problems accelerating

[mjoekingz28]

On my SC2 Saturn, I have a problem. It was running fine one minute then I began to notice problems. At idle it kind of slightly misses. But when I floor it, the engine will growl alot louder than normal (sounds good and powerful) and it will lose more power the harder I push the pedal. Also, when floored it will top out at 4500 rpms (redline 6500), but at part throttle it will go higher.

And when I was revving it in the driveway I could smell fuel. I changed the plugs and wires hoping old wires would be it, but no luck. So i took it to Firestone and they said they ran fuel system cleaner through it and replaced the fuel filter after they found dark colored junk coming out of it. Then they said they hooked up a scanner and found one of the injectors plugged or stuck so they replaced it.

So I get my car back and its doing the exact same thing as before they got their hands on it. But now, I get an engine light since they used a non-Saturn fuel filter after I said only it would work.


So what would make the engine growl louder under heavy throttle, have an off idle and have less power the more you put your foot down.

Thanks for any guesses or ideas or answers.

Checked with Saturnfans.com and all one guy could guess was the ECTS which I've already replaced.


When I floor it and it get to around 4k rpm it feels/acts just like a clogged main jet on a motorcycle after it has had stale fuel in it all season. Also, it acts like my RX7 did when the TPS was out of adjustment, so I will replace that with a spare I have before I go back to Firestone.

 

[Colt45ws]

I would suspect TPS.

 

[chad8]

Do all firestones use the same mechanic?
Lets see, replace parts by looking at a scan tool and if it doesn't work , charge the customer, and give them back the car anyway.

 

[chad8]

get the tps tested. The check engine light has nothing to do with a filter.The fire me stoned idiots left something unplugged or broke something.
You’d be amazed what a TPS (Throttle Position Sensor) can do if it jumps from .5 of a volt to lets say 3.5 volts, the poor computer thinks you just jumped on the throttle and throws a whack of fuel at the engine, causing it to flood out.
Now I’m not saying it’s the TPS but just using it as an example, because the computer knows that around .5 of a volt is closed throttle and at 4.5 volts is wide open. Anything in between is normal for the computer to see, depending on where your foot is on the throttle. It’s a variable resistor something like a dimmer switch in your house that can turn your lights in a room from full bright to dim.

 

[chad8]

I forgot to add to test the coolant temp sensor too.
it can tell the main computer that it is cold all the time, hence the too rich mixture and the stumbling idle after warmup. the cutting out at 4200 rpm and kicking back in at 4000 is normal. it has a high-rev sensor to protect the engine too.

 

[Chris Meutsch]

Originally Posted By: chad8
I forgot to add to test the coolant temp sensor too.
it can tell the main computer that it is cold all the time, hence the too rich mixture and the stumbling idle after warmup. the cutting out at 4200 rpm and kicking back in at 4000 is normal. it has a high-rev sensor to protect the engine too.


I remember reading about this from others here a while back. Something about how the original sensor is made of resin or something that cracks and stops working? Sounds logical to me.
Shocking that your chain "mechanic" didn't fix things.

 

[Trav]

Since you have a spare TPS try it,they usually throw codes but sometimes not.
I would be looking at the MAP/MAF sensor also as these can cause all sorts of problems.I think yours uses a MAP.

If you have a plugged injector there is little hope of cleaning it through the rail or with in tank products,this method is fine for varnish but any particulate matter will just get forced deeper into the injectors internal filter.
These can be changed and the injector back flushed but requires removal of the injector.

 

[salv]

What trouble codes did they read? Was there a lean code? P0171?

 

[tmorris1]

What about Fuel Pressure Regulator? It could be leaking fuel into the intake, thus the fuel smell. I have had this happen before.

 

[mjoekingz28]

Thanks guys. The code was a PO172 and Im quite sure it was because they used the wrong filter/ FPR because it is common over at saturnfans. The tps has been changed and it is not it. I have a spare MAP somewhere and will try it, but the next thing is to change the ECTS. After that, If I dont luck out, we'll be visiting all the mechanics in the area.


Take this! After we took the car back a second time, he tells me my timing chain and sprockets are wore down and that is the next thing to try. Im no expert, but if you go from a fuel problem to a timing chain problem it just sounds to me like your guessing or have other motives.

I'll go get the car shortly and we'll see how the bill turns out.

/crosses fingers its the ECTS. I changed it with the brass tipped one about 75k miles ago.

The 4000rpm thing is not at idle. I know it has the safety feature, but it bogs at 4k while fully warm and driving down the road. Its uncanny how similar it is to a carb bike got WOT after being set all season with old gas.

 

[eljefino]

Your cat's plugged.

There's some test you can do with a vacuum gauge, intake vacuum after revving it a while will be less than the 21 inches or so you're supposed to get. You could also pull your front o2 sensor (briefly) to see if that relieves pressure.

With reduced vacuum, your MAP is overfueling.

The key is the sound, the exhaust is strangled trying to get out.

 

[Eddie]

+1 a plugged Cat.

 

[mechtech2]

All of a sudden? No power with odd noise?

It's the timing chain system.

A cat would do this only if a chunk broke off to plug the pipe, but he noise would not be increased.

 

[eljefino]

A saturn timing chain will sound like living death when it's going out, and from that particular area of the engine. IMO the power output should still be proportional to accellerator input.

Haven't seen them jump teeth messing up cam timing measurably, but plastic pieces of the guides sometimes chip away, and often the oil filled tensioner sludges up leading to a benign rattle and *mild* cam timing changes.

I have had a saturn cat toss a chunk, that wound up in the outlet area, misaligned so it wasn't breathing through the honeycomb, matching OPs symptoms. Interesting to nurse along at 1/10 throttle, resisting the urge to downshift. An automatic transmission would probably go berzerk.

 

[Rix]

PUll your pre-cat o2 sensor(s) and drive it, see if it improves.
If it's a plugged cat, the exhaust having someplace to got (o2 sensor holes) should make a marked improvement.
Don't go far, there's a chance you can catch stuff on fire!!

 

[mjoekingz28]

Changed the ECTS and now the temp reading is high. Went from barely under 3/8 to over 3/8. Runs the same.

Took the 02 sensor out and it still runs the same, just louder. Does that mean the cat is ok and is not the problem?


Cousin told me the dealer can hook up a computer and it will tell you the problem. There is a dealer that still stocks Saturn parts but the building just reads GMC and Buick.


I don't see how the timing chain could cause this. I figure it would run the same up until the point the chain broke and it wouldn't run at all. Any in between would just be noise.

Thanks for the suggestions, but do you have any more?

 

[chad8]

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[Maritime Storm]

Get the part number for the fuel filter off your receipt and post it here. Some aftermarket fuel filter list the same fuel filter for 97 & up S-Series cars as the same as for a Flex fuel S-10, the pressure regulator is set too high and it will cause the engine to run rich and kill your cat amongst other things.

 

[Warstud]

Originally Posted By: Eddie
+1 a plugged Cat.


Was thinking the same thing. OP didn't say what the mileage was though.

 

[mjoekingz28]

219k miles

This weekend I changed the fuel filter back to the factory original for now, a new Denso O2 sensor and a new ECTS. Now, I still have problems accelerating but its much different now. I no longer get the hanging up at 4k rpm, now its just a lack of power through the entire rev range. It accelerates pretty smooth now.

One independant mechanic suggested the O2 sensor, then check the cat and if the problem persists then change the fuel filter. I had midas drill a hole in the exhaust and they stuck a meter of some sort in there and told me that the cat was not the problem.

Just got back from another mechanic who suggests its still the cat although I've had it checked. He said some stuff is loose in there and rattling and sometimes it will clog up, sometimes not.


Would I be better off getting a fuel pressure reading with the car in motion OR having the fuel pump replaced OR replacing the Cat con next?