC pipe is disconnected while the car is running.
Question is how long is yours continuing to run for before stalling when the IAC pipe is disconnected while the car is running, ie how long do the revs slowly drop for before the car stalls?

project.r.racing · Postby **project.r.racing** » Wed Dec 02, 2015 1:02 pm

Chicken_Lips wrote:
93_Clubman wrote:Partially similar issue with this NB8A, also without posted resolution, but maybe try suggestion in last post of first page: viewtopic.php?f=29&t=29296

With the IAC disconnected the revs slowly drop and the car stalls

that sounds like an issue also. cos disconnected it should be fully open and engine should be over revving, not stalling.

but that is a completely separate issue to your bogging down issue.

93_Clubman · Postby **93_Clubman** » Thu Dec 03, 2015 11:08 am

project.r.racing wrote:cos disconnected it should be fully open and engine should be over revving, not stalling.

If we're refering to the same pipe (2cm OD approx from IAC to engine intake cross pipe), on my NA8, from memory disconnecting it while running fairly quickly caused my motor to stall.

project.r.racing · Postby **project.r.racing** » Thu Dec 03, 2015 2:58 pm

93_Clubman wrote:
project.r.racing wrote:cos disconnected it should be fully open and engine should be over revving, not stalling.

If we're refering to the same pipe (2cm OD approx from IAC to engine intake cross pipe), on my NA8, from memory disconnecting it while running fairly quickly caused my motor to stall.

But the car in question is not a NA8. So it does not have that pipe.

The the poster said he disconnected a NB8A IAC, I could only assume he meant the electrical connection.

93_Clubman · Postby **93_Clubman** » Thu Dec 03, 2015 5:23 pm

Yeah, know OP has an NB8A, hence saying my comment was in relation to an NA8.
My thinking in terms of ampz's post was pipe as opposed to plug, but just as easily plug as opposed to pipe.

Chicken_Lips · Postby **Chicken_Lips** » Fri Dec 04, 2015 2:00 pm

When I disconnect the plug to the IAC the first time i start the car idles at about 500rpm. Very lumpy idle. After that I give a little press on the accelerator and the car stalls after the revs drop. From there it just stalls every time I start it. I can't make it idle if I try.

hks_kansei · Postby **hks_kansei** » Fri Dec 04, 2015 3:22 pm

Chicken_Lips wrote:When I disconnect the plug to the IAC the first time i start the car idles at about 500rpm. Very lumpy idle. After that I give a little press on the accelerator and the car stalls after the revs drop. From there it just stalls every time I start it. I can't make it idle if I try.

That sounds normal to me.

The IAC is simply a valve that opens or closes to let some air past the throttle.
With it unplugged it will be closed all the time, less air to the engine means lower revs (hence the low idle)

When you blip the throttle the throttle opens and allows more air in, hence revs rise.

It will stall afterwards because normally as the revs drop the IAC opens a little before it's needed in order to have some air already there for when the throttle is closed. Without the IAC able to do that the engine basically is starved of air for long enough to stall.

You could likely get it to start again if you started it with the throttle open a bit.

Chicken_Lips · Postby **Chicken_Lips** » Tue Feb 16, 2016 7:05 am

I finally got around to stripping the intake down. Problem solved (fingers crossed).

It's been a couple of cold morning starts and I haven't had an issue.

I think that the problem was a clogged EGR tube within the lower manifold. The tube from the EGR that runs through the lower manifold into the upper manifold was completely blocked off with carbon deposits. The tube that runs into a copper pipe to the exhaust was nearly closed over also.

Last step will be to get that copper tube out and cleaned.

Thanks for all the advice.

Steampunk · Postby **Steampunk** » Tue Feb 16, 2016 9:14 am

I don't mean to be a downer, but I doubt it's an EGR issue as its a very non-vital component. people have either blocked them off on purpose or accidentally placed the tube (with the one-way valve) backwards. The one from the exhaust manifold is also often blocked off, or non existent, on aftermarket headers.

If it actually does solve it , then great.

Chicken_Lips · Postby **Chicken_Lips** » Wed Feb 17, 2016 12:12 am

Fair enough, something I did along the way had an impact anyway. Seems to have gained a few ponies too. What I did was take the intake out completely and clean everything from the throttlebody to bottom. Everything went back as before. Strange.

Chicken_Lips · Postby **Chicken_Lips** » Wed Feb 17, 2016 10:59 am

Steampunk wrote:I don't mean to be a downer, but I doubt it's an EGR issue as its a very non-vital component. people have either blocked them off on purpose or accidentally placed the tube (with the one-way valve) backwards. The one from the exhaust manifold is also often blocked off, or non existent, on aftermarket headers.

If it actually does solve it , then great.

You were right. Hesitation is still there, I jumped the gun. It has definitely improved, I only make it to the end of the street before it fades away and I certainly have an increase in hp.

I can probably live with this as long as it doesn't get worse, the car is a pleasure to drive now.