I Need Technical Advice

[primeratec5]

Background: Until 2 days ago, 86 coupe ran without any major problems--------then all hell broke loose!

a. it started to backfire on start-ups
b. after it ran for a couple minutes, it started to miss
c. then it stopped running but would restart
d. could not go more than 30mph in D or OD (although floored)
e. it would run smooth up to 4000 or so rpm in 1 or 2

My garage has checked fuel pump(ok), PCV valve(ok) but it has a vacuum leak somewhere------still searching for that

Only other clue is that car had odd smell just before acting up---could this be cat converters? Prev owner said he had cleaned those out????? Any suggestions would be helpful!!!!!!!!!!

 

[Ken]

...could this be cat converters?

The '86 had three, two pre-cats in the front y-pipe and a main cat in the tunnel. Sounds to me like a clogged cat.

 

[Redbob]

Probably the one thing you can rule out is catalytic converters; as long as you can smell them, they're "converting."

What you've described sounds like an ignition problem; do you know that the plug wires, cap, and rotor are all in great shape. no more than a year old? If not, I'd recommend starting there.

Check the plugs: is one of them fouled, black & wet? If it's just one, I'd suspect the injector on that cylinder. If it's all of them, I'd go back to the ignition.

Just a couple things to start with.
- R

 

[vigman]

Check timing first

See if it's moved.....
That being said My 88 distrib upper shaft was a bit wobbly... chewing into the cap... throwing little bronze shavings all over the place causing horrible misfire... lack of power & generally poor performance.

I cap & rotor later tada... but 1 month later same thing... I had to replace the distrib.. but now all is well.


Vig!

 

[primeratec5]

Thanks for input--------see if I can bring you up to date. Car still running poorly after a. fuel pump checked----it is ok
b. plugs and wires replaced(had Bosch plugs)
my guy likes ac delco so we replaced
c. cat are ( or I should say had been) disabled
d. pcv replaced
e. thought problem might be in distributor cap but it turns out to be ok.
f. I copied the three replies and have faxed to my mechanic---he was goimg to play with ignition tomorrow so the saga continues.
g. as a ps-------I only use Amoco 93 and usually put in a can of engine and fuel injection cleaner with every fill up so I do not think I got some bad gas!

I see this post is getting read but I need some more good ideas--I really need this car to be reliable transportation---if this keeps up, wife will make me use the bike!!!!!!!!!!!!!!!!!!!!!!!!!and I am not talking Harley here!

 

[cntrhub]

I thought it was a, "NO-NO" to add injector cleaner to the tank on GM cars? Last I heard is that, the material that covers the injector coil windings decompose, (from the additive) and short out the injectors?
I would rule out ignition, since you said it, "........stopped running but would restart."
Start chasing a fuel related problem. Use "Caution!!!" with this test!! Rev the engine up at idle, in neutral/park. Will it fall on it's face or stop running? Move the car outside and away from buildings. You will be using a volatile propellent for this test.
Have someone work the gas pedal, so you are not doing two things at once. If you hear the engine starting to shut down, spray WD-40 into the intake plenum. Did the engine begin to rev up again and not shut down? You might have a fuel related problem.

 

[Redbob]

OK, here's one that produced similar symptoms in my car, on more than one occasion:

Has the fuel filter been replaced recently - to your own personal knowledge? I mean, did you do it yourself or see it done?

A clogged fuel filter will periodically starve the engine under heavy load, like in the upper gears, but let it run fine in first or second. Until it gets really clogged, that is.

One place I lived, I had to replace the fuel filter about every 10K miles, fuel quality was so bad. And unfortunately, it always seemed to take me a while to figure it out...

 

[vigman]

Check the following

1) On the back of the distrib.. there is a 4 pin connector running twds the fire wall on a 6" pigtail... make sure it's clean & seated correctly.

2) Make sure the PICKUP in the distrib ( down at the base, inside under the rotor is not OFF CENTER.

3) Fuel filter...just change it to be safe.

4) Any codes?


Vig!

 

[DJS]

I had the same thing happen to my '87 Convertible. When I took it to a local Performance shop, they found the two Pre Cats guts had blown into the Cat and clogged it almost totally closed.

They verified the Pre Cats to be gutted and put a new Cat on and it ran Great!

 

[primeratec5]

ITS BACK AND RUNNING GREAT but I am $700 ( really $1,400---see below)out of pocket.

Problem turned out to be a combination of a few small and one big problem. The computer that controls the right side puked out so everything was left up to the left bank. This did not show on the scanner, but my mechanic is persistant and found the problem-------actually runs great now. Thanks to all that gave us ideas and maybe this will help somebody else down the road.

This needs to be it for this year---this baby is breaking me!!!!!!!!! I give matching funds to wife for Christmas club. Not too bad though cause I'm going to ask for a 383 for Christmas!!!!!!!!!!!!