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Intermittent Crossfire Miss - HELP!

Z

Zora1

Guest
Vig,

I relpaced the wires last year with MSD 8mm Helicore wires, and probably only have 3-4 thousand miles on them. I can't see how the wires could cause an intermittent problem? Not sure what the EM is. If that means the ignition module, I replaced that while on a trip to Panama City about 3 months ago. It was missing so bad on the trip there while in a line with 350 other vettes, that I bought a new Wells coil and module from Auto Zone and replaced them. It ran great on the way home, but now has started doing the same thing. If EM is the ECM, I have a reman unit on order right now from the dealer. I've never replaced it in the 3 years I have owned the car, and it has never thrown a code. However, Robby Tucker at Classic Corvettes in GA recomended I replace it.

Z
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
EM

As in Them.... Sorry


Looks like you have it covered.

Vig!
 
Z

Zora1

Guest
Now I get it. The cap & rotor were replaced the same time as the wires, about 4K miles ago sometime last year. I used Accel. Do you think it's time to replace again, and do you recommend I stay with the Accel products?
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Well 4 months....

Pull the cap & rotor... see if you have a bit of metal dust inside of the cap ( bronze ) It could cause misfiring/ missing.

Vig!
 
Joined
Dec 27, 2001
Messages
160
Location
Matthews, NC USA
Corvette
1984 Coupe
Dist terminal lugs

Relpacing them is probably a good Idea.

The last time I checked mine, they were starting to disintegrate.


Good luck with your 84, mine has been quite a learning experience.

Ken
 
Z

Zora1

Guest
Kmcewan,

Probably good advice. I am relacing only one part at a time so that I can isolate the cause. I have bought both the 3-wire & 4-wire terminal distribution blocks, but am waiting until it misses again. I drove the car this weekend after replacing the fuel filter, and it didn't miss once. However, that doesn't mean much. This has been a very irratic event, so I'm going to wait a week or two before I add any more new parts. I will check the cap again, though it is fairly new!

Allan
 
Z

Zora1

Guest
Now I'm really getting upset. First, the new fuel filter did not help. Second, I just installed a reman ECM unit yesterday, hoping that it might be the problem. Well, that was $118 bucks down the drain. It's still has the miss. Just driving the 8 miles to work today, it did it twice. I did check the oil pressure during one of these events, and it didn't vary, staying at around 55. I am going to replace the terminal distribution blocks in the distributor this weekend, and see if that helps. If that's not it, I feel like I must either have a faulty sensor somewhere that is sending bad signals to the ECM, or that one of my TBI's is messed up, probably the one with the pressure regulator. Does anyone have any recommendations on what sensors to replace. I will probably start with the coolant sender unit. :Roll
 
C

c4ever

Guest
Zora,
Rather than throwing money at it I suggest purchasing a GM service manual for the 84 and going through the diagnosis offered. It will save a ton of time and $$$$.
You'll have it running like a champ in no time.

Just my .02

:cool

By the way, my daughter lives in Kathleen. Never been there but she loves it.

Carlo
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Does it die suddenly...

Or slow loss of power.....

Sudden=electrical

Slow= Fuel

Vig!
 
Z

Zora1

Guest
Carlo/Vig,

I have a factory manual, and have tried most of the tests I could find. However, it runs perfect in my garage, it only acts up once in a while while driving. It will run great, then suddenly develop a terrible miss, though it continues to run. It sounds like only about 2-3 cylinders are firing. I lose power and people start passing me while I pump the gas pedal to no avail, then suddenly it catches, and acclerates normally. I can drive 50 miles and it won't act up once, or like this morning, drove 8 miles, and it did it twice. I don't see what choice I have but to start replacing parts, unless I want to wait until it dies for good and leaves me stranded somewhere. Any more ideas??

P.S. What a small world. Most people have never even heard of Kathleen!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
If I had to throw $$$$$$

Guessing wildly

( Yesterdays post... that I didn't hit send on)

I would FIRST replace the Ignitor module ( in the distrib )

THEN

Check ALL YOUR GROUNDS!!!!

Then

Fuel PUMP relay


Try those... cheap fixes


Vig!
 
C

c4ever

Guest
Zora,
The manual lists the following order
Ignition :Wire,boots,cap,coil
Distributor: Worn shaft,shorted wires
Plugs
Fuel line,hoses
Fuel pump
Strainer in tank

I'm no mechanic but maybe one of the above will help.
Good Luck
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
THROW AWAY THE THERMOSTAT! replace w/ a 180 or so

If the 160 is too cold the car will go back into open loop mode when the coolant temp drops below 175 or so. That may be (part) of your problem.

Also, check the balancing of the TB, it may be off.

Also, wiggle the connection to the CTS (coolant temp sender, in front of manifold). If it has a poor conenction the engine will get lots more fuel all of a sudden.

Marck
 
Z

Zora1

Guest
:s Well, I found the problem. My miss got so bad last week that it missed all the way to work, and was still missing when I went to leave for home. This was the opportunity I was waiting for. I opened the hood and removed the air cleaner cover, then started it up. I got out, and before it stalled, I noticed no gas coming out of the rear TBI. While it was stalled, I wiggled the terminal on top of the injector, and when I went to restart the motor, it fired back up perfectly, no miss, and had a good spray pattern. It hasn't missed now in over 6 days and 200 miles. I think there must have been just enough corrorsion on the injector terminal that all it needed was a wiggle. I had removed the front injector terminal months ago when this miss first happened, and wiggled both of them. I've been so happy driving the car, that I haven't even lifted the hood since. I'm going to remove both injector terminals and ensure everything is spotless tonight. I'm out about $300 bucks on all the parts I have replaced, but am just happy it is fixed. Thanks for everyone's help. Also, has anyone ever heard of these terminals getting dirty??
 
C

c4ever

Guest
Great to hear that Zora. Amazing how it's always the little things;)

Carlo
 

JonM

Well-known member
Joined
Mar 12, 2002
Messages
2,421
Location
East Haven, CT- USA
Corvette
84 Coupe
Zora...glad you found the problem...While you are at it, your two injectors have fuel screens in them you may also want to change.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Great news

Well at least you now KNOW what the problem was...just consider all the other work maintance.. and less to do later.



Vig!
 

RS84Syr

Well-known member
Joined
Jan 12, 2002
Messages
47
Location
Syracuse, NY, USA
Corvette
1984 Red/Graphite Auto 66k Z51
Good thread.
Haven't had that problem before, but with my 65K to
your 70K, I'm paying attention.

Rick
 
Z

Zora1

Guest
It would be great if someone else could avoid the suffering I went through. Now that I think about it, it was like the car was running on just one throttle body. It would keep running if I pumped the gas pedal, but would not have enough gas to continue running if I kept my foot off the pedal. I recommend all crossfire owners remove those injector terminals every so often and keep everything clean. I did notice some rust on top of the injectors, and I guess some of it spread to the terminal area. I'm also going to remove the injectors, clean them up, and replace the screen, but have to order another gasket kit. These kits cost $16 per injector at the GM dealer (you have to order two) and that's with a club discount. Cheers!
 

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