Engine Stuttering

Fi-Alero · 12-19-2009, 12:06 PM

Hey guys,
Ever since I boosted my car, I've been having an engine problem that is annoying me.
I'm going to try to describe it the best way I can lol:
Whenever I'm cruising at ~55mph and trying to normally accelerate to 60, my engine will stutter horribly. I've tried everything I can think of to fix it. At first I thought maybe it was running lean, but my wideband gauge is reading 13arf and according to my HPTuners AFE table, it is less than 1% off designated AFR.

The only way I can stop it from stuttering is by letting off the gas for a second (making me get into a different gear) and then make the car quickly accelerate to 60. It isn't a random thing. In fact, it does it every time. I can tell exactly when the car is about to stutter because the exhaust gets really low (only way I can explain it lol.)

What could be causing this? It is extremely annoying because I cruise at 55-60 everyday for 60 miles.

Thanks for any input.

[ion] C2 · 12-19-2009, 12:14 PM

Does it happen when the boost is up high? When I'm in a higher gear and put heavy load on it (10-13 psi) the car will stutter, but if I downshift it it'll pull fine.

Seems to be a low-RPM high boost situation that causes it. Try gapping down to like .028. Your problem sounds a bit more problematic than my issue.

AlbinoMonkeyRat · 12-19-2009, 12:52 PM

http://www.srtforums.com/forums/f10/...es-wtf-462210/

different engine, similar symptoms...possibly similar answer. I hope that link helps.

Fi-Alero · 12-19-2009, 01:29 PM

Wow thanks for the quick responses guys.
I am having the same problem as that guy, but I'm not in boost when it is occurring. Could it still be the plug gaps even though I'm not in boost?

And also, .028 is where I should gap at even though I'm not in boost in this situation?

[ion] C2 · 12-19-2009, 01:53 PM

Oh, unlikely then, but it's always at least worth a try. Our spark plugs are easy to play with. I didn't know you were still in vacuum. My car runs PERFECTLY in vacuum, but if in high gear and under high boost, it sometimes misses or who knows.

Oh yeah, use di-electric grease. I'm going to snag some from AutoZone and put that on all my connections too.

Fi-Alero · 12-19-2009, 02:57 PM

Thanks, Chris.
I'm at work right now, but I took my valve cover off for a second and realized that one of the rubber boots surrounding the spring was broke off (may have been causing a bad connection). I glued it back on so I'll see if that fixed anything on the drive back home.

Speaking of being in a boost situation, it also sometimes stutters when I get on it with full boost (5psi).

I hope it is just the spark plugs.

Nate's Alero · 12-19-2009, 03:01 PM

Spark Blowout... 100%

Fi-Alero · 12-19-2009, 03:24 PM

Yeah, Nate, I've been looking into it. If what I did today doesn't work, I'm going to regap the plugs and also use some of that grease Ion is talking about.

Chris, what gap size would you recommend me try?

[ion] C2 · 12-19-2009, 03:30 PM

Like I said, real low, .028, just to test. You should always try to run the largest gap you can without blowout. (more spark surface area)

Oh yeah, look at the spark plugs too. This happened to me a month or two ago. Caused some weird things to happen, stuttering under load, etc., but the datalogging overall didn't point to any definite cause.

Fi-Alero · 12-19-2009, 07:00 PM

w00t!
No more stuttering

Turns out, the rubber boot around the spring that was broken was causing it to not get a good connection.

Tomorrow I'm going to do a little more work to the plugs just for safety.

Thanks for everyone's help!