Why?

[quattrorunner]

I think I know the answer but wanted some confirmation. I've been tracking some odd running issues and have a couple figured out but
1)why is my boost gauge going slightly beyond 1bar and then spiking past 1.2bar on throttle closing? I have a 1bar Spring.
2) And also I'm getting an issue where the car acts like it's hitting a sandbag when I lift the throttle before pushing the clutch. Hard to explain but it never did that before and I suspect the throttle plate is getting pushed closed by excess boost when it's still slightly open.
The issues I think are figure out are the plug wires. I'm getting a set soon. It's a high rpm stumble. Could that be related to the other issues? Vague I know. Thoughts?

[mark houghton]

Originally Posted by quattrorunner

I think I know the answer but wanted some confirmation. I've been tracking some odd running issues and have a couple figured out but
1)why is my boost gauge going slightly beyond 1bar and then spiking past 1.2bar on throttle closing? I have a 1bar Spring.
2) And also I'm getting an issue where the car acts like it's hitting a sandbag when I lift the throttle before pushing the clutch. Hard to explain but it never did that before and I suspect the throttle plate is getting pushed closed by excess boost when it's still slightly open.
The issues I think are figure out are the plug wires. I'm getting a set soon. It's a high rpm stumble. Could that be related to the other issues? Vague I know. Thoughts?

Spiking past 1.2 on throttle closing may be enough to trip your over boost sensor switch, instantly shutting down the engine for a second until the boost drops. That might be your sand bag.

[kenikh]

I've seen a few adjustable switch options - they are all NPT threaded though, so you'll need an adapter or drill-and-tap.

That doesn't answer the question why it is happening now and not before with the same configuration.

[quattrorunner]

Sorry, should have noted I don't use an over boost switch.

[Ronnie's.930]

Brandon, is the pickup point for the boost gauge before or after the throttle plate on your car?

[quattrorunner]

Boost gauge is taken before throttle plate I believe and diverted is behind. I'm looking into switching them but can't figure how they might have been switched because the niples (your welcome) are not the same size. In other words the hoses don't fit.

[quattrorunner]

I switched the lines so that the boost gauge reads from behind the plate and that operates correctly now but I'm sure the plate is getting shut by the boost. Has anyone heard of that?

[T77911S]

the boost wont shut the plate. it would only do that if the pivot point of the plate was at the edge and it opened "up", the shaft is in the center.

if you are lifting the throttle BEFORE you push in the clutch its going to do that. you are putting a LOT of power down then suddenly lifting, thats has a big reaction from accelerating to slowing.

i have gotten on the gas then had to lift pretty quick, its pretty "violent". my wife kinda freaks out.

you have to have a very gentle foot.

[RarlyL8]

What you are describing is normal for a modified CIS engine.
The boost spike is being read from the intercooler. During a snap throttle lift there is a split second before boost is diverted around the throttle body. A rapid decel accompanies this action as the engine goes from full boost to shut throttle plate. You can modulate that out a bit with your right foot or by changing to a different BOV.

[quattrorunner]

The car isn't new to me, but the transmission kinda is. I have been driving it for a couple months thoug and haven't noticed the throttle issue before. It could be a simple seat adjustment issue. One thing that is new is rennline peddals. I have the cool throttle extenders that make heel toeing amazing and I really like that but I feel my driving issues started with the installation of those. It's inly been a couple weeks.
Switching the hoses fixed the boost gauge problem but my high speed stumble is still something.
Would ignition wires affect the boost gauge if if was slightly missing? Like the gauge bounces a little while the miss is happening.
I hate to add hat the afr reads really rich on boost when it's colder hear days as well. Like into the 9's. This also could be part of the miss or just complicating it. I have like 4 things hitting me at once. Lovely.

[T77911S]

i am no expert and this is the highest HP car i have ever owned so i am basing this on my "learning curve" for this car and i still sometimes dont get it as smooth as i would like.
its the timing of pushing in the clutch VS lifting off the gas. sounds like you are lifting before getting the clutch in. try staying in the gas just a tad more. be gentle and soft with the right foot. if you do this you can keep the RPM from dropping too fast and it will help make the release of the clutch and transition back onto the gas smoother.
when you have a 170 hp car things like that are not as critical.

[quattrorunner]

I know I've made myself to look a little retarded here.....
But imagine giving half throttle and then letting off slightly, Not to change gears but just letting off to slow the accell only to find the engine feels like it's bucking as if the plate is shutting and opening rubber band like. This is the best way I can describe it.

[RarlyL8]

Could be your BOV is malfunctioning.

[quattrorunner]

Hmmm. I'll look at that.

[gsxrken]

I'd suspect the shuttle valve as well. My car always did what you described to some degree until I went to a long neck with the updated BOV. I was so pleased on my test drive with the new intercooler installed for last year's 'Palooza when I learned how smooth the on and off was going to be from that day forward.

[quattrorunner]

I use the Bosch diverter valve and long neck. I have an extra valve I'll throw on. Maybe that's all it is.

[quattrorunner]

My issues are fuel related. I need to figure out why my wur or fuel pressure is not staying consistent. It feels temperature related. I know that sounds dumb to say but it varies back n fourth. I'll be driving along and the afr will go from 14cruise to 11.5/1 cruise in like 5 minutes driving in cold weather. And when cruise afr is that rich part throttle afr goes too damn rich. Like low 9's and it suffers and falls flat this is the issue I've been having. The diverted to valve is just trying to figure out what to do is all. I have some wur adjusting to do.

Who knows what the voltage should be at the bimetal plug while running?
Is it just 12v? I need to check this

[T77911S]

12v at the plug. use a meter and a test light. a meter will measure 12v but there may not be enough current.
measure from pin to pin and each pin to ground.

are you venting the valve to atmosphere or recirculating it.

i think you and me have the same setup. euro FD, 009 injectors?

do both fuel pumps keep working.
when it does it i would stop and pull each FP relay individually.

how long does it stay like that.

[quattrorunner]

You know it's very strange, From one minute to another.
I got out of my car and it had been idling at 14/1 afr and then got back in 2 minutes later and had 12/1 afr restarted. This system is simple, no overboost switch, one 044 pump. I feel like it's a system voltage issue because the higher/lower voltage could change pressure from the pump. simple CIS!
Earlier today after 30 minute sit time the idle afr qas at 17/1! On boost it's normalish. When lower afr like when cold the part throttle afr's are super rich and causing stumble and flat power. But when afr's are onpoint...........whew at 1 bar all is well my friends. Problem is that I cant drive full throttle everywhere
Someone tell me why my afr's on an otherwise good running engine might act like this? Voltage regulator?

[krasuskyp]

Originally Posted by quattrorunner

Problem is that I cant drive full throttle everywhere

wait, what?

you can't??

Whoops.