Start Up Problems

[shamefoot]

Ok this has been a progressive problem -- car has 200k miles on it
is a 1993 SL2 -- The car at times would not start unless you floored it when you turned the key. Other times it starts just fine -- Though upon deceleration ie stopsign car looses power and almost stalls --

Now it will not start at all -- No check engine light --

Did a check of voltage of the TPS, MAP, and the Idle air control value(IAC) -- Here i stopped the voltage delivered to the IAC is plain wrong should fluctuate from 1.5V to 10.5V according to the book -- Was fluctuating from 8.5V to 12.5V -- According to the book two of the lines should fluctuate in the manner (1.5 to 10.5 V) the other line that should fluctuate stands at 0.48V and does not move -- So i am guessing the PCM is bad in some way. --

Did test of car on and not running (naturally not running as won't start) -- Car turns over and will sort of stutter as it runs -- Disconnected the IAC and jsut checked to see if the PCM was delivering correct voltage.

So any way by looking up parts on internet i see that a 91 to 95 PCM replacement part is the same so will probly try changing that out -- If any one has any ideas I'd be much obliged.

[sierrap615]

DON'T CHANGE THE PCM!!.....yet.

changing the PCM is the LAST thing you do, don't worry about the IAC....yet

so this is a no start but it will crank right?
quick side note - the computer is programed to not start if the thottle is wide open, partally open it will.(remember this is fuel injected not carborated)
first take the intake tubing of and look in the throttle body, i bet its gunked up, spray some sensor-safe carb and choke cleaner in there, be sure to spray some on the IAC too.

if you still have a no start, pull the spark plug wires off the coil pack towers. have a second person crank the engine for a few seconds. there should be a spark tower to tower, if not, replace the CPS

if you still have a no start, and the ECT sensor has not been replaced since 2001(new design), replace it.

if that doesn't work tell me and i'll post the next few steps.

[shamefoot]

Had removed the throttle body and degunked it so its fine ( was severly gunked about 1/8th an inch thick right in their ) Spark is fine. Not really worried about the IAC just the fact the PCM is sending the wrong voltage to it -- makes me question what else it is sending wrong too -- sound like it wants to start just won't -- if u pump the gas you will get a stutter of pure grey smoke as long as u hold down the ignition at same time. ECT is new so is EGR -- Starter, Alternator, and Water Pump have been replaced -- is definately getting fuel -- When u pull plugs out they are wet with fuel -- is delivering way too much fuel or just not lettting itself run ( has had really bad gas milage of late )

[shamefoot]

Clarification the plugs are only wet if u do not pump the gas and get the stutter thing.

[shamefoot]

Woah nevermind ECT not replaced ( which sensor is that ? ) The Oxygen sensor is also new --

[shamefoot]

OK Engine Coolant Temperature Sensor Not replaced that got car in 2001 with 130k miles on it so at least that old if not older -- car ran at jsut a hair under 1/2 always though -- except for a week in md up in the snow ran to red when idle there for my vacation -- went away so maybe it is it sstill not explain wrong voltage sent out by PCM though

[shamefoot]

ok neighbor had wrecked saturn got a PCM off of it voltages now read correct still no go. same thing

[shamefoot]

It works Now WOOT!! -- have run it both new computer and old much better with new Any way i changed out the ECT was indeed cracked ( thank you sir ) changed it out did not start took plugs out sanded them with an emory board started instantly smoked like a steel mill for a while -- Runs lack of get up and go from a dead stop but she will fly got her to 80 ( ran out of road ) -- check engine light will come on shortly after start but when u check for check engine codes u don't get any stored --

Need to retork the intake down gettting a slight steam leak there but no other leaks ( woot i did something right )

Thank You sir for your speady reply Words can not express my joy at seeing her roar to life that first time. ( I'm a computer programmer not a mechanic so very pleased I got it to run again -- Did computer repairs on my car ) Any ways till another day sirs

[sierrap615]

wow, sounds like you had a long day, what year/model did the new PCM come from?

[shamefoot]

It came out of a 1996 SL2

[shamefoot]

oh about the idle air control -- I can not find how to test it itself -- maybe the high voltages and the low vlotage on the other line it was experienceing damaged it?

[shamefoot]

ok figured out why she takes a slow acceleration -- does not switch gears is always 3rd or 4th so guess i need find a computer from a 95 or earlier after all cause the new computer definetly fixed other problems

[sierrap615]

yeah, 96 won't work. find a DOHC 93 or 94 without californa emissions PCM (it should say PERF on it). depending on what exacty it came out of you may need your saturn dealership to flash the opitions to the EEPROM

[shamefoot]

Aye definetly not work -- Was best idle I've ever seen from that car however -- My car's got all the options except leather seats and fog lights

[shamefoot]

Nearest saturn Dealership is about an hour away on the interstate