sporadic ideal and power surge

power
Hello I'm having ongoing problems with our 86
V-6 GT it seams to run along good then all
sudden at a stop the rpm will bounce around
from 1450 down to 300 almost a stall out it will
also when driving along in 3 or 4th all of a
sudden feel like a pow
er ban will kick in and the power is awesome. I
put it in a shop they replaced the comouter and
changed out the distributor (completely new)
also changed all filters and fluids it still was
doing same thing so they sai it was our exhaust
so they replaced it from manifold back all new
(cat,pipe,muffler) now still doing same but also
some new things like turn signal reversed they
said that would fix it's self once the computer
relearns. We've put over $3500.00 into repairs
last month with no resolve can anyone shed
some light or tell me where to take it to have it
fixed. This is suposto be a car for my son and
me to enjoy together and sofar all we've
shared is a depressing feeling looking at it and
not enjoying the ride. Please help thank

They checked pressure it was good we did not replace ignition coil yet
was just looking on line at MSD one at Lordco. We live in Port
Coquitlam BC. Not sure what the Tach filter is but they said all filters
were changed fuel filter was changed.

Not sure to be honest what the pressure was it
was worked on at Tremblay motors in Vancouver
they were nice people but I would guess not to
familiar with the Feiro. Who do you or people in
the club use I'd be more then happy to take it to
them.

thank you that that really helps my son and I
are trying to do as a project together so we
don't mind learning together. Ill go check out
pick a part they are the one with the pink
dusOseter out front..dose the hole turn signal
thing with the computer needing to relearn
make cents. Also would pick a part be a good
place for seats or would you order from the
West coast on line store in California..have
you been a club member for long I'd like to
join with my son

Back to your problem. I would have guessed based on the symptoms that you had a paritally clogged muffler (Form the cat converter dying and ejecting material into it). However, you said you are new from the manifolds back, so that has been dealt with.

Your idle symptoms could also be a EGR stuck open. An egr is a exhaust recirculation valve which opens to allow exhaust gasses into the intake stream to cool the combustion process and lower nox production. in other words, it's pollution control. At idle it should be closed, but sometimes they stick open causing poor/rough idle. To check it I usually pull it off and block the entrance with a plate, then run the car and see if there is any difference.When you're in there, check for a cracked egr tube, which is a classic failure on the Fiero.

It could also be a failing vaccuum tube, especially theone feeding the map sensor. This would cause no end of poor running. It doesn't quite fit your symptoms though.


If that's good, that leaves you with the big 3.

1) Compression
2) Fuel
3) Spark, and spark advance



I'd start with spark as mentioned above. Check the wires leading to the distributor to make sure they are not obviously damaged. Check the pickup coil (inside). Check the ignition coil by swapping it and checking symptoms. Ignition control modules (icms) die from time to time, but their symptoms tend to be different. Kepp it in mind though, they can do strange things!! Check plugs and wires of course.

Then I would go fuel. It could be an intermittent injector, although that is rare. Fuel pressure is a much more likely culprit. Pull off the fuel filter and try to blow through it. It should flow easy. If not, replace it. Check the fuel pump flow by jumpering it on at the ALDL (Get a container obviously, observe safety precautions). If it seems ok, reconnect and get a fuel pressure guage on the rail to make sure the pressure is ok. You could check the fuel return line by blowing it out with compressed air.


Buy a compresion tester and check at least the rear 3 cylinders to get an idea of where your engine is at. Test the fronts if tyou think it's necessary. I don't think you are dropping a valve but maybe you are.

Lastly, get a scanner and check the sensors feeding the ecm. You never know.

It's a process, but not too hard. Let us know your results.

Chay