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Car almost impossible to restart when hot


mario_82_ZXT

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"Hot" as in driving around in traffic and water temp is halfway on the gauge (though about 205 in MT, 190 deg thermostat).

If I turn it off then go do something for a few minutes (like run in the store) and come back out of my it will "catch" when you crank it and instantly die.

 

The only way I can get it to start right up is if I reset the MS box so that it injects the priming pulse then pump the gas as soon as it catches so that it keeps hitting accel enrichments and eventually revs up. All the while I'm getting intake backfires/popping. The car will then idle but run rough for about a minute and then it will be back to it's good ol self.

 

I've never had this problem before in the close to 4 years that I've had the car Megasquirted but this is my first time with the v3 MS-I box, though it has the same code I had in there in my v2.2 hardware and I never had that problem then.

 

I'm stumped on this one... Help!

 

If the car sits for a while (like an hr) it starts right up. If it's cold outside and the temp gauge never got to half way it will start right up. If it's 30 degs outside it willl start right up...

Mario

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  • 2 weeks later...

I am having this same problem with my V3 running Extra code. I just hooked up a Palm XIII to my unit and can now monitor parameters as I run real time and I did notice one item when I was having this problem. The AFR is like 10 to 1 when it is running really rough after a hot start up. However after I rev the engine or drive it a bit the AFR's are back to a normal 13 to 14 to 1 range.

 

So what is causing this increased running rich after a hot restart??

 

HB280ZT

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Mario, I have a similar problem as far as hot restarts go but probably not as bad as your symptoms. I wrapped the stock turbo manifold with header wrap but I need a turbo blanket of some sort too. Also, just got some phenolic spacers for the fuel rail mounts as well as some insulation for the fuel itself. Firesleeve for the fuel line is probably in order too.

 

I was reading on the MS website about people with similar lean restart problems and it looks like vapor lock of some sort. The only other thing I can attribute it to is a heat soaked IAT sensor....which after some testing was not my problem.

 

Just wondering, when your AFR numbers are changing on a hot restart do your PW's change at all. For example mine are in the area of 2.5 or .6 give or take and even though they are not changing at idle my AFR's will sometimes be all over the place until cooler fuel finally reaches the rail and cools the injectors.

 

As I mentioned in another post, I just enabled my EGO correction at 600 and even on heat soaked restarts it smooths things out very well. I'll take some pic's when I get everything insulated

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Well I will have to eat crow on this one. I checked the AFR on my car after a long run and restart and I came up with a different issue. Before I was getting a rich condition upon restart but it seems that my LC-1 had not timed out when I was doing the readings. So this time I let my LC-1 time out first then started the car and was getting a really lean condition like the rest of you all, how does 19 or 18 to 1 AFR sound! So why are we running this lean?

 

I really need to data log one of these to get a better reading of what is going on, but I always seem to forget to do it.

 

HB280ZT

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Any maps or datalogs to post? Are you sure you guys have hot start enrichment on? The few maps I got off of the 'map thread' didn't have it enabled. There were numbers, but the whole ASE system was shut off by an option at the top of the screen. Hot restart requires a decent chunk of fuel and usually not a lot of extra timing (if any; but I've seen quite a bit added by some).

 

Mark

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Sounds like classic heat soak in the fuel rail. Two things to help the problem.

 

1 Insulate the fuel rail.

2 Make sure the fuel system is holding fuel pressure for at least a half hour after the car is turned off.

 

On number 2, my fuel pump check valve failed and caused vapor lock. That's how I figured that out. Liquid fuel under pressure will have less tendency to vaporize.

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Mark,

 

What table are you talking about?

 

"Are you sure you guys have hot start enrichment on?"

 

I am not sure but i think you are talking about the More Settings, Idle control table. Is this correct if not can you point me in the right direction?

 

HB280ZT

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Does the MS have seperate Cold Start and Hot Start enrichments MAPS? Does the MS squirt prestart fuel every time the Key is turned off and then turned on?

 

Kevin

 

I think the "cold" start is only tuneable to 160deg. It's not really a map either. I'll have to double check.

 

And MS does have a tuneable "priming pulse" every time it is powered on.

 

It seems like it was heat soak and an innacurate water temp sender (for the gauge not MS). The car was running a lot hotter then I thought. A 4 core rad and distilled water with Water Wetter seems to have fixed the problem so far.

 

Plus the car is running great!

Mario

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