Just bought a 2000 SL1, 5 speed, 137k. It has several issues, not sure if any or all are related.

The engine misses at all RPMs. Pulled plug wires while running, and there is no change when the #1 plug wire is pulled. There is very strong spark coming from the #1 wire. Pulled #1 plug and nothing looked odd. Pplug didn't seem overly wet, normal carbon of a used plug. Repplaced plug, but the miss persisted. Checked compression on#1. On the first stroke the gauge went up to 75psi, and on the second stroke it jumped to 120. Wasnt sure about compression, but ive seen motors run on less.

There is NO check engine light on (it does illuminate when key is cycled)

When I bought the car, I noticed there is is a significant amount of oil seepage on the back side of the head on the rear side of #1 cylinder.

The engine idles high. If you start the car cold and leave it idle, it will run at 2000rpm for a few seconds and drop to 1500rpm after 30 seconds or so. If you drive the car, when you shift, the engine will rev (if you disengage clutch at 3000 rpm, it will rev to 3500-4000. If you shift at 4500, it doesnt seem to rev higher, but it will very slowly drop to 3500-4000.) If you allow the engine to rev, after 30 seconds or so (warmer the engine, the sooner the drop in rpm) the engine will idle down in the 1500-2000 range.

If you start the car warm, it will run excessively rich. Some time it needs to be held at WOT until it smoothes out.

Engine doesnt warm up. Im in Wisconsin, and we havent been above 10 degrees for several weeks. When starting it cold, the temp guage is a fuzz below C on "cold". After running it, regardless of distance, temp guage will rise to a fuzz above C. Heater will throw only very luke warm air. Coolant feels scalding hot on radiator hoses, and both heater hoses.

Replaced TPS, no change on idle issue. TPS looked new, but replaced anyways.

Thermostat looked new, but replaced it regardless. No change on temp gauge or heater.

Flushed heater core. No debris or forgin color. No change in heat output. Heat control feels like is is operating the blend door.

Changed #1 plug. Still misses.

Any thoughts on the miss?

Any thoughts on the heat?

Any thoughts on the temp?

Thanks!

 

Cyl 1 missfire....could be a leaking intake. (common problem)
Does the engine cooling fan run all the time?

Stop in the new member area and introduce yourself. Once done open the USER CP and add your first name, location, and year/model of your Saturn to your "signature".

 

This engine has a history with the intake manifold gasket around the #1 cylinder. The intake port on the # cylinder is not bridged to the other intake ports on the head and the port only has three bolts around the port, all the others have four. The upper outboard corner of the intake manifold is not bolted for some reason. In 2000, GM went from a metal backed gasket to a fabric gasket. without any support, the gasket gets sucked in on this port.

A little trick when replacing this gasket, use a felpro gasket and use a belt or some type of strap to pull the engine toward the front of the car. There isn't much room back there. Remove the throttle body, then the fuel rail and finally the manifold. You will be surprised how much gunk will build up in this models intake manifold. I used a small toilet brush and a lot of kerosene to clean mine out.

 

ditto on the intake manifold gasket. common problem o #1 cylinder. cheap test is to spray some carb /choke cleaner around #1 intake and if rpm changes that is where the problem is. if you are mechanically inclined you can fix yourself with a little patience

 

Yep..

 

Bry......I'm going to jump on the intake gasket bandwagon.

 

Bry, I've used this forum for a couple of years and from my observations during that time the respondents so far are the most knowledgeable so their consensus on this means that the intake manifold is probably what the problem is. I would only add that being able to get a spark with the wire and/or plug while it is removed is very different than being able to get one under compression. It could still be the coil or wire or plug. Jmo...

 

Thank you all for the responses. I can certainty see the intake causing the hi idle and runnablitly issues.

Do you guys think that would also cause the heating issues?

 

Here is a step-by-step for figuring out the idle issue that I picked up on this forum -- or perhaps another -- no longer remember -- that I found useful for my son's 1995 SL1..

As for not heating up when its really really cold, your comment about how hot the coolant hoses are, plus you changed the thermostat and coolant, would imply that the sensor is not working. Of course the heater only putting out luke warm air contradicts that thinking.

Are you sure that you have the right coolant mix and that you aren't getting a little freezing in the exposed coolant lines where they go into the firewall?

I'm interested in what you find here.

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How to Diagnose/Solve High Idle Issues

Due to the numerous threads about high idle, I have made this to help those with the issue...

Saturns tend to have high idle issues. There are a variety of possibilities that cause it, and a variety of solutions depending on whether the engine is a SOHC or DOHC. Regardless of engine, there are a few possibilities that apply to both SOHC and DOHC.

ECT- is the most common cause to all issues if not replaced. So even if you do not have a high idle issue, replacing the ECT will help to avoid future problems. It is a relatively cheap repair, and can be picked up aftermarket. You will need Teflon tape to wrap the threads of an aftermarket ECT to avoid leaks.

Engine Coolant Temperature Sensor R&R Saturn S-series

ECT connector - The connector has a tendency to corrode. It is not necessary to replace it if it is fine, but if you see any green gunk in there, then it needs to go. You will have to get this from a dealer, or you can go to a junk yard and find a IAT sensor connector.

Engine Coolant Temperature Sensor Connector Replacement

Vacuum Leaks - Vacuum leaks will cause high idle and are relatively easy to diagnose and find. On a SOHC around the years of 99-02 the intake manifold gasket is the most common issue for high idle. To find a vacuum leak you simply take water or brake cleen and spray around the intake manifold gasket to the head, the gasket for the Throttle body and all vacuum lines. Do this with the engine running. Should the idle change at all, you have just found the leak. An IM leak is probably not the likely cause of a DOHC high idle.

Carbon Build Up - This causes the IAC (Idle Air Control) valve to stick and gunks up the Throttle Body. If you turn on the car and turn it back off, then turn it back on and the high idle is gone. Replace the TPS with a dealer replacement and clean the connector. To clean the throttle body and IAC, follow RichPin's TB cleaning videos. This should be done on both motors regardless of the solution. This may also increase MPG.

Throttle Body Cleaning (part 1)of 3

Throttle Body Cleaning (part 2)of 3

Throttle Body Cleaning (part 3)of 3

Thermostat- If the ECT has been replaced and the high idle continues and the other common symptoms have been checked, check your temperature. For 1991-1995 your temperature should be around the half way mark. For 1996 up your gauge should read a needle's worth over the 3/8ths mark.

Saturn S-series Thermostat R&R

EGR valve- Try to clean the EGR valve if still no success then replace it.
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The order of sequence in which I would do these for a DOHC; ECT and ECT connector, Throttle Body Cleaning and IAC valve, Thermostat, EGR valve, then Vacuum Leaks.