I have had a wonderful relationship with my recently purchased 87 GT V6 5 speed. It is a blast to drive and I do not regret for one second buying the car. My issue is that I have recently noticed a slight hesitation or power drop (fraction of a second, but enough to notice) while holding the throttle steady and cruising along in 3rd or 4th, but just occassionally. It may also be happening at other gears or even under acceleration, I just seem to notice it more at constant throttle as the car will jerk a little. I also noticed that my Tach needle will jump up and then settle right back down exactly when that happens - a little odd I thought, and perhaps a clue for you knowledgeable Fiero lovers out there. My immediate thought was something in the ignition, but that is simply a guess on my part. To add to the recent misbehaviors, the car does not like to start as easily when it is warm. It does not seem to fire on all cylinders when starting, but then it clears up as soon as the motor gets going fast enough. Sign of something serious?

I should preface this by saying that I feel like the engine is always pulled down too much by the A/C kicking on, but I may just be too used to it not bothering a V8, which is what I have in my other vehicles. That maybe normal and/or totally unrelated. I have also recently cleaned out the IAC valve with some carb cleaner recently, but that was over a month ago. The idle has been wonderfully solid since then.

Anyone esle out there had the same problem? If so, how did you fix it? I have seen other posts similar to this one, but none exactly the same. I apologize in advance if this is something simple or already posted...

Thanks

A couple of thoughts on your problems: First guess is that the ignition module is getting ready to fail. Second guess is that one of your fuel injectors is leaking, which would explain the hard starting when warm. I'm sure others with more expertise will email you soon. Good luck.

Thanks Tom - I will check the module for signs of thermal stress or popping capacitors - if I can. Any ideas how to check the injectors? Can they be removed and visually inspected?

the module will have to be taken to an auto parts palce and tested. have them run the test a few times to heat the module up good. it is a sealed unit, no ispection possible. while it's out, us an ohm meter to check the pickup coil, shoul be between 750 and 1500 ohms resistance. if it loos like it is all powdered m tape falling off, and cracking, that could be the problem. (alterntively, the plastic on the coil turns to mush, like soggy macaroni)
verify the connectors to the module and coil have no corrosion in them treat them with some crc 2-56 spray to lube/clean/protect them.
when reinstalling the module, clean it well and the dist, and put a thin layer of thermal compund on, just like a cpu, thin and even. the white paste from radio shack is fine. do not use dielectric grease, it is not made for heat transfer.
the external coil itself could also be causing the problem, overloading the module, but resistance tests on that are really iffy as there is no load and heat involved.
after you are sure of the ignition system, then worry about the injectors. they won;t cause tach dropouts!

Leaky injectors can be deteted with a fuel-pressure gauge. There is a Shrader Valve on the fuel rail where you attach the fuel-pressure gauge. I can't rtemember exactly what the static pressure shoud be - the pressure in the fuel system when it is charged, but the engine isn't running - but I think it's about 40 PSIG. The important variable is pressure reading over time. If the pressure drops off over a time span of about an hour, then one or more of the injectors is leaking. I'm really surprised that more people haven't responded to your post. Good luck.

for ref, key on pressure no run should be around 45 psi +- 3 psi.
idle will drop to 35-38. blips will cause increases to static.
key on, then off no run watch the pressure, should hold the static pressure for at least 30 min. slow drop, if still over 30 in an hour is likely ok. dropoff can be the injectors or the regulator or even the pump. to isolate you have to pinch off the lines. if it holds then, release one at a time to wee where it is leaking back.

from your symptom, I would look at ignition first, the tack drop out is telling you something.

Thanks - I will try to get the coil checked once I have eliminated the ECM as a possible cause. Too bad you cannot examine the components or the circuit board. I have some sentiment late eighty's electronic technology. Is there a write up with pix for removing the ECM?

not the ecm, that is the main unit behind the console. we are talking about the ignition control module in the distributor.
while not unheard of, ecm's are one of the last replacement items.

Where is the ignition module located, or is it fairly obvious once you are looking at the distributor? Is it located inside the distributor? I have also seen some discussion about a "pigtail" causing the troubles I am experiencing. Where is this "pigtail"?

quote Originally posted by computer_engineer: Where is the ignition module located, or is it fairly obvious once you are looking at the distributor? Is it located inside the distributor? I have also seen some discussion about a "pigtail" causing the troubles I am experiencing. Where is this "pigtail"?

After you take of the distributor cap--you`ll see it, the pigtail will lead from it to your ignition coil, I`ll paste in a pic of the modual and coil for you.
Modual pic:
http://www.rockauto.com/ref/ACDelco/Detail.html?D1943A.jpg
selection:
http://www.rockauto.com/catalog/x,carcode,1249152,parttype,7172
coil pic:
http://www.rockauto.com/ref/SMP/SMPDetail2.html?DR37.jpg
selection:
http://www.rockauto.com/catalog/x,carcode,1249152,parttype,7060

New information, it seems to be getting a little worse and it happens more now at lower RPM's and after it has been idling for several seconds. It is almost impossible to get going at a stop light or at an intersection. Starting it is getting more difficult as well. However, if I keep my RPM's up, it will run just fine. I still believe it is ignition related, as fuel related items just would not seem to produce symptoms like this...and in light of the tachometer jumping, I feel it is pretty safe to start with the spark module in the distributor, and work my way up out of the distributor.

1 - Spark Module
2 - Rotor
3 - Cap
4 - Plug Wires
5 - Ignition coil

If those don't work, I'll check the connections to/from the module an the coil, and then dive in for the pickup coil. I'm a little nervous about the coil as it looks like I will have to completely dissassemble the distributor. However, if I am careful and mark everything, I should be OK.

Any advice or recommendations?

check the connections to the module and coil carefully. they get corrosion in them, but can be carefully cleaned.
the pickup coil requires pulling the distrib, removing the shaft for replacement. note the location of the rotor before you start pulling it and just after it is out, so you can get it back in the same. (hint:digicam )

when were the plugs replaced last?

I am pretty sure the plug are still orginal. I still think I am going to try the spark module first, but I will most likely finish up, even if that does take care of the problem, but replacing the plug wires and the spark plugs - they are almost 20 years old after all.

The tach needle jumping when it hesitates has me really thinking it is that module. I will let everyone know what I find.

[This message has been edited by computer_engineer (edited 09-21-2006).]

Yeah if those are OEM plugs, do them first...prob is your problem. Changing the ignition moduale would still be a good idea though, but do the moduale, plugs, wires cap and rotor all at the same time, hell maybe even do fuel filter, air filter, PCV valve, may as well give it a tune up, not ganna hurt anything, and with the prob your having, im prety confident that would solve your problems, but DEF do plugs and the moduale

quote Originally posted by computer_engineer: I'm a little nervous about the coil as it looks like I will have to completely dissassemble the distributor. Any advice or recommendations?

This should help with the distributor--great write up with pics by jetman
http://jetman.smugmug.com/gallery/1356050

All the above is good. Just something to keep in the back of your mind in case your still have the problem when you complete the repairs to this point.
The Map sensor or EGR valve could also cause the afftects your having.

Also do your changes one or two at a time in case you introduce another problem.
If you change a lot of parts at once and then have a different problem will make it easier to backtrack.

Well guys,

I can sure drag out a thread when I get busy with other things . I thought I would let all of you know that had offered suggestions what I actually found. I removed the distributor cap in the process of going in to replace the ignition (spark) module, and found that the center tap was completely gone . The pin and the spring was impacted (melted) into the rotor and there was massive evidence of arcing. How the car even ran like this, I will never understand. I put in a new rotor and cap and it was running much better.

Question: I still get some very slight hesitation (not nearly as bad as before) under load at lower RPM's in th lower gears. Could the ignition module be causing this (not replaced yet), since at higher RPM's I do not notice any push/pull (slightly lower power, then back to higher power) when in 2nd or 3rd. In 4th and 5th gear, it is not noticeable at all. Based on previous suggestions for the same issue, I think I should limit my search to the ignition module or the pickup coil on the distributor.

Opinions?

Could very well be the module since you where seeing the tach affected.
I'd go ahead and change it with new heat sink grease and see if that resolves your problem. If not then you still have a spare one to carry in the car.
I'd still check the fuel pressure just to verify it's where it should be.

Thanks Dodge.... I will check it this weekend.