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JSTDV8 10-06-2017 02:36 PM

SL2 lags bad on acceleration
 
So I just bought this car. It's got 83k on it, no leaks or anything noticeable.
When I first test drove it I didn't notice anything at all.
So, a few things it does that are all related.
1.) When you start it if you put it in gear before it gets to its final idle RMP it will just die.
2.) When you do wait for it to get a good idle first and then put it in gear it drops down pretty significantly and then revs back up
3.) If you feather the throttle to go it goes fine, but if you kind of give it a bit more than normal throttle it lags so bad that it will die if you don't let up on the gas, once you let up it will continue to try and get it's bearings and then after about 1.5 seconds it will slowly go. Or sometimes it just dies.
4.) If it's in park and you recreate the same thing with the throttle it will be at an idle at about 1100 RPMs and then it will drop down to about 600 like its going to die, but it catches itself and then bounces back and forth between 600 and 1500 RPM until it corrects. Again, sometimes it just dies.
5.) And lastly, two out of about 12 times I've been messing with it at an idle it just starts accelerating RPM's, the first time it climbed to about 2500 before I just shut it off, the second time it climbed to about 1600 and just stayed there and I shut it off and restarted and it came right back to normal idle.
No codes are present.
I tried the obvious and changed the plugs and wires.
The plugs looked like it had a fine layer of oil on it, I'm not sure what that indicates.
Also odd is that the manual says that the firing order is 1342, but I see two different firing orders online, the other being 4123. It only starts with 4123, would not start with 1342
I'm thinking TPS, but i thought I'd check here first as you guys have really helped me in the past with a couple other saturn's I've had.
I read a bunch of other threads abut the subject and someone had suggested getting some Techron complete fuel system cleaner. So I got that, but it says to use it on a near empty tank with at least 12 gallons of new fuel. I'm at just under 1/2 tank. I don't know how long the car had been sitting, so I guess it could have old fuel.
Any other ideas? I'm surprised it can miss this bad and not throw a code.

billr 10-06-2017 02:52 PM

Re: SL2 lags bad on acceleration
 
Firing order is not 4-1-2-3 (which is really the same thing as 1-2-3-4). Have you seen pictures of how those cylinders are numbered, and how each plug wire is to be routed and which coil tower they go to? Lots of threads here about that. Get that sorted out, as a first easy step.

Next, take out the plugs for inspection/replacement and take compression readings.

What year is this beast? If it is OBD2, then use live-data to avoid a lot of guessing and parts-changing about the various sensors.

If you can't get live-data to check the ECT sensor, then remove it for inspection/replacement. The OEM sensors always fail sooner-or-later, so going after that "blind" is a pretty safe guess; and they are inexpensive and easy to change.

JSTDV8 10-06-2017 03:05 PM

Re: SL2 lags bad on acceleration
 
The car is a 2001 SL2 DOHC

As far as I can tell
then looking at the car from the front
The Cylinders are numbered 1234 from left to right
And then on the two packs below that are side by side
I currently have them 41 23
I tried the 13 42 twice and the car wouldn't start at all.

alordofchaos 10-06-2017 03:10 PM

Re: SL2 lags bad on acceleration
 
1 Attachment(s)
+1 to what billr said, ECTS is the next thing I would check (unless it is an '02).

Sounds to me more like a fuel and/or sensor issue rather than spark/ignition, but including info below anyway

Spark plug wires at the plugs are 1 2 3 4
They connect to the coil towers 4 1 2 3

1 & 4 should run parallel for most of their length, ditto 2 & 3

This is a SOHC engine, but same principle (attached a color coded one for clarity)

alordofchaos 10-06-2017 03:15 PM

Re: SL2 lags bad on acceleration
 
[QUOTE=JSTDV8;2256292]The Cylinders are numbered 1234 from left to right
And then on the two packs below that are side by side
I currently have them 41 23.[/QUOTE]

This is correct :) You posted right before me

edit: pics of plugs? Where on the plug was the oil; above or below the hex?

fdryer 10-06-2017 03:33 PM

Re: SL2 lags bad on acceleration
 
1 Attachment(s)
As mentioned, remove the coolant sensor for examination and replace it if its the original one. Try not meddling with the throttle stop screw unless you're aware of how factory setup works. Meddling without knowing procedures may result in additional problems with incorrect idle and more. The original faulty coolant sensor creates many issues.

JSTDV8 10-06-2017 04:35 PM

Re: SL2 lags bad on acceleration
 
You guys are unfreakingreal.
Popped the Engine coolant temperature sensor out, sure enough, it looked just like the one fdryer posed with the crack
Napa had one in stock for 30 bucks,
put the new one in. It still lags just a bit, but the main issue is gone where it bounces randomly around RPM range and wants to die.
You guys are seriously my heros.

For others having similar issues that may be reading this.
The sensor is located right behind and under the upper coolant line where it connects to the motor.
13MM deepwell socket and a 2" extension.
Pop the 4 prongs off the air box and remove the rubber hose at the back of the air tube so you can flex the air tube out of the way. Or take 1 more step and take the clamp off the other end of the tube and remove it entirely.

Find the sensor (it has two wires coming out of it) Squeeze the little plastic ring around the sensor and gently wiggle it outwards and it pops right off.
13MM deepwell socket, take out the sensor, a little coolant will leak out, but not much. Put the new sensor in, don't overtighten it.
Plug the wire back on paying attention to where the indents on the outside of the sensor are and line those up perpendicular of where the squeeze points are on the wire. plug it in. Replace the Airbox cover and hose and you're all set.
10 minutes tops.
Thanks again guys!!

billr 10-06-2017 05:11 PM

Re: SL2 lags bad on acceleration
 
If the ECT sensor was bad, the ECU was trying to adapt the fueling based on bogus data. Give it a little bit of driving, it might need to readjust for correct fueling now.

Note that the "firing order" is [I]not[/I] either the way the cylinders are numbered, or the coil towers ordered.

fdryer 10-06-2017 05:58 PM

Re: SL2 lags bad on acceleration
 
1 Attachment(s)
With the correct coolant sensor replacing the faulty one, note cold engine startup rpm and after a full warm up. Normal cold engine idle will run around 1200 rpm and continually drop down to around 650-900 rpm after ten minutes of driving.

If the temperature gauge needle hovers over the 1/4 mark, replace the thermostat. The faulty coolant sensor may have overheated the engine and melted the t-stat seal, letting the engine never warm up to operating temps. You might want your heater working in Alaska winters. A damaged t-stat seal won't allow full operating temps and result in colder heater output.

Jonasan308 10-06-2017 07:45 PM

Re: SL2 lags bad on acceleration
 
If its anything like what mine was like, youll REALLY want it working right. Im in one of the more mild(ish) lower 48, and it was miserable, waiting for it to warm up and even if, never seeming to be quite as hot as it could be. Now, with the sensor and t-stat replaced, my car is a hot oven when the heat on.

JSTDV8 10-09-2017 06:27 PM

Re: SL2 lags bad on acceleration
 
[QUOTE=fdryer;2256315]With the correct coolant sensor replacing the faulty one, note cold engine startup rpm and after a full warm up. Normal cold engine idle will run around 1200 rpm and continually drop down to around 650-900 rpm after ten minutes of driving.

If the temperature gauge needle hovers over the 1/4 mark, replace the thermostat. The faulty coolant sensor may have overheated the engine and melted the t-stat seal, letting the engine never warm up to operating temps. You might want your heater working in Alaska winters. A damaged t-stat seal won't allow full operating temps and result in colder heater output.[/QUOTE]


I think I'll have to look into this. It does hover just above 1/4 mark
And while the heater puts out heat, its not overly hot. Its fine while the temps are in the 40's right now, but I'm sure it wouldn't cut it in the real cold months.

The car is running extremely well now.
My dad is a mechanic/welder and he was baffled that a sensor could be that messed up and not throw a code pointing you to the sensor. They must have missed that one when they made the OBD2 codes lol

fdryer 10-09-2017 10:00 PM

Re: SL2 lags bad on acceleration
 
The sensor failing was just one of those gotcha moments GM never saw coming. In hindsight it's easy to understand when figuring out what this sensor does, fooling the PCM into thinking the engine's either freezing or very hot. In sensor terms, sensor outputting very low voltage (operating between 0.01-4.9v) below 1 volt or less tells the PCM the engine is freezing with the pcm sending extremely rich fuel mixtures on startup, sometimes flooding it. The faulty sensor sends incorrect signals that tells the PCM to continually run the engine rich all the time. A few members describe the opposite symptom where starting up resulted in a backfire with flames shooting out the throttle body when the air intake tube was left off. The sensor output a higher voltage from a very low resistance, filling the PCM into thinking the engine is extremely hot so fuel is leaned out. The leaned out fuel mixture resulted in backfires out the throttle body. Same sensor, two different failure modes. All documented here from members sharing experiences.

alordofchaos 10-10-2017 11:04 AM

Re: SL2 lags bad on acceleration
 
[QUOTE=JSTDV8;2256572]
My dad is a mechanic/welder and he was baffled that a sensor could be that messed up and not throw a code pointing you to the sensor. [/QUOTE]
He shouldn't fee bad. The ECTS baffled many professional mechanics, with many years experience.

I never heard of an ECTS before owning a Saturn :)

Melissa_M 10-10-2017 02:35 PM

Re: SL2 lags bad on acceleration
 
ECTS was my first part to get replaced (by dealer). My previous car had horrible cooling system issues, so when my [B]very [/B]new saturn coolant gauge started freaking out, I was regretting my purchase. Dealer was quick to figure it out, so that was good. I had forgotten the part name, until I started hanging out here, then went ahead and replaced mine again.

Highmile 10-12-2017 08:04 AM

Re: SL2 lags bad on acceleration
 
A good cleaning of the throttle body may be in order too. This is a good 60k-80 maintenance item either way.

I would also spark check the coils. easy and fast and cost is zero. Pull the plug wires off and have someone crank it for you. Should see a spark between each pair of contacts on the coils that looks like a lightening bolt.

With it not knowing what the engine temp was I might take a bit of driving to get the computer reading and fueling correctly as was pointed out.

Highmile
'95 SL1 641k and counting

Diamond193 10-13-2017 06:25 AM

Re: SL2 lags bad on acceleration
 
[QUOTE=JSTDV8;2256572]I think I'll have to look into this. It does hover just above 1/4 mark
And while the heater puts out heat, its not overly hot. Its fine while the temps are in the 40's right now, but I'm sure it wouldn't cut it in the real cold months.

The car is running extremely well now.
My dad is a mechanic/welder and he was baffled that a sensor could be that messed up and not throw a code pointing you to the sensor. They must have missed that one when they made the OBD2 codes lol[/QUOTE]

Hell mine dosnt even have heat or ac they both never worked and had the car going on 5 years haha


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