Rough idle/engine noise in new motor

jrod01 · August 29th, 2011, 06:45 PM

Just replaced the engine in my 01 cobra. had it started 2 nights ago and it ran fine with the exception of a 1000rpm idle, turned vehicle off to check oil and dipstick end broke off and went into the oil pan. i did not start the car with the piece in there. I spent the the weekend pulling the motor out to get to the oil pan. got the engine put back in and everything hooked up started her up this afternoon and now the engine is running like crap. idle is about 850 and there is a loud noise coming from the passenger side that increases with acceleration and the engine is shaking terribly. when i give it gas the rpm's take off on their own and i have to shut the car off. no codes are being thrown. hooked up the scanner and looked at parameters when running. not sure what they all mean but fuel pressure is at 40psi and TSP is at 20.2. this is a brand new engine, and i am running correct oil weight and all the connectors appear to be plugged in. sorry for the long post just want to give all the details. any help would be appreciated. thanks guys.

4valvegt · August 29th, 2011, 11:39 PM

What kind of a noise? It can be very difficult for anyone to diagnose this over the internet maybe post a video of the issue? As for the rpms taking off on their own there must be a fault with the idle air contol motor i have seen it happen after the iac was bolted on the wrong way around but not sure thats even possible on the 01 intake.

jrod01 · August 30th, 2011, 12:53 AM

I will post a video tomorrow. Car is at my shop. As for the revving I think the return spring was disconnected.

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jrod01 · August 30th, 2011, 06:53 PM

Went to my shop after work to get a video of the engine noise, started the car up and the throttle just took off. Had to shut it down before I could get a video. Also the driverside header was pouring out raw fuel. Not sure but I think it has something to do with the PCM or electrical components. I made my own mil eliminators for the back o2's could this be causing a problem? Thanks again.

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Frdlvr35 · August 30th, 2011, 07:07 PM

Could also be a shorted injector driver holding the injector wide open in the PCM. I would stop running it until you figure out what is causing the fuel to dump. You need a H manual with the proper pinpoint tests and a 104pin breakout box...to properly diagnose it....Know anyone that works at a Ford Dealer?

4valvegt · August 30th, 2011, 07:21 PM

Have you pulled the injectors back out and seen if any where stuck open?

jrod01 · August 30th, 2011, 09:17 PM

injectors were remanufactured cleaned and flow tested/matched. havent tried pulling them yet. may have a line on a ford tech to come out. i am in illinois right off I-80 if you know of anyone in the area that would be willing to come out i'd throw them some cash. Could a leak in the lower intake cause this? ie. if a harness line got caught under the intake? i spent over50 hrs on the car last week in addition to working a 9-5. just looking for some ideas before i tear into it again. thanks guys.

4valvegt · August 30th, 2011, 09:43 PM

A large vacuum leak will cause the engine to rev up like that but doesnt explain your fuel issue.

August 29th, 2011, 06:45 PM	#1
jrod01 Newbie Join Date: Aug 2011 Posts: 4 iTrader: 0 reviews	Rough idle/engine noise in new motor Just replaced the engine in my 01 cobra. had it started 2 nights ago and it ran fine with the exception of a 1000rpm idle, turned vehicle off to check oil and dipstick end broke off and went into the oil pan. i did not start the car with the piece in there. I spent the the weekend pulling the motor out to get to the oil pan. got the engine put back in and everything hooked up started her up this afternoon and now the engine is running like crap. idle is about 850 and there is a loud noise coming from the passenger side that increases with acceleration and the engine is shaking terribly. when i give it gas the rpm's take off on their own and i have to shut the car off. no codes are being thrown. hooked up the scanner and looked at parameters when running. not sure what they all mean but fuel pressure is at 40psi and TSP is at 20.2. this is a brand new engine, and i am running correct oil weight and all the connectors appear to be plugged in. sorry for the long post just want to give all the details. any help would be appreciated. thanks guys.

August 29th, 2011, 11:39 PM	#2
4valvegt Enthusiast 03 Cobra Join Date: Oct 2009 Location: Nebraska Posts: 809 iTrader: 1 reviews	What kind of a noise? It can be very difficult for anyone to diagnose this over the internet maybe post a video of the issue? As for the rpms taking off on their own there must be a fault with the idle air contol motor i have seen it happen after the iac was bolted on the wrong way around but not sure thats even possible on the 01 intake. __________________ MM Cobra Club #86 2003 Mineral Grey Cobra 2004 True Blue F-150 FX4

August 30th, 2011, 07:21 PM	#6
4valvegt Enthusiast 03 Cobra Join Date: Oct 2009 Location: Nebraska Posts: 809 iTrader: 1 reviews	Have you pulled the injectors back out and seen if any where stuck open? __________________ MM Cobra Club #86 2003 Mineral Grey Cobra 2004 True Blue F-150 FX4

August 30th, 2011, 09:43 PM	#8
4valvegt Enthusiast 03 Cobra Join Date: Oct 2009 Location: Nebraska Posts: 809 iTrader: 1 reviews	A large vacuum leak will cause the engine to rev up like that but doesnt explain your fuel issue. __________________ MM Cobra Club #86 2003 Mineral Grey Cobra 2004 True Blue F-150 FX4

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August 30th, 2011, 12:53 AM	#3
jrod01 Newbie Join Date: Aug 2011 Posts: 4 iTrader: 0 reviews	I will post a video tomorrow. Car is at my shop. As for the revving I think the return spring was disconnected. Sent from my Autoguide iPhone app

August 30th, 2011, 06:53 PM	#4
jrod01 Newbie Join Date: Aug 2011 Posts: 4 iTrader: 0 reviews	Went to my shop after work to get a video of the engine noise, started the car up and the throttle just took off. Had to shut it down before I could get a video. Also the driverside header was pouring out raw fuel. Not sure but I think it has something to do with the PCM or electrical components. I made my own mil eliminators for the back o2's could this be causing a problem? Thanks again. Sent from my Autoguide iPhone app

August 30th, 2011, 07:07 PM	#5
Frdlvr35 Newbie Join Date: Aug 2011 Posts: 20 iTrader: 0 reviews	Could also be a shorted injector driver holding the injector wide open in the PCM. I would stop running it until you figure out what is causing the fuel to dump. You need a H manual with the proper pinpoint tests and a 104pin breakout box...to properly diagnose it....Know anyone that works at a Ford Dealer?

August 30th, 2011, 09:17 PM	#7
jrod01 Newbie Join Date: Aug 2011 Posts: 4 iTrader: 0 reviews	injectors were remanufactured cleaned and flow tested/matched. havent tried pulling them yet. may have a line on a ford tech to come out. i am in illinois right off I-80 if you know of anyone in the area that would be willing to come out i'd throw them some cash. Could a leak in the lower intake cause this? ie. if a harness line got caught under the intake? i spent over50 hrs on the car last week in addition to working a 9-5. just looking for some ideas before i tear into it again. thanks guys.

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