2002 SL1 Intermittent high idle and bucking
 

Hello all,

I've an '02 Saturn SL1 (manual transmission) with about 210k kms on it. The past couple months it has been acting up with a couple issues.

1. Intermittent high idle (~2000rpms). Occurs upon starting the car. Will settle briefly, but over the course of the drive, the higher rpm baseline will creep in and before too long the 2000rpm is there. When the clutch is depressed when shifting gears, the RPMs will also climb.

2. Bucking - Occurs intermittently when I'm cruising around highway speeds (60 - 80km/h).

Unfortunately I don't remember all the different codes the car was throwing, but most recently it was running a P0404 code that has since not ahown up after switching out the EGR.

Initially I replaced TPS (STANDARD MOTOR PRODUCTS - PART NUMBER TH387) This only helped for a day or so. Then I replaced the entire throttle body assembly (with a used throttle body from a donor car that had 170k kms on it) per a mechanics recommendation, I switched out the original TPS that came with this used throttle body assembly with the new TPS I had just bought. Afterwards I cleared any codes that were on the computer. The car behaved normally for about a week until I got the P0404 code. At that point, I replaced the EGR valve (STANDARD MOTOR PRODUCTS - PART NUMBER EGV618) and cleaned out the pipe that led to it. The car seems to drive a little rougher now and it makes a slapping sound upon turn over that I have never heard before.

I've read a good amount of forum posts regarding this issue, but am still at a loss. What are some things I can do to further suss out potential causes? I still have all the original parts I replaced as I have heard there are quality concerns with aftermarket parts...

Thanks

3rd generation SOHC engines were prone to come off the production line with the intake manifold gasket partially folded around one of the intake ports. This would usually cause an increased idle speed and usually a misfire on that cylinder. The currently have any misfire codes?.

You can also try inspecting the wiring, connector, and resistance across the ECTS. Corrosion on the connector greatly affects the resistance of the circuit and the PCM interprets The vehicle is being much colder than it actually has. Get a Dephi censor and I believe dorman makes a pigtail for the connector.

As for the bucking at highway speed, do the RPMs track with the bucking? Is the SES light on? If so, is it solid or blinking?

As for the slapping sound, isn't mental to metal? Does it happen just a tiny tiny bit after the engine starts? Does it feel like something is smacking the underside of the car or does that sound come from under the hood area?

Hey thanks for the response!

1. No misfire codes
2. Sure, the ECTS is original. I will first inspect the existing ECTS before replacing.
3. No I don't believe the RPMs track with the bucking. No SES light on either
4. Not sure if id call it metal to metal, I'll upload a clip of it in a bit. Yes it sounds like it is coming from under the hood and its for a few seconds after turning over, then its gone.

Start up noise

Make sure that you know the connector to the ECTS is a squeeze type and not one that just pulls out. If you start pulling and tugging on it, you'll most likely crack it.

If that is truly the original ECTS, it should be the all brass design I believe but there's only one way to tell which is pulling it. If it is resin tipped, throw it as far as you can because it has failed.

I know the later s cars had smog air pumps that would kick in at startup and only run for a short amount of time. Usually it will throw a code if it is not functional. It is just mixing air into the exhaust I believe. I think it's over on the passenger side. Recruit someone to listen for you or to crank the engine.

Will do. It'll take a while for the ects to come, will report back when it comes in.

A correction - the bucking is happening at all speeds, not just at highway speeds.

What would I reference for the correct voltage /ohms that should be running through the electrical connector? I plan to buy a multimeter this weekend and start checking.

I'm not a mechanic and neither is Rube, but that sounds like possibly a bad lifter or possibly an issue with something not getting sufficient oil at startup.

These engines have hydraulic lifters which means they need to fill up with oil to fully expand to the correct height. And they need to maintain their shape and size when in use. If the oil runs out of a lifter, you get that tap tap tap tap tap sound until oil gets back into the lifter, it expands, and takes up the gap.

Bucking at all speeds sounds more like a clutch/hydraulic issue

Sounds like typical lifter noise.

Yes and no. While the s car engines make the routine tap tap tap lifter noise while running, they do not in general make lifting noise that goes away right after startup. I think he has one collapsed lifter that might be part of his other problems but I don't remember what they are cuz I can't see them on my phone while I'm answering