You know, now that the talk of the distributor has been so involved. I have been thinking back to when I spoke to the original owner, and he was telling me things about his time with the car. He was not a very bright man to say the least. And did worse for the car than better. In working on this beast, we have found many loose parts, and just shotty work. I am going to get with my guys and look into this further. Do some research and pull that top end back off and take a closer look. If it is the wrong distributor, it will be an easy fix for us. But I am not laying my bets all on that just yet.

Tho, it would make sense. With the occasional hard starts. and the running rough. It does not hop like it did before, but maybe the part seller sold the guy the correct cap, but he had in the wrong distributor.

Would this cause the car to feel like it is fighting itself? Kinda feels like back pressure. I get engine response. And when it starts chugging, if I push down on the accelerator, it goes and the chugging stops.

I know some of you have said maybe the distributor itself, kudos. Time to investigate.

 

if you have the earlier year distributor, all those parts you bought were a waste, it sounds like it was retrofitted and then made to run by bypassing things...quite a few things.

 

You need to test abck pressure in the exhaust...a cat that old is bound to be plugged if its the original.
BUT...if it clears out with more pedal, that is the opposite of what a dead cat would do.

Slow to rev...retarded timing,...struggling to come off idle and rev up. You also have ESC module, as well as the ign module IN the cap. Both of those can cause issues and be forwarned, the Vette hates cheapo electronics...it likes its delco ign parts.

Compression check? Leakdown on cyl? Valve seals DO and will leak...thats a L98 deal,.

Fuel pressure and regulator tested? Vac test at plenum port?

Buying an abused car can mean anything....flat cam lobe from a moron that ran it for weeks low on oil...and never changed it. Lifters screwed down so tight that valves never actually close...who knows.

To me, half the fun is in figuring out the mystery repairs. The other half comes when you get to drive it when its "right" for the first time and the fever hits to do more.....

One thing....
these under the hood wire harnesses are CRAP....and at this age they are half rotted and broken. Be extremely careful when washing under the hood...they will not tolerate water inside most plugs and connections.
The Corvette electrical system operates by completing the GROUND path to ALL componants, not a power source as most cars would. The grounds are CRITICAL, and they are everywhere. You have 5 that are very important that are located near the oil filter on the block....those MUST be clean and tight or you will have run issues.

If you really want to work under the hood of a C4, you have to learn the C4 electrical system. Its crutial that you understand how and why it works. Plastic cars are different.....

Go thru all the plugs and fix the seals and seal them with silicone grease to block water out. If a plug gets wet, the resistance changes and the signal to the ECM goes to hell and the engine runs like crap. Its a delicate system, functional and efficient when taken care of but be prepared to do some harness repair and restoration. They ain;t cheap...a used C4 harness sells for $800-$1000. So baby the one you have unless its so rotted that it can;t be saved. Wire in a C4 is what an artery is to your heart.

By the look of those pics.....the P.O. needs an *** whoopin for doing that to a Corvette ! Thats how you treat fords...not Vettes. The paint and your new wheels go a Loooooong way to hide the sins under the hood.

 

[quote=MysticDreamer;1578732876]You know, now that the talk of the distributor has been so involved. I have been thinking back to when I spoke to the original owner, and he was telling me things about his time with the car. He was not a very bright man to say the least. And did worse for the car than better. In working on this beast, we have found many loose parts, and just shotty work. I am going to get with my guys and look into this further. Do some research and pull that top end back off and take a closer look. If it is the wrong distributor, it will be an easy fix for us. But I am not laying my bets all on that just yet.

Tho, it would make sense. With the occasional hard starts. and the running rough. It does not hop like it did before, but maybe the part seller sold the guy the correct cap, but he had in the wrong distributor.

Would this cause the car to feel like it is fighting itself? Kinda feels like back pressure. I get engine response. And when it starts chugging, if I push down on the accelerator, it goes and the chugging stops.

I know some of you have said maybe the distributor itself, kudos. Time to investigate.[/quote not to flog a dead horse, but , things have been getting lost in the translation from you to us, us to you, and I suspect from the prev. owner to you, and I dont mean that to be rude, just whats going on

 

Yes, I think the old owner left a lot of info out. As on my part, I never said yeah or ney on the distributor, just the cap.

Yes, exhaust was tested. Taken off and inspected and well as compression test. All came out fine. So before I go further on this distributor, why would this problem occur only sometimes. And for 2.5 months, drive with no problems? I took it on 2 out of state 1400 mile round trips and it did GREAT! awesome mpg 25, and now it runs like crap. Very similar to when we first got it.

Ok time to get, be back late tonight or tomorrow

 

I think we need to bring it down a little bit.

Forget about the distributor for a second and let's do kind of a reset on the thread.

How is the car acting right now. As far as I can tell from reading...

Basic tune
new distro cap (may or may not be the correct distro.. we will deal with that later)
It IS an L98 TPI, but IS NOT the original motor.

 

After seeing this latest response.....I can almost gaurentee harness condition issues are the cause of the mystery.....I can see part of the harness pulled apart beside the booster,,thats the area of the harness thats most sensitive AND has all the splices that ARE NOT SOLDERED....just twisted and taped by the good folks at GM assy Bowling Green. The splices come apart very EASY and as stated previously, resistance values are altered thru poor connections and the ECM gets lost with the misinformation that its receiving. The result is NO CODES, NO Service Eng Soon lite....and PP performance. Misfiring, dead holes, sluggish. All symptoms of false signals or bad connections and the biggest clue is the intermittent condition.

I'd get it running and grab a big handful of wire and start jerking things around and see what changes.

the other thing would be to pull some (all )plugs and see what they have to say. That will pin down any cyls that are misbehaving and even tell you what or why....oil fouling or fuel, lean or burnt. Plug condition is a snapshot of what is happening inside the combustion process.

 

From what I can see in the picture the cap is definitely a L clamp style so we know that isn't right. Who knows what the ecm can control on that distributor. Check & see if there is a connector coming out of the dist. that goes into the harness. The wires on this connector are only 5-6 inches long. I feel there may be other issues too like leesvet says but I also feel the car needs all the correct parts in place before disecting the harness. See about picking up a good used distributor on ebay and get the wrong one out of there & we can go from there.
This is a long shot and to be honest, I am not smart enough to know if this could even be the case. I am wondering if the PO put a regular old HEI in there and ran power to it like oldalaskaman said. If that's the case then the ecm is going nuts trying to compensate for signals it's not getting.
My vote is to start with the correct dist.
EDIT:
Can you get a little bit better shot of the dist.? I went back & looked and I don't see a vacuum canister on it that would be on an older HEI. Also I can't really tell if it truly is an "L" clamp cap. If in fact the dist. is the right one then I'd say leesvet is on the right track.

 

good info

 

Hey Bob, I just had a great nap, are we doing the night shift again tonight??
Chuck

 

not sure yet, I'll know better later in the day....nite....something like that,

 

You know , we've spent three pages of posts trying to convince this lady she has issues with her distributor, they didnt and still havent pulled any codes from what I have read. I've been a mechanic in one form or anther for over 40 years, boats, trucks , equipment, the very first thing I do is pull codes on a 'puter' controlled machine, and read the directions if I'm not sure bout things. Now the original story's changing, Think I'm gonna get off this thread, good luck , lady

 

I wonder if anyone has explained "flash codes" to Miss Mystic ?

Not to worry....1st time ownership is truely a learning experience. The car gets more amazing as its systems are understood. The goal is to be satisfied before the savings is completely emptied... Spending the childrens inheritance is completely justified...it IS a Corvette after all.



I was always amazed at how fast the savings would go....faster than the damn car ! Like the feds, I had my own super-fund! Classified as "super" by the speed in which it went.......


I crack myself up sometimes.

 

I have to agree, it's awful strange that they are refusing to do the very first thing that needs to be done. I almost feel like I have been feeding the troll.

 

amen

 

Mystic, we need to get back to basics, here. You mentioned the car ran fine for 2 1/2 months. That is a game changer. We were under the impression that it has had problems from the get go, that working on it had "mellowed it out some", which doesn't exactly describe a car that was running great.
As far as the distributor goes....if you need a screw driver to take the cap off, you have the right distributor.
What problem did you fix right before the car started running poorly? This may help us figure out what could be wrong.
The code check is very important. Jump the A-B terminals on the ALDL and count the flashes. The codes are needed.
There is a short thick vac hose on the inside (intake) side of the driver side valve cover between the intake and the metal tube that follows the valve cover. Notorious for leaking, and it is almost hidden. Carefully spraying some starting fluid where leaks might exist will uncover them in a hurry.
If everything has been checked, it is time to recheck them. I have a 85 and was probably where you are at now. Keep posting, and the forum will figure it out.

 

I disagree with that. The old L style hold-downs required a screwdriver. On my '86 it takes a 1/4" socket to unscrew the hold-down screws.

 

Hi My 85 has the 4 x 1/4 screws on the cap,
I saw your ignition leads touching the exhaust
You really need good leads, plugs and set your base idle then confirm the throttle position sensor 0.54vdc (top and middle wires)
To set base idle, you need to use a paper clip on the diagnostic link,
Ignition on for 30 seconds minimum and unplug the iac valve connector (a square connector) then disconnect the timing acl plug (near the fuel pump relay a single wire)and turn off ignition.
Run the engine with handbrake on in drive and set to 450 rpm
then check tps sensor .54vdc turn off ign.
Reconnect the iac connector and acl timing connector and start the car.
It should run 1200 rpm for a second or so then slow to 600rpm.
The idle may be a bit up and down while the ecm re learns.
Without setting the base idle the vette wont start easily. Also if it has not run well disconnect the battery for min 10 secs to remove stored codes and reset any changes the ecm has made to compensate for something that went wrong. Good luck
The easiest way to check all cylinders are fireing is start the car cold and run for 20 or 30 seconds and shut it off, feel the exhaust temp an inch from the heads. That is how i found i had a bad injector connector one was cold.
Regards
Gerard

 

I see the "night shift" was pretty quiet.....

 

That's because our "employer" has disappeared.