Mechanics

SATURN SC1 COMPRESSION PROBLEM

2002 Saturn SC1 • 178,000 miles

I bought this car not runninI checked all the fuses with a test light and found the body comp fuse blown replaced it. The car would not start prior to this. So far I have checked compression 140psi in 1and4 and 130 psi in 2and3 the cps tested 836 for resistance and the ects is the brass on not the plastic however I haven't replaced it. There is spark at all the spark plugs. The fuel pump will cycle when the ignition is turned on and I have pressure at the fuel rail.
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Showd
November 14, 2012.




For starters your compression is too low min compression on that engine is 175psi. Any coxes?Does it even try to start?

Saturntech9
Nov 14, 2012.
It acts like it wants to start almost like a flooded engine would be however the plugs are realitivly dry
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Tiny
Showd
Nov 14, 2012.
Would bad or stale gas cause something like this it was also backfiring through the intake

Tiny
Showd
Nov 14, 2012.
The timing chain could have jumped causing the low compression and back firing thru the intake manifold.

Saturntech9
Nov 14, 2012.
I have gotten the car to start it took it being floored and ran very rough. I took the coils and ecm off and cleaned the connections and had the O2 sensor unplugged. It only ran a few minutes and then stalled and went back to the trying to start again almost getting there but not catching and running. The SES light is on now so I can actually try and gets codes. Also the comperssion tester is old and might not be accurate and the mileage is in kilometers not miles. When it started there was alot of black smoke when it was running rough it almost sounded like a miss and when I pulled the #1 plug wire it stalled and when back to not starting.

Tiny
Showd
Nov 15, 2012.
Lets rent a compression tester from auto zone and redo the compression test. While checking the compression be sure to have all the plugs out charged up battery gas pedal all the way to floor and crank it ten compression strokes you will feel when it hits the compression stroke the engine will kick. Also I would look at the coolant temp sensor and also see if the connector terminals to it are blue or green instead of silver also if theres coolant in the connector?The brass connectors go bad also I have put 4 sensors in my 1999 saturn sl2 in 6yrs of owning it.

Saturntech9
Nov 15, 2012.
Ok so I have got it too run and I am getting code p0340 misfire in cylinder 4 by the scanner. However if I pull the #4 wire off the car will run the same and if I pull the #1 wire off the car will run the same. So I have changed the plugs and wires there was a bad arc on #2 still the same cleaned the contact on the ICm and mounting point checked all fuses still no spark on #1and #4 swapped coils and attaching bolts with #2and#3 car will run the same and still no spark on #1and4 last night I started it in the dark to look for any arcing could not see any. Pulled the plug wires off the #1and#4 coil towers there is no arcing between the two towers. So I know there is no spark at the coil could a CPS cause one side to fail and is there anyway of testing it? And is there anyway of testing the ICM short of replacing the unit it self I found a troubleshooting guide for testin for shorts between the PCm and the ICM with some voltage checks. If it were a groinging issue for the #1and#4 coil could I just ground it directly with a jumper? I have kinda went through everything short of changing ou the ICM as they are expensive also I changed the intake gasket manifold and the ECTS

Tiny
Showd
Nov 19, 2012.
If your not getting spark from 1 and 4 your sure of that and you swapped the coils that were sparking then more then likely you have a bad icm. The cps would not just take out two cylinders spark like that it would take out all four of them. Do you have a pick a part around you were you can pull your own used car parts?Those modules dont fail often and I would put a used one on my car even.

Saturntech9
Nov 19, 2012.
So I got a ICm and coils from a auto wreckers I have spark at all 4 cylinders now however it runs very rough at idle but still progress there are no codes now and the vehicle sat awhile so the quality of the gasoline could be poor or a stuck EGR valve I am also going to clean the butterfly and intake. The person who had this car before me didnt do alot of regular maintance. Thanks for your help

Tiny
Showd
Nov 20, 2012.
Have you rechecked the compression again?Your compression readings you were giving before were way bellow min to run good.

Saturntech9
Nov 20, 2012.

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