So I have a 1984 automatic fiero that I have been working on for the past 8ish months and have gotten it to run pretty well... until it didnt.
A few nights ago I was replacing a valve cover gasket, EGR valve, and the throttle position sensor, afterwardss, I started it, and it ran pretty decent. The engine would surge a few 100 rpms a little bit, but I chalked that up to being minor vacuume leaks (Pretty normal) So this morning, I go to start it, and it starts like it normally would, and I take it probably a mile to the store, at which point it starts to bog down. I park the car in the parking lot and try to restart it. It fires, but no idle, dies immediatly.
I manage to limp the car back home and replace the throttle position senor with the original one I had on the car, and no dice. same problem of not wanting to idle at all. I also checked over all of my electronics and the only unplugged cables are the VSS and TCC cables (minor tranny issues) everything else is still connected.
I have absolutley no idea what the issue is right now
list of parts Ive replaced:
Throttle position sensor idle air control valve map sensor fuel/air filters fuel injector EGR valve ignition coil distributor rotor and cap ignition cables spark plugs 6ish months ago valve cover gasket airbox gasket headgasket
just checked the fuel pressure and have 10 psi, which is within spec. I still dont know whats going on.
Did you spray starting fluid into the TBI like Patrick mentioned? You can either use carb cleaner, or even WD-40 to some extent. But if the car runs while you're doing that... then it's definitely a fuel issue.
10 PSI sounds to be at the bottom of the range... I remember reading that 10-18psi is the optimal operating range. 14-18psi is OK because it's a return-system so any additional fuel will just go back into the tank. Everything I see online says you really want 12-PSI... but the engine will likely demand more at RPM. The ECM, particularly the TBI system, has a whole bunch of emissions programming that can reduce the amount of fuel flow depending on varying conditions and temperature (besides normal fuel mapping). There's a bunch of conditions it could run into (even at idle) where it intentionally reduces fuel flow (just read a whole page on that on the 86 service manual).
I'm still curious if maybe you have an injector problem too. It could be anything.
Can you take some videos and post them? (create a YouTube account and share the link). I'd like to see what the spray pattern looks like from the TBI, and I'd also like to hear it try to start.
Originally posted by 82-T/A [At Work]: 10 PSI sounds to be at the bottom of the range... I remember reading that 10-18psi is the optimal operating range. 14-18psi is OK because it's a return-system so any additional fuel will just go back into the tank.
9-13PSI per GM.
9-10 the engine runs but may have fuel plumbing issues like small section of "rubber" line is leaking for various reasons. Why say that? Many times GM set this regulator to 12-13PSI Over 13psi often is something wrong w/ return line can also set "Bogus" DTC 45 because high pressure making the engine to run rich. Bad return can kill the pump as have enough flow is coolant & lube for it.
"Bad" hose often mean the rubber is "good," the pump will run & fuel will flow but even rust between the rubber & steel line mean bleeding off pressure & fuel flow for the engine. This won't kill the pump but often the regulator stays close so return line does little or nothing.
------------------ 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)
So I ended up replacing the fuel pump that was rated for 13 psi rather then the stock psi, I also ended up replacingh some of the lines.
I also checked for spark which I have on all cylinders
still ahve the same issue, car wont idle. im 5 seconds away from giving up.
mind you I have a new fuel filter and injector, also literally all of the sensors on the throttle body are new. the engine might just be toast.
did you check that the new sensors are reporting correctly? also not idling is in my experience with 84s usually the computer being weird after replacing sensors also do try the old map sensor and such until it idles again
did you check that the new sensors are reporting correctly? also not idling is in my experience with 84s usually the computer being weird after replacing sensors also do try the old map sensor and such until it idles again
hopw would I check if sensors are reporting correctly? I have no idea where my old MAP sensor is as I replaced that thing probably 7 months ago, but i could buy a new one to see if that works.
hopw would I check if sensors are reporting correctly? I have no idea where my old MAP sensor is as I replaced that thing probably 7 months ago, but i could buy a new one to see if that works.
main ones you can check are the tps sensor and stuff like that. something that gets a voltage and gives a voltage back we will say the map is good for now... have you tried giving it starting fluid to see if it backfires or starts up then sputters and dies? if it does nothing then that tells us quite a bit as well
Remove valve cover. Crank engine. Do you see the rockers move? If not the nylon camshaft gear has stripped out. This is common on the Fiero Duke engines. Replacement is not hard just an all day job.
------------------ " 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, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, 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 "
Remove valve cover. Crank engine. Do you see the rockers move? If not the nylon camshaft gear has stripped out. This is common on the Fiero Duke engines. Replacement is not hard just an all day job.
so I doubt that the cam shaft is busted since the engine still runs, but only when I give it a little gas. the only issue I can think of happening to the cam is either the valves on one of the cylinders are stuck, or the cam lobe is stripped, or the push rod is bent. all of which I severly doubt would happen.
im in the process of getting winALDL and the usb to obd1 will arrive next week so ill be able to see whats wrong with the computer soonish.
[This message has been edited by BruhMans06 (edited 07-08-2024).]
so I doubt that the cam shaft is busted since the engine still runs, but only when I give it a little gas. the only issue I can think of happening to the cam is either the valves on one of the cylinders are stuck, or the cam lobe is stripped, or the push rod is bent. all of which I severly doubt would happen.
The title of this thread is It Wont Start. The content here now says otherwise. Time to borrow, rent or buy an ALDL scan tool. That should get you closer to identifying the problem. Perhaps a member here can run over and do the scan for you. It only takes a few minutes to do so. Just guessing, it sounds like a fuel starvation problem.
------------------ " 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, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, 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 "
[This message has been edited by Dennis LaGrua (edited 07-08-2024).]
The title of this thread is It Wont Start. The content here now says otherwise. Time to borrow, rent or buy an ALDL scan tool. That should get you closer to identifying the problem. Perhaps a member here can run over and do the scan for you. It only takes a few minutes to do so. Just guessing, it sounds like a fuel starvation problem.
actually he has to hold the throttle to keep it running. that ain't fuel starvation. that's more likely too much fuel or a stuck iac.
actually he has to hold the throttle to keep it running. that ain't fuel starvation. that's more likely too much fuel or a stuck iac.
see this is why im confused since everything on both the fuel system and throttle body (mosly) are new. I think the only part ive skipped over is the fuel regulator, which i actually inspected at one point and saw no issues with it (no tears and the spring moved freely) but I have a new IAC thats maybe a month old. Ill find out if any of the parts ive bought are duds or not.
Ill be able to actually see what the car is doing once I get my ALDL cable this week. So ill find out.
now that i think about it i guess my fuel regulator could cause some issues between now and when I last checked it... :P
[This message has been edited by BruhMans06 (edited 07-09-2024).]
So I ended up replacing the fuel pump that was rated for 13 psi rather then the stock psi, I also ended up replacingh some of the lines.
And how quickly does the fuel pressure drop when the fuel pump stops? It shouldn't drop, not for quite awhile. If it does drop immediately/quickly, then possibly the fuel pressure regulator diaphragm is leaking fuel into the throttle body.
quote
Originally posted by BruhMans06:
now that i think about it i guess my fuel regulator could cause some issues between now and when I last checked it... :P
And how quickly does the fuel pressure drop when the fuel pump stops? It shouldn't drop, not for quite awhile. If it does drop immediately/quickly, then possibly the fuel pressure regulator diaphragm is leaking fuel into the throttle body.
[QUOTE]Originally posted by BruhMans06:
ok, so I dont remember the pressure dropping much, i left the tester on the engine for maybe 15 minutes and the lowest it dropped to was 9 psi. so I guess that might rule out the regulator
I have yet to get the winALDL adapter because the shipping is taking years so idecided to mess with the engine a little bit while I wait.
I decided to run the fiero for a little bit without the top of the air box, and to my surprise it idled. it idled like crap but it did idle.
the only difference is I had the cap of the aircleaner off. I slapped it back on when it was running and it bogged down again. so now I know its running rich.
I also noticed a **** load of fumes pouring out of the intake, which seems like it might a crap load of blowby on the cylinders since the fumes are coming out of the breather.
I decided to run the fiero for a little bit without the top of the air box, and to my surprise it idled. it idled like crap but it did idle. I also noticed a **** load of fumes pouring out of the intake, which seems like it might a crap load of blowby on the cylinders since the fumes are coming out of the breather.
Guys I might be cooked.
You might have a mouse nest or something clogging up the water separator in the fender.
As for the fumes coming through the breather, replace your PCV valve, or check if it is working. Mine was clogged, which made the small amount of natural pressure spray a bunch of oil into there, my whole intake system, everything, had a grimy layer of black oil, bad enough that when I removed my EGR tube to replace it, it was dripping liquid oil from there. Check that your EGR isn't stuck on, if it is, it would be idling horribly or not at all, and you would have literal exhaust coming into the intake, potentially burning any oil from a clogged PCV valve. Check those 2 things, EGR and PCV valve.
EDIT: TAKE WHAT I SAY ABOVE WITH A GRAIN OF SALT, I just reread the thread, yours is a 4 cyl, I'm not at all sure how everything lines up and fits on it, my post may still be useful, but it is specifically for the v6, I would still check EGR and PCV, although I don't know whether the PCV would be an issue, maybe more so the EGR.
[This message has been edited by 1985 Fiero GT (edited 07-12-2024).]
I have yet to get the winALDL adapter because the shipping is taking years so idecided to mess with the engine a little bit while I wait.
I decided to run the fiero for a little bit without the top of the air box, and to my surprise it idled. it idled like crap but it did idle.
the only difference is I had the cap of the aircleaner off. I slapped it back on when it was running and it bogged down again. so now I know its running rich.
I also noticed a **** load of fumes pouring out of the intake, which seems like it might a crap load of blowby on the cylinders since the fumes are coming out of the breather.
Guys I might be cooked.
I concur with 85 Fiero GT... check your PCV valve... if it's bad, it'll cause additional blow-by which is what it sounds like you're getting. A puff of blue or black smoke on start-up is usually bad oil rings, but continuous smoke is usually bad oil control rings, or a failing PCV system.
Either way, these engines are quick and easy to fix... so if you need to rebuild one. You're looking at $1,000 for everything... including machine-shop costs.
So I pulled the PCV valve and swapped it with a new one, didnt fix the issue.
what did fix the issue was removing the pcv valve from the throttle body. this allowed the engine to idle somewhat consistantly. when I puilled the pcv valve, there was an immence amount of thick fumes and smoke pouring from it.
theres so much to the point that it is entirely suffocating the engine.
ive come to the concusion that my rings have gone bad. because the amount of crap coming out of these NEW breathers is immense, and I dont know what else would be causing this.
im not super pressed about the engine going kaput since i have a k24 on the way in the next 3 weeks. so now i have an excuse to replace the engine
[This message has been edited by BruhMans06 (edited 07-14-2024).]
So I pulled the PCV valve and swapped it with a new one, didnt fix the issue.
what did fix the issue was removing the pcv valve from the throttle body. this allowed the engine to idle somewhat consistantly. when I puilled the pcv valve, there was an immence amount of thick fumes and smoke pouring from it.
theres so much to the point that it is entirely suffocating the engine.
ive come to the concusion that my rings have gone bad. because the amount of crap coming out of these NEW breathers is immense, and I dont know what else would be causing this.
im not super pressed about the engine going kaput since i have a k24 on the way in the next 3 weeks. so now i have an excuse to replace the engine
do me a favor and block off the egr vaccum lines and them smack it with a rubber mallet and lemme know if it stops the blow by. also maybe loosen the exhaust a bit to see if the cat is clogged solid (will matter for the k24 swap anyhow)
Did you check for a plugged catalytic converter as someone mentioned in a previous response? It's been about 3 years since my son and I went through all of these tune up adjustments on his 87 2.5l. We replaced everything you mentioned you did on yours. Did you replace the new injector with your old one just to make sure the new injector isn't the issue? It could be dialed in wrong and overfueling. Is this the engine with the distributor or is it electronic ignition with the coil packs on the side of the engine facing the back of the car? My son's 79 AMC 304 had an overly long hot wire to the distributor coil that caused so much voltage drop, it was 6Vdc when cranking and less than 8Vdc when running and only got worse as the rpm was increased. This caused the engine to appear be running rich when in fact a weak spark was not burning all the fuel. I chased that issue for over a year trying to adjust the Edelbrock for hours then walking away from the project for months before trying something else. We finally got it running great and now cylinder #2 only has 60psi compression. So, we get to tear the engine down again with less than 500 miles on it to see what's going on. But, at least we got a replacement transmission in his Fiero so he can drive that again now.
I digressed. Have you run a compression test on all of your cylinders before assuming the rings are shot. I've never seen an engine go from running great to blubbering like yours is from overnight ring failure. If it went from running and driving before all the parts replacement then one of the parts replace was bad out of the box. There are several ground wires bolted to the bell housing bolts, make sure those are all clean and tight.
Did you disconnect the battery for a few hours and then reconnect to reset the computer?
