4.9 help again
Printed From: West Coast Fieros
Category: Technical Topics Forum
Forum Name: Technical Questions and Discussions
Forum Description: Got a technical question about your fiero? ask it here.
URL: http://www.westcoastfieros.com/forum/forum_posts.asp?TID=2200
Printed Date: 24 April 2025 at 11:19pm
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Topic: 4.9 help again
Posted By: orange
Subject: 4.9 help again
Date Posted: 26 November 2010 at 7:22pm
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Yes im back and need more help. If you remember what was
happening before... well its the same thing. Fuel in the oil, black smoke, high idle. and for some reason when i just crack the throttle blades a millimeter it drops a bunch in RPM and idles worse. It revs fine though...??? it has a fast and clean sounding rev, and idles ok. I took the oil pan off and took a look and although i have not completely checked all the cylinder walls, they look good, no scoring. They are nice and shinny. Also as you might not know, the 4.9 throttle body has two separated blades, im assuming one for one bank and the other for the other bank. Well i look in them and one is slightly coated in a black layer, looks normal, but the other is the same but wet with what i think is fuel. Also after i finally timed it right (i think) it is idling really high, like 2500. And when i turn the distributor till it idles nice at 900 it indicates a spark after top dead center. ??? the crank mark is off the marker chart. This might be unrelated to my real problem but its still a problem, maybe crank pulley was taken off and not put on right? But anyway, could my other problem be really bad rings ( But wouldnt it be blowing blue smoke?) or a stuck injector? Low fuel pressure? Another thing to add, LOTS OF FUEL IN OIL. Please help again... sorry. I just want it fixed. I also took on to someone saying it could be a bad sensor, but i dont have a scan tool to check codes, but check engine light is on. ------------- Orange 4.9 |
Replies:
Posted By: Dawg
Date Posted: 26 November 2010 at 11:47pm
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I know you're doing your best here, but I really think you need to take it into a shop now. Someone needs to read the codes and start from scratch with the timing and so on. Frankly, I think you've done all you're going to do with your abilities and equipment. Good luck. The Dawg ------------- You dream it up....I'll make it |
Posted By: orange
Date Posted: 27 November 2010 at 4:53pm
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Ok, yeah i was hoping that wouldnt be an option but oh
well. I proly wont be able to get it to a shop, ill have to bring the shop to me. I've got a couple friend mechanics. But still any insight on the problem youd be great. I think i could narrow it dont a bunch more. I can check a bunch of things, and could proly get my hands on a code reader. Im just so confused about the black smoke and not blue when the oil is black within 40 mins of run time on a new oil change and fuel in it. Plus i dont wanna pay 100 bucks for a diagnosis when i could do what they do at the shop. Thanks for the reply though! ------------- Orange 4.9 |
Posted By: Romeo
Date Posted: 27 November 2010 at 6:43pm
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How does the MAF sensor look? Do you use a K&N Air Filter? If so, has it been recharged lately? Over oiling the air filter can occasionally encase the MAF in oil, which wont generate a code (As the sensor technically works fine) but which will screw the fuel map completely. ------------- Never shift into reverse without a back-up plan. |
Posted By: Romeo
Date Posted: 27 November 2010 at 6:45pm
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And if it does turn out to be fuel on the throttle blade, take a look at the air filter. If there's a black spot on one spot, it's the PCV dumping a ton of oil/fuel, which would indicate excessive blowby (Which the compression test would've picked up). ------------- Never shift into reverse without a back-up plan. |
Posted By: orange
Date Posted: 28 November 2010 at 12:00pm
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I dont have an intake on it so no filter. And i have a
map sensor, no maf. MAP sensor is from the fiero V6 so I could see it going bad. And about the MAP does that sensor have to be oriented a certain way? Level? And im pretty sure its fuel on the blade but not any oil. And the excessive blow by makes sense because the compression test did yield lower numbers. So as i see it now, i should check all sensors and see if anything changes? Im still leaning towards rings, along with maye a fuel problem, which i can replace rings without too much trouble. Is there a device where i can check air/fuel ratio? does the code reader tell me that? Thanks guys ------------- Orange 4.9 |
Posted By: orange
Date Posted: 29 November 2010 at 4:23pm
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I drained the oil and took the oil pan off to take a look
and the whole bottom end is really clean and shinny. No indications of scored cylinder walls yet. I let it sit with no oil pan for almost two days and found a puddle of gas under the engine. I turned the engine about 2 revolutions and im going to see if more fuel is found tomorrow. There was a lot of fuel on the garage floor but could this have just been leftover that eventually made its way down? Or does this indicate a stuck injector. I will be installing a fuel pressure gauge soon to see if pressure is being lost overnight. ------------- Orange 4.9 |
Posted By: Patrick
Date Posted: 29 November 2010 at 4:31pm
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You don't need to "install" a gauge. Just hook a fuel pressure tester up to your fuel rail at the schrader valve.
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orange wrote:Posted By: orange
Date Posted: 29 November 2010 at 4:37pm
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Thats what i meant haha sorry.
I just thought of something though... could a bad thermostat make it run rich because coolant sensor is sensing cooler temps and adds fuel? just a guess, and this proly wouldn't be making it run rich enough for fuel to be in oil. ------------- Orange 4.9 |
Posted By: Patrick
Date Posted: 29 November 2010 at 4:42pm
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Did you read my http://www.westcoastfieros.com/forum/forum_posts.asp?TID=2195&PN=1 - Recent thread ? No, a bad (stuck open) thermostat wouldn't lead to fuel being dumped like what you appear to be experiencing, although it would lead to a very rich running condition. I suspect you've got stuck (in the open position) injectors. Get that fuel pressure test done!
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Posted By: orange
Date Posted: 29 November 2010 at 4:45pm
Thanks! Will do, and get back with you guys. ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 30 November 2010 at 10:33am
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If you injectors are accessible, get an injector connector from a junkyard (Most North American cars injector connectors are the same, so it's easy). The best way is to pull the fuel rail so you can see the bottom tips of the injectors. Then use a battery charger and connect each one in turn, very briefly. I bared the wires on the injector connector, then connected one battery lead solidly, then swiped the wire on the other lead. Hear a click? I found 2 bad injectors on a engine which had sit for 1 year this way. They were just gummed up. You can also use compressed air to see if any injector is open when it shouldn't be. I'd use 20-30psi. Re-do the jumper test an feel the on/off with the air.
Chay ------------- 86 SE 3.4 |
Posted By: orange
Date Posted: 30 November 2010 at 2:53pm
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Cool, i will do that procedure. Could a stuck injector get
restuck after its free easily? The reason i ask is because when i first tested them, 5 of 8 were stuck shut, and after a night with 44k injector cleaner soaking they all worked (at least clicked) when 12v was going to them. So im confident they all fire but maybe one that didnt get cleaned all the way got stuck open? Oh and by the way, after i turned the motor a bit about 24 hours ago, there is more fuel on the ground coming from the crank case. So im pretty confident i have a stuck injector, whether this is my only problem or not. ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 30 November 2010 at 3:41pm
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I don't have too much experience with injectors. I've found a few bad is all. I think that depending on the type you could get a click (open/closed), but not a full seal when closed.
Chay ------------- 86 SE 3.4 |
Posted By: Patrick
Date Posted: 30 November 2010 at 6:01pm
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Good point. An injector that opens and closes may not necessarily be shutting off completely when closed. Doing a leak-down test using a fuel pressure gauge connected to the schrader valve on the fuel rail seems like the best option to me at this stage of the game.
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Posted By: orange
Date Posted: 02 December 2010 at 3:29pm
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Leak down in progress. But i had a question, Would one or
more cylinders not getting a spark shove all the fuel from that cylinder down past the rings every compression stroke? The reason i ask is because i found 2 plug wires completely cut open, like when they opened the box the knife just slit them, its a nice clean cut. So could this be the fuel in oil trouble? Also, how long does it take for an engine to turn its oil black, in hours of operation. Mine is black and i only ran it 3/4 times of 15 to 20 mins a piece. ------------- Orange 4.9 |
Posted By: Romeo
Date Posted: 02 December 2010 at 5:09pm
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Not from what I've seen. We're talking a very small amount of fuel being left over, most of it gets shot down the exhaust manifold and burns the catalytic convertor up. The engine will run choppy as hell if this is the case, and your check engine light will illuminate if it's a '96 or later engine. ------------- Never shift into reverse without a back-up plan. |