Starting/idle problem

1995 SW2 DOHC auto a/c @184,000

Problem: Starts hard when cold, must floor accelerator, blows blue-gray smoke
for about five seconds after start. Will not start at all when hot; just cranks
and barely fires. Acts like it's flooded. Runs fine when it does start, although
idle speed is high (@1,100 rpm on the brakes, as when at a red light; unloaded
idle speed fluctuates between 2,500 and 500, before settling at about 1,200;
previously, idled at 600-700). Occasional bursts of rpm to 3,000-3,500, not
dependent on speed (happening on daily basis now; did have eight or ten such
incidents in the last couple of months). Does not "down idle" after reaching
operating temperature. Fuel mileage off about 20%. Some slight fuel leakage
around #3 injector (due to overpressure/excess flow in fuel rail?).

Recent work: Replaced water pump and belt tensioner 10 days ago (Thu). Currently
running cooling system flush and water; will replace with coolant/water mix
later this week. Cleaned engine at U-Wash-It last Sunday (allowed engine to cool
@30min before; U-W-I is less than two miles from the house). Next oil change due
in 500 miles; not losing oil. Problem began on Tuesday after engine wash, no
problems on Sunday or Monday.

Troubleshooting to date: Replaced spark plugs (due replacement in two weeks
anyway); plugs slightly fouled, probably due to excessively rich mix. Checked
all accessible electrical and vacuum connections; all appear dry and tight.
Serpentine belt tension good; belt scheduled for replacement after I get the
current problem corrected. Unseated injectors and cleaned in place with
carburetor cleaner, also cleaned injector bores; unable to remove fuel rail due
to frozen throttle cable bracket bolts (plan to replace all injector seals after
I get the bolts broken loose at a machine shop). Fuel line connections good. Air
filter dry and reasonably clean. Cleaned throttle body and butterfly valve with
carburetor cleaner. Both air filter and fuel filter scheduled for replacement
next month.

Items eliminated: Internal engine (rings, valves, etc.) since engine runs
relatively smoothly (no missing or stumbling). Plugs, plug wires, coils, etc.
Fuel feed system (except as noted below).

Possible problems, based on information from the Haynes repair book for this
model: Oxygen sensor on exhaust manifold. Fuel pressure regulator on fuel rail.

Anything else I should look at? I'm leaning toward a bad O2 sensor as the
culprit, based on my limited understanding of the fuel injector system and the
information in the Haynes, but at $70+ for a replacement part, I'd rather not
unless absolutely necessary - can't afford it until after payday anyway.

 

If you haven't already, please read the codes before replacing any more
parts.

Instructions are at http://www.differentracing.com/tech_articles/index.html
.. Refer to Diagnostic Trouble Code Information, and Diagnostic Trouble Code
Chart for 1st Gen Saturns. Or, people posting here have said you can stop
by any Auto Zone and have them read the codes for no charge.

If that still doesn't shed any light on your problem, consider having a
diagnosis done by your local Saturn. If it saves you from buying one part
you don't need, it has paid for itself.

Lane [ lane (at) evilplastic.com ]

 

Pencilled in for Wednesday on the way home from work.

 

The first thing I would check is coolant temp sensor. If its stuck in the cold
position it will keep the engine rich and idle high all the time(trying to warm
the car up).

 

Hmm... possible. That would account for it not "kicking down" after it's been
running for a while. And it would tie-in to the water pump replacement and
radiator flush - possibly some crud got into somewhere it shouldn't. Also, $8 is
a lot better than $70.

Thanks for the tip. The Usenet RPOE* comes to the rescue again!



* Resident Panel of Experts

 

Hmm... possible. That would account for it not "kicking down" after it's been

That's what I'm betting on. Let us know how it works out.

 

Removed the connectors for both sensors near the EGR, cleaned everything with
carburetor cleaner, let dry and reconnected. The car now starts when hot, or at
least, warm. Still high-idling, though. I have a couple of things I'm going to
look at after it cools (just got back from the grocery).

First, I'm going to disconnect the battery and let the PCM reset itself.

Then there is another sensor of some kind on the front of the transmission
housing; I'm going to disconnect and clean that.

Finally, I'm going to take another look at the #3 injector and see if I can seat
it better.

Oh - I also have to drain the cooling system of flush/water mix and refill it
with coolant/water.

 

Then there is another sensor of some kind on the front of the transmission

That would probably be you vehicle speed sensor.

 

There are three sensors that are identical The CTS ATS and Transmision
Temperature Sensor !

 

They can be tested with an ohm meter !

 

AutoZone will read your codes out for no charge.
Sounds like either the O2 sensor or coolant temp sensor to me. Could be
the throttle position sensor, but they usually just cause the rpm's to
hunt.

Key here is the smoke. You're running rich, so suspect the O2 or CTS.

 

Local AZ didn't have a reader for Saturns.

Definately figured on the rich mix; gas mileage dropped 50%. Changed out the CTS
on Thursday; seems to have corrected 90% of the problems. I have an injector
O-ring kit on order, but that'll have to wait until I get the throttle cable
bracket bolts broken loose.