Finally! fired up my 4.9 but it runs badly

No check engine light. No codes...... just code 12

It shakes and misfires badly and sounds like a Harley.... dead cylinders right?

Well I changed all the injectors and cleaned fuel rails thinking that the engine sat around too long and got varnished up.

Still runs bad

Changed all plugs and wires

Still runs bad

Changed the ignition coil and module

Still runs bad

Checked compression. All cylinders have equal compression. Changed cap and rotor

Still runs bad
It runs like it has dead cylinders.... Bad ECM maybe? What else could it be?

Bad gas? How long has it sat?

I'd confirm the wires on the correct plugs first of all. The next thing would probably be the cam sensor I think. Could also be a vaccum leak but it would have to be a pretty bad one.

have you checked the timing?all the spark plug wires are going to the right plug right?

The gas is very fresh (two days old).... I changed the fuel pump to a high pressure unit for the Cadi PFI system and tossed out all the old gas and added a new filter in the process. All fuel lines are new

Since it sounds like you've got the ignition side covered, let's check fuel.
You MIGHT be able to just feel the injectors and see if they are ticking. If not, do you know what a noid light is? Google it to find sources, they're relatively cheap. You can use it to see if the ECM is sending pulses to the injector. If it is, the injector is probably stopped up or electrically bad. If the ECM isn't sending anything, check the wiring (or bad ECM). Oh yeah, check fuel pressure and also fuses.

------------------
Mick
1986 GT

To find the dead cylinders I take a bottle of water with a squirter on it and with the engine running I spray it on the exhaust manifold by each cylinder. Which ever cylinder is dead the water does not boil off but just runs off. Once you find the dead cylinder or cylinders you can then check spark, compression and then leak down to see why that cylinder is not working. I once ran into a 3800 V-6 that had sat a long time and the injectors were stuck. I took a hammer and a screw driver and tapped on the side of the injector while running and got them freed up.

My .02 worth
Steve

Thanks 86soon3.4 and cropduster. I will try those methods. Let you know more tommorro

How many pounds of fuel pressure at the schrader valve? The 4.9 needs to see about 38-40 psi to run correctly.

[This message has been edited by Frizlefrak (edited 02-24-2007).]

quote Originally posted by MaxCubes: I played around with the timing like crazy.... no matter how I turn the distributor it runs like crap.

You may have it one notch off.... remember that when you put it back in..it turns a bit on the gear before it seats.

Do you have the firing order wired clockwise or counter-clockwise on the distributer cap?

It's gonna wind up being something reeeeal simple. On both the 4.9 swaps we've done, we've encountered issues that were frustrating to find, and simple to correct.....things that make you go DOH!!!

And it sucks to be so close to having it running and having one minor glitch keep it from happening. You'll find it, just follow a methodical method of troubleshooting. Here's how us professional backyard bubbas do it.

Remember the three things they need to run.

1. Suitable mixture of fresh fuel and air.
2. A suitably strong spark delivered at the correct time.
3. Suitable compression.

Everything else is fluff. If you meet those three requirements, they run. The trick is finding out which one is out of whack without cluster bombing it with new parts and emptying your wallet in the process. I always say start with the easiest and cheapest first, which is why I always test fuel pressure first. If that checks out, let's test our injectors with a noid light to see if all 8 are firing. If they are, let's look at the injector wiring and ensure that all 8 are connected to the correct connectors....trace them back to the PCM if necessary. Since you have new injectors, and have cleaned the fuel rail, we can safely assume they aren't clogged, unless there was some contaminant lurking below where you cleaned that was sent upward once you ran the pump.

You have suitable compression on all 8 cylinders with no major variances, so you can now move on to the ignition / emissions side of our 3 sided coin.

Since you've already replaced a lot of parts, let's focus on timing. Hook an inductive timing light to plug wire #1 and check base timing. From what I've read so far, I think this is where your particular demon may be hiding.

Keep at it, you'll get it. There nothing quite like hearing it roar to life for the first time.....except the thrill of driving it once it's running right.

$5 says its the coil.

#1 you don't really need to know the firing order, the coil is numbered which goes to which cylinder. The intake manifold is also stamped which cylinder is which (actually it has the firing order stamped on it as well). Verify your wires are correct as indicated on the motor. The #1 cylinder is the one closest to the passenger as the 4.9 sits in the Fiero.

#2 are you completely sure the timing is correct? Double check TDC on the #1 with the distributor in the #1 spot.

#3 double check you injector wiring (did you make your own harness or used a premade one?).

#4 double check your distributor wiring.

You also meantioned you changed the cam sensor ??? Just wondering where you found this? The 4.9 does not really have a cam sensor per say - it uses a hall effect switch that tells the ECM when the distributor is is at the point that the opening point of the #1 intake valve - there is physically nothing attached to the cam. So if the distributor is out, the sensor is out, which makes the fuel delivery out, etc.

This sounds like a timing issue more than anything - check it to make sure your are at TDC on #1 and the distributor is correct - then check your wiring.

Have you checked the injector fuses in the fuse box?
If you car was a four cyl, it will only have a fuse in one of the injector holes. 6Cyl cars have both fuses installed.

It will run bad...Ask me how I know......

I like scrabbles idea, as I forgot to change out the 5amp fuses on my last swap and I ended up popping one. I knew what it was right away, so I just changed it out for a 10amp

Maybe I need to get the Alternator wired up. Right now I am running on the battery only... maybe not enough volts for the computer and ignition to operate correctly?

I bought a new distributor and computer also. Will try those tommorro..... let you all know if any of this works. Thanks so much for all the input so far.

lol..yeah could be.. hook the alternator up dude..!!

your battery is not gonna be enough to run it.. and...the longer you run it..the more the voltage drops....

[This message has been edited by kyote (edited 02-27-2007).]

quote Originally posted by kyote: lol..yeah could be.. hook the alternator up dude..!! your battery is not gonna be enough to run it.. and...the longer you run it..the more the voltage drops....

The car will run without an alternator using battery power - it will get to a point however when the battery is not enough and it will die.

On the other side, you should at least finish your wiring...did you also check your timing in reference to TDC???

[This message has been edited by Mickey_Moose (edited 02-28-2007).]

quote Originally posted by Mickey_Moose: The car will run without an alternator using battery power - it will get to a point however when the battery is not enough and it will die.

umm.. I didn't say it WOULDN'T run without an alternator.. lol..... meant car needs at least 12 volts to run efficiently...after starting and running it.. the voltage is going to be dropping steadily... making it run like sh*t

I found the problem!!!!!!!!!!

And its a real STUPID mistake!!!


The 4.9 has the same firing order as a chevy........ I even checked and rechecked it several times...... 18435672

BUT IT SPINS CONTERCLOCKWISE !!!!!!!! ...... not clock wise like a chevy


Its amazing it even ran....but it did....but very poorly

Now it runs smooth.

Thanks for all your inputs!

Been there done that! When I was trying to prime the oil pump on mine, I kept spinning the pump clockwise and it never picked up the oil. Then I had the thought to change the direction and it instantly started pumping. We live and learn.

quote Originally posted by Mickey_Moose: #1 you don't really need to know the firing order, the coil is numbered which goes to which cylinder. The intake manifold is also stamped which cylinder is which (actually it has the firing order stamped on it as well). Verify your wires are correct as indicated on the motor. The #1 cylinder is the one closest to the passenger as the 4.9 sits in the Fiero. #2 are you completely sure the timing is correct? Double check TDC on the #1 with the distributor in the #1 spot. #3 double check you injector wiring (did you make your own harness or used a premade one?). #4 double check your distributor wiring. You also meantioned you changed the cam sensor ??? Just wondering where you found this? The 4.9 does not really have a cam sensor per say - it uses a hall effect switch that tells the ECM when the distributor is is at the point that the opening point of the #1 intake valve - there is physically nothing attached to the cam. So if the distributor is out, the sensor is out, which makes the fuel delivery out, etc. This sounds like a timing issue more than anything - check it to make sure your are at TDC on #1 and the distributor is correct - then check your wiring.

is it? i thought number 1 was the one to the left of the bat+ /tach post when you are looking at the engien bay from the back of the car...

quote Originally posted by MaxCubes: I found the problem!!!!!!!!!!

EXCELLENT!!! Good job. Glad to hear you solved it. It's really a good feeling when you've got a nagging problem with a swap and then you solve it and everything runs like it's supposed to. Been there, done that, bought the shirt...twice now

When I finished my 4.9 / 4T60E swap into my 88 coupe, the engine ran fine, but the trans only had 2nd and 3rd gears....and second had to be done manually. I checked and rechecked the wiring a hundred times over, and everything was correct...so I thought. I finally did what I should have done right off and posted the question here. I was using a drivetrain from a 94 Deville....my diagrams were for a 92. GM changed the trans wiring after 93. 5 minutes to study the new diagram, 30 seconds to cut and splice wires, and I have all 4 gears. DOH!!

Anyhow, congrats....enjoy that car!

[This message has been edited by Frizlefrak (edited 03-29-2007).]