I am in dire need of help. I have a 1997 SL1 with 174,000 miles. It sat for 3 years (got it from my brother) and when he last parked it there was only one issue. It fouled out #3 cylinder after about 40 miles. He changed it out with another cylinder and it was good to go for another 40 miles or so. He averaged 44 mpg and the worse he ever got was about 35 in the city (maxed at just under 50 on the highway).


I got it a few months ago and figured I just needed to change out the head gasket. I changed it out and also changed out the valve guide seals. The cylinder walls looked brand new...still had the scoring marks on them. Also changed out the spark plugs and put in synthetic oil. I put everything back together and it did not run. I found out it was the fuel pump. Changed that and it fired right over but ran "funny" so I changed out the fuel filter. It still ran funny and the idiot light was on. I checked the compression in the cylinders and they run 155-160 psi.


Took it to Advanced Auto and they said it was the temperature sending unit. Changed that...still ran bad. I put in Lucas Fuel Injector cleaner (twice the recommended amount), Heet, and some super high octane booster in with a full tank of 93 octane gas. Thought something was there I'd have to burn out. To my dismay, that didn't work either.


Then the idiot light came on again. This time it was the TPS unit. Changed that....still didn't help. So, as it stands, I've driven it just over 1000 miles. I get about 21 mpg (have gotten 22.1 mpg once).


I have absolutely no power whatsoever. I give it gas and it is like it is only hitting on 2 cylinders. (I have checked the fuel injectors as well and they are good). It takes forever to get up to speed and that is if I am on level ground or even going down hill. If I am going uphill from a stop, it only goes up to 25 mph. When I finally get up to speed, if I go uphill, I cannot maintain speed at all. When it slows down I give it more gas and it slows down. If I floor it, it is like I hit the brakes...it REALLY slows down.


I get irritated at it now and then and when it does that I just hold it to the floor and the service engine light comes on, but it flashes. When I get off the gas it goes off.


I took it to the Saturn dealer last week and they tested it on their computer. They said the temperature was being read at 40 degrees less than what it actually was and the plug for the temperature sending unit was corroded. I let them change both the sending unit and the plug. He said the fuel economy would drastically go up and it would run better. Needless to say when he drove it, it ran the same way.


He continued to work on it for another two hours and could not find anything else wrong with it. He did confirm that everything I did was done correctly. He said without tearing into the engine, he has no idea what is wrong with it.


He did speculate that it is possible that there is a flat spot worn on the cam. He said it would cost more to fix the engine than to replace it. I would like to put in the least amount of money possible, but I cannot help but think there is something I am missing.


I am not super mechanically inclined, but I get around nicely once I've seen it done or been told how to do something. I need thoughts on what to do...any ideas???
Edited by: sw2cam

 

We had a similar issue with our 2000 SL2, turned out to be the catalytic converter was stopped up. Will cost you around $300 at a muffler shop.
Edited by: sw2cam

 

That is what I thought at first too, I forgot to add this part. I disconnected the exhaust at the flange of the exhaust manifold which should have opened up the restriction and add power. This didn't work either. Saturn did not say anything about it being bad either. I did buy one to replace it, but I did this test first (disconnect to see if it helped). Any other ideas?
Edited by: sw2cam

 

Whats the compression?

 

The compression is uniform accross the board from 155-160.


Also, I failed to mention that the rpms only go up to about 4000-4200 and cuts out bad like the govenor is kicking in. This is whether in neutral or in gear (it is an automatic).


The dealer did not mention anything bad about the computer either or any other electronic part being bad.


What was said on the report is listed as follows:


Diagnosed to coolant temp sensor reading 40 degrees too cold caused by a heavily corroded connector. Replaced CTS and connector, test drove and found vehicle has no power. Checked fuel pressure and volume, both ok. Found spark modifiers excessive caused by internal engine noise due to possibly worn internal engine components. Recommend engine tear down to futher diagnose.





NOTE: This car ran perfect when it was parked aside from fouling out the #2 cylinder.
Edited by: sw2cam

 

185 is the service limit, so those numbers are pretty low.

After sitting for so long, the rings could be stuck.

 

Mike,

Could you elaborate on what you mean "stuck". Could this also be causing the knock problem as well?

 

Sometimes the ring get stuck in a position that allows oil and compression to pass by them. You can do a piston soak to try to cure this problem.

 

How do you do a piston soak and what is it? As far as I have noticed, there is no blowby since I have installed the new valve guide seals. I have not noticed any oil consumption either. When the engine is running, there is no "smoke" when you pull the oil fill cap.

Thank you so much so far with your help.

 

You take a solvent, like GM top end cleaner, MMO (Marvels Mystry Oil) or Seafoam and put it into the cylinders.

Heres how I do it:

Pull the wires and plugs. Pour in the solvent into each cyliner and replace the plugs. DONT ATTEMPT TO START THE ENGINE. Let it sit overnight and remove the solvent. You can suck it out with a wet/dry vacuum or crank the engine with the plugs removed and let it fly out of the cylinders. Replace the plugs and wires and start it up. There will most likey be a ton of smoke coming out the back end. Your neighbors will hate you. Once its running smoothly, replace the plugs, oil and filter.