$projecthp
Results 1 to 11 of 11
  1. #1
    New Member
    Join Date
    Dec 2019
    Location
    Charlotte, NC
    Posts
    4
    Corvette(s)
    93' Manual
    Post Thanks / Like
    Rides
    0

    Default 1993 Intermittent Issues

    Hello all,
    I recently purchased my first corvette (93’ Manual Coupe) this summer. I’m loving the car and truly enjoy driving it! Over the last few months or so I’ve encountered some issues, which I’ll go into detail below.

    I’ve been lurking in forums and reading articles for some time now - but as I cannot seem to isolate the issue, I figured I’d try my own post.

    Thank you in advance for any insight you can provide…

    Timeline


    • Purchased the car in August. Drove it back home approximately 3 hours without any issues whatsoever. Continued to drive it a few times a week over the next two months with the engine running reliably and strong. During this period I only encountered one strange issue. Randomly, I went to press the yellow hatch-release and the system failed to respond. I tried troubleshooting for a while and went to install the manual hatch release string, when “boom”, the hatch released and has never given me any trouble since.



    • Mid October – Car running normally up to this point. I stopped at a red light and the car experienced a surge at idle and hit redline (bouncing on & off). I immediately cut the engine and waited a few seconds. Car started up normally and the idle returned to the appropriate 700RPM. Has never happened again. (I’ve seen on some threads and articles that this is a known issue? Possibly MAP, TPS, or IAC?)



    • Late October – Went to start the car. Cranked but wouldn’t start. I needed to be somewhere so I left the car there and returned about an hour or two later to troubleshoot. Strangely, the car started up with just one crank and ran/idled perfectly.



    • Early November – All of a sudden the clutch petal had no resistance. Made it extremely hard to put the vehicle into gear as the clutch wasn’t being fully disengaged from the flywheel. Unbolted the ECM and couldn’t find leaks anywhere around the master cylinder. Topped off the reservoir with brake fluid and the problem seems to have been resolved as the pedal has remained firm since.



    • November 21st – Car started up normally and was running strong. Stopped at a light and was idling normally. Light changed and I shifted into 1st from N and I began to accelerate. All of a sudden I had no response from the pedal/throttle and the car became jerky. It would begin to run again normal for a few seconds and then lose response and power (this happed a few times before I turned onto a side street and turned the engine off just before it stalled out completely). I noticed that my LCD panel was dimming during this event. I had no diagnostic tools on me at the time but I did notice that my battery meter read 12volts. I attempted to start the engine a few times (similar to the crank, no start issue back in October), making sure to keep the key on the “on” position and listen for the fuel pump to buzz/hum (which I heard and confirmed was working). Repeated this process 4-5 times until the car suddenly started up slowly (almost as if it was fuel deprived) with the tac gauge slowly rising as well. While attempting to start I did notice a faint smell of gasoline build up in the cabin like the engine was flooding. Drove straight home and only experienced a slight loss of response/power once for approx. 1-2 seconds. Once home I repeatedly cut the engine and then cranked it back up with no issues, no codes…



    • Last week of November – Took the car out to the auto parts store and within a mile it stalled. Upon dying the battery light came on (the gauge cluster read volts read 12 with the needle bouncing alongside the hazard lights). Jumped the car and returned home. After that I ran some tests:



    • Hooked up fuel pressure gauge. Fuel pressure raised to 40PSI and remained constant
    • Battery volts read 12 (also load tested the battery at Advance Auto Parts and associate told me that the battery was good, despite it being 5 years old?!)
    • With car idling the battery read 14.3 volts
    • Unhooked the negative terminal and car continued to run off of the alternator alone. I turned on all of the lights and radio with no issues. However, when I switched on the A/C the car died.



    • December – Could not isolate the issue, and didn’t want to just throw parts at the problem so I was considering hiring a mobile mechanic to come take a look with me. However, now the car has been running perfectly since conducting my minor tests. I’d driven it around town with no problems whatsoever. I did notice that when I press in the brake pedal the LCD panel dims for half a second. I can repeat this whenever I press it. I also notice that when I go over minor bumps the panel flickers (grounding problem?).



    • December 14th – Took the car out for a self-service wash. I Drove it to the gas station and filled up. While attempting to drive home the dash suddenly began to flicker rapidly and I experienced the same stalling issue as the month prior. I clicked the right turn signal to get off of the road and then all the symptoms went away???. I continued on and about a minute later the dash began to flicker again, this time the engine cutting out and dying. I sat patiently for a second and tried to start the engine. Turned right over and I hightailed it home. Turned the car off in the garage and pulled the codes as hopefully something was there. All I received was code 50 (system voltage low). Went to start the car and it immediately died (no lights, dash, etc). I heard a strange sound from the dash and the “passive keyless entry” illuminated???...


    Summary
    I live in North Carolina, so I’m fortunate enough to be able to drive the car year round (I also have it stored in a gated garage). However the bulk of these “gremlins” seem to have been awakened with the colder temperatures starting in November.

    The previous owner kept meticulous records/receipts and I do believe that he cared for the vehicle greatly. The opti was recently replaced, new Nitto tires, Bilstein shocks, brake rotors and pads, bushings, joints, injectors, fuel pump and filter, water pump, plugs, belt, fluids.

    I love owning my Corvette, and I'd like to get these issues resolved so that I can have piece of mind when taking the car out for a drive. I apologize for the length of this post – but I wanted to be as detailed as possible.

    Thanks again!

    -M

  2. #2
    Member
    Join Date
    Oct 2005
    Location
    NW Iowa
    Posts
    30
    Corvette(s)
    1990 conv. 6sp
    Post Thanks / Like
    Rides
    0

    Default

    Clean ALL grounds. Some of what you said pointed to electrical. Poor grounds on these corvettes cause strange problems.If that don't cure most of the problems have the alternator checked.Also it would be a good idea to get the service manual. I believe Helms is the publisher.
    Thanks Dry_Pancake thanked for this post
    Likes gmjunkie, Wayback liked this post

  3. #3
    Member gmjunkie's Avatar
    Join Date
    Nov 2004
    Location
    Old Fort NC/Vero Beach FL
    Posts
    4,467
    Corvette(s)
    03 Z-51,78 L82 Coupe
    Post Thanks / Like
    Rides
    0

    Default

    Quote Originally Posted by GWinter View Post
    Clean ALL grounds. Some of what you said pointed to electrical. Poor grounds on these corvettes cause strange problems.If that don't cure most of the problems have the alternator checked.Also it would be a good idea to get the service manual. I believe Helms is the publisher.
    Hi'ya Glen...…….

    grounds,Grounds,GROUNDS………….. High Resistance or Non Existent Grounds make Electronics do weird Sh*t!

    As Old Man Winter says most of your problems will probly be resolved!~~! (Oh wait,I'm an old man now too!)

    Clean and inspect All Grounds, ALL of them,And there are a bunch on C4's!
    Some are hidden and hard to get to!

    As far as your clutch, Clutch master is probly seeping and fluid is running down under your carpet inside and you cant see the leak!

    PS Stop running it with the Battery cable off,Or you'll need a Alternator too!
    It's got so it seems to me that the Internet has created a lot more Horses A$$'s than we have Horses!
    junk!~!!
    Founding Member: 10 Corvettes Anonymous

    Thanks Dry_Pancake thanked for this post
    Likes mailmaninvette liked this post

  4. #4
    New Member
    Join Date
    Dec 2019
    Location
    Charlotte, NC
    Posts
    4
    Corvette(s)
    93' Manual
    Post Thanks / Like
    Rides
    0

    Default

    Quote Originally Posted by gmjunkie View Post
    Hi'ya Glen...…….

    grounds,Grounds,GROUNDS………….. High Resistance or Non Existent Grounds make Electronics do weird Sh*t!

    As Old Man Winter says most of your problems will probly be resolved!~~! (Oh wait,I'm an old man now too!)

    Clean and inspect All Grounds, ALL of them,And there are a bunch on C4's!
    Some are hidden and hard to get to!

    As far as your clutch, Clutch master is probly seeping and fluid is running down under your carpet inside and you cant see the leak!

    PS Stop running it with the Battery cable off,Or you'll need a Alternator too!
    GWinter & gmjunkie - Thank you for your feedback. I'll get in there and clean the grounds. I'll report back with my findings!
    P.S. I'll make sure to not to run it with the cable off again

    -M

  5. #5
    New Member
    Join Date
    Jun 2017
    Location
    Alberta
    Posts
    2
    Post Thanks / Like
    Rides
    0

    Default

    I have 2 1990 ZR-1 cars, both will not start. Have bypassed clutch switch, installed a vats bypass device, installed new fuel pumps, changed out ignition switches.
    I found my FSM and I have the electrical supplement. There was a part about locking and unlocking the door locks to reset the security light that needs to be flashing, and also remember the dome light needs to come on with door opening, also remember something about the horn needs to be working, and maybe even park lights, all of which are tied into the ECM and VATS. If requested I could take a photo of the checklist and post it here, if someone could explain how to post a photo.
    Also, over on Corvette Net Registry, there is 4 pages to read there, search for "My 93 won't Start" or "won't crank"

  6. #6
    New Member
    Join Date
    Jun 2017
    Location
    Alberta
    Posts
    2
    Post Thanks / Like
    Rides
    0

    Default

    Correction: ZR-1 NET REGISTRY

  7. #7
    New Member
    Join Date
    Dec 2019
    Location
    Charlotte, NC
    Posts
    4
    Corvette(s)
    93' Manual
    Post Thanks / Like
    Rides
    0

    Default

    Hey everyone - I apologize for the delayed update. Between being out of town for Christmas and friends visiting for New Year's, I couldn't get a moment to myself.

    Some Updates...

    The Good
    Checked and cleaned all ground connections (I hope…as it is entirely possible I may have easily missed one). I then changed the battery as it was 6 years old and I thought it wouldn’t hurt. Got the alternator + new battery load tested at the auto parts store. All checked out good and from what I could tell the symptoms had disappeared. I left for home during Christmas and disconnected the negative terminal (also wrapping it in electrical tape, and moving it away from any grounding points). When I arrived back in town 1-2 weeks later I connected everything back up and the car fired up STRONG. No excessive cranking or sputtering. Drove it for a little while that day and continued to drive it for the last few weeks with no issues whatsoever!

    -But not so fast-


    The Bad

    Last night I took the car out for a self-service wash. All was well as I continued to drive into the evening down some winding roads and onto the highway when *BAM* – I noticed that there was a slight jerking/bucking sensation when I applied pressure to the gas pedal. I then noticed that the engine temperature on the LCD panel began to glitch out and read “LO” then 50 degrees and then changed rapidly back up to the normal 180-200 degree readout. It almost seemed as the computer was trying to figure out why the temp was all of a sudden reading low and would try to correct itself. While this was happening that’s when I would lose all response and experienced a “higher than normal rev”. Once the digital readout was back up to the proper engine temperature I would regain all throttle response and control over the vehicle? This cycle repeated about 3-4 times for my 20minute drive back home. (I’ll be posting a video I managed to capture of this phenomena while parked and idle on the next post). It also appeared that if I kept slight but constant pressure on the gas pedal the car would run normally – would jerk/buck lose power when I pressed harder. One additional note was that the battery light briefly flashed on during the initial LCD engine temp readout glitch and jerk/buck/throttle response.

    The only constant between the last intermittent issue I spoke about in my original post and yesterday was that the external of the car obviously got wet at the self-wash.

    I’ve researched some and found a local specialty shop for vintage vehicles here in Charlotte, NC. It’s called Midnite Auto LLC and I’ll be looking to set up an appointment to get a professional to take a proper look.

    I’ll post any further updates soon.

    Thanks!
    -M

  8. #8
    Member Robertwav1's Avatar
    Join Date
    Jan 2003
    Location
    Ocala, Florida
    Posts
    811
    Corvette(s)
    1993 Blue
    Post Thanks / Like
    Rides
    0

    Default

    Lot's of grounds on this car. Follow the frame rails for a lot of them. I happened to take out the spare tire and noticed there's one under that as well. Hope you get her straightened out! Sounds like an intermittent loose connection. Have a look at the computer connections as well.

  9. #9
    New Member
    Join Date
    Dec 2019
    Location
    Charlotte, NC
    Posts
    4
    Corvette(s)
    93' Manual
    Post Thanks / Like
    Rides
    0

    Default

    Here is the video of this glitch happening.

    YouTube
    Last edited by Dry_Pancake; 01-25-20 at 01:12 PM.

  10. #10
    Member
    Join Date
    Oct 2005
    Location
    NW Iowa
    Posts
    30
    Corvette(s)
    1990 conv. 6sp
    Post Thanks / Like
    Rides
    0

    Default

    those numbers flashing all over the place, those temp? if so something wrong in the temp circuit , could be ground, I belive there is a group of ground wires on one of the bell housing bolts fun to bet at .

  11. #11
    Member gmjunkie's Avatar
    Join Date
    Nov 2004
    Location
    Old Fort NC/Vero Beach FL
    Posts
    4,467
    Corvette(s)
    03 Z-51,78 L82 Coupe
    Post Thanks / Like
    Rides
    0

    Default

    Quote Originally Posted by GWinter View Post
    those numbers flashing all over the place, those temp? if so something wrong in the temp circuit , could be ground, I belive there is a group of ground wires on one of the bell housing bolts fun to bet at .
    2nd bolt up drivers side,Also could be some right above the oil filter on the side of the block,Also there is a woven ground strap that runs from the 2nd bolt over to the top of chassis behind the battery about striate down from the brake booster by the air bag sensor. ALL those grounds are very critical and can effect several systems and sensors.
    Last edited by gmjunkie; 01-26-20 at 09:55 AM.
    It's got so it seems to me that the Internet has created a lot more Horses A$$'s than we have Horses!
    junk!~!!
    Founding Member: 10 Corvettes Anonymous


Similar Threads

  1. Intermittent PCM issues?
    By badnews in forum C4 Technical and Performance
    Replies: 5
    Last Post: 08-28-17, 08:54 AM
  2. Has anyone seen this before? 09 LS3 intermittent start issues at less than 40k mi
    By LS3LNewman in forum C6 Technical and Performance
    Replies: 9
    Last Post: 08-08-14, 02:36 PM
  3. 2009 ls3 less than 40k intermittent start issues
    By LS3LNewman in forum C6 Technical and Performance
    Replies: 0
    Last Post: 08-06-14, 04:30 PM
  4. Intermittent tire monitor and key fob issues
    By XLR8 in forum C5 Technical and Performance
    Replies: 6
    Last Post: 08-01-05, 10:03 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •