1998 SL2 Extremely Sluggish Acceleration

[sd_98saturnsl2]

Hi,

I have a 5 speed manual 1998 Saturn SL2 with about 210k miles. Recently it's acceleration has been extremely sluggish, especially when going uphill. On flat ground it can eventually get up to freeway speeds. It happens in all gears and maybe a little worse when cold, but occurs when the engine is cold or warmed up.

Based on other thread searches, I have tried the following with no significant improvement.

* Replaced the front O2 sensor and ECTS
* Removed, cleaned the EGR, and reinstalled
* Temporarily removed front O2 sensor. Car continued to idle normally and still had sluggish acceleration. I read in another thread that if this fixed the acceleration issue then it would have likely been a clogged catalytic converter. But, the acceleration issue remained for my car.
* Temporarily disconnected electrical connection to EGR. Car continued to idle normally and still had the same sluggish acceleration. I read in another thread that if the acceleration issue changed without the electrical connection, then the EGR may be bad. It didn't change for my car.

Additionally, the car had been idling high (~2000rpm) for a while until I removed and cleaned the throttle control valve about a month ago, prior to the extremely sluggish acceleration issue. The car now idles around 900rpm after warmed up, maybe around 1100rpm when cold.

Any more ideas of things to try to diagnose the issue? Or what else could be the cause?

Thanks.

[billr]

Take compression readings and check fuel pressure with a gauge.

Block off the EGR ports. Disconnecting the electric cable is not a definitive test. If disconnecting the cable does improve the engine power, then it shows the problem is probably EGR related; that is true. However, if disconnecting the cable does not change things, the EGR system may still be bad. You have not proven it is good, only that is not definitely bad, and is still suspect.

Likewise, that driving with the front O2 sensor removed is kind of iffy for proving this isn't a clogged cat/exhaust issue. Removing that O2 sensor provides a new exhaust path of only about 3/4" diameter, still not much for even a small engine like this. Removing the down-pipe and cat would be a more sure test, but quite a bit harder to do than just removing the O2 sensor. That said, R&R of the pipe and cat could be done in about 1 hour, if things go OK. It is not an unreasonable thing to try, if other easier stuff gives no joy.

[sd_98saturnsl2]

I'm not an experienced mechanic and I don't have access to a gauge for fuel pressure measurements or exhaust R&R.

For reference, right after cleaning the throttle body valve about a month ago, the car passed a smog test.

When you say block the EGR ports, do you mean remove the EGR and cover the ports with some electrical tape or something? Then drive the car to see if the sluggish acceleration remains to eliminate a bad EGR as a possible culprit?

Thanks.

[Greg1]

You would need to use a piece of sheet metal to cover the EGR port. A soup can makes a good donor.

[billr]

"Soup can" means you need to use a steel can, not an aluminum beverage can.

[sd_98saturnsl2]

Ok, I'll take off the EGR valve again and put a piece of metal covering the ports and reattach the EGR valve to clamp down on the metal. How should I expect the car to run when I do this? Especially compared to the current extremely sluggish acceleration. Basically, what am I expecting and what would indicate a bad EGR?

Any other ideas of what it could be?