well i picked up my first fiero this spring. its a 87 with the 2.8 with auto trans. hasnt seen the road legally since 97. lol. i put a new fuel pump and did the bypass. car will start but wont stay running unless i keep giving throttle. once in a while it will backfire through the intake. i checked fuel presssure just in case and thats in spec. i had someone mention the car could be flooding and check the fuel regulator. i just took that out and no rips. any ideas you guys can give me would be great
Been here, done this. Ok first place to start is look at the harmonic balancer, car has been sitting for almost 10 years they will dry out and come loose, check your cap, rotor and wires as well as cleaning up the distiburator if have one, if not check coils or coil, clean throttle body , ckeck vacuum lines and the check all the sensors, TPS, IAC, EGR....also make sure both intake plenums are tight, if not replacement of gaskets will need to be done and torque them down, after that then you should have eliminated all from the equation
By the way has nothing to do with fuel pressure
[This message has been edited by henryj53 (edited 05-20-2017).]
first place to start is look at the harmonic balancer, car has been sitting for almost 10 years they will dry out and come loose
Yes, they can come loose (been there, done that)... but unless the ignition has been re-timed after the balancer's outer hub has spun, the spun hub itself will not affect the engine's ability to run.
Yes they can, have an 86 and 87 might be the non distributor type, if so if the outer ring comes loose, had it happen on a 85 cavalier with a 2.8 the balancer was loose and rubbed on timing cover throwing timing off enough for it not to run correctly because of the positioning sensor, my 86 the balancer was bad and caused a slight knocking that could be picked up by the anti knock sensor and advanced timing to compensate
[This message has been edited by henryj53 (edited 05-21-2017).]
Your TPS sensor should have 5v with key on and when move the lever should be about 1.5v out put should be able to put test probes from the wire entry and get a signal without poking thru wire insulation itself
...the outer ring comes loose, had it happen on a 85 cavalier with a 2.8 the balancer was loose and rubbed on timing cover throwing timing off enough for it not to run correctly because of the positioning sensor, my 86 the balancer was bad ond cuased a slight knocking that could be picked up by the anti knock sensor and advanced timing to compensate
None, I repeat none of which applies to the 2.8 in a Fiero.
[This message has been edited by Patrick (edited 05-21-2017).]
May not apply to the Pontiac Fiero, but does apply to the 2.8, seeing they were the same GM engine just different location in the car and that was what was talking about, not weather it applied to one car or the other just the engine being they same
well i picked up my first fiero this spring. its a 87 with the 2.8 with auto trans. hasnt seen the road legally since 97. lol. i put a new fuel pump and did the bypass. car will start but wont stay running unless i keep giving throttle. once in a while it will backfire through the intake. i checked fuel presssure just in case and thats in spec. i had someone mention the car could be flooding and check the fuel regulator. i just took that out and no rips. any ideas you guys can give me would be great
Hasn't been driven legally in 20 years? There may be a lot of things that need inspected, checked for ohms, filthy gas tank plugged injectors, huge mouse nest in muffler, plugged cat, etc. Vacuum leak?
[This message has been edited by 2.5 (edited 05-22-2017).]
well tested one theory out having a clogged exhaust. not that. legally it hasnt been driven. still gotta test the tps sensor. now bout the cold start injector? if that dont work would that cause my conditions?
Did you check your fuel pressure... both while the engine is running and after it's turned off? Maybe you have an injector or two (or more) that's leaking bad?
engine only runs for a few seconds then stalls out. i was reading about 45ish pressure
And? How quickly does it drop?
quote
Originally posted by Patrick:
Did you check your fuel pressure... both while the engine is running and after it's turned off? Maybe you have an injector or two (or more) that's leaking bad?
well figured i let you in on progress. friend of mine gave me his camaro 2.8 block and trans. well he had new injectors in there. i noticed nothing else i could really use. i just tried starting it and it runs...well it idles at 3500 rpms but it idles. lol. tried swapping around iac's but no change. so i plugged in my scanner and looked at datastream. if im reading right tps is at 3.76 volts..could that be my problem? from what ive seen i should be at .5
The TPS should send a voltage between roughly .5V and 4.5V proportional to throttle percentage. If it's reading almost 4V with no throttle applied, the sensor has failed.
Your off reading of your TPS isn't going to cause the engine to run fast. The ECM barely uses the TPS readings. It uses it to 1 - determine if the engine should be idling (TPS <.6ish) and if it is then tries to adjust idle speed using the IAC - and 2 - to determine if you just stabbed the throttle so it knows it needs to add extra fuel to accellerate the engine.
Your off reading could be that the sensor failed or it could be a bad connection between the TPS and the Black wire of the connector. Key on engine off and scanning watch the TPS reading. Unplug and then reinsert the TPS connector. Does that maybe fix the problem? Try moving the throttle by hand (still engine off but scanning) and see if the reading moves like it should.
The MAP is the main sensor the ECM uses to determine how much fuel to inject. It measures the air pressure in the intake and then injects the right amount of fuel. The ECM really doesn't care how the air got in there.
Your engine is running at 3500. That much air can only get in the intake three ways - 1 throttle is open - 2 the EGR to intake manifold tube is rusted out and severed - 3 the IAC passage is allowing it in.
Check to make sure the throttle is moving correctly. Do not adjust that throttle stop screw. Leave the cap on.
Assuming you still have the trouble, and assuming you haven't taken the throttle body off, then #2 is the most likely suspect.
Cut a strip of aluminum can the width of the UPC label. Take the dist cap off but leave the wires on and put it to the side. Loosen the two 10mm head bolts on the bottom of the intake manifold inlet that connect the EGR tube to the bottom of the manifold. It will be difficult but you can do it. You will swear a little however. Once loose, slip the aluminum strip between the tube's flange and the intake manifold. Then tighten the two bolts. Replace the cap and start the car. If your idle is now normal, the problem is a leaking EGR to intake manifold tube.
[This message has been edited by phonedawgz (edited 07-03-2017).]
Well, those are the only three places that can flow enough air to idle the engine at 3500 rpm. The IAC passage has an o-ring that can get out of place but that is on the engine side of the throttle body. Unless you or someone else had the throttle body off, that would not be a suspect.
If the problem with your very high idle is a stuck open IAC valve, putting your finger over the IAC air inlet will bring the idle down below a normal idle or it might even stall. If it doesn't you could still be looking at a dislodged o-ring where the IAC feed tube inserts into the throttle body or one of the other two suggestions I had listed earlier.
The o-ring can get dislodged if the throttle body is removed from the intake manifold and when it is reattached when the feed tube is inserted it pushes the o-ring out of its internal groove in the TB.
I have only seen this happen when someone removes the throttle body.
95% of the time it is a broken intake to EGR tube.
[This message has been edited by phonedawgz (edited 07-04-2017).]
It is a whole lot easier to use the aluminum strip to block it off than it is to take it off. If the strip cuts the idle down, then you can take it off and look at it. If the strip does nothing then look elsewhere.
I don't think you can get the IAC tube out without taking off the throttle body. That said a while back you said injector o-rings. If they were not in place that could do it but I wouldn't think they would be missing but he did just replace the injectors.
