My Fiero has been running really well, and i have been delaying a 3800 swap because it has run so well. But last night my 84 Duke idled really well, but lacked power. i had to floor the engine to get it to rev at all, and had to keep my foot down on the floor the whole time just to keep it at freeway speeds. Fortunately, i made it home. Engine is basically stock altho i removed the cat, and just have a pipe in its place. Where should i start? Is it worth it to buy a scanner? Will an OBD II tool work with my Duke? This forum has helped me keep my baby running (thanks guys) and i hope that it will help me this time as well. jon
------------------ I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun! 3800 SC swap to come!
Check your fuel pressure first. First change the filter. It is only $12 at autozone and is easy to change. The pump could be going out or the line inside the gas tank could be deteriorated. You can buy a cheap gauge at Harbor freight but you will have to either adapt it into the fuel line or use it in place of the filter while testing.
There are actually several thing that can cause this condition. Plugged cat etc. Try googling "2.5L fiero no power above idle" or " fiero 2.5 no power" That will give you links to the fiero forum that you can look at.
You can use search on the forum itself but I find it doesn't always pull the info you are looking for.
So to answer some of your questions No an OBD 2 scanner won’t hook up however The ogres cave has an excellent write up of how to do trouble codes on these cars Do a full basic check of systems (fuel, air and spark) pull the dizzy cap off and check the rotor and cap. I would pull the plugs and take a gander at them, they can tell you a lot about the health of your motor
i have no cat - i took it out several years ago. And at that time i was having fuel pressure issues and i dropped the tank and found the pickup filter clogged, so i replaced the filter. The tank was perfectly clean - like it was new! At that time i made a fuel pressure adapter out of a fuel filter - by soldering in a valve - so i can test my fuel pressure tomorrow. i also have a timing light and will check the timing and the spark plugs. The computer is not throwing a code, and i know how to read codes. Could it be that it is throwing a code but it is not showing? jon
------------------ I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun! 3800 SC swap to come!
[This message has been edited by longjonsilver (edited 06-12-2018).]
Originally posted by longjonsilver: Could it be that it is throwing a code but it is not showing?
No, if there's a fault code then the check engine light will come on. The only exception would be if the check engine light is not working. When you turn on the key, engine off, the check engine light should come on. Then it turns off when you start the engine. If a fault is detected, it turns back on while driving. It's easy to have a badly running car that still doesn't set a check engine code. The parameters the Fiero ECM uses for setting a code are pretty basic.
You probably already know this, but just to make sure, remember to jumper the A-B pins of the ALDL connector when you check the timing.
If you have low pressure AND low flow, the fuel line could have dissolved at the pump. I had that happen a few years ago.
Common problem when the fuel pump is replaced using anything other than J30R10 submersible fuel injection hose in the tank. Measure the fuel pressure and flow to determine if this happened. You will need a gauge set.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Thanks guys, i'll be checking this stuff later today. When i had a bad fuel pickup filter a few years ago, i made a fuel pressure valve out of an old filter and soldered in a valve so i could measure the pressure. i still have it, so i will measure the pressure. jon
------------------ I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun! 3800 SC swap to come!
Timing with the A and B ports jumped with a paperclip was 7 degrees - it jumped between 6 and 8 so i averaged at 7 degrees. Same reading for cylinders 1 and 4.
------------------ I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun! 3800 SC swap to come!
Set timing to 8 degrees. Installed custom fuel filter with valve - measured the fuel pressure at 9lbs with the key on, 10 lbs running. Check engine light works, but has not thrown a code. jon edit: going to take her for a drive and see if she runs better with the custom fuel filter - if she does, then i know that the "new" fuel filter is clogged edit again: i couldn't even make it out of the driveway! When i press down on the accelerator the engine doesn't rev at all unless i press down HARD to the floor and even then it is an anemic rev at best. Whazzup? third edit: She idles just fine and starts up right away. hmmmmmmm ------------------ I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun! 3800 SC swap to come!
[This message has been edited by longjonsilver (edited 06-13-2018).]
i pulled the sparkplugs out for you guys to look at. They are in order. Tranny side to left drivebelt side to right. Whaddya think? jon
Funny, idles good, starts good, won't rev. Do the plugs look too white, like the mix is too lean? Or could the timing off by 1 degree have done this?
------------------ I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun! 3800 SC swap to come!
You can have pressure at idle, but when fuel is needed, not enough flow, like a plugged fuel filter, if the sock is also plugged.
By the way, did you try blowing through the fuel filter? I had one that was definately plugged and I could not get air to flow through the filter, by mouth. Blow in the direction of fuel flow.
When the fuel pump hose was gone, the filter had plenty of air flow.
The other problems could be the injector(s) is/are plugged, or the pump is going bad, or even a kink in the fuel line... The reason I bring up the fuel line is, a friend of mine thought it would be cute to kink my fuel line and see if I could figure it out. It took a couple of hours, but I found it...
Push Hard? Pedal should move easy all of the range of movement allowed. Go to the TBI and see if revs up at the throttle "arm." Is good there then cable or pedal have problems.
If Car is auto trans could be problem(s) w/ TV cable or trans itself. Not sure how TV cable is connected to TBI on 84 cars... don't think goes to TBI but links into bracket hold gas pedal cable.
TBI "Arm" can feel stiff because of spring on the shaft but moves easy. If binding then carefully remove throttle sensor and see if binding is reduced or gone.
Engine does not try to stall? Check MAP vac line anyway. Block/broken line cause problems but often won't cause high idle line most vac leaks. (TBI port for MAP is small is why.) Testing MAP is possible but need a "mighty vac" type hand pump w/ gauge. See my Cave, Sensors Quick Ref
Need OBD1 scanner but might not help. See my Cave, Scan Tool Help and other pages.
Don't drive w/ mod'ed filter. Plumbing/electrical Solder may fail and gas leaks can burn the car fast. I'm surprise solder bonded to the filter. I though was some kind of SS and many solders won't stick to it. I would need to see how solder flowed to tell. Maybe sticking enough to handle 9-13psi when parked but don't trust to drive.
If Gauge is "High Pressure" and reads 60 to 100+ PSI max, maybe lying to you. Many gauges aren't very accurate near bottom or top of dial. "Standard" Fuel pressure test sets are often 100PSI... switch the gauge itself to read 30PSI max.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Push Hard? Pedal should move easy all of the range of movement allowed. Go to the TBI and see if revs up at the throttle "arm." Is good there then cable or pedal have problems.
The Ogre WINS! The TBI moved freely and when i moved it while the motor was running, she revved just fine. i went to take a look at the linkage at the pedal and found that the bolt that holds the pedal to the "floor" was loose and ready to fall onto the floor. Tightened it up and she runs just like she is supposed to. Maybe a little better now because of better initial timing.
Thanks guys. My car would have been dead and unfixable (by me) a long time ago if it hadn't been for some of you guys here on this forum. i put in a clutch, a throwout bearing (separate repair), rebuilt my steering column, rebuilt my headlights, found a sneak path (thanks Ogre), fixed my fuel pressure issue (thanks Phonedawg), rebuilt my suspension, and innumerable other repairs along the road. So thanks again guys, another Fiero on the road again!
------------------ I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun! 3800 SC swap to come!
i went to take a look at the linkage at the pedal and found that the bolt that holds the pedal to the "floor" was loose and ready to fall onto the floor. Tightened it up and she runs just like she is supposed to. Maybe a little better now because of better initial timing. 
