Here's a cool one, car quick to start when hot

[eighty6gt]

I've got a roush air charging system under my VMP TVS.

When I drive my car for a while at operating temp and park it in a parking lot, go in a store for say 20 minutes, come out, the instant I touch the key the car fires up and spits out the starter, fairly awkwardly.

If I shut the car off when hot, wait 1 minute, start it, it starts normally.

Couple theories - stuck injector leaking after I shut the car off (seems unlikely as this would affect one cylinder,) or, the big pool of oil and volatile combustion byproducts that is sitting in the bottom of the intake manifold under the intercooler is vaporizing and is allowing the engine to start on fumes that fill the entire intake.

I have a decently functioning oil sep. system, but over time you'd have to believe that enough gets past that that intake has some stuff in it.

Anyone else?

 

[drive_55_not]

I've got a roush air charging system under my VMP TVS.

When I drive my car for a while at operating temp and park it in a parking lot, go in a store for say 20 minutes, come out, the instant I touch the key the car fires up and spits out the starter, fairly awkwardly.

If I shut the car off when hot, wait 1 minute, start it, it starts normally.

Couple theories - stuck injector leaking after I shut the car off (seems unlikely as this would affect one cylinder,) or, the big pool of oil and volatile combustion byproducts that is sitting in the bottom of the intake manifold under the intercooler is vaporizing and is allowing the engine to start on fumes that fill the entire intake.

I have a decently functioning oil sep. system, but over time you'd have to believe that enough gets past that that intake has some stuff in it.

Anyone else?

I'm presuming you mean you have the Roush fuel charging manifold and a VMP TVS.

My car was doing some weird ch!t for a couple+ years when it was up to operating temp, then as you said, shut the car off for a few minutes and restating it would run the gasuntlet from going pig rich, lean and flat out run like crap til it warmed up agin,

I tried numerous things and last year when I pulled the heads off to change the head gaskets I found my Borla LT's had a couple cracked tubes.

Welded them up and it ran normally after that. Upstream or Downstream Un-metered air getting into the system is a bitch.



.

 

[702GT]

I'm presuming you mean you have the Roush fuel charging manifold and a VMP TVS.

My car was doing some weird ch!t for a couple+ years when it was up to operating temp, then as you said, shut the car off for a few minutes and restating it would run the gasuntlet from going pig rich, lean and flat out run like crap til it warmed up agin,

I tried numerous things and last year when I pulled the heads off to change the head gaskets I found my Borla LT's had a couple cracked tubes.

Welded them up and it ran normally after that. Upstream or Downstream Un-metered air getting into the system is a bitch.



.

I'd roll with this theory. Unmetered air is a PITA. If an injector was leaky/stuck open it would flood out the cylinder given enough time and fuel. I'm dealing with leaky/stuck open injector(s) as we speak, and trust me, my car is not turning over very quickly lol. I pretty much have to floor the pedal to kill the injectors just to clear the engine to start. It's just something I deal with for now, since I don't have time to rebuild/clean the injectors and it's not my daily. Even fumes in the manifold would just cause a rich condition, it needs air to pop, like air the computer doesn't know about lol. Now if you had some nitrous hooked up to your manifold and you're getting some quick peppy starts, I'd say you have a fume issue LOL.

 

[eighty6gt]

Cat runs great, afr's good - seems like an unmetered air problem wouldn't depend on the engine sitting turned off for 20 minutes?

 

[drive_55_not]

Cat runs great, afr's good - seems like an unmetered air problem wouldn't depend on the engine sitting turned off for 20 minutes?

My cracked LT's were where the tubes were welded to the collectors, so air was sucked in right in front of the upstream O2's.

My car ran fine until it sat for a few minutes and when I fired it back up, it lost it's mind till the headers warmed back up and sealed the cracks.

.

 

[eighty6gt]

That makes sense, during the first start you're on warm up mode, possibly open loop. O2's turn on for warm idle, bad things happen.

I'm 100% stock exhaust. I'll check it for leaks I guess.

 

[bobbaloo]

Are you talking about the oil that comes from the lower intake manifold , under the intercooler ,via the bubbler line , back up into the elbow on your supercharger ? If so would a catch can in the system from lower intake to elbow work ? I had a similar problem with excess oil in the lower intake when I had an m90 on my car , just it assumed it was from too many short drives , put a catch can on that line but haven't driven to test if it works yet .

 

[eighty6gt]

I have the bubbler line run to the inlet side of my catch can. Maybe the can is too high, vac is not pulling fluid from the bottom of the intake. I'm going to unhook the line, apply vac to a can, see if anything comes out.

 

[bobbaloo]

wouldn't it be forced out when you go into boost ?

 

[eighty6gt]

Yeah, you'd think that would work like a charm, wouldn't you!! Good point.

With how I have my can/lines right now, I don't see evidence of much oil passing into the inlet after the throttle body. With the M90, the inlet would weep oil onto the intake/etc.

 

[bobbaloo]

I was looking at pictures of your set up as I recently installed a 1.9 as well and don't care for the blocking off of the passenger side pcv line as it says in the instructions , currently have a catch can on the bubbler , trying to find some way to hook up a second can on the passenger line that I will be happy with . Then get up the ambition to put the stock crank pulley back on and see what it will do .

 

[skwerl]

The Roush intake manifold is aluminum and acts as a giant heat sink for the blower. Under normal driving it can reach 200 degrees and can reach 275+ under hard driving. The constant flow of fresh air keeps temps reasonable while driving but as soon as you shut the car off intake temps will shoot up. It can take a couple hours to cool back down without air flow. So starting the car back up after shutting it off for 20-60 minutes means the intake is still hot and intake air temps will be very high until you start moving some air through it.

This is a fact of life for all owners of FI with an aluminum intake. I'm surprised so many don't know.