Fronzizzle

Hello All,

This is my first post on this forum - sorry it's so long but I want to make sure to provide as much information as possible to try & figure out what's going on.

First, the details of my car: it's a 1985 Camaro with a fully rebuilt 383. Edelbrock RPM heads, Holley Stealth Ram MPFI, MSD distributor & coil, mild Comp cam. The computer and wiring harness have been updated to the speed density system out of a '90 Camaro. Basically everything is brand new - new Walbro fuel pump, new 30 lb. injectors, new plugs, wires, distributor, etc. I also went through the chip burning-data logging-re-burning process three times, to the point that the vendor says the chip is "perfect".

Now, what I've checked (multiple times): valve adjustment, timing, fuel pressure, TPS voltage, spark plug wires, no vacuum leaks, no spark jumping.

The problem: The car idles just find, right around 950/1000 RPM. No evidence of a miss or backfire or anything of that nature. If you rev it up quickly, it sounds great, RPM's rise steadily & come back down normally.

If you take it for a ride, however, there is an issue. When you are at a stop & step on the gas, the car falls on its face. It just bogs down & stutters for a few seconds, then eventually goes. It sounds almost like a miss at that point, but eventually smooths out and the car goes. Then, if you are moving along at cruising speed and give it a little gas (like you are trying to maintain a set speed), the RPM's will jump up 300-400 & then drop back down, you can both hear & feel this as well as watch it on the tach. It seems that the higher the RPM, the less noticeable the issue is.

Some other information: my engine builder originally screwed up, didn't have the timing marks lined up correctly so I had a hell of a time getting this thing started at first - I have no faith that the rest of the engine is correctly put together so nothing is off the table in terms of possible causes.

I noticed the other day that the electrode that comes out of the coil is very loose, you can spin it around with your fingers. I know this isn't normal, but not sure if that could be causing my issue? I've also read that perhaps the PCV valve could be bad or the wrong one, acting like an intermittent vacuum leak. Other than that, not sure what else to check or what to look for? All of the data I have on the TPS tells me that it's working fine, but at the same time a lot of the research I've done points to perhaps that being bad.

Any advice/information on this is greatly appreciated. Alternatively, if there is a recommended shop in the metro Detroit, Michigan area I'm not opposed to taking the car there & getting it checked out. Thanks in advance.

Z28SORR

Almost forgot, wecome!
Is your dist. an HEI type? Coil in the dist. cap. If so and you are talking about the carbon electrode inside the cap that rides on the rotor, then it is normal for this to be "loose". It is in fact spring loaded and can move up and down and twist. If you remove the coil from the cap you'll see what I'm talking about.
Also what is your initial timing, total timing advance and timing curve,(when does it start)?

Fronzizzle

No, I have a small HEI cap distributor with an external coil, something like out of a 1995 Camaro. The electrode (not sure that's what it's called) that you plug the coil wire on that runs to the distributor is what was loose. I have since replaced the coil with no change in my issues.
I think I ruled out fuel pressure. I've been playing around with, taking it up and down and all around and while I can get the car (generally) to run better or worse, my issues are still there. I set it where it seemed to run best (44 psi, I think) and then moved on to other things. Not sure what any of this means, though.

First, I checked the vacuum. At idle, it has 15 in. Bounces a little between 14-16 but nothing major. At higher RPM, it's nice and steady at right around 17 PSI.

My timing, on the other hand...no idea what to make of this, I just don't enough about timing to know if this is normal. Back when I set it when the engine was first installed, I started the car, disconnected the timing plug (remember, this is the wiring harness & ECM out of a 1990) and set the timing to 8. Plugged the timing connector back in and away I went - I wasn't smart enough to check the timing after that.

So today, I check the timing with the connector plugged in - it's at 28. I disconnected the plug and checked it, it's between 9 or 10. Plugged the connector back in, it stayed at 9 or 10 and my engine light was on. Shut the car off & restarted, light was off and timing was back to 28. I then held the idle up and checked it, I don't know exactly what RPM I was at because I was doing this by myself from under the hood but I kept creeping higher and higher until the timing stopped changing. Based on the sound, I'm guessing I was around 3,000 or 3,500 RPM. Anyway, at that point my timing was at 52 or 53. Is this normal?

One more question, going back to my hesitation. I was paying more attention today and noticed that my two issues may be two separate things (or one thing causing two different symptoms). The two symptoms:

1) When pulling away from a dead stop slowly and the car bogs down/hesitates, the tach doesn't move - if I'm at 2,000 RPM, the car will start to sputter and jump a little but the tach stays right at 2,000 RPM. Does this point to anything?

2) While driving, if I'm going 35 or whatever and give it just a little gas to maintain speed, the RPM will start to jump up and down, like from 1,400 to 1,700 then back to 1,400, back to 1,700, etc. You can hear and feel this, too. When this happens, if you give it more gas it immediately goes and the jumping goes away.