Long, but trying to give all symptoms...

Shortblock was rebuilt this past summer by Mike Norris. Local machine shop did some measuring, balancing, line honing, etc and Mike assembled the bottom end. The top end and re-installation happened at another friends shop because the car was on his lift. Originally had a coolant issue where the temp kept climbing so we pulled the heads to check the gaskets (OK) and it appears a faulty stat was the issue. In the process of taking the heads off, I think I lost at least one of the c-clips when pulling them off. New rings and new main studs on the bottom end. New head & intake gaskets and new lifter trays & LS7 lifters up top.

I want to say 3-4 weeks after the car was back on the road, the passenger side head seemed to be ticking more pronounced than the driver side. Mike put a long screwdriver on that head and said that it seemed to be coming from the center of the head. He asked if the preload was checked and I said I didn't know, but the only thing that would have changed was the base circle from switching from a LSK to a XFI lobe, and that it was measured last year on the previous build.

The low oil has been on intermittently even though the level is fine when manually checked. When I changed to synthetic oil around 1500 miles, there was what appeared to be two pieces of the end of a c-clip on the plug. Prior oil changes only showed minor metallic dust. No trace of the remainder of the c-clip. Asked around and it seemed improbable that the remainder of the c-clip would be worrisome.

So I continued to drive it daily, autocrossed two days since then. Fuel pump was whining pretty bad one day at autox and the gauge had been acting erratic, but both seem to have gone away. Car is running OLSD, but the O2 sensors are still plugged in and one cable has become frayed on the outside, presumably what's regularly blowing the engine sensor fuse. The clutch pedal has recently begun to be pretty stiff for a LS7 clutch. Sometimes when I start it from cold it's normal soft, but shortly thereafter it stiffens up. I also notice that my bleeder extension coming off the slave cylinder is hanging down instead of being routed up behind the heat shield. Perhaps that's related to the pedal pressure.

About 1-2 weeks ago we were driving in the slight rain down a bumpy paved residential street with speed bumps. Car was acting as if sometimes the engine would completely unload and then kick back in. Soon thereafter it just up and died right after a speed bump. Got it restarted and took it back home and loaded a different tune thinking that it was related to the weather. Did that, and took a different route to our destination without any further problems.

When tropical storm Fay came through, coming home from work last Thursday the alternator apparently became waterlogged and it was overcharging. Since the dealer had tested/repaired the wiring and replaced two alternators last year for the same symptom, I took it back in. Since it had gotten wet and they didn't know how high it splashed, they dried everything off with compressed air and then it seemed fine. Two days later I wash the engine bay with a slow stream of water and it overcharges again. As it dried , the overcharging problem went away and has been stable since then. I still plan on taking it back to have the alternator replaced before the next storm.

Then today coming home from work, completely dry sunny afternoon, the car is working fine and then it started the same issue cutting out while driving, died once when coming to a stop, idling high when coming to other stop signs. Let it idle for maybe a minute while I went to listen to the passenger side of the motor and it died by itself coming back to turn it off.

So, with all that said, are these a lot of individual problems, or are some of them related? I've not been too worried about the low oil because I'm manually checking it, nor worried about the engine sensor fuse because it doesn't appear to be harming anything other than making reverse difficult to engage. I'm obviously irritated at the alternator, but concerned about the engine cutting out and dying sporadically.

I'm looking for ideas on how to troubleshoot the cutting out mostly, but perhaps some other stuff is related?

 

Car died at a stop light last Thursday night. Left it in a parking lot and had Next Level Performance check it out the following morning. They said it started right up and they drove it back to the shop without any of the symptoms. Repaired a cracked PCV tube, checked grounds and fuel pressure. Couldn't duplicate problem. Driving it home it started again and I drove it back. Geoff got in the car and experienced the problem... random bucking in the middle of driving, stalled soon after coming to a random stop light. Long story short he thought it'd be better financially to take it to the dealer as they would only charge a flat rate for diagnosis instead of per-hour there.

So I take it there that Friday, and get a call back Saturday. They'd recommend taking it to a speed shop because of the aftermarket tune, cam, etc. I explained the symptoms and that I had already been to a speed shop and they recommended the dealer check the crank position sensor, burned wiring, etc. They said it would need to wait until today for their senior tech to come back.

 

It sounds like crank sensor problems to me also have them check connections at the PCM for signs of water intruision. i worked on a truck that had the same problems as yours the owner lyed and said the truck was never in water. had to replace the PCM and both pin connectors.

 

Senior tech at dealer refused to look at it because of the modifications. Suggested taking it back to the speed shop who built it (ha, which one over the last 10 years). The PCM was replaced last year because it was the only thing left to fix the false KR, and it did fix it.

 

Hey Jim! Been a while

Sorry to hear about the issues but it DEFINITELY sounds like the crank position sensor. You can do the re-learn with your efilive after you get the sensor replaced . . . forget how many miles they're good for . . . 75k or 100k IIRC.

On a side note . . . 3 of Brenda's issues come out over the next few months! Shoot me a PM or e-mail Jim



Christopher

 

What should I expect to pay for the CPS? I don't even know if mine is the original with how often the engine's been out, but if it is it almost made it to 130K.

 

If you suspect the crank sensor maybe you could
just pull / dry / reseat it. It's low enough on the
motor that it could've gotten wet.

But with all the stuff going on I'm thinking more of
a harness intermittent, a loose ground strap or
something of that sort. Maybe with all the motor
messing-around one got left off, or loose.

Any scan tool you could use to look for abnormal
sensor readings (ECT is especially prone to jack the
idle and mixture around if it's flaking out, I have
run across ECT connector problems before)?

 

You're definitely on the factory sensor then

I'd say it's most likely your CPS sensor since my car did all the same crap your car is doing when mine went.

I can't remember the price but it wasn't that bad . . . the re-learn is what f#(ked me since I didn't have EFILive at the time (think the dealer charged me $100 just to plug in their tool and push a button )

Replied to your PM about Brenda

 

I have a local buddy who said he had the same symptoms but it was due to a failed ignition switch under his steering column.

 

Hit me up Jim, I'll offer you a hand. ASEP is on electrical the next few weeks.

 

i had problem like the one you had when it would rain. sometimes it wouldn't even start when it was about to rain. i used to have to pop off the fuse box and re-seat my ignition relay or swap it back and forth with the another relay. there is two or three relays in that box that are interchangable. i changed relays with new ones and have been good since. good luck

 

The tech found that the inside of the crank position sensor was damaged. The motor was re-built this past summer, and he said the crankshaft end-play was dead-nuts accurate. All new bearings were put in also, so we don't know exactly know what caused the damage. I'll get the part back and see if I can post photos. ~3.5 hrs to R&R header, starter, CPS and swap out the connector with a weather-pack version. Hopefully there aren't any other issues with the relays, etc, on top of that.

 

Yay! They replaced the sensor, I paid a $400 bill, and the problem recurred 1/2mi away and stalled in the center lane less than a mile from the dealership Managed to get it restarted and took it back to the dealer, but they had just closed Friday night and the tech wasn't there Saturday. So I need to fight with them regarding the $400 to replace a good part, as well as the rental fees they're running up on me so far.

 

Instructor drove the car 340 miles in multiple trips and it hasn't done anything except "drive perfectly". He spoke with a dealer tech near his home and he said he had that problem when the ignition relay was randomly dropping voltage to the PCM. He's going to get me the part number and we'll swap it out and I guess I'll take it back and see what happens. Still need to fight with the dealer ont he $400 refund because the both the service manager and general manager were in an off-site meeting on the last attempt.

 

Replaced the ignition relay (12177236) and nothing to report so far. Service manager at the dealership is giving me grief about how much time his tech spent trying to diagnose a modified engine. I'm waiting for a callback from him to see what sort of middle-ground we can arrive at.