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Car dies under load..

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canhsusername

Probationary Member
17
0
Dec 26, 2003
Littleton, Colorado
Hey everyone. Any help would be appreciated. After getting my car up and running I've broken in the motor, changed the oil, and tried WOT for the first time on the highway, it died. Under boost in third gear last night about 4000 RPM the car just died and the RPM gauge went to zero. I don't know if it would matter that it was in gear or not, but it was in gear and the RPM gauge read zero. I tried to step on the throttle but that did nothing. I couldn't start it again, turning over but no spark. I had it towed back to my house later that night. In the morning I started the car up just fine, had to play with the throttle a little bit until it gets to this 'warming up' point then let it idle and the car ran like it did before, fine. I don't know about the rough idle up until the 'warming up' point however, but that could be something else. Drove the car all day... no boosting.. but tonight, I just got back from walking about 3 miles from my car to my home, it broke down after trying a 2nd gear WOT and coasted to a stop. I can't start it again, I'll try again in the morning. Could the coolant temp sensor do something like this?

I'm using the stock MAF still with an S-AFC. The car has always had idling problems until I adjusted the AFC. My timing is right where it should be. Battery & ALT connections are good. The TPS is was reading .66 volts at a stand still. I know spec is somewhere around .48 but I adjusted the TPS so I could get 100% throttle reading from my AFC. I've tried adjusting it back to spec to see if that would start it, and no. My fuel pressure is good also. I've tried resetting the ECU too.

BACKGROUND: The motor is a 1st gen head w/ a 2nd gen block. I've eliminated the cam and crank sensor in favor of the 1st gen CAS. I am wondering if the coolant temp sensor would cause these problems. I've read another guys problems concerning his boost and so far relating to that, the knock sensor is new, my rear o2 is new, I have no cat, and the front o2 is relatively new. I remember wiring my rear o2 back together again after accidently pulling the wires out. Does the ground on the rear o2 matter at all if they happened to be switched around(grounds for the heater & sensor)?

Under WOT, the car can run nice and strong through 1st until a heavy load in 2nd or 3rd, then it just dies and can't be started again. The only reason why I think it's the coolant temp sensor is because I started the car this morning after being broken all last night(after dozen tries trying to start it again).

My main question is, what sensors, failing, could cause the car to die under load(boost) and keep the car from starting(no spark) again? Any help would be greatly appreciated.
 
No experience here.

That said messing with the cas can cause these problems and as you changed the setup for the swap it is probably the best place to look...somebody else will have to give you specific help here.

It is known that the 1g cas can cause spark problems after this swap is done.
 
After checking basics and the ECU harness it's leading me to believe it could be my ECU. I didn't know the 1G Cas has caused spark problems, but that makes sense considering it's making up for the 2g cam and crank sensor. After talking to a few technicians at my work(Burt Subaru, I know 4G63 and Subaru.. not common :D ) but they mentioned that perhaps my ECU could be the cause considering I've checked eveything else.. that perhaps the ground to the ECU or power may be loose or cut near the connector(I soldered my S-AFC in) which wasn't the case. So the last thing to lead me to believe is the ECU. Has anyone encountered this in their DSMs?
 
I run a 1G head as well, but I use a 97-99 Cam Angle Sensor, instead of the 1G unit. I've had the wires melt loose a few times on it, and it WILL kill the car. INSTANTLY. I would check your wiring to your crank angle sensor. I doubt it's the computer.

When I drive the car hard in HOT weather, it would cause it to melt. PM me or IM me on AIM if you wish. Good Luck!

EDIT: If it's just a cylinder misfire, that is typical of using the 1G CAS on a 2G unit.
 
I haven't checked the CAS wires yet, but I have considered using the '97 CAS instead. My reason for this is and I'm sure it's refutable, is that a 1st gen CAS is an older technology being, excuse me, 'mish mashed' with the 2g ECU. So Perhaps misfires and the like can happen. So, is the wiring the same? Do I keep my crank angle sensor and just modify the '95 CAS for the '97 one?

Also, someone suggested that because the ECU has just about 200K miles on it, to check the caps in the ECU. No, they've never been replaced, is it something that goes out on 2g ECUs? I've heard of them going out on 1g ECUs but not 2g ECUs which shows how much I know. What's involved? What is the part number for these 'caps'(ill probably end up finding them anyways but hey I thought I'd ask anyways)?
 
Okay, checked CAS wires, they are good. Checked ECU.. opened it up, didn't smell like anything other then old computers :D last guess I suppose is the ECU. Thanks for the help guys.
 
Alright.. plugged in a friend's ECU. Car still won't fire. He was suggesting it's the cam angle sensor. So I'll get another one and see if it works. THe only reason why I'm posting is so that you other guys, if you happen to run into this problem in the future, will have a better idea of what's going on.
 
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