sputtering/missing under 1700 RPM

[Craig 94 TA GT]

This isn't a post about my T/A, rather for Steve93Z, who is out of town. He took his Z on a trip and said that the thing started missing/sputtering under 1700 RPM with slightly higher load, in any gear. By load, I mean anything slightly more than normal acceleration. Beyond 1700, it's fine. There are no codes, no SES light. He thinks it's the opti or possibly a loose plug. I am thinking those possibilities, or possibly the ICM. Does anyone have any ideas? Thanks in advance...

[N20LT4Bird]

This isn't a post about my T/A, rather for Steve93Z, who is out of town. He took his Z on a trip and said that the thing started missing/sputtering under 1700 RPM with slightly higher load, in any gear. By load, I mean anything slightly more than normal acceleration. Beyond 1700, it's fine. There are no codes, no SES light. He thinks it's the opti or possibly a loose plug. I am thinking those possibilities, or possibly the ICM. Does anyone have any ideas? Thanks in advance...

This seems to be a common problem as of late. I thought I had mine licked with a new coil. It was better for a few days, and then back to the same symptoms as you described, only it happens only when warm.

Ive replace the coil, ICM, coil wire. Opti and plug wires are less than 4 mos. old. I havent poored too much time into it, as I have been driving it less and less as the weather degrades. So, I dont have an answer.......anybody else dealt with this before?

[Craig 94 TA GT]

Thanks for the reply. I can't verify the cause either, so maybe we'll just have to go step by step, and hopefully it will run back from his trip. I just hope it's not going to be one of those things we throw a bunch of money into in order to find the cause.
And mine's been having a bit of trouble down low, but nothing compared to his. I've replaced the opti, plugs, wires, coil, ICM, fuel pump, fuel filter, all injectors, fuel pressure regulator, valve springs, roller rockers, lifters, pushrods, etc etc yet it still stumbles!!! I'm in the same boat as you...too much time into it, so I'm already giving up.

Mike, I really hope Steve's problem is something simple like a loose plug. Otherwise, I know his Z possibly caught my T/A's *disease* lol

[94 formula]

I'm in the same boat, and have a new opti on the way. Mine got really bad this last thursday coming back from school and I got a SES light. I scanned it and found it to be the right side 02 wasn't working. Further investigation showed that I was being a dumb a$$ and didn't run the wires for my 02's to my new headers right and it burnt up. So long story short I got rid of alot of my stumble and hopefully next weekend my new opti will have it all solved.

[Z Ya Later]

I just got back into Sac. and drove her today. When cold, she's fine. Thus, its temp. related. There's no backfie or anything, I would think of it almost as surging. Could it be something else besides the Opti? I am revising the range to 1000-1500 rpm. Thanks everyone.

[Mike71]

im not to well versed on the opti system..but if its temp related could it be the opti?

maybe check things that are close to other things that get hot..maybe something is getting hot because it is to close to the exh. or something..worth a shot

[Fastbird93]

I just got back into Sac. and drove her today. When cold, she's fine. Thus, its temp. related. There's no backfie or anything, I would think of it almost as surging. Could it be something else besides the Opti? I am revising the range to 1000-1500 rpm. Thanks everyone.

When my opti went out (coincidentally on my 93) I had the the exact same symptoms. Cold it was fine, at op temp in the low RPM load range, hesitation and stutter.

[Craig 94 TA GT]

Fastbird, did it ever throw the SES light when your opti went out? I know mine did several times when the opti went, but Steve's didn't/doesn't Just wondering...

[94 formula]

Thats exactly the symptoms of mine and I'm almost certain that it is the opti. I think its more when it gets warm it goes into closed loop and thats what does it. I've replaced almost everything else ignition related so I'm hoping its the opti I guess I'll find out this weekend. Also watch your tach when its sputters at low rpms does it jump around irratically (go up or down 200 or so rpms).

[N20LT4Bird]

Keep me posted to let me know if the opti fixes it.....

[Fastbird93]

Fastbird, did it ever throw the SES light when your opti went out? I know mine did several times when the opti went, but Steve's didn't/doesn't Just wondering...

Nope, mine never threw a code.

[Mike71]

i think ur car is just mad because it meet me and hassent me again..those mike withdrawls can be harsh tee hehe

just get the GN running steve then the Z wont brake because itl have to compete with the GN =)

[Z Ya Later]

Ok guys, I made it back to the bay just fine. She only stumbles at ~1500 rpm. She's fine through the rest of the band up to redline. I got the SES light, so I'm going to check the code and see what comes back. I'll keep you guys posted. Thanks for all the help. Take care.

[Mike71]

dang it wemon log onto aim so i can find out wahts going on..bastard!!

btw i went wheelin at 1am..tipped the hooptie and now its sititng in the driveway with a new ding and totaly sloshed in mud!!!!! u have to see it its funny

[Fastbird93]

Ok guys, I made it back to the bay just fine. She only stumbles at ~1500 rpm. She's fine through the rest of the band up to redline. I got the SES light, so I'm going to check the code and see what comes back. I'll keep you guys posted. Thanks for all the help. Take care.

When you pull the code, take a look at the link in my sig. I've got the entire DTC section from my 93 service manual scanned in there, to include the DTC Descriptions and Charts.

In case you don't know, you can flash the codes on the 93's using a paper clip and jumping the two top right ALDL pins together. If you need more specific directions let me know.