Hopefully someone on this amazing forum can help me out.

I have a 1984 2.5 sport. I have been dealing with this issue for several months, but I am now at a loss and need to reach out for other ideas. I've searched and read for hours on here and other sites and tried many things.

The problem: Once the engine warms up and I am at Hwy speeds of 55 to 70 mph and cruising, the engine feels like it is stumbling, but it will be fine for a few miles and then stumble a little and then it will run fine for a mile or more and might do it again, or it will do it for miles and then stop for a while and start up again. It doesn't die, just doesn't feel right. The best way I can describe the feeling is, it feels like I have my foot on the gas maintaining speed, and someone else is tapping the brake occasionally.

I have replaced the fuel pump and strainer, fuel filter, ignition coil twice, ignition control module twice, spark plugs, wires, dis. cap and rotor, and the TPS module. I've reset the timing, checked the grounds, moved the ignition coil to the trunk wall to get it away from the heat and vibration. Checked the injector and filter.

I just don't know what to check or do next...

[This message has been edited by 2Sly4U (edited 08-25-2011).]

Any engine codes?

Did you check the EGR?

It's not throwing and codes. I haven't checked the EGR do you think that would have anything to do with this problem?

It could, not saying it is, but it could. What plugs did you use, and are you sure the wires are seated properly? Did you check the timing (doubt this, but if you don't know the history)?

Plugs are stock AC plugs and I just reset the timing last night the wires are good and seated.

When you reset the timing, did you short the A to B in the ALDL while setting?

Yes I did short the A to B in the ALDL while setting the timing. I guess I'll take a look at the EGR and see if it is sticking. I was wondering if it could be the ECM?

[This message has been edited by 2Sly4U (edited 08-24-2011).]

Do you have any way to run WinALDL on it. Need to see what the ecm is seeing for temp from the sender. I had one that was doing that until I finally changed the ecm temp sender. On mine you could hold the throttle open at a steady rpm and watch the spray from the throttle body. Randomly the spray cone would flutter/stop for just a half a second and of course you could hear and feel the engine miss immediately. Would feel it when cruising. It eventually gave me an ecm temp code and an O2 code. If I remember right it was codes 15 and 13. Don't know how that would cause such a random problem, but changing the ecm temp sensor and O2 sensor fixed it.

More of a Mac guy, but I do have a pc. Where could I get a hold of that program? How do you hook it to the car?

Your description sounds very similar to what mine is doing. I would be so glad to get this fixed...

Program is here: http://winaldl.joby.se/

connecting cable was here. Don't know if Dodgerunner still makes them or not.: https://www.fiero.nl/forum/Forum4/HTML/041052.html

edit:
Here is another thread with something that is supposed to help the WinALDL program. : https://www.fiero.nl/forum/Forum1/HTML/073532.html

[This message has been edited by 2farnorth (edited 08-24-2011).]

Awesome 2farnorth, thanks so much! I will see if I can get that working. I have the ability to run windows on my Mac and it shouldn't be a problem. I just need to get a cable.

I'll let you know what I find out.

From the description, sounds like the lockup TCC acting up. Have you tried unplugging that? Mine does the same thing.

quote Originally posted by armos: From the description, sounds like the lockup TCC acting up. Have you tried unplugging that? Mine does the same thing.

Sorry mine is a 4-speed manual, not an automatic...forgot to add that.

could even be an o2 sensor. was that replaced (I can't remember).

O2 was replaced, but that was about a year ago.

download the service manual and start looking at the section related to mis-fire under load?
http://www.fieronews.net/fu...nloads.php?cat_id=13

Other things to check... the wiring around the injector. Mine was pinched and chaffed from the air cleaner housing by the previous owner. The injector would not fire right when we first got the car running. I had to cut out the bad section and crimp the wires & all was well there. Then we ran some seafoam through the intake... Ran some Lucus fuel treatment through the tank to help clean the injector...smoked out the neighborhood and it ran much smoother.

I also checked through my grounds and added some, but sometimes you just have to replace them to be sure there are not issues under the insulation that you can't see. Seems I had alot of that I just discovered. Check the power lines as well. Mine were seriously corroded when I really got to digging. Especially due to the 84 having power wires distributed from the starter. If you have not you might consider updating the car with a 85 style distribution power block to move the wires away from the starter and exhaust.

Check your vacuum lines as well.

At the dealer we had a guy that only got a miss when the car warmed up... it was intermittant. It turned out to be a crack in the internals of the distributor cap. You could not see it, the plastic was fine. It was the metal inside the cap. Once the engine bay warmed up and the dist warmed up and expanded, the metal would loose contact and it happened.

[This message has been edited by redraif (edited 08-25-2011).]

thanks redraif.

I have to go back over all my vacuum lines and wiring. I still have a warranty on the cap and rotor, so I'll pick up a replacement tonight just to be on the safe side.

I found one cracked vacuum line on the line going to the canister, but that was all. Replaced the Dist. cap and rotor, and drove it this morning and it's still the same.

I am going to make a serial cable tonight to read the ECM info using the WinALDL program. Not exactly sure how to use the program, but I'm a quick learner. I'm sure I'll figure it out.

Check the EGR, using the manual I recommended you download?

quote Originally posted by jaskispyder: Check the EGR, using the manual I recommended you download?

I plan on it. Still reading through it, what page were you talking about? Can't seem to find it. It was late last night when I was looking at it I may have just missed it.

quote Originally posted by 2Sly4U: I plan on it. Still reading through it, what page were you talking about? Can't seem to find it. It was late last night when I was looking at it I may have just missed it.

Check out section 6E2-B-1 (I am looking at my '87 manual, which will be different, but I think the sections are correct).


SURGES AND/OR CHUGGLE
Definition: Engine power variation under steady
throttle or cruise. Feels like the car speeds up and
slows down with no change in the accelerator pedal.
• Use a "Scan" tool to make sure reading of VSS
matches vehicle speedometer. See "Special
Information", Section "6E".
• CHECK:
- For intermittent EGR at idle. See appropriate
CHART C-7.
- Inline fuel filter for dirt or restriction.
- Fuel pressure. See CHART A-7.
- Generator output voltage. Repair if less than 9
or more than 16 volts.
- TCC Operation. (CHART C-8)
• Inspect oxygen sensor for silicon contamination
from fuel, or use of improper RTV sealant. The
sensor may have a white, powdery coating and
result in a high but false signal voltage (rich
exhaust indication). The ECM will then reduce
the amount of fuel delivered to the engine,
causing a severe driveability problem.
• Remove spark plugs. Check for cracks, wear,
improper gap, burned electrodes, or heavy
deposits. Also check condition of the rest of the
Ignition System.


CUTS OUT, MISSES
Definition: Steady pulsation or jerking that follows engine
speed, usually more pronoun(~.ed as engine load increases. The
exhaust has a steady spitting sound at idle or low speed.
• Perform careful visual (physical) check as
described at start of Section "B".
• If Ignition System is suspected of causing a miss
at idle or cutting, out under load:
• Refer to appropriate ignition "Misfire" Chart in
Section "C4".
• If the previous checks did not find the problem:
- Visually inspect ignition system for moisture,
dust, cracks, burns, etc. Spray plug wires with
fine water mist to check for shorts.
- Use a "Scan" tool to check for erratic TPS
voltage.
- Fuel System - Plugged fuel filter, water, low
pressure. See CHART A-7.
- Perform compression check.
- Valve Timing.
- Remove rocker covers. Check for bent pushrods,
worn rocker arms, broken or weak valve springs,
worn camshaft lobes. Repair as necessary. See
Section 6A.

Thanks

quote Originally posted by jaskispyder: When you reset the timing, did you short the A to B in the ALDL while setting?

Whats the purpose in this? Reason I ask is because I didnt do that when I installed a new distributor in my Duke.

This sets the base timing for the computer, otherwise the computer is trying to adjust the timing when you are. The computer needs the base to then adjust the timing.

Have you checked your vaccum lines?

Yeah, checked them again last night. Everything is good now still the same problem.

EGR looks promising for a fix. Won't be able to test til I get home.

quote Originally posted by GADJet: So, so I need to set the A B Pins and readjust my timing then?

Yes, jump A and B, then set the timing.

Awesome. Thanks.

Have you checked the throttle position sensor. Mine went bad and caused some weird problems, mainly bucking. Never threw a code. EGR is a possibility, an easy way to see if the egr is functioning is to start the car, while at idle put your fingers under the erg and press up on the diaphram. the car should stumble.
You said you changed the fuel pump, was the tank clean? A rusty tank can foul the screen filter pretty quick.
Good Luck.

TPS is new, and gas tank was cleaned when I replaced the fuel pump. Picked up a EGR on Saturday, haven't had time to install it, maybe tonight or tomorrow.

Well, here is an update...

I haven't been able to get my serial cable to work yet to use WinALDL, but I replaced the EGR and added a ground to the intake manifold last night. I drove it to work today and it wasn't cutting out for about 25 miles into my 35 mile trip where I get off the highway and start hitting stoplights, then it started stumbling and dying at every light. It is very difficult to start but does eventually start up and I can drive it to the next light. So frustrating!!!

I am going to go out at lunch and see if it starts up and runs again.

Hmmm, so does it only run bad when warm now? Just a thought, the injector could be causing problems. Hard to tell without seeing it, but I had issues where the injector would work one time and not the next. It was spraying fuel, but something was faulty inside. If you have access to another injector (even used) you could swap it out.

That would be easy to swap out, but I don't have access to another one, and hate to buy a new one just to try it out. I'll have to find one I guess. Too bad I don't know anyone in the area that has a Fiero or extra parts.

quote Originally posted by 2Sly4U: That would be easy to swap out, but I don't have access to another one, and hate to buy a new one just to try it out. I'll have to find one I guess. Too bad I don't know anyone in the area that has a Fiero or extra parts.

Yeah, You could put an ad in the mall, I picked up a used one pretty cheap that way. BTW, junkyards would have them, just get one from the same TBI (some trucks use the same TBI in their dual TBIs).

OK, I'll do that. I was just at the junk yard Saturday and both Fieros they had were picked over and no injectors and couldn't find any others out there. They are having another 1/2 off sale this weekend. Maybe I'll try again if the mall doesn't work out.

Here is some cross reference information for the injector.
http://www.fuelinjector.cit.../5448589/5391125.htm

Check fuse box for minor corrosion at the fuse grip contacts.

Had a similar problem only not as severe on my black 2M4. It wouldn't appear until the car was driven for 20 minutes or more. I tried all sorts of remedies. None helped until I removed the fuses, coated the contacts & fuse ends with Deoxit, wiped it off & reinstalled the fuses. Problem solved.

Or use some fine sandpaper.

[This message has been edited by 30+mpg (edited 09-07-2011).]

I suspect out of place electrical underneath coming in contact with exhaust. This would act up after warm up and may be pushed into exhaust when windy or at high speeds. Check loose wires between driver compartment and catalytic converter. Anyway it sounds electrical.

This goes to careful visual check as described under "cuts out" in the above trouble shoot.

Good Luck...... I may have an injector hanging around but a faulty one would have more uniform symptoms...I think.

[This message has been edited by White 84 SE (edited 09-07-2011).]