miss or hesitation during acceleration

[tinysmoke]

I bought a used 2000 SL, 1.9 L sohc engine, 5 speed manual with about 55k miles.

Shortly after I got it, it developed a miss during acceleration. When that occurred, the check engine light would come on solid. Not having a code reader I cleaned and gapped the plugs with no change. Then I replaced the spark plug wires which solved the problem, until now.

At about 70k miles, I installed new splitfire plugs.

Now at 86k miles, the miss/hesitation has returned. It occurs during acceleration especially if I shift too early and lug the engine. Sometimes, 2 or 3 misses occur before acceleration smoothes out. To my surprise, the check engine light does not come on when this happens.

I cleaned and regapped the plugs (they weren't bad). I inspected (but did not replace) and reinstalled the plug wires. I replaced the air cleaner. The symptoms remain.

Oil consumption is about the same at .5 qt every 3,000 miles. Gas mileage is about the same at 39 to 42 mpg depending on weather and the mix of highway/city driving.

Any ideas would be appreciated.

[peppermrj]

might be something as simple as plugs. They recommend ngk's. I've run AC delco in mine without problem. Stay away from the fancy stuff especially platinum.

Autozone will read codes for free. Don't need a light to set one. Did you ever clear the last one? If not don't now but have it read first.

Good luck.

[tinysmoke]

thanks for the info. I found the splitfires (new) on ebay and have often wondered if a particular brand or style of plug, oil, oil additive, or gasoline really makes a difference. I can't tell any difference (good or bad) on the plugs.

I cleared the check engine light (and presumably the codes) by disconnecting the battery. The check engine light has remained off (except at engine start) since I replaced the spark plug wires at about 58k.

The miss or hesitation has the symptoms of a plug or wire, but perhaps it is something else.

[peppermrj]

Preventitive maintence is something I try to do ahead of time but when a problem arises sometimes it will also cure it.
PM for your mileage would be to
Run fuel injector cleaner (chevron with techron) thru a couple tanks
Replace fuel filter OEM (saturnparts.net or .com)
Replace the ECT with OEM brass tipped updated sensor (same source^)
Clean the throttle body,IAC valve, and egr valve.

It occurs during acceleration especially if I shift too early and lug the engine.

Bad plugs or wires definitely show up under load. I think that new plugs and injector cleaner might be all you need.
a miss is usually electrical while a hesitation is A/F related

The other PM items will save future aggrivation tho.

I try to be consistent with plugs, fluid, filters. I do think that a certain brand can be more effective on individual vehicles. I've heard it from both gm and ford factory techs that weren't selling me anything. My personal experience with $5 bosch plugs was that there was no difference that I could discern except for my wallet being $4 dollars a plug lighter.

[tinysmoke]

[quote=peppermrj]Preventitive maintence is something I try to do ahead of time but when a problem arises sometimes it will also cure it.
PM for your mileage would be to
Run fuel injector cleaner (chevron with techron) thru a couple tanks
Replace fuel filter OEM (saturnparts.net or .com)
Replace the ECT with OEM brass tipped updated sensor (same source^)
Clean the throttle body,IAC valve, and egr valve.

I believe I have had some small success. I cleaned the throttle body but not the IAC or egr yet. I did clean the pcv but it wasn't really suspect. I also put in fuel injector cleaner. Tonite, after most of the cleaning effort, the miss/hesitation seemed to be much less. Will test better tomorrow.

Should I plan on replacing the egr gasket when I clean it?

I am using a Haynes repair manual- it makes no mention of the ECT. What is the ECT?

[peppermrj]

The EGR gasket came off in one piece on the 96. I had a new one just in case so I just changed it. The little o-ring on the IAC valve is over $11.00 and a dealer only item don't lose it. I put a little vaseline on it and reused it. Be sure to clean the port that the IAC fits into.

The ECTS (engine coolant temperature sensor) was a poblem up to the redisigned repacement in 2001. It was a composite/plastic material that did not take well to living in hot coolant. They all will fail in time (90,000 miles on the SC). The new version (brass tip) is available from saturn (saturnparts.com or net) for under $20.00 including $8.25 S&H.

They effect gas mileage, engine idle, and finally even starting when they crack. They also control the temp gauge. If it is acting up time for a new ECTS. Good how to's at: Saturnalia .

Have at it and good luck.

The intake manifold gaskets have a bad history on the SOHC's. If the above mentioned doesn't help that is the next place to look.