High Speed Stall Out

[MagickMan0730]

Ok guys, so I have looked around the forums for a while and I cant seem to find any threads on this. If there is one please point me in the right direction and delete this thread. So here we go. I recently bought a new car. YAY! 1990 Mitsubishi Eclipse GSX. 4g63t Cyclone Motor w/20g turbo at 15psi currently. The problem is, at speeds normally anywhere above 110mph(on the track) when I go to throw it into neutral and slow down after going so fast my rpm's will drop to zero and my car would die. I dont know what it could be. From what I was told the car was tuned at TurboTrix and she runs really good. This is the main thing. As a side note.(Normally after going hard on it) after I turn it off, when I try to turn her back on it wont crank. Everything comes on,fuel pump, lights, etc. It just wont crank at all. I waited for like 10 minutes and still nothing. So I tried to pop start it. She sputtered but nothing. Weirdly though, after the failed pop start she cranked over and ran fine. Any guesses on these 2 things. I think the 1st problem links to the other. EGR Valve? Plugs? Alternator? Starter? Lol Help?? Thanx in advance.

 

[jrohner]

Why do you slow down in neutral? Are you just trying to destroy your brakes as fast as possible?

 

[MagickMan0730]

Well whats the best way for me to slow down going this fast?

 

[jrohner]

Well whats the best way for me to slow down going this fast?

Um...get on the brakes. I just am not understanding the whole throwing it in neutral thing. Use engine braking to your advantage; slowing down quickly in neutral will fry the **** out of your brakes extremely fast. It'll glaze your pads (maybe crack them), and you could warp your rotors too. If you were going quite a bit faster than you are, you'd maybe lose your brakes before you even get stopped. I'd never do it unless something in the engine or drivetrain broke.

Is your BOV recirculated like it should be? How were you throwing it in neutral -- such as: after letting off and getting a little bit of engine braking, or the instant you let off? Idle control is different depending on if you're stopped or moving (at least on 2G's and newer), so that could be part of it as well.


As for the starting issue: next time it happens, pull the battery cable off for a min (ground) and put it back on. If it starts then you have something such as a bad relay. If it starts only after rocking the car back & forth, or an attempted push start, or tapping on the starter, then you're starter is probably bad.

Does the starter click or spin, or just nothing?

 

[Gasolinebaptism]

Okay, well I know the '90's are the black sheep, but I can possibly help with one of the tests. the issue about dying. I want you to unplug the ISC, warm would be best. there are 6 pins, when hooked up to a closed line (as you need to test, there are three circuits, 1-2, 3-4, 5-6) you need to show at least 30 ohms. I show about 38 ohms.
The ISC is easily accessible, looking under the hood on the passenger side it is just below the TB and slightly towards the Firewall. If it fails then order a new one from DSMisc.com

 

[MagickMan0730]

Thanks for the tip. As for the neutral dropping, I recall usually just dropping it into neutral instantly. But instead of the rpms going back to idle position until I re-engage a gear it drops completely. Also I didnt know I HAVE to be re-circulating? Im running a Greddy Type S and I believe its atmospheric.

For the starting issue it just clicks once and you can hear the fuel pump and everything. I think it may be the starter =/

 

[jrohner]

Thanks for the tip. As for the neutral dropping, I recall usually just dropping it into neutral instantly. But instead of the rpms going back to idle position until I re-engage a gear it drops completely. Also I didnt know I HAVE to be re-circulating? Im running a Greddy Type S and I believe its atmospheric.

The instant you let off, you go extremely rich with the BOV dumping to atmosphere. That would definitely cause it to die in a situation like that.

All that air has already been metered by the airflow sensor, and then you're just dumping it to atmosphere (as well as pulling in some new air and metering that too). The ECU thinks that air is going into the engine (but it's not obviously), so it dumps in what it believes is the right amount of fuel (but it's WAY too much).



BTW, I sent you a PM as well (not sure if it actually sent since my sent items folder doesn't work right).

 

[MagickMan0730]

I understand what you mean. That sounds like a really strong culprit. So would this happen with alot of turbo cars running atmospheric? Also then, can I fix this or should I just stay in gear and slow down steadily?