new motor in my 89, popping in my intercooler piping? HELP

89ohmy

Registered User
okay im lost now..so my motor seized and i replaced it with a fully rebuilt 91 motor. mine is an 89 so i figured it wouldnt make much of a difference. the motor does have a gasket matched intake and ported stock headers just like my old motor, the only changes i made were a front mount intercooler and an 85mm throttle body. I did set the camshaft position sensor at 26 degrees ATDC and checked it who knows how many times. it seems to run fine and hold vacuum (around 19 inhg at idle) so i doubt its a vacuum leak.

So heres whats happening, at idle or all throughout the rpm range it makes this popping noise inside an elbow on the intake pipe that connects to the intake manifold, now i was having an issue where the piping elbows were being sucked into themselves at idle when the car was in vacuum but as soon as i t enters boost the elbows open up..what i want to know is what is causing this popping sound as this has me baffled, here are my mods now:

255 lph fuel pump
Scorpion 1.73 roller rockers with .060" longer pushrods on the stock cam
85mm throttle body
front mount intercooler
ported intake
ported headers
new awsf 34 motorcraft plugs gapped to .050

any help is appreciated i really miss driving this car its been too long

Thanks, Zach
 
okay im lost now..so my motor seized and i replaced it with a fully rebuilt 91 motor. mine is an 89 so i figured it wouldnt make much of a difference. the motor does have a gasket matched intake and ported stock headers just like my old motor, the only changes i made were a front mount intercooler and an 85mm throttle body. I did set the camshaft position sensor at 26 degrees ATDC and checked it who knows how many times. it seems to run fine and hold vacuum (around 19 inhg at idle) so i doubt its a vacuum leak.

So heres whats happening, at idle or all throughout the rpm range it makes this popping noise inside an elbow on the intake pipe that connects to the intake manifold, now i was having an issue where the piping elbows were being sucked into themselves at idle when the car was in vacuum but as soon as i t enters boost the elbows open up..what i want to know is what is causing this popping sound as this has me baffled, here are my mods now:

255 lph fuel pump
Scorpion 1.73 roller rockers with .060" longer pushrods on the stock cam
85mm throttle body
front mount intercooler
ported intake
ported headers
new awsf 34 motorcraft plugs gapped to .050

any help is appreciated i really miss driving this car its been too long

Thanks, Zach

89 and 91 engines should be fully compatible.

Is the firing order correct? Dave neibert has a great post on here. Many manuals out there have our ignition timing incorrect.

It will still run and pretty damn near smooth with two cylinders off.

Check out page two of this post.

http://www.sccoa.com/forums/showthread.php?t=120621&highlight=Firing+order&page=2
 
Believe me, i checked my coil pack wires and the wires have 4000 miles on them..Im really thinking that the timing is off, Im not the one that built the motor i was told that it was correct by the person who sold it to me, i really dont have the time to rebuild it so i bought it done already..
 
Believe me, i checked my coil pack wires and the wires have 4000 miles on them..Im really thinking that the timing is off, Im not the one that built the motor i was told that it was correct by the person who sold it to me, i really dont have the time to rebuild it so i bought it done already..

Are you certain the cam sensor timing is right on? I do not believe the cam sensor controls ignition timing. I believe it only controls fuel timing.
 
correct cam sensor syncs for sequential injection has nothing to do with ignition timing

popping through the intake is a lean engine, is the stock maf still on the vehicle? are you sure the fuel pump lines are intact and not leaking in the tank? did the lean pops occur immediately after replacing the pump?

how old are the hegos? is the ecu throwing any codes?
 
ill try the mass air today but i think it might be the balancer, believe it or not the timing marks are the exact opposite on this balancer than the marks on my other stock 89, i bought another sc because i needed something to drive for the time being, and to keep myself motivated for the white one to be finished..the timing marks on my stock sc say atc where it says btc on my aftermarket balancer..so i guess i have to stick a pushrod in the spark plug hole just to figure out where tdc is at and go from there..
 
ill try the mass air today but i think it might be the balancer, believe it or not the timing marks are the exact opposite on this balancer than the marks on my other stock 89, i bought another sc because i needed something to drive for the time being, and to keep myself motivated for the white one to be finished..the timing marks on my stock sc say atc where it says btc on my aftermarket balancer..so i guess i have to stick a pushrod in the spark plug hole just to figure out where tdc is at and go from there..

Pull the number one plug out and put your finger over the hole. Turn the motor over and when you feel air that is the comp. stroke. When you feel it start to suck you just passed TDC.
 
okay so i reset the cam sensor, i found tdc for #1 and went 3/4" past tdc, set the cam sensor with both valves closed, it starts like my stock sc (much easier than before). i changed he maf and dis module and coil pack, now the popping is lighter and for a few seconds it went away, my friend and i just looked at each other, shrugged and then it started popping again, the only thing i can think of is the crank sensor, although it is functioning and the balancer isnt rubbing up against the pickups and it definitely wont start with the crank sensor disconnected. the only thing i can think of now is maybe the intercooler piping? maybe its too long? Im stumped:/
 
Popping

You stated that the intercooler tubing was contracting at idle and expanding at boost. Depending upon the material your using, that could be making/causing your popping sound. It could be the bypass valve is stuck, a vacuum leak, or the hose is weak and needs replaced. I hope this helps
 
update

Okay so on Sunday i took my time and took all the rockers and pushrods out and put everything back to stock, and preloaded all the lifters and now she purs like a kitten..all i have now is a slight vacuum leak and then i can put the rest of the front end together as drive it. I gotta get it done because this morning i was driving to work and i heard my favorite noise..bearing noise..now Im an hour from home and hoping that ill make it back later today..
Thanks everyone for your input!
 
Okay so on Sunday i took my time and took all the rockers and pushrods out and put everything back to stock, and preloaded all the lifters and now she purs like a kitten..all i have now is a slight vacuum leak and then i can put the rest of the front end together as drive it. I gotta get it done because this morning i was driving to work and i heard my favorite noise..bearing noise..now Im an hour from home and hoping that ill make it back later today..
Thanks everyone for your input!

Sounds like an intake valve was not closing all the way.
Bearing noise, as in engine bearing noise?
 
yeah its an engine bearing noise, the blower is a low mileage 92 so its not that, i drove it to and from work and it the car didnt make any noises at all..itll come back im sure, and if it does come back ill have a parts car:) i did take the other one for a test drive and that vacuum leak is pretty big, ill do a propane test tomorrow probably but the leak makes the brake and antilock lights come on for a short time but not setting any codes
 
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