I've got a 1998 SC2 and it's been giving us trouble for about the last 6 months or so.

If you just put the key in the ignition and fire it up, when you let go of the key and get ready to press the brake, put it in gear, and back up, IT DIES.

What we have to do to get it to start up is this: we put the key in the ignotion, fire it up, press the gass so it's revving at like 2k, then slowly let off of the gas. IF WE CAN FEEL THAT IT'S ABOUT TO DIE WHEN IT GETS DOWN TO LOW RPMs, WE HIT THE GAS AGAIN untill it gets back up to about 2k again. We keep doing this until finally, we let it idle and it doesn't shut off. WE'RE STILL NOT OUT OF TROUBLE YET, because once it gets down to idle without shutting off, we still have to put it in gear and back up, right? Well, when we do that, sometimes it will die.

If this helps any, every time we start up and rev it up to 2k RPMs, a big billow of light smoke comes out of the exhaust. It's almost got a blue tint to it.

Any help?

Our mechanic thought at first (last year) that maybe it was the fuel filter, so he replaced that already. A friend at work suggested we put Lucas Oil in the gas tank and run through. We've done that twice, and it helps for a day or two, but that's it.

 

how many miles on the car?

 

Well, it's got about 114,000, but I had the engine completely rebuilt last summer @ 100,000.



Here's the help I got from another message board: What do you guys think?

 

Nobody?

 

1) Throttle body cleaning is a good place to start. Pay particular attention to the area at the bottom, in front of the throttle plate -- there is a passage for the idle air control (IAC). If this gets clogged/mucked, you will have a nasty time maintaining idle.

2) Blue smoke in exhaust = oil burning. This should not happen 14K into a rebuild. What kind of warranty did you get from the folks that rebuilt it?

3) Why was it rebuilt at 100K? (what triggered the rebuild) Massive oil burning?

4) Have you done a compression check since the rebuild?

 

Have you checked for a cracked engine coolant temperature sensor? Its resin tipped, prone to cracking, and the replacement is brass. Also check the two-wire connector for corrosion and replace it if necessary. This ECTS fails in two ways;


1-Failing so that the engine always runs at a high idle and never returns to normal idling.


2-Failing so the engine is hard to start, sometimes backfiring into the intake manifold, requiring a depressed gas pedal to keep the engine running till its warmed up where an idle finally returns.

 

I would normally agree and start there, Ducky--however, if the car comes back down to something close to idle on its own, I would tend to think the PCM is getting a singal from the ECTS -- otherwise, it would never know that the engine has warmed up (coolant temp would still read -40).


That, and I think the brass sensor design came in 98 (not sure on this).


This car does not idle properly on its own. Once idling in park, it stalls in gear (lower rpm and under load). I can't see this type of behavior being caused solely by the ECTS.


SES light on? Any codes?


May also want to try an EGR cleaning, especially if it was an oil burner before the rebuild.....EGR may be sticking open when it should be closed (like at idle....)

 

As to when the brass coolant sensor was finally placed into production cars it was in '02 and on, from information at a competitive Saturn site. I suggested this first as virtually all S-series and early L-series cars were equipped with this poorly designed coolant sensor, easily checked and replaced to eliminate a whole host of engine/transmission related problems.


We seem to disagree as to the interpretation of the idle as I read it as a possible lean starting problem and trouble maintaining engine running until warmed up. If a normal cold start-up isn't followed by a high idle of approximately 1200-1500 rpm and the opposite is occurring there is still a distinct possibility ofa coolant sensor failure as I stated before.

 

Thanks for the ECTS re-design into production year -- no more guessing on my part[img]smileys/smiley17.gif[/img]. And I don't think these forums should be viewed as competitive -- some are hardcore techie, some are more relaxed....we're all here to help each other, no?

In my experience, the hard starting due to ECTS failure is usually because the if ECTS fails, its resistance is read by the PCM as that which corresponds to -40, and the a/f mix is absurdly rich--not too lean.

Indeed, the ECTS may be bad - I simply stated that I didn't think that the ECTS alone </span>could be responsible for all of the symptoms described.

Definitely worth changing + connector --especially if it is the original.

No disagreement there.

 

The reason for the engine rebuild was... well... knocking, and then severe knocking... and then the engine pretty much sucked.

As for a warranty on the rebuild: a friend rebuilt the engine, so there is no warranty. He's a gearhead, enjoying amateur racing and rebuilding older cars that he resells for upwards of $75k after buying them for hundreds at junkyards and what not. I mean, I definitely trust his work, but... yeah... no warranty.

I'm going to go ahead and take it to a Saturn dealership sometime this week. I just wanted to avoid that because #1- it's 2 hours away, and #2- I'm afraid they're going to just take 2 looks under the hood and go, "Yep, we're going to have to replace everything under that hood. Engine, sensors, hoses, lights, bolts, even the air under that hood needs to be replaced."

I want to try and clean the throttle body, but just looking under the hood, I can't locate it. I know what the throttle body should look like in a carburated engine, but this isn't carburated, so I'm lost.