bureau13

I still haven't had time to fashion any sort of smoke testing apparatus or get a wideband O2 sensor, but the problem is really bugging me....it feels mechanical to me, although I could easily be wrong. I wonder if there's a good way to determine if it's driveline vs engine...

I tested my Temp II, and it seemed in-spec...can these things cause issues even if hot and cold resistance measurements seem to be in order? (I also run very rough when cold, fwiw)

I'm tempted to get my MAF rebuilt regardless. At 85K+ miles it's got to be at least somewhat degraded, right?

For possibilities like ignition or injectors, why would it only show during that specific rev range? Is there a logical reason that might happen?

Someone was riding with me today, and kept asking if I were sure it wasn't the clutch. It feels very much like a bad shift and then lugging the engine, only it is unrelated to when I shift. If I shift into gear a 2K and slowly accelerate, it starts well after the car is in gear, and once it starts, if I give it more gas it gets worse...but if I do a WOT blast from the start (i.e. before any shuddering starts) everything seems fine. I think I'm going to try taking an in-car video and posting it...I don't know if it will help visualize what is happening...maybe it will be obviously the same or different from some of the similar-sounding issues others have posted. I don't know.

JBGold07

Hey,
Did you get around to putting in those new ignition leads?

bureau13

No, I didn't. I guess it's pretty silly to have them sitting there and not have them on yet, while asking for suggestions about what other things I can buy.

bureau13

OK, well now I have replaced the ignition wires, and it did not help with the shudder. This is not surprising, although of course I was hoping it magically would fix it...but at least it eliminates that possibility.

Landseer

Pull the intake, replace the injectors. There are a few options. The Bosch design 3 that is specified for the Jeep inline 6 is just about perfect IIRC. Check the latter part of Hilton's thread where we discussed possibilities. My set, I think from Five O, was bosch design 3 without retainer slots, which I cut. They were rated at 27lb or so, and cost $160 delivered new. But the Jeep ones, at $310 should have been the ones I chose.

My mistake was waiting, hoping it would clear-up.

The intermittency was maddening. Pulling out of a stop sign to the right, full throttle, it would run perfect sometimes. Sometimes not. Pull out to the left, terrible. Common symptom though, whenever it happened, it was under some sort of significant load. It could be a terrible or a minor shudder, but it was all injector related. Another thing you might try to diagnose, if you insist, is drop the exhaust. Look to see if either downpipe is white inside, clear evidence of running lean. Running lean is bad, btw.

You could also pull yours and have them cleaned if possible. They have little tiny screens that are replaceable and will need new pintle caps. Witchunter does this work for about $20 per.

bureau13

Injectors are definitely on my list of things to eventually refresh, but I'm really hesitant to do that now, for this problem, mainly because it doesn't make complete sense to me. That may be my problem, however...but for my case, it only occurs at very light throttle and only in the specific rev range. Above that, or under heavy throttle, no issue. Wouldn't an injector problem tend to occur, as your issue did, under significant load, and throughout the range? My current injectors were "refreshed" by the PO as part of making it driveable before I bought it. I know he replaced the o-rings, not sure what else he may have done, and they weren't sent out for a formal refresh.

Not saying you haven't nailed the solution...just that the list of things I need to do for the car eventually is pretty long, so I'd like to feel that there's a solid, logical reason why the items being replaced are connected to the problem. I know, I did the wires...but I had other reasons to do them, which seem to have been cleared up.

Someone mentioned getting a wideband to get a definitive look at what's going on with the mixture. Can I just temporarily replace the existing O2 with the wideband for this test? Or is this the excuse I've been looking for to get an X-pipe with two O2 attachments

granprixweiss928

Wideband sensors like the innovate motorsports one have an output for the ecu, in the 0 to 1v range.

wopfe

Maybe another approach: go to a shop and let them balance your wheels. Thats what i did after checking motor mounts, T-tube and other stuff. Never thought it would be related to the noise i heard around 300 and 60mph. But it fixxed it! Good luck!

bureau13

Hmmm...but if coasting at that speed, I don't feel it. Wheels wouldn't require to be under light throttle, would they?

I really need to take a video of this...

Regarding the Innovate, I thought I had read that the simulated narrowband output didn't play nicely with the 928 computer. Maybe that's no longer true?

Landseer

Unfortunately for your year 32V it doesn't have the knock sensors so the sharktuner can't read it. Running lean with associated knocking is a really bad thing. Wait and see has perils. If you have to have confirmation, I suggest you get a good shop with a portable unit to either stick it up the tailpipe or screw it into the existing O2 sensor port and confirm it is running lean in short order. Don't make the mistake I did to keep driving it.

bureau13

I see your point about that. I don't hear any knocking...but something is doing something. Ugh...

Landseer

Knocking isn't heard by ear, per se. But its deadly to these 32V cars when running lean. S4 has knock sensors that adjust the timing to reduce the potential for damage. You probably want to research this a tad.

bureau13

I wonder why there are no aftermarket knock sensors that feed an indicator? Or, maybe there are, but I've never heard of one. Could be a useful diagnostic tool perhaps?

I know from my rotary days the perils of knock...I think those cars were more susceptible to it, to be honest.

bureau13

Well, I went to tale a video, bit the car is not running like it should, after changing the ignition wires. When I first tested it, it did run better, but now it's very spluttery and raspy sounding, down on power and seems to miss. I'm not sure what's gone wrong...

Landseer

Do you have the right coil wires? Or the later ones?