Got a sweet deal on an '84 with only 86K miles on it. It still has the stock 2.5L with auto transmission. It appears that it came with factory AC but the compressor and other components have been removed.

Problem is that it is running pretty bad. It has been sitting for at least two years with a full tank of gas. I first figured that I would start off by replacing everything involved in routine maintenance just so that I was at a known starting point. It has: new distributor cap and rotor, plugs and fuel filter. I have drained the tank and just put a couple gallons of super unleaded. Tomorrow I plan on changing the oil, oil filter and air cleaner. Timing was set at 8 degrees BTDC, but I need to triple check that tomorrow.

None of what I have done so far has improved the idle. I have taken off the EGR valve and cleaned it and it now moves freely. I have also tried running the engine with the vacuum line disconnected and plugged. The IAC valve is something a bit new to me. I checked resistance across the poles at it is as 45ohms, I retracted the IAC cone and with ALDL pins A & B jumped I can hear the stepper motor. I took the thing off, cleaned up the cavity in the throttle body and the cone of the IAC. I then manually adjusted it to that it was VERY close to fully seated once reinstalled. Leaving pins A&B jumped and the ignition on I can see the end of the cone moving in and out of the seat. Upon removing the jumper and starting the car it will run for a bit and apparently the IAC retracted while it was warming up because I could no longer see the tip of the cone looking down through the throttle body.

While in diagnostic mode, the only code displayed is '12'. I looked for vacuum leaks but nothing jumped out at me. I think tomorrow I will buy a can of starting fluid and spray some spots while the engine is running to see if there is any change.

Anyone else have any ideas/suggestions? The wife's new Camaro gets the garage, so I kind of queue up tasks for the Fiero to be done during the day. Based on the reading of many other threads, the IAC would seem to be the culprit, but I wish there was a way to know whether what I am seeing is what is expected.

Thanks in advance

Forgot to mention, if I can get the thing up at 3k rpm then it smooths but if I let off the throttle it either stalls or goes back to really poor idle conditions. When I purchased it, I managed to drive it up on the trailer, but that required holding it at about 2k rpm and dropping in to drive. I really had to stay on the gas in order to keep it running while in gear.

Welcome to the Forum!

Low fuel pressure will create some of the problems you are describing. Maybe the injector is gummed up after 2 years.

[This message has been edited by Gall757 (edited 12-15-2012).]

I did get a pint of Sea Foam that I am planning on putting in the tank once I get more than just a few gallons of gas in it. I am working on making a fuel pressure gauge using a couple of dial gauges that I seem to have lying around, so perhaps I can test that. What number am I looking for on the fuel pressure? The multi-port injection Z cars ran about 60.

You only need 10-15 lbs. of fuel pressure on a 2.5. But I have heard of engines running badly with 8 lbs.....

Well, I still haven't checked the fuel pressure. Turns out that the gauge that I used once upon a time was no longer showing any needle movement if I pressurized the line with my air compressor. Seeing as how the family was asking what I needed for Christmas, I asked Santa for a fuel pressure gauge so I will be waiting until after Christmas to test that one. In the meantime, I ordered a IAC valve and installed it as well as ordering an ALDL cable from DodgeRunner. I also changed the oil and oil filter because I couldn't remember whether the guy I bought the car from indicated whether he had recently changed the oil, and if he hadn't, that meant that it had been sitting for who knows how long.

I watched RAW data stream by while the car was idling, all the while showing MALFFLG1 with a code of 4 and MALFFLG2 with a code of 2. If I use this page: http://ws6transam.org/aldl_47.html, a code of 4 would indicate something wrong with the TPS. Anyone work with ALDL before on the 2.5L ECM? Does that code truly indicate something with the TPS?

Thanks in advance

I've had my Duke for a little over a year. It was running very rough when I got it, though it never threw any codes whatsoever. I first off did all the routine maintenance. I changed the oil and filter(started running synthetic oil), plugs,wires, distributor cap, rotor button, coil, and ICM. It started to run better, but it still didn't seem "right". I found that the EGR valve was stuck closed and had a crack in the diaphragm, allowing a vacuum leak. So I changed that and it ran even better, but it still lacked power and was running very rich. So I changed the TPS and it's running like a champ. I would say it's the EGR, TPS, or a substantial vacuum leak. Might want to check the throttle body seal and make sure the TB is tightened down. Its a common problem for the Dukes TB to rattle loose.

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-Hambone
1984 Fiero SE 2.5 Duke

Well, I think vacuum leak(s) may have been part of it. I plugged the line going to the cold air sensor as well as one of the lines going to the vacuum canister and the car idled for a record time. Stalled the instant I put it in gear, but I think we are on the right track. I am going to plug the line going to the brake booster but I need to get a few more gallons of gas in her. After draining the tank I only put two gallons back in. I think I am going to put about 6 gallons in and then add the Sea Foam and it her run for a bit longer. I did get perhaps a sixteenth of a turn from one of the throttle body bolts, not much but I know that every little thing could contribute.

I went ahead and ordered a throttle position sensor, but it won't be in until tomorrow morning.

Car still stalling. Upon blocking off a bunch of the vacuum lines it ran for record time but still stalled when I put it in Drive. And now it is back to doing the same thing where it will idle for a while and eventually stalled. Update to what I have done includes replacing and adjusting the TPS so that at idle it is showing 0.56V at idle and is now idling while cold (when it idles) at about 1K RPM. I have checked the fuel pressure and it is registering 12psi measured between fuel filter and throttle body. IAC has also been replaced and adjusted by shorting ALDL pins A&B and leaving the ignition turned on for a couple minutes then turning ignition off and removing the short.

Currently I have the vac. lines plugged that go to the brake booster, cold air thingy in the air filter housing and one of the lines that go to the charcoal canister.

Anyone have any ideas to help me out. I would appreciate any ideas. Seeing as how I didn't replace the plug wires I am planning to pull those and check them with an ohmmeter.

So I am pretty sure that I found my major vacuum leak. It is somewhere in the vacuum line going to the brake booster, or in the brake booster itself. After plugging that line from the manifold I was able to at least drive the car around the block. Today I wanted to put the ohm-meter to the plug wires and also verify that the wires were in the right order. And here is where I hope to get a smidge of input from the community.

In most drawings and explanations of the firing order on the distributor cap, they all seem to indicate that plug one is in the ten o'clock (or thereabouts) position. Then clockwise through the 1-3-4-2 firing order. My cylinder one plug wire, however, is in the seven o'clock position. The engine runs but seems to misfire or sputter under load and I had the timing light on it yesterday and, well at that time I thought I was on cylinder one but now I can't be positive, the timing was showing as about ten degrees BDTC.

So my question is this, is it possible that the car would actually idle with the timing 90 degrees off? And if so would if exhibit the symptoms I described where I am able to drive it but it has low power and sputters?

Thanks in advance,
Scott

[This message has been edited by sjdannen (edited 01-20-2013).]

Here is what I have on firing order and dist position. Is yours like this? I had an '87 Duke with DIS so I don't know the 84-86.



Also, do you still have the cat converter? A clogged cat can produce your symptoms too. Remove the O2 sensor to see if it picks up power. (A vacuum leak usually causes a high idle.)

The idle speed is near correct now that I have the line to the brake booster blocked.

The diagram that you posted is what I was using. It appears that perhaps the distributor was removed at some point and when it was put back on it wasn't aligned correctly. I moved the engine until the timing mark was a zero degrees and then looked at the rotor position and it was pointing to the seven o'clock position. So now I am wondering if when the person that put the distributor back on at the wrong angle whether they then put the wires back on 180 degrees off.

I replaced the wires, because I was getting some inconsistent reading with the ohm meter on the cylinder 4 wire, and after looking at the rotor position when the timing mark was up I got distracted with trying to fix the parking brake. The mechanism that allows the pin to be pulled away from teeth of the handle was gummed up and as a result, one of the previous owners disconnected the parking brake lines from the calipers instead of fixing the handle.

Anyway, still need to pinpoint the cause of the car not running well under load.

I chased a miss and low power for a long time before discovering I had 2 plug wires out of order (V6). I don't remember reading where you verified your wires were correct?

And you can make any position number 1 on your dist by lining up the #1 piston at TDC and rotating the dist so the rotor button is pointing at your chosen #1 plug wire. Then run the spark plug wires clockwise, 1-3-4-2. Usually you want the ICM connection to be easily accessible though.

That was one of the things I did today based on another person having found that he had plug wires 2&3 reversed. So I checked that today while I was changing plug wires. I will double check that tomorrow though. Could never hurt to double check things when the solution seems to be elusive.

Thanks

Removed the O2 sensor and performance did not improve. Pulled the EGR valve so that I could throw together a quick block off plate and see how it performs with that. I left work a tad early today just to get those couple things done before it got dark. Plans got cut a little short when the automatic shift handle button stopped working for some oddball reason so I had to get that taken care of which wasted what little daylight I had left.

Probably not. The car just stays in open loop waiting for the O2 to start sending good info.

EDIT: Mine acted up under load a few times. Once it was the TPS. Only happened at a certain throttle position equating to about 45mph cruise. Once the fuel filter was clogged. Anything over 1/2 throttle and it bucked. I've read of others though: Weak coil, bad spark plug wire, hole in the rubber fuel line inside the tank between the pump and metal fuel line.

[This message has been edited by Hudini (edited 01-21-2013).]

If you look up my post "what else can I do?" you'll see that I did just about everything you did. The ultimate problem was several leaks in the vacuum lines under the plenum, as well as a bad EGR valve.
Before the repair above, that car would barely get in gear (which I thought was a bad clutch), slipped at the beginning of each subsequent shift, and stuttered at cruising speed. It runs great now, so I hope you can bypass some of the repairs I made, if, indeed, it is a sub-plenum vacuum leak.

Thanks Bruce. I am going to focus on the EGR area next. I'm not sure what is meant by plenum. Are you referring to the air filter housing? Or the duct that does from the side intake to the air filter? How did you find the vacuum leaks? I was thinking about taking up cigar smoking just to let the car run and blow smoke around everything and look for movement. Wife said no to the cigar though, plus I wasn't sure how well the smoke idea would work on venturi vacuum areas that only have a measurable vacuum during acceleration.

Thanks and I hope your comments lead me to a solution. I am nearing the point where I want to drop it off at a shop, but I think I am just getting lazy the older I get. Haven't had to do that in who knows how many Nissan Z car rebuilds.

quote Originally posted by Hudini: Probably not. The car just stays in open loop waiting for the O2 to start sending good info. EDIT: Mine acted up under load a few times. Once it was the TPS. Only happened at a certain throttle position equating to about 45mph cruise. Once the fuel filter was clogged. Anything over 1/2 throttle and it bucked. I've read of others though: Weak coil, bad spark plug wire, hole in the rubber fuel line inside the tank between the pump and metal fuel line.

While it was still at a point where it wouldn't idle, I thought TPS too, so I replaced it and then it didn't help I returned the part. I have checked voltage levels on the TPS and it appeared smooth but I will recheck that too now that I am troubleshooting the low power issue and no longer trying to figure out why the car simply wouldn't stay running.
Thanks

The throttle body feeds into the plenum (the big, red thing with "Fiero" on the top).
After I changed all the sensors, etc, etc., I finally took my car to a computer diagnostician. He found the problem, changed the vacuum lines, and changed the EGR valve.
I found two cracked insulators on my not-very-old AC Delco spark plugs last week. I changed them for NGK, and the car runs extremely smooth.
I just rechecked your first post (duh), and learned that you have a 2.5L. I have the 2.8, so the vacuum lines are obviously different. Someone on the Forum should chime in soon to tell you where and how to look for leaks.
Stay with it!
bb

Hey! Another ABQ member!!! If you ever need an extra set of hands I would be glad to help just shoot me a PM schedule permitting
(Not to mention my roommate is a Z guy)

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1988 White T-Top "Natalie"
1993 Chevy Lumina "Lauren"
<('-'< )(^'-'^)(>'-')>

[This message has been edited by Mini_moosee (edited 01-23-2013).]

Thanks Bruce. I think I will plan on replacing all of the rubber vacuum lines either Friday or Saturday when I test the EGR with my temporary block in place.

Mini_moosee,
It's good to know another enthusiast is near. I may have to take you up on the offer of a paid of hands closer to summer if you are still interested. I am keeping an eye out for a good deal on a running 3.4L or 3400 to start working on a swap. I know that there will be a bit more work involved because I am starting with an 84 2.5L. WHat I may end up doing if keeping this one as the 2.5L and if I come across V6 Fiero nearby, I may just pick that one up. When I was doing Z restores, the wife would let me have two, one that was a daily driver (which would be the 4cyl and my daughter would be the driver) and one project. Getting the current Fiero running reliably is a prerequisite to selling the Jeep, which I am very hesitant to do because that Jeep has hauled a Fairlady Z back from Phoenix as well as hauling this Fiero from East Albuquerque to the westside.

With many traditions I have seen across this great forum this would of course be a free set of hands though a beer or two never hurts
My first Fiero was an 84 that I swapped a 2.8 into so if you decide to swap a 2.8 or 3.4 I have all the build information. Also whenever you're in the market for a V6 Fiero, or even need a few parts for your current one hit up Carver1, he is located out in Edgewood about a 45 minute drive from ABQ. He is an excellent guy and has hooked me with a lot parts and knowledge over the years.

Well, I replaced every vacuum line except for the brake booster line, which is blocked off.
I created a makeshift gasket for the EGR valve that blocked off the opening in the intake.
Car still sputters quite a bit. What is strange is that I think it might just happen under acceleration but possibly not holding that speed, which I would think would indicate fuel pump or clogged filter. Spray looks to be coming out of the injector in a nice cone, but you know how visible checks of a fuel injector are.

I think my next thing will be to just let the car idle while I get a spray bottle of water and spray around all of the mating pieces. TBI to intake, intake to head.

SJ,
After I had the vacuum leaks and EGR valve fixed, my GT was still running a little rough. I'd been reading about AC Delco vs NGK spark plugs, even though I had only changed the plugs a few hundred miles ago. I had free time, and the price was right at RockAuto ($1.50 per NGK), so I changed over. It turns out that 2 of the ACs had cracked ceramic installation, and the change made all the difference.
Checking the plugs in the 2.5 has to be much easier than the 2.8 (understatement), so it might be worth your while to do so.
It's always the little things that you miss. Or it's not.
bb

Seeing as how I am now able to manipulate the throttle and get the thing to move, I pulled it in to the driveway backwards. Now I can work on it without pulling the 500watt lamps that we used to use at the track.

I will pull the plugs and take a look, possibly tonight. My dad stopped by to drop off my daughter after they had a "play day" and reminded me of the propane trick to find vacuum leaks. With carburetors, we used to do a propane drop technique to get the idle mixture close as well as to find leaks. This will make the wife happier than coming out to find me smoking a cigar to look for the leak.

So I have been using WinALDL with config number 1227170 because that was all I was ever able to find on the forums on what to use. Everything always seemed a little fishy because the only tab that worked is the RAW Data tab. However, today I went back to the WinALDL site and found that the only config applicable to 2.5L engines was "1225550, 1225570, 1225610". There isn't a listing for 1226156, which is a number pulled from the TunerPro site for the 84 Fiero.

Anyway, long story short, using that configuration, the error codes tab shows 42 EST (Electronic Spark Timing). The page for Fiero codes, assuming that the same codes apply to an 84 points to the ignition control module. My question is this, if the ignition control module is bad or is going bad (is there an inbetween with an ICM?), would it exhibit what I am seeing where the car will run, but run poorly under load?

Another question, is 1225550, 1225570, 1225610 the correct configuration to use in WinALDL for the 84 Iron Duke? THere is probably a different config for the 2.5L that uses the coil packs, so if anyone has any input on using WinALDL with the distributor based 2.5L, that would be great.

Tested the MAP, figured it couldn't hurt seeing as how there is a test. Voltage measured 3.92V with ignition on and car not running and 1.99V with 10psi of vacuum applied. So that is supposedly good.

Gonna test the coil next and then order a new ICM.

Check your fuel pressure. I wasted time and money not doing so.

https://www.fiero.nl/forum/A...040223-2-039319.html

Thanks Bonzo. After seeing the values of the integrator, I was kinda thinking that too. I checked the fuel pressure earlier in the troubleshooting but, like the spark plugs, it wouldn't hurt to go back over all possibilities. My hope for tomorrow is to get the ICM back on and verify that all connections are good (Ogre's page says that the ground wire from the ICM to the ECM will trigger the 42 error code) and get the fuel pressure tap back in place between the throttle body and fuel filter. Oh yeah and adjust the TPS.

Thanks everyone, I really appreciate all the help.

[This message has been edited by sjdannen (edited 01-27-2013).]

So I finally got a chance to work on the car again. Earlier this week I tested the ignition module and it checked out okay, so I cleaned up the contacts and squeezed the prongs in just a bit in case any of the individual contacts were loose. Today I adjusted the throttle position sensor so that at idle it was at about .75V and hooked the fuel pressure tester up again. (Still at 12psi during idle under no load). Started her up and let it idle for a while until it died and tried to crank it up again but the battery was dead. Hmmm, not really surprised that the battery was dead because the guy that I bought the car from said that he had put an old spare battery that he had in the car when he was getting ready to sell it.

So I put in on the charger set to 10amps for about an hour and went in to kill some aliens in Halo 4. Went back out and the car fired right up. I hooked the laptop up and it is no longer reporting error 42, so perhaps it was a bad connection to the ground. It is also not reporting the error for low TPS voltage, of course. So I pulled it out and started driving it around the block and it felt pretty good, except that I could tell I had a brake dragging. Probably from when I tried fruitlessly to adjust the parking brake. But after a few trips around the block, I looked at the TunerProRT dash which showed by battery voltage at 11.2 and not long after that the car started running poor. Funny thing though is that every time is stuttered, the tach and speedometer did something strange. The speedometer would go to 0mph and the tach would jump around a bit.

Anyone experience this? And could this be one of the issues all along? So far the things that I have done that actually made a difference are: the vacuum line to the brake booster plugged off, adjusted the TPS, fixed the connections to the ignition module. This doesn't list all of the other things that I have done to the car either to troubleshoot the problem or just to get to a known point of routine maintenance. But could a battery that is 1. forcing the alternator to work extra hard due to 2. only keeping 11V be causing the funkiness that I am experiencing?