Bad misfire (underload)after motor swap

[Vicecreed]

Pulled a 420a and 5speed transmission out of a 95' Eclipse RS and put it into a 95' Talon ESi.
While in the Eclipse, the only issue I had was when I started the car, I had to give it a little gas for a few seconds for it to idle, other than that it ran fine.

Now after swapping the motor(along with the ECU), it starts and idles fine, but when you first take off in 1st, and while going up even the slightest incline, or when you try to "go fast" it sounds like crap, like its running on three cylinders.

Sounds a lot like a Subaru, the best way I can describe the sound.

Took it to Advance auto and had them check the CEL, and it had two Camshaft Position/Angle(not sure which it is on these cars) Sensor codes don't remember exactly what the codes were, but both were saying it wasn't working right.

Checked out the sensor and somehow the plastic clip on the connector had broken off and the plug slid out.
Well cut it off, and grabbed the one off the Eclipse shell and soldered it on, and hoped it'd solve my problem.

It still misfires when you start moving, but then starts running fine around 2k RPMS and above, and while going up any incline, doesn't loose power unless its a steep incline, even then its very little, it just sounds horrible.
After I get home in the AM from work, it'll be parked till I figure this misfire out, don't want to take a chance of blowing the motor or something.

Now the Talon has sat for over a year between the previous owner and me with 3/4 of a tank, and I changed the fuel filter(which had some lovely smelling black crap coming out of it), could the gas be bad/contaminated?

Or maybe the Cam sensor just went bad somehow from the motor swap?

Any other ideas on what this could be, its only started AFTER the motor swap, so I'm thinking its something wrong on the Talon maybe.

 

[Dsmkauai]

Did you reset the check engine light after swapping harnesses? And heck ya your gas is bad bro. Drain it and start over

 

[Vicecreed]

There was no CEL right after the swap, it came on a few miles after drivin . When the miss started, the guy cleared the code after he scanned it.

I worked 12 hour shift last night, left the batteey unplugged all night.
This morning it actually ran great, it didnt miss at all till about 2 miles down the road, even then it wasnt anywhere as bad as before, a couple times it even climbed a hill with no miss.

For the first few miles(after the miss) it didnt throw a CEL, then it'd blink slowl. A few times, stay on then go off when the miss stopped abd flash back on when itd miss again.

Im going to see about bborrowing some gas money from some family to get some fresh gas in the tank now that im below half tank, see if that makes any difference and if it does I'll fill up friday wheb i get paid with some non-ethonal fuel.

If it doesnt help, ill look into replacing the CPS.

 

[Vicecreed]

Dumb question, can i drain the gas without dropping the tank?

 

[ohlegend]

Yes/No. Read this thread, it will help
http://www.dsmtuners.com/threads/need-to-drain-gas-tank-merged-6-8-draining-fuel-2g.284464/

 

[Dsmkauai]

Something is still loose or not right then if the cel keeps blinking or going off. You cleared the codes by having the battery unplugged all night. That's what I was asking if you cleared it again after fixing the cam sensor problem. If you don't drain the gas and just add to it make sure to use some kind of fuel restorer.

 

[Vicecreed]

I read several places that said flashing CEL means misfire

 

[Vicecreed]

Well tomorrow going to put some gas treatment and some fresh gas and see if that helps any.

Thanks for the help everyone.

 

[Vicecreed]

Well just thought I'd let everyone know, the issue was a combination of bad gas.. and spark plugs.

Since I changed them back in February after we swapped heads when the head gasket blew, and it ran fine in the old shell that they couldn't be bad.
Well I had a coupon to save $5 on a purchase of more than $30 so grabbed some NGK plugs for the Talon and the wife's Subaru.

BOOM. No more misfire, no more rough idle, no more hard starts.

My theory is the plugs were worn, but running with the fresh gas I had been using in the Eclipse shell they could still spark enough to burn the fuel mixture.
BUT with the old/bad gas in the Talon, they weren't strong enough to burn it efficiently.

While some argue brand doesn't matter, it could also be that I was using Autolite before and now have NGK again.

Either way I found the problem, and its running like a dream now.

I thank everyone for their help in this matter.