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  #1  
Old 04-19-2011, 08:54 PM
Cam Cam is offline
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Strange stall...

Okay, so in an attempt to correct my rough idle, I have been running diagnostics the last couple weeks.

Coils were tested, and they were fine.

Compression test was performed, all 6 cylinders within approx. 13% of each other. While doing test, I inspected all plugs, and they looked identical. Pretty normal, and what I would expect to see after only 3,000 miles on the engine.

Fuel pressure was tested, and fp at idle was 30 psi, raising to 35-36 psi when throttle was applied. I can tell you from smell alone, that the car is running RICH at idle...very rich. STORMINORMAN even commented on this at the maintenance meet, which was either before or after he scolded me for my (less than favorable) brake fluid level/condition.

Car seems to be lacking power down low, but has quite a bit of get up in the mid-upper rpm range.

The latest installment happened this morning. I was approaching a stop sign, and decelerating. I got the christmas tree lights, the ECU clicked a couple times, and the car sputtered. It accelerated off the line more or less normally, but almost immediately stalled and died. I rolled to the side of the street and quickly did a check list of symptoms.

- With key on, all lights displayed illuminated, with the exception of the CEL.
- Car cranked at normal speed, battery was obviously charged and strong.
- Car would not fire.
- When key turned to ON position, fuel pump could be heard priming.

I believe what happened was the car flooded the cylinders...I am not sure why. I returned to the car after a 10 hour work day, and the car fired right up like normal. I drove her home with no problems (only a few blocks).

Is it possible the fuel pressure regulator is on the fritz? Has anyone else had this happen? I believe I read that the fp at idle should be about 23 psi, and 36 at WOT. Can anyone confirm this? Also, where is the regulator located? It is vacuum controlled, if I am not mistaken. Maybe I have a vacuum leak on the line that controls it?

A few days ago, I was talking to LAN and he mentioned it sounded like I had a vacuum leak. He inquired about the O-ring for the IRIS. I do not remember any O-ring on the IRIS valve. When I installed it to the intake manifold, I siliconed around the stud holes and the periphery of the base plate for the IRIS.

Any insight would be much appreciated. Thanks guys.
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'92 Ls-L Dark Teal
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ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
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  #2  
Old 04-20-2011, 02:46 AM
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Re: Strange stall...

Hey there Cam.
I'm assuming that you are still running the stock injectors, MAF and ECU.
I'm not that great with computer controlled cars but here's my 2cents worth.
It sounds like the ECU is trying to compensate for the change in compression and the new cam profile by dumping in more gas.
I could be wrong but it's something to think about .
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Old 04-20-2011, 06:38 AM
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Re: Strange stall...

Andrew, that was my original thought when I rebuilt the engine. However, I swapped the stage 2av1 stuff in a couple weeks ago and it did not help. The car would not start this morning. it must be because of the cold...
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'92 Ls-L Dark Teal
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Balanced & Blueprinted
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  #4  
Old 04-20-2011, 11:33 AM
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Re: Strange stall...

Leaky injector? Or did you get the injectors checked out first?
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Old 04-20-2011, 11:40 AM
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Re: Strange stall...

I had exactly this happen with my 96 just a day or so before I loaned it to my girlfriend's brother. He encountered the exact same thing about two weeks later, and a quick diagnosis led us to replace the alternator. Basically, it was working fine until it was warm, then the volts would stay constant but amps would suddenly drop through the floor at random. Since we replaced it, no problems.

I think the problem with the flooding/starting (I had that too) was because the ECU got scrambled when the amps dropped, dumping fuel into the cylinders.

It also explains nicely why my Kenwood would randomly crash/reboot while driving... that gremlin also vanished.

HOWEVER, I would still check your injectors... that could well cause the issues you report.
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  #6  
Old 04-20-2011, 11:42 AM
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Re: Strange stall...

Also looking through that again, I'd check out the fuel pump regulator. Maybe that's acting up?
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  #7  
Old 04-20-2011, 12:46 PM
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Re: Strange stall...

Alternator is fine. I drove the car without a working battery recently. Had to jump it everytime I turned the car off.

I suspect the regulator is correct. Maybe its a vacuum line controlling the regulator, or a seal where it attaches to the fuel rail. I am going to test it this afternoon with a vacuum gun.
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'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #8  
Old 04-20-2011, 05:45 PM
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Re: Strange stall...

I did a quick check when I got home today. Car started immediately (i suspect, like I said before, that it didn't start this morning because of temperature) and I unplugged the vacuum line that connects to the Fuel Pressure Regulator. There was no noticeable change, at idle, when disconnecting the vacuum line.

I called Nate (WickedJugalo) who I met at the maintenance meet last weekend, and asked him to do the same thing with his car. He said the idle raised on the car, and it noticeably ran more rich.

I am about to leave and go to my buddy's shop, where I will definitely be treating the regulator as suspect. We are going to apply vacuum and see if we can get the car to lean out and make some real power. Up till now she seems pretty much stock, since I am running too rich to make any low end ponies. Don't get me wrong, after about 4k RPM, she RIPS, but it's not the same when it almost seems like turbo lag...

I am also going to be going over the intake manifold with a vacuum gauge and some throttle body cleaner, looking for vacuum leaks.
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'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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  #9  
Old 04-21-2011, 05:59 PM
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Re: Strange stall...

At LAN's request I checked the vacuum on a stock a stock SVX, at the back of the intake manifold, on the passenger side, where the line goes to the FPR.
19.5 inches of vacuum on a cold engine.
And yes we do have a couple of nearly stock SVXi.
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  #10  
Old 04-21-2011, 08:18 PM
Cam Cam is offline
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Re: Strange stall...

TIMING!

My tensioner was leaking, and caused the belt to jump around. Luckily the belt was not damaged, and everything still looks okay. Ordered a new tensioner, and it should be here tomorrow morning about 11 am thanks to a friend I have. Brand new from the factory .

I will get to drive my car for the first true time tomorrow when I get home from work.

I suppose the performance issues I have been having and the rough idle and crank no start when could can all be attributed to the belt jumping. I would bet my life that is what was going on. Timing was WAY OFF.

Silly old me...
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'92 Ls-L Dark Teal
11:1 CR ECUTUNE pistons
ECUTUNE .256 duration intake/exhaust cams
ECUTUNE STAGE 2AV1 ECU
Z32 MAF/SR20DET injectors
Balanced & Blueprinted
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