84 4+3

Sorry about the long winded posts, I'll keep them concise from here out. The other forum I'm on we get into long discussions so I'm just used to that. My apologies.

Rechecked the rotor, zero side to side play. Then ran a compression test. Across all 8 cylinders 156-160 with the spike occurring at around 175-180 psi. Seems about normal to me. My gauge is well... older than me so it's not 100 percent but it's giving me the right readings. Tested against another to confirm and they were even. I'll try a back pressure test later on in the weekend.

84 4+3

So I haven't really worked on or driven the car since my last update, the other cars took priority for reasons I won't get into now.

Anyway here is the update I have: reset the computer so it'll be good from the balancing I did a month ago. Car ran well the first time I hit it and pulled hard right up to 5500 in second. Rest of the day it would break up real bad at the same mid band spot.

Later I drove another car to a meet and my dad said he started it up and it ran rough, Had a check engine light and was bucking with no movement of the accelerator. This cleared up but it would still buck. By the end of the drive the cel went out so I couldn't retrieve the code(s). He ran through third after it sat on the ride home after the show (towards the end of the drive) and it was flawless. Then did it again.

At this point I am pretty certain it's on the electrical side of things. I'm probably going to run a back pressure test tomorrow and throw the timing light on it and tap the knock sensor and see if it pulls timing but I'm wondering if I'm looking at a failing ecm or something to that effect. Sorry about the detail a but a lot has happened in the last month or so and I'd rather not leave out any details. Input is much appreciated.

84 4+3

Update 2: pulled codes for the hell of it. Code 12 (normal) and 22. The light is off but the code 22 i guess is in history. I set the voltage with a meter at the tps to .530. Possible losses in the wire to the ecm? I didn't think the old ecms held a code history.

84 4+3

So I've been researching this all week now. I found mention somewhere on here of a gentleman who had a similar issue and described it as a rev limiter type effect. Couldn't find a troubleshooting thread and it seems he gave up on it anyway.

Plans for this weekend if it isn't raining is to datalog with winaldl, I know needing the 10k resistor changes things but I am still hoping that I'll see something. Also I plan to do a quick valve adjustment because why not right? Might as well try the free stuff before I start throwing parts at it.

ex-x-fire

Try unhooking the knock sensor and taking it for a drive. Maybe the KS is picking up some noises at 2500rpms. I had a car that had some noisy rockers, it was nearly undriveable, unplugged the KS and it drove like a new one.

84 4+3

So before unplugging the knock sensor I wanted to get a baseline after valve adjustment with winaldl running. I have the data log I'll upload later but my knock count went to 37. Considering that I drove 3 miles is that high or normal? I don't want to unplug it of its going to be dangerous you know? I don't hear a knock or ping when it happens so I'm probably safe but I just want to check.

383vett

I'm new to this post. I noticed you didn't change the ignition module. You might want to give that a try. A bad module might give you the intermittent problems you are now experiencing. It's worth a try. I keep a spare one just in case my car isn't running right. I'll change it just to eliminate the module as a source.

84 4+3

The little one under the distributer? I swapped that and it had no real effect.

383vett

Yup, that's the one.

84 4+3

So here is the data I promised. The BLM numbers are worse then I had thought and the car actually is pretty rich...
20171013_155931_LOG.txt

20171013_160956_KNOCK.txt

20171013_161010_BLM.txt

84 4+3

Updates: pulled out fueling to keep BLM around 128, no change but it seems better. First few runs it didn't do it at all. Pulled knock sensor still no change. Driving and testing continuing. Still don't understand why it is as intermittent as it is.

84 4+3

Update 2: swapped back to oem ignition module. A little better.

Bfenty

I don't see anywhere that you've done anything with your injectors-are they old? I know I've had a ton of trouble with missing/bucking engine before swapping injectors out. They get clogged really easily on these cars. The Ignition Control Module was the other thing I would have told you to check but it looks like you've already done that.

84 4+3

So I ran 80lb injectors as well as the factory ones. (Had both) They are original to the car but were rebuilt about 10 years ago. The car ran much better with the factory injectors. I'm going to pick up a new delco module and condenser because it ran better with the old one and the plug on the condenser is crumbling. (30 year old plastic)

A couple of other things I thought of maybe: could I have the timing chain off a tooth? I mean I wouldn't think it would be intermentent with that. Also I noticed the computer sees 176 degrees when the dash says 190ish. I have a 180 degree t-stat in it I could swap to a 195. I don't think that's it though...

84 4+3

Update: I beat the living **** out of it today. Like more than any car I've ever driven and it seems really close at wide open. (I don't beat on anything really but I figured it would surface under abuse... for testing.) I am only getting it really bad at part throttle. It is still there but the best it has been to date. The tach freaks out a little still so I'm hoping the new module and pick up help. I also plan on checking end play at the gear as I have shims laying around. It seems fine but I may as well since I'm in there right?

84 4+3

I was happy for 20 minutes. Magnet on the coil pickup was cracked. Ran the car through first and second and halfway up 3rd 10 times. Not a single sign of it. Swapped drivers to my dad so he could drive and it did it worse than ever. I recorded some video of it I'll upload later but of course it didn't do it bad once I was recording. Lighter fluid and a match is looking real good right now because I can't find anything else wrong.

84 4+3

Can't hear it well but you can hear it. Best I could do with what I have.

https://youtu.be/lE2F1Cn2ieM

84 4+3

Weekly update: drove the car yesterday and it seemed particularly bad. Now I don't know if washing it had anything to do with that. But anyway I went on a 15 mile drive 80% in town and the rest highway. Half throttle up hill on the on ramp and the car barely moved. I punched it and it behaved like you were clearing a rich condition and then it went fine. Still did it when I got off the highway and left the next light. Got where I was going and it sat for 2 hours.

Started it up and let it idle to warm up for 15 minutes or so. Then left there. Pulled out into the road and had to punch it a little to avoid being run over (really bad intersection) thought it was going to die on me like zero power. Got about half way home and sat at another light. Took off slow then decided to hit it and it was like some one flipped a switch. All of a sudden all power was back and it just went. Next light turned green so I left it in second and pulled from about 25 up to 65 no problem at all. Next light same thing it was fine. Last time I hit it was before my block I down shifted to second and punched it and it went fine. Ambient air temp was maybe 60 all driving at sea level and low humidity. I don't get how it can just 180 like that and go from borderline undrivable to perfectly fine.

Could I be looking at a computer issue? Or a knock module issue. I bypassed the knock sensor and it pinged a little on shifts and engine braking by down shifting but not really much at all. It would do it like once just a faint ping and that's it.

The only thing that I've been changing was the timing and I started at the factory six and at this point have it at about 10 but I mean as I bring it up the car takes it. Knock counts stay the same so I think I'm good in that respect. At this point aside from the knock module, everything ignition side is new. Compression is good. Temps on the manifolds are all equal according to my ir gun and the cat is hotter at the outlet than the inlet so that seems correct as well. I've got 17.5 in of hg at idle and 19 at 100 so I seem good there too. I personally can't think of anything else except that I somehow have the timing chain be off a tooth? But it shouldn't be random like this and I know I went for to dot. It doesn't make sense at all. And if it ran like it did when it was good it would be way better than any l98 car I've driven. (Only three but stock for stock they were better than the crossfire, now stock vs slightly modded my car hands down is way more responsive across the rpm band.) My cousin has a low mileage GTA and when I took him for a ride and it was good he just looked at me like "how does it pull that good?" I have been in his car and I know it's fun but this feels better... When it's good smashing the skinny pedal from rest for more than 10 seconds will get me points on my license on any highway in this state and will cause me to more than likely lose it on anything else. I don't get it.

Sorry about the rant. I'm just really frustrated and it bothers me. Will update when I figure something out but for now it's back to researching.

Bfenty

Thanks for posting an update-I'm running into something that seems similar (won't hijack your thread-mine is here). Could be different issues but the symptoms seem similar. I'll keep watching your thread, I'll post any updates on what I find on mine

84 4+3

it does seem very similar. Gald I'm not the only one suffering lol. Seems like yours happens at a broader range but it's the same none the less. I've come this far I'll make sure to post the solution when I find it and keep everyone in th loop.