SS quit Options

[lotsacars]

SS quit on the way to work today. First time I've had to call Tow Mater...

I pulled up to a red light and was sitting and idling fine. Right before the light turned green I noticed the idle came up just a tad - only 50 rpms or so - just enough to notice. Went to pull away and car nearly stalled. I pushed in the clutch and blipped the throttle a few times and it came back to life. Pulled away and went about a tenth of a mile to where traffic had backed up a bit. I pushed in the clutch and it stalled. And that was it. No restart. Cranks just fine, but doesn't even think about starting.

Checked fuel pressure - 45 at the first turn of the key, then rests at about 40. Falls to 30-35 while cranking. Should be good there.

Plugged a noid light into the injector harness and I'm getting juice there.

PCM grounds OK. Opti harness still plugged in (clip broke off during cam swap).

Going after the coil tomorrow. Anything (besides that and the Opti) I might be overlooking?

[SSweet9C1]

That sucks!
I would guess you are on the right track with spark... It's always the opti or coil isn't it?
Jonathan

[fatvet]

If you blew a fuse somewhere would the CEL be on ?
if not maybe worth a look...

Good Luck
-ALF out....

[Roadkill]

Luc, check for spark at the plugs. If nothing then coil, ICM, opti.

May want to check the wire harness at the PCM where it rubs on the inner fender well if the rest is good.

[lotsacars]

CEL is on, but has been for about two years (ran 14.65 stock and got 20 mpg so I've never worried about it).

Tonight while I was futzing around with my USB cable (driver not installed) getting ready to check the codes with Freescan a co-worker of mine was futzing around under the hood. He ended up asking me to crank it while he pulled a plug wire and checked for spark. Fair enough. He got spark. At this point we had cranked it a bit and we could smell gas. He was under the impression that if it was cranked at WOT that the PCM would cut power to the injectors and allow you to purge the cylinders of fuel - essentially de-flood the engine. With nothing to lose I floored it and cranked away. Didn't the bastard start? Started right up and I've restarted it a dozen times (without needing to floor it to do so). Normal crank, normal idle.

While it was running I gave the engine harness a pretty good wiggle test. Gave the PCM a good wiggle test, too. (Mental note: secure PCM better than "tossed over there in the corner"). All the wiggling in the world wouldn't make it stall. Or even quiver. Now I can't get it to NOT start. Which was kinda what I was afraid of. Intermittent problems can take many a man hour to diag. It's not leaving the parking lot until I've changed *something* and I have a good feeling about it.

[Roadkill]

CEL is on, but has been for about two years (ran 14.65 stock and got 20 mpg so I've never worried about it).

Intermittent problems can take many a man hour to diag. It's not leaving the parking lot until I've changed *something* and I have a good feeling about it.

Sounds like a grounding problem, I would re-check the ones on the engine and then the ones on the frame in the back for the fuel pump.

[SSweet9C1]

Isn't intermittant no-start condition usually O2 or Opti?

[SSweet9C1]

When was the last time you changed the O2's? How many miles on the car? Are the Delco or Bosch?
Jonathan
*been actually driving the 9C1 since Rob got bored and came down and installed the alternator*

[larstonx]

A bad O2 wouldn't make it not start. At worst it'd throw a code and hurt the mileage. I agree about checking the grounds since you've done a lot of work on it.

[lotsacars]

O2's could be original for all I know; I've never changed them. 146K miles on the car. Opti is a used one from Jeremiah that had ~70K on it when installed 35K ago. It's no spring chicken. After I did plugs/wires/coil/used Opti it's consistently gotten right around 20mpg in mixed driving. Until that dips I'm inclined to leave the O2's alone.

I'm thinking the grounds are my best bet.

[dservati]

If I recall - one of the three wires that connected to the ignition module had broken off ... not sure if you fixed it or we just looped it under the nut that holds the module to the block ...might want to check there too!

HTH -Dave

[lotsacars]

So I finally had a chance to work on it (ahh, the luxury of having back up transportation. read: drove the rusty winter rat for a couple weeks...)

I got Freescan to communicate with the PCM for a few minutes and discovered my coolant temp sensor was reading incorrectly. In futzing around with it I could only get it to read ~ 85 deg (at operating temp) or the default -40 deg.

Newsflash: I'm just now realizing that it must have been reading in Celsius, not Fahrenheit. Idiot. 85C is 185F which would be correct.

Anyway, it was reading the default of -40 at times even when plugged in. I pulled the terminals out of the weatherpack and 'put a little more spring in their step' and drove it home. The sensor is new, but it's not a Delco. I think I'll pick up a Delco one just for the peace of mind.

In my research, having a non-functional coolant temp sensor will have it running overly rich which can cause hard starts and poor running. Since my car was a little prone to stalling anyway with the T56/Hotcam and stock tune, I'm thinking this was actually my issue. I didn't crank it all that much on the side of the road so perhaps it had flooded itself after it stalled an I was cranking while coasting to a stop? It's just a guess, but everything else seems to check out. Thoughts?

I really need to get it tuned so I can eliminate all of the driveability issues connected with my OEM tune and my new combo. It may not have stalled in the first place and saved me the tow bill.

[Heavy Chevy 95]

The sensor is new, but it's not a Delco.
I think I'll pick up a Delco one just for the peace of mind.

In my research, having a non-functional coolant temp sensor will have it running overly rich which can cause hard starts and poor running.

Since my car was a little prone to stalling anyway with the T56/Hotcam and stock tune.

I'm thinking this was actually my issue.
Thoughts?
I really need to get it tuned so I can eliminate all of the driveability issues connected with my OEM tune and my new combo. .

Luc

I recently picked up an AC-Delco Waterpump Coolant sensor for the Lt1 Engine.

AC-Delco -- # 213-928
GM -- #15326386
List -- $31.42
Price --$18.46

After you get your Impala SS squared away.
I would highly recommend Brian Herter from PCMFORLESS,
to DYNO Tune your vehicle on a Dyno Machine.

Over the years I have seen Brian do this to many Lt1 Chevrolets.

Long Island, New York -- LISST.
North Syracuse, New York -- RAISSE/UNYISSO
South Jersey -- BEASST/POSSI
Pocono Race Track -- Nationals.

I remember when Gary Meier installed on Dave Wilson's 95 9c1 engine.

https://www.inegma.net/4images/details.php?image_id=1341
GM LT4 Hot Cam
GM LT4 Heads
GM LT4 Intake
SLP Headers
SLP Catback
https://www.inegma.net/4images/details.php?image_id=721

Brian Herter was able to grab another 30-40 HP after fine tuing on the DYNO with this engine combination.

Brian tuning my Chevy on the Rollers.



This post has been edited by Heavy Chevy 95: Sep 16 2010, 08:24 PM